WO2007033378A1 - Lightweight reinforced castings and method for making same - Google Patents

Abstract

Particular aspects provide selectively reinforced composites (e.g., brake drums, brake rotors, cylinder liners, clutch components, armor, etc), comprising a matrix material and an integral porous preform having an internal porous preform portion and at least one external surface portion, wherein the porous preform is infiltrated by the matrix material, and wherein the at least one external surface portion or at least one portion thereof has been subjected, prior to infiltration by the matrix material, to selective particle enhancement comprising directed deposition or impingement of selected enhancement particles onto the porous surface and/or penetrating further into the porous preform to provide for selected particle deposition into and integration within the porous preform. Preferably, the at least one porous external preform surface portion that has been subjected to selective particle enhancement is coincident with at least one external surface portion of the reinforced composite. Novel Eddys current brake systems are additionally provided.

Description

LIGHTWEIGHT REINFORCED CASTINGS AND METHOD FOR MAKING SAME

FIELD OF THE INVENTION

This invention relates generally to the field of reinforced castings, and in particular to novel lightweight castings (e.g., brake drums, disk brake rotors, cylinder liners, etc) comprising novel infiltrated performs, and methods for making same.

CROSS REFERENCETO RELATEDAPPLICATIONS

This application claims the benefit of priority to United States Provisional Patent Application No. 60/717,542, filed 14 September 2005, which is incorporated by reference herein in its entirety.

BACKGROUND

Traditional materials (e.g., metals, plastics, ceramics, resins, concrete, etc.) do not always provide components with all the requisite properties sufficient for adequate performance under field/service conditions. Moreover, despite decades of intensive research to provide improved methods and materials, substantial demand still exists in many commercial and industrial applications for improved technology and low-cost methods to improve final component performance (e.g., enhanced strength, enhanced mechanical behavior characteristics, weight reduction, improved wear resistance, enhanced surface activities/reactivities and/or properties, enhanced thermal conductivity, low and/or balanced and/or controlled coefficients of thermal expansion (CTE), reduced residual stress during the forming process and during thermal cycling of reinforced components in service, enhanced recycle potential, reduced fuel consumption, reduced pollutant emissions and green house gases, etc).

Reinforcement of traditional materials. Matrix composites generally refer to traditional materials (material systems) comprising one or more discrete reinforcement constituents (the reinforcement material(s)) distributed within a continuous phase (the matrix material). The distinguishing characteristics of such matrix composites derive from the properties of the reinforcement constituent(s), from the architecture shape and geometry of such constituent(s), and from the properties of the interfaces between and among different constituents and the matrix. In particular applications, prior art forming and manufacturing processes are designed to provide a uniform distribution of the reinforcement constituent in the matrix. In alternate applications, the distribution of the reinforcement constituent is non- uniform. For example, centrifugal casting applications provide for gradient or layered distributions of reinforcement constituent(s), and applications comprising infiltration casting of matrix materials into porous reinforcement 'preforms' provide for positioning of reinforcement constituent(s) within a defined portion of a larger casting. In both uniform and non-uniform applications, it is important that there is an adequate bond formed between the matrix material and the discrete reinforcing constituent(s), without substantial degradation of the mechanical properties of the reinforcing constituent(s). Particle reinforcement is a preferred reinforcement constituent/material, and typically comprises non-metallic and commonly ceramic particles {e.g., SiC, Al₂O₃, etc.). Reinforcement of matrix material with continuous-fibers, monofilament, and/or short-fibers is also known in the art. Generally, different types of matrix composites require or are preferably associated with different primary processing routes/methods {e.g., in-situ reactive processes, diffusion bonding, blending and consolidation, vapor deposition and consolidation, liquid-state processing, stir casting/slurry casting, centrifugal casting, and infiltration processes involving infiltration of matrix material into porous 'preforms'). Deficiencies of the art. Post-manufacture machining of matrix composite materials comprising durable reinforcement can be time-consuming and expensive, and near net-shape forming, and selective reinforcement techniques have therefore been used to help reduce manufacturing costs. For example, in situ selective reinforcement methods involving placement and positioning of a pre-cast reinforcement material member into to a near net- shape casting mold, followed by casting of matrix material around the reinforcement member is known in the art. However, while the amount and/or density of pre-cast reinforcement material can be varied as desired, the reinforcement constituent material of the reinforcement members is not integrated (not infiltrated) with the matrix material (except perhaps in a limited extent at the interface between the reinforcement member and the unreinforced matrix material). Therefore, such in situ methods are hindered by abrupt and problematic differential coefficients of thermal expansion (CTE) between the matrix and reinforcement member. Such abrupt transitions in CTE at the matrix :reinforcement interface boundaries not only give rise to residual stress during the forming process (e.g., residual stress- concentration), but also manifest in stress fractures during thermal cycling of the reinforced components in service.

Likewise, in another example, there are substantial deficiencies in in situ selective reinforcement methods involving infiltration casting of matrix material into porous 'preforms' (comprising reinforcement constituent(s)) positioned in near net-shape casting molds. While such prior art 'preform' methods are fast, and result in a more integrated, infiltrated reinforcement 'preform' with substantially more contact area between the reinforcement and matrix materials, they are still substantially hindered/limited by abrupt transitions in CTE at the interface/boundaries between the 'preform' and the unreinfoced matrix material that results in stress problems as described above. Additionally, there are practical limits to the amount/density of reinforcement material in the porous 'preforms,' because resistance to infiltration casting substantially increases at high reinforcement levels (e.g. beyond 15% to 20% material in the 'preform'). Furthermore, while 'preforms' are typically positioned in casting molds that are preheated to facilitate infiltration, such preheating, for practical reasons, is at a temperature significantly less than the melting temperature of the molten matrix material (e.g., aluminum). Therefore, there are practical limits to the thickness/cross-sectional area of such prior art performs, because the matrix material must completely infiltrate the 'preform' prior to significant cooling of the molten matrix material. Because of this, prior art 'preforms' are typically not thicker than about 0.400 inches, placing a practical limitation on the extent of reinforcement that can be integrated into the finished casting.

In yet another example, there are substantial deficiencies in selective reinforcement methods involving centrifugal casting (in near net-shape casting molds) of composite material to favorably place or distribute reinforcement particles within a matrix material of differing density. While abrupt transitions in CTE at the matrix:reinforcement interface boundaries can be reduced in those centrifugal embodiments where continuous particle gradients are formed within the matrix material, such methods still suffer from differential CTE effects in cost-effective embodiments comprising layered reinforcement particles. Moreover, all centrifugal casting embodiments are relatively slow (particularly when used with high reinforcement particle densities) compared to other casting methods (e.g., high pressure die casting, squeeze casting, etc.), and are thus too expensive and impractical for most commercial applications. Additionally, in centrifugal methods, the attainable variations of particle distributions are limited to layers and/or continuous gradients, and if different reinforcement particle types having differing densities are simultaneous desried/used, it may be impossible to get adequate coordinate (co-localized) particle gradient distributions for the divergent particle types, or to get both particle types where you need them, and in the pattern in which they are needed or desired.

In further examples, there are substantial deficiencies in selective reinforcement methods involving deposition or spraying (e.g., by low or high velocity spray techniques) of reinforcement particles onto the surface of near net-shape matrix material castings. A major limitation of such methods for these applications is that the spray or deposition is superficial, because it is applied to the surface of solid matrix material castings, and does not substantially penetrate beyond the surface. Additionally, such superficial reinforcement coatings must generally be significantly machined prior to placing the reinforced casting into service. Moreover, absent resurfacing with more reinforcement, the effective service life of such castings is over once the superficial reinforcement layer is worn and/or otherwise degraded. Furthermore, in such superficial reinforcement applications, bonding and integration of the sprayed/deposited reinforcement with the matrix material is limited, even with the most optimal spray/deposition methods. Therefore, there are substantial deficiencies in prior art selective reinforcement composite material applications, including but not limited to impracticality and lack of versatility (e.g., centrifugation methods), differential CTE problems (e.g., in situ reinforcement member casting, and in situ reinforcement 'preform' castings), limitations on 'preform' thickness/cross-section, and superficiality problems (e.g., surface spray/deposition methods). Moreover, these deficiencies have substantially limited the scope of current casting or forming crafts including, but not limited to: centrifugal casting; high pressure die casting; vacuum die casting; squeeze casting; high vacuum permanent mold casting; low vacuum permanent mold casting; vacuum riserless/pressure riserless casting, surface spray and deposition methods, etc.

There is, therefore, a pronounced need in the art for novel and effective methods and compositions to increase the scope of current selective reinforcement casting or forming crafts by making the methods and compositions more practical {e.g., faster, more cost effective, etc.), more versatile (in terms of the amount, thickness, distribution, pattern and types of reinforcement constituents that can be applied/used), and less susceptible to mechanisms {e.g., differential CTE between materials) that give rise to stress-fracture during formation and/or thermal cycling during service conditions.

There is a pronounced need in the art for more effective methods to produce functional gradient and non-gradient reinforced composite materials with optimum and/or customized properties {e.g., enhanced strength, enhanced mechanical behavior characteristics, weight reduction, improved wear behavior, enhanced surface reactivities and/or properties {e.g., enhanced reactivity between a surface of a composite material and a friction material interacting therewith), enhanced thermal conductivity, low and/or balanced/controlled coefficients of thermal expansion (CTE), reduced residual stress during the forming process and during thermal cycling of reinforced components in service, enhanced recycle potential, reduced fuel consumption, reduced pollutant emissions and green house gases, etc).

There is a pronounced need in the art to improve the effectiveness of spray /deposition techniques. There is a pronounced need in the art for novel and improved matrix composites {e.g., lightweight brake drums, disk brake rotors, cylinder liners, etc.) made with such improved methods. BRIEF DESCRIPTIONS OF THE DRAWINGS

These and other features and aspects and advantages of the present invention will become better understood with reference to the following description, appended claims and accompanying drawings where:

Figures 1, 2A, 2B and 2C show, according to particular aspects of the present invention, an exemplary inventive brake drum comprising an infiltration cast porous 'preform.'

Figures 3 and 4A show, according to particular aspects of the present invention, an exemplary porous 'preform' for use in the inventive compositions and methods. Figure 4B shows, according to particular aspects of the present invention, an exemplary porous 'preform' comprising a porosity (and/or density) gradient, for use in the inventive compositions and methods. The figure shows variants having reinforcement wrappings internal to the 'preform' (upper panel), and external to the 'preform' (lower panel). The center panel shows an enlarge projection of a cross-section of the infiltrated 'preform' to illustrate a porosity gradient within the 'preform.'

Figures 5 and 6 show, according to particular aspects of the present invention, exemplary particle 'guns' for deposition/impingement of selected particles into porous 'preforms' as described in the novel SPE and SPGE embodiments disclosed herein.

Figures 7A and 7B show, according to particular aspects of the present invention, exemplary deposition/impingement of particles into the wear surface of porous 'preforms' according to the presently disclosed SPE and/or SPGE embodiments/methods. The shapes and the sizes of the shapes shown for representing the particles are illustrative and are not intended limit the scope of the type, nature, size, etc., of the particles that can be applied.

Figures 8A and 8B show, according to particular aspects of the present invention, exemplary deposition/impingement of particles into the wear surface, and into internal positions of porous 'preforms' according to the presently disclosed SPE and/or SPGE methods. The shapes and the sizes of the shapes shown for representing the particles are illustrative and are not intended limit the scope of the type, nature, size, etc., of the particles that can be applied.

Figures 9 A, 9B, 1OA, 1OB, HA and HB show, according to particular aspects of the present invention, different embodiments of reinforcement of porous 'preforms' using reinforcement support/wrapping. In these exemplary embodiments, the reinforcement wrapping is exterior to the infiltrated 'preform.'

Figures 12 and 13 show, according to particular aspects of the present invention, exemplary embodiments of reinforcement of porous 'preforms' using reinforcement support/wrapping that is internal (e.g., integrated within) to the porous infiltrated 'preforms.' Figures 14A and 14B show, according to particular aspects of the present invention, exemplary disk brake rotor embodiments comprising infiltration cast porous 'preforms' and the use of SPE and/or SPGE as disclosed in more detail herein. The figure shows two rotors separated by a channeled central member.

Figure 15 shows, according to particular aspects of the present invention, a perspective view of an exemplary cylinder liner embodiment, comprising an infiltration cast porous 'preform,' and the use of SPE and/or SPGE to treat the wear surface of the infiltrated 'preform' as disclosed in detail herein.

Figure 16 is a side plan, cut-away view of an exemplary brake drum.

Figure 17 is a perspective view of a length of wire being wrapped around an exterior surface of a tubular inner member.

Figure 18 is a perspective view of the tubular inner member of Figure 17, with two layers of wire wrapped around the exterior surface.

Figure 19 is a perspective view of the tubular inner member of Figure 17, with three layers of wire wrapped around the exterior surface. Figure 20 is a perspective view of the tubular inner member of Figure 17, with four layers of wire wrapped around the exterior surface.

Figure 21 is a side plan view of a vehicle with an enlarged, cut-away view of a wheel assembly having exemplary inventive features. Figure 22 is an enlarged, longitudinal cross-sectional view taken from line 7—7 in Figure 21.

Figure 23 is perspective view of an exemplary tubular inner member with a generally continuous, circular, helical groove on the outer surface. Figures 24A and B illustrate two exemplary circular helices (and pitch angles) plotted on two three-dimensional Cartesian planes.

Figure 25, according to particular exemplary aspects, is an side plan, cut-away, exploded view of a tubular inner member with a groove and a recessed cavity, sprayed on bonding layer, one layer of wire or cable wrapped around the inner member, and the outer shell molded (e.g., cast) to cover all or substantially all of the wire wrapping.

Figure 26, according to particular exemplary aspects, is a side plan, close-up of a tubular inner member with a groove and a recessed cavity, sprayed on bonding layer, wire wrapping, and outer shell molded to cover all or substantially all of the wire wrapping.

Figure 27, according to particular exemplary aspects, is an exploded view of an inner member with a groove and a recessed cavity, sprayed on bonding layer, wire wrapping, and outer shell that is molded to cover all or substantially all of the wire wrapping.

Figure 28 shows, according to particular exemplary aspects, a brake drum system, comprising a selectively reinforced aluminum or magnesium brake drum or brake rotor as disclosed herein, and a pair of generally opposed magnetic field-generating means, suitably configured and operatively to induce an Eddy current within the rotating drum or rotor.

Figure 29 shows, according to particular exemplary aspects, an alternate brake drum system, comprising a selectively reinforced aluminum or magnesium brake drum or brake rotor as disclosed herein, and a pair of generally opposed magnetic field-generating means, suitably configured and operatively to induce an Eddy current within the rotating drum or rotor.

Figure 30 shows an alternate embodiment of the inventive brake drum system, comprising a selectively reinforced aluminum or magnesium brake drum or brake rotor as disclosed herein, and a pair of generally opposed magnetic field-generating means, suitably configured and operatively to induce an Eddy current within the rotating drum or rotor. SUMMARY OF PARTICULAR ASPECTS OF THE INVENTION Particular aspects provide novel selectively reinforced composite materials and methods for making same involving infiltration casting of liquid matrix material (e.g., aluminum, aluminum alloys, etc.) into porous 'preforms' comprising one or more reinforcement constituents (e.g., SiC, Al₂O₃, etc.).

In particular embodiments, the porous 'preforms' comprise at least one porosity gradient, with either the pore number or pore size, or both increasing toward at least one 'preform' surface. In particular embodiments, prior to infiltration casting, the porous reinforcement

'preforms' (with or without the presence of a porosity gradient) are subjected to 'selective particle enhancement' (SPE) involving directed deposition/impingement of selected enhancement particles on and/or penetrating into the porous 'preform' material to provide for selected particle deposition/impingement and integration extending to a desired depth within the porous 'preform.' Essentially any type of particle or particles is/are used for SPE, and are preferably selected to impart one or more particular desired properties or characteristics to the resulting infiltration cast, selectively reinforced composite product. In particular gradient SPE aspects, such SPE comprises SPE by applying a gradient of deposited/impinged particles (i.e., selective particle gradient enhancement; "SPGE"). This particle gradient is distinguished from any porosity gradient that may; optionally be present within the preform. The inventive methods are broadly applicable to the fabrication of selectively reinforced composite products including but not limited to wheels (e.g., cars, trucks, trains, etc), brake drums (e.g., cars, trucks, etc.), disk brake rotors, cylinder liners and/or cylinder blocks, clutch parts (e.g., pressure plate, center plate, etc), armor (e.g., body armor, field armor), etc. Preferred aspects encompass fabrication of lightweight reinforced composite products, and methods for make same.

Particular aspects provide novel lightweight selectively reinforced brake drums and methods for making same, the drums having an inner tubular member (e.g., wear liner) having an interior surface suitable for contacting a brake pad and an exterior surface, at least one length of reinforcement wrapping (e.g., fiber, wire, cable, array (mesh), etc.) either snugly wrapped around at least a portion of the exterior surface of the wear liner or integrated within the tubular member, and at least one fastener member for securing at least a portion of a wheel assembly to the brake drum. In preferred aspects the inner tubular members are porous preforms as described herein, that are integral to the drum, having been infiltration cast in casting of the drum. In particular aspects, the brake drum includes a tubular outer shell molded over the inner member (or infiltration cast into the inner member), and in particular embodiments the outer shell covers or substantially covers the length of reinforcement wrapping to protect the wrapping and provide additional support to the brake drum. In particular aspects, a bonding layer is disposed between the wear plates and the outer shell (or between the integral infiltrated preform and the outer shell). In alternate aspects, particularly those using integral infiltration cast preforms, no bonding layer is used, or specific particle enhancement (SPE) may optionally be used in place of a bonding layer, or SPE applied particles may constitute an effective bonding layer. Particular exemplary aspects provide novel lightweight selectively reinforced brake drums, having an integrated inner tubular member (wear liner) comprising a tubular porous 'preform' into which matrix material-has been infiltrated, and wherein the 'preform optionally comprises reinforcement wrapping, integrated therein or on the exterior surface, to inhibit expansion of the inner member. Preferably, prior to infiltration casting, the porous reinforcement 'preforms' (or porosity gradient reinforcement 'preforms') are subjected to SPE as described herein. Preferably, the type of particle or particles used for SPE are selected to impart one or more particular characteristics to the resulting infiltration cast, selectively reinforced composite product. In particular aspects, such SPE comprises SPGE. In particular embodiments, the porous 'preforms' comprise at least one porosity gradient, with either the pore number or pore size, or both increasing toward at least one 'preform' surface.

Further exemplary aspects provide novel lightweight selectively reinforced composite disk brake rotors, and methods for making same. Particular embodiments, comprise an annular center rotor section (e.g., formed of a first material), and a pair of annular or generally annular wear plates (e.g., formed of a second material). In particular aspects, a bonding layer is disposed between the wear plates and the outer surfaces of the center rotor, and in operation, the external surfaces of such bonded wear plates are generally disposed to be engaged by one or more brake pads of a brake assembly. Preferred aspects provide novel lightweight selectively reinforced disc brake rotors, having one or more integrated annular wear plates comprising in each case a porous 'preform' into which matrix material has been infiltrated. Preferably, prior to infiltration casting, the porous reinforcement 'preforms' (or porosity gradient reinforcement 'preforms') are subjected to SPE as described herein. Preferably, the type of particle or particles used for SPE are selected to impart one or more particular characteristics to the resulting infiltration cast, selectively reinforced composite product. In particular aspects, such SPE comprises SPGE. In particular embodiments, the porous 'preforms' comprise at least one porosity gradient, with either the pore number or pore size, or both increasing toward at least one 'preform' surface.

Yet further embodiments provide for novel lightweight selectively reinforced composite cylinder liners and/or cylinder blocks or portions thereof, having integrated cylinder liners, and methods for making same. Particular embodiments comprise novel fluid- cooled composite cylinder liners, comprising a generally annular cylindrical member having top and bottom cylinder ends, and having parallel or generally parallel inner and outer surfaces. The cylinder member comprises a fluid channel integrated within and between the surfaces of the member, wherein the channel has a first and a second end. Additionally, there are first and second channel openings at or near the first and second channel ends, respectively, wherein one channel opening opens to at least one of a cylinder end and the outer cylinder surface, wherein the other channel opening opens to at least one of a cylinder end, the other cylinder end, the outer cylinder surface, and the inner cylinder surface, and wherein the channel and channel openings define a fluid passageway. In certain embodiments, the cylinder liner comprises a plurality of separate fluid channels. In certain embodiments, the cylinder liners further comprise a flange at the top cylinder end, the flange suitable to be received into a counterbore in a cylinder bore. The cylinder liners and/or cylinder blocks can be manufactured by standard casting methods. In certain embodiments, infiltration/infusion casting is used. Preferred aspects provide novel lightweight selectively reinforced cylinder liners and/or cylinder blocks, having one or more integrated cylinder liners comprising in each case a porous 'preform' into which molten matrix material has been infiltrated. Preferably, prior to infiltration casting, the porous reinforcement 'preforms' (or porosity gradient reinforcement 'preforms') are subjected to SPE as described herein. Preferably, the type of particle or particles used for SPE are selected to impart one or more particular characteristics to the resulting infiltration cast, selectively reinforced composite product. In particular aspects, such SPE comprises SPGE. In certain embodiments, the porous 'preforms' comprise at least one porosity gradient, with either the pore number or pore size, or both increasing toward at least one 'preform' surface.

Likewise, selectively reinforced composite clutch disk, clutch pressure plate, and armor (e.g., field armor and body armor) embodiments are encompassed within the scope of the present invention and preferably comprise infiltrated preforms that have been subjected to SPE or SPGE, as defined herein, and optional may comprise preforms having at least one porosity gradient.

In particular embodiments, for example, the brake drum, disk brake rotor, cylinder liner, clutch center plate, clutch pressure plate and armor (e.g., field, body, etc.) embodiments comprise the use of porous 'preforms' (or porosity gradient 'preforms') comprising carbon graphite foam, which has high thermal and electrical conductivity.

DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION DEFINITIONS

"Infiltration casting" as used herein refers to various art recognized methods of introducing liquid matrix materials (e.g., metals, etc.) into porous matrices of reinforcement material (e.g., rigid porous 'preforms,' fabric, etc.). The inventive methods encompass any appropriate means for such introduction of liquid matrix material, including but not limited to centrifugal casting; high pressure die casting; vacuum die casting; squeeze casting; high vacuum permanent mold casting; low vacuum permanent mold casting; vacuum riserless/pressure riserless casting, surface spray and deposition methods, etc. A "porous 'preform' as used herein refers various art-recognized 'preforms' suitable for infiltration casting and include, but are not limited to: porous ceramic preforms that contain ceramic particles; porous ceramic hybrid preforms that contain ceramic fibers and particles; ceramic matrix composites; carbon graphite foam 'preforms', pre-cast Duralcan or other MMC materials formed into a wear liner, etc. In particular aspects, ceramic 'preforms' will comprise ceramic particles to reinforce, strengthen, and increase the wear/abrasive resistance of the cast part. Hybrid ceramic 'preforms' may contain both ceramic particle and fibers, which preferably should not shrink during the firing process (the sintering process that completes the manufacture of the preform). Carbon graphite foam 'preforms' may contain silicon carbide particles, and may be produced so that carbon nanotubes are created during manufacturing thereof to increase the ultimate strength of the final part. 'Preforms' may be created with functional gradient porosity, which means that during the preform forming process, pores of varying sizes are created within the structure of the preforms (or the density of pores may vary to form a gradient). Such gradients can be either continuous, step, or combinations and/or gradations therebetween. The purpose of the functional gradient porosity is to facilitate complete infiltration of the preform and to reduce the abrupt decrease in CTE at the intersection of the unreinforced and reinforced area. This is accomplished, for example in the context of a wear surface embodiment (e.g., brake drum, disk, cylinder liner, etc) , by forming a preform having pores on the matrix-proximal side of the preform that are larger than the pores present in the interior of the preform or at the wear surface side of the preform. Alternatively, the pore size could be consistently large throughout the preform, for example, sufficiently large to assist in accomplish the softening of the changes in CTE. Preferably, by design, the 'preforms,' whether ceramic, carbon graphite foam-based (or other composite fiber based) have a porosity (window holes) characteristic. Significantly, according to preferred aspects of the present invention, the manufacturing procedure for the 'preform' material is altered to provide areas or gradients of higher or lower quantity or percentage of porosity (window holes). A denser 'preform' comprises less porosity (smaller window holes). According to preferred aspects, the inventive high-pressure die-cast selectively reinforced composites comprising the inventive 'preforms' equal or exceed the desired physical strengths normally associated with the traditional forging techniques. Additionally, and significantly, the inventive selectively reinforced composites comprise additional improvements to address coefficient of thermal expansion (CTE) issues, which could result in residual stress at the interface between an abrupt edge or end of a reinforcement 'preform' and the un-reinforced aluminum. Therefore, in particularly preferred embodiments a porosity (window holes) gradient is present in the 'preform', which have larger pores on the outer surface of the 'preform' (i.e. the surface next to the interface with the un-reinforced aluminum. Preferred aspects of the invention thus provides for a gradual, smoothed transition from more porous, less dense 'preform' material (larger or more numerous window holes) to more dense 'preform' material (smaller or less numerous window holes). This smoothed porosity gradient is associated with a complementary gradient of infiltrated aluminum. The materials gradients created, therefore, obviate the "residual stresses" otherwise encountered at an abrupt interface between the 'preform' and the un-reinforced aluminum (or other infiltration material). The gradual change in window hole porosity provides for particularly beneficial CTE properties in high temperature applications involving substantial heat cycling (e.g., truck wheels, brake disks, etc.). The potential of crack formations from residual stress due to abrupt transitions between materials having mismatched CTE values is substantially reduced or eliminated. Additionally, the 'preform' porosity gradient provides for less capillary action resistance during infiltration casting of the metal or resin that is forced under pressure during casting procedures.

"Selective particle enhancement" or "SPE" as used herein refers to a preferred process disclosed herein where, prior to infiltration casting, a porous reinforcement 'preform' (or porosity gradient reinforcement 'preform') is subjected to 'selective particle enhancement' (SPE) involving directed deposition/impingement of selected particles on and/or penetrating into the porous 'preform' material to provide for selected particle impingement and integration (e.g., extending to a desired depth) within the porous 'preform.' Preferably, the type of particle or particles used for SPE are selected to impart one or more particular characteristics to the resulting infiltration cast, selectively reinforced composite product. More than one type of particle may be used, particles may have differing properties, sizes, shapes, and densities, and different particle impingement/integration patterns/designs and combinations are encompassed within the present scope.

"Selective particle gradient enhancement" or "SPGE" as used herein refers to a preferred process herein where, prior to infiltration casting, a porous reinforcement 'preform' (or porosity gradient reinforcement 'preforms') is subjected to 'selective particle gradient enhancement' (SPGE) involving directed deposition/impingement of a gradient of selected particles on and/or penetrating into the porous 'preform' material to provide for particle gradient integration (e.g., extending to a desired depth) within the porous 'preform.' More than one type of particle may be used, particles may have differing properties, sizes, shapes and densities, and different particle impingement/integration patterns/designs and combinations are encompassed within the present scope. Such SPGE gradients may be continuous gradients, step gradients, or combination or gradations thereof.

Aspects of the present invention provide novel and substantially improved selectively reinforced matrix composite castings and products, and methods for making same. Exemplary embodiments provide novel selectively reinforced matrix composite products including but not limited to wheels {e.g., cars, trucks, trains, etc), brake drums {e.g., cars, trucks, etc.), disk brake rotors, cylinder liners and/or cylinder blocks, clutch parts (e.g., pressure plate, center plate, etc), armor {e.g., body armor, field armor), etc. Matrix composites that contain mechanically inhomogeneous multiphase materials

{e.g., matrix composites comprising discrete constituent reinforcement) are susceptible to stress/strain damage mechanisms either during the manufacturing forming/solidification process, and/or during thermal cycling under service. Certain aspects of the present invention relate generally to novel cost effective methods of improving fabrication, wear properties, and the behavior {e.g., mechanical behavior) of, and reducing or optimizing the coefficient of thermal expansion (CTE) differentials in matrix composite materials, particularly those behaviors and/or CTE differentials between the two-face boundary interface of selectively reinforced matrix composites comprising infiltrated porous 'preforms' {e.g., rigid porous 'preforms') utilized in the manufacture of many matrix composites. Particular aspects provide novel selectively reinforced composite materials and methods for making same involving infiltration casting of liquid continuous phase matrix material (e.g., non-ferrous metals such as aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, titanium alloys, zinc alloys, copper, or resins/epoxies, polymers, plastics, various blends of concrete/cement, etc.) into porous 'preforms' (e.g., with defined shapes ) comprising one or more reinforcement constituents (e.g., SiC, Al₂O₃, etc.). Various art-recognized means can be used to infiltrate the continuous phase matrix material, in a liquid state, into the porous pre-forms, and such means include but are not limited to use of low/high vacuum, low/high pressure, gravity, or induced centrifugal force (e.g., centrifugal casting, high pressure die casting, vacuum die casting, squeeze casting, high vacuum permanent mold casting, low vacuum permanent mold casting, vacuum riserless/pressure riserless casting, etc.). Exemplary porous rigid perform materials (reinforcement) include but are not limited to ceramics, carbon graphite foam, metallic foam, concrete and other fibrous composites. Typical preferred porous rigid pre-forms comprise a material system comprised of binders and multiphase (discrete reinforcement constituent(s)) materials in various volume fractions. Preferred porous rigid 'preforms' contain open-cell porosity (window holes). In particularly preferred porous 'preform' embodiments, at least one porosity (window hole) gradient (or a series of stepped, functionally gradient porosity (FGP) layers) is present with either the pore number or pore size, or both generally increasing toward at least one 'preform' surface, so that there are significantly larger pores on one or more outer surfaces of the 'preform' (e.g.,. the surface next to the interface boundaries between 'preform' surface and the un-reinforced continuous phase matrix material) relative to, for example, the 'preform' interior or the wear surface area (with friction surface embodiments).

Selective Particle Enhancement ("SPE"). According to particularly preferred aspects, prior to infiltration casting, the porous reinforcement 'preforms' (or porosity gradient, or porosity layered reinforcement 'preforms') are subjected to 'selective particle enhancement' (SPE) involving directed deposition/impingement of selected particles on and penetrating into the porous 'preform' material to provide for selected particle impingement and integration extending to a desired depth within the porous 'preform.' Preferably, the type of particle or particles used for SPE are selected to impart one or more particular characteristics to the resulting selectively reinforced composite infiltration cast product. In particular aspects, such SPE comprises SPE with a gradient of deposited/impinged particles (i.e., selective particle gradient enhancement; "SPGE"). SPGE involves directed deposition/impingement of a gradient of selected particles on and penetrating into the porous 'preform' material to provide for particle gradient integration extending to a desired depth within the porous 'preform.'

In particularly preferred embodiments, a controllable high-velocity deposition/impingement technique (e.g. adjustable high velocity particle 'gun') is used to apply selected particles (SPE) (with significant characteristics that are similar or dissimilar) to porous rigid 'pre-form' (comprising reinforcement material with or without functionally gradient porosity (FGP)) prior to infiltration casting thereof. Preferred particle application methods for SPE or SPGE are those art-recognized automated or automatable methods that are precise and accurate, including but not limited to: cold spray deposition; combustion power spray; high velocity/low velocity oxygen fuel (HVOF/LVOF); plasma spray arc; combustion wire spray; chemical vapor deposition (CVD); physical vapor deposition (PVD), etc.

Different particle impingement/integration patterns/designs and combinations are encompassed. Additionally, a very broad range, and more than one type of particle may be used for SPE and SPGE, include particles having differing chemical compositions, properties and densities. Exemplary materials for particles include, but are not limited to: Silicon Carbide (SiC); Silicon; Alumina Oxides (A12O3); Mangesium oxide; Tungsten Carbides; Chromium Carbide; Carbon Diamond; Polycrystalline Diamond; Nickel; Copper; Zinc; Titanium Boride; fibrous material (e.g., acrylic fibers, aramid fibers, glass fibers, silica fibers, carbon fibers, metallic fibers, mineral fibers, carbon graphite foam, and mixtures thereof); carbonaceous material (e.g., petroleum coke, metallurgical coke, natural carbon, synthetic carbon and mixtures thereof); iron powder; inert fillers (e.g., whiting, talc, barytes, clays and mixtures thereof) and binders (e.g., resinous binders); metal sulfide-iron powder alloy; metal sulfides, including but not limited to ZnS, FeS, MoS₂, CuS₂, TiS, CdS, Sb₂S₃, MnS, CoS, Co₃S₄, CaS, BaS, SrS, FeS₂, ZrS₂, Cu₂S, Ni₃S₂, NiS, Ni₃S₄, MnS₂, CoS₂, Co₂S₃, SnS; etc. For example, according to particular aspects of the present invention SPE, of 'preform' surfaces that represent operational friction surfaces (e.g., friction surfaces in brake drums and disc brake rotor embodiments, etc.), using metal sulfides or metal sulfide-iron powder alloys will provide for enhanced functional communication between the selectively reinforced matrix composite friction surface and the friction material of typical brake pads, resulting in substantially decrease stopping distances that will be required, for example, to meet upcoming regulatory deadlines for improved braking in the trucking industry (The National Highway Transportation Safety Administration is poised to recommend that heavy duty brakes provide for a 30% reduction in stopping distances).

Functional Improvements. ₎ Through the inventive application of infiltration casting of porous 'preforms,' functionally gradient porosity (FGP) 'preforms' (or 'preforms' with stepped FGP gradient/layers), and preferably using such 'preforms' in combination with selective particle enhancement (SPE, or SPGE), long-standing problems with selectively reinforced matrix composites,such as differential CTE effects, interface debonding, nucleated inclusions, and phenomena such as constraint/deformation mechanisms are reduced or effectively eliminated. The effect of thermal residual stress and growth effects in the base matrix material are likewise improved. The novel selective particle enhancement (SPE) utilized in combination with infiltration casting of porous 'preforms' is a substantial improvement in the overall mechanical behavior and performance of selectively reinforced matrix composites. Mechanical behavior, coefficients of thermal expansion (CTE) differentials, concentration of stresses, and cost-effective methods of manufacture are improved. Likewise, improvements of weight reduction, wear behavior, and recyclability provide for effective, efficient products that reduce fuel consumption, and pollutant emissions including green house gases.

In particular, residual stress created during the manufacturing process of forming and solidification is substantially reduced, and stress damage due to thermal cyclying during service is substantially reduced. In preferred aspects, SPE, and particularly SPGE treatment of porous preforms (having a relatively low CTE value) is used to deposit/impinge a material {e.g. particle material) having a CTE value that is intermediate between that of the infiltrated 'preform' and the continuous matrix material. For example, where 356 aluminum alloy is used for the matrix material, and ceramic 'preforms (with or without functional gradient porosity (FGP) or FGF layers) are used, SPGE is used to integrate 390 or 398 aluminum alloy particles (having an intermediate CTE value), or a gradient thereof, into the 'preform' prior to infiltration of the 'preform' with 356 matrix material. A gradual smooth CTE value transition is thereby established across what would otherwise be a two-face boundary interface between the unreinforced matrix material and the 'preform.' Generally, any type of particles that provide intermediate CTE transition/buffering, or that enhance bonding between the matrix material and the 'preform' are suitable for these inventive aspects. This CTE smoothing and/or enhanced bonding is particular effective when SPGE is combined with the use of functional gradient porosity (FGP) 'preforms,' or FGF layered 'preforms,' because mechanical differential issues are relaxed more efficiently by an increased presence and microplasticity of the continuous phase matrix material (because of the larger or more numerous pores at the interface 'preform' surface). According to additional aspects, relative to non-porosity gradient porous 'preforms,' the use of porosity gradient preforms allows for improved SPE penetration/impingement, and also for improved infiltration casting.

The properties of the two-face boundary interface become increasingly important as multiphase materials (discrete constituent reinforcement), usually ceramic, are introduced in making matrix composites (e.g., metal matrix composites (MMC) that can be used at medium and high temperatures). However, when metal matrix composites (MMC) are fabricated at high temperatures and subsequently cooled to room temperature, residual stresses are induced in the composite due to the general mis-match of the thermal expansion coefficients (CTE) between the continuous phase matrix material and the reinforcements (discrete constituents) matrix composite component when exposed to thermal cycling. Therefore, the inventive methods to relax mechanical differential issues at the two-face boundary interface using SPE or SPGE are particularly beneficial for such applications.

In addition, the inventive methods comprising SPE and SPGE of porous 'preforms' allow for, if desired, coordinate (co-localized) particle gradient distributions for divergent particle types, or to get both particle types where you need them, and in the optimal pattern and/or gradient/distribution. Significantly, the present inventive methods remove a major limitation of prior art methods for these applications; namely that prior art spray or deposition methods comprise relatively superficial, non-penetrating particle applications that not only must generally be machined prior to placing the reinforced casting into service, but also, absent resurfacing with more reinforcement, wear out relatively quickly. By contrast, the present methods provide substantial versatility selecting different particle combinations, patterns, and extent of penetration/impingement (integration) into the porous 'preforms.' In particularly preferred wear surface embodiments (e.g., brake drums, disk brake rotors, cylinder liners, etc.), the inventive methods allow for directed deposition of one or more particle types, in essentially any desired pattern and/or gradient, and further provide for particle integration/impingement to depths that correspond to, for example, the effective wear depth of the matrix composite part.

EXAMPLE l

(Novel Brake drums and methods for making same)

Brake shoe and brake drum-type brakes have been used on motor vehicles for many years. While many automobiles now use disc-type brakes, brake shoe and brake drum-type brakes are still used in many automobiles, and especially for braking the rear wheels in almost all heavy duty trucks (e.g., class 8), and medium duty trucks (e.g., class 7). The weight of a motor vehicle's brake drums has become increasingly more important to the vehicle manufacturer and to the vehicle operator. Primarily, the weight of the vehicle's brake drums affects the mileage efficiency of the vehicle, and this factor is becoming increasingly important to the manufacturers of automobiles sold in the United States and elsewhere. The Federal Government wishes to provide incentives for automobile manufacturers to continuously increase the mileage efficiency of their automobile line. Automobile manufacturers are diligently searching for ways to reduce the weight requirements on even the smallest automobile and truck components. The weight of brake drums is very important to truck manufacturers. The weight of a truck's brake drum not only affects the truck's mileage efficiency but also directly affects the amount of cargo which can be transported by a truck. This stems from the fact that governmental regulations strictly limit the gross weight of all commercial vehicles. Thus, any savings in the weight of a commercial vehicle allows the owner of that vehicle to carry a like quantity of additional weight. In the highly competitive trucking industry, the total quantity of freight that can be transported per load is critical to profitability. Conventional brake drums are manufactured from ductile iron, cast iron or steel. A typical large truck brake drum weighs about 120 pounds. Attempts have been made to reduce this weight by manufacturing the drums from lighter materials, such as aluminum and aluminum alloys. However, the use of lighter materials (e.g., aluminum and aluminum alloys, such as '319' or '356') is restricted by strength requirements. For example, a typical truck brake drum must have an internal yield strength in excess of 40,000 psi. Brake drums constructed from aluminum and aluminum alloys alone do not have this high of an internal yield strength. In an attempt to take advantage of lightweight materials while retaining adequate strength requirements, several attempts have been made to use brake drums made of a combination of lightweight and heavier materials. For example, in U.S. Patent No. 1,989,211, a bimetallic brake drum is proposed that comprises a cast aluminum housing in combination with a steel internal liner. The resulting brake drum is lighter than conventional brake drams and has sufficient internal yield strength. However, such a drum is yet not sufficiently satisfactory. The steel liner must still be fairly thick to provide for adequate wear life, and for truck brake drums, the steel liner must be at least 3/8 of an inch thick to obtain sufficient internal yield strength. This means the brake drum remains relatively heavy. Additionally, the internal liner has a strong tendency to slip within the outer housing. This requires that the liner:housing interface be provided with transverse ridges or spines to lock the liner within the housing, (see e.g., U.S. Patent No. 1,989,211). In practice, this generally means that the housing and liner must be cast together. Another concern with such composite drums is the lack of efficient heat transfer between the liner and the outer drum, because of the inevitable interface created between the material. Adequate heat transfer is important to keep the brakes cool under, particular under heavy load and demand conditions (e.g., medium and heavy duty trucks). Brake drums and brake discs have been homogeneously fabricated from aluminum-based metal matrix composite (MMC), comprising silicon carbide particulate reinforcement. Such aluminum MMC provides for reduced weight, improved mechanical and thermal properties relative to aluminum and aluminum alloys, and is commercially available, for example, under the name DURALC AN® (Alcan Aluminum Limited). However, there are significant disadvantages with such homogeneous MMC castings. MMC castings are expensive relative to iron and conventional aluminum alloys. Additionally, compared to iron and conventional aluminum castings, aluminum MMC castings are relatively difficult to machine because of the silicon particulate reinforcement. Accordingly, there is a need for a lightweight brake drum which is even lighter than the bimetallic lightweight brake drums of the prior art, a brake drum for which stability does not depend on cast ridges or spines that interface between the housing and the liner, and a brake drum which does not require dissimilar brake drum components to be cast in a single operation. There is also a need in the art for a brake drum with improved thermal and acoustical behavior. There is further need in the art to incorporate sensor devices, sensor materials or other materials such as heat transfer enhancing materials to enhance performance, monitoring, maintenance or utility life of brake drums and systems. There is a pronounced need in the art for additional means to provide secondary braking means (e.g., improved drag-type brakes) in the trucking industry.

Illustrative Embodiments:

With reference to exemplary FIGURES 1, 2A, 2B and 2C, according to particular aspects of the present invention, there is drum 10, comprising a porous 'preform' 2 that is an inner liner or member that becomes a wear surface once a liquified matrix material (e.g., 356 aluminum alloy) is infiltration cast into the porous 'preform.' This component design method is generally referred to as selective reinforcement of a matrix composite. In particular aspects, the porous 'preform' inner liner or member 2 comprises, or could be created with any one or more of the following: porous ceramic 'preforms' that contain ceramic particles; porous ceramic hybrid 'preforms' that contain ceramic fibers and particles; ceramic matrix composites; carbon graphite foam 'preforms'; pre-cast Duralcan™ or other MMC materials formed into a porous 'preform' wear liner, etc.

A typical ceramic 'preform' will contain, for example, ceramic particles. Such particles reinforce, strengthen, and increase the wear/abrasive resistance of the cast part. A typical hybrid ceramic preform will comprise both ceramic particle and fibers, and preferably, the fibers to be used will not shrink during the firing process (the sintering process that completes the manufacture of the preform). Typical carbon graphite foam 'preforms' may comprise silicon carbide particles, and may be produced such that carbon nanotubes are created during the 'preform' manufacturing process to increase the ultimate strength of the final part. An exemplary porous 'preform' 2 is shown in FIGURES 3 and 4.

In preferred aspects, the 'preform' comprises functional gradient porosity (gradient of pores or 'window holes,' which means that during the 'preform' forming process, a gradient of pores of varying sizes or numbers are created within the structure of the 'preforms.' According to particular aspects, such functional gradient porosity, where the number or size of the pores increases toward at least one 'preform' surface, provides several advantages. For example, such a porosity gradient facilitates complete infiltration of the 'preform' during infiltration casting, and serves to reduce or 'smooth' the abrupt change or differential in coefficient of thermal expansion (CTE) at the intersection of the unreinforced matrix material and the infiltrated 'preform' surface. Preferably, this is accomplished by forming larger pores on at least one exterior surface) of the 'preform' relative to pores in the interior of the 'preform.' Particular embodiments comprise larger or more numerous pores on the surface of the 'preform' that interfaces with the unreinforced matrix material (FIGURE 4B). Alternate embodiments comprise larger or more numerous pores on the surface of the 'preform' that corresponds to the wear surface (contacted by brake shoe friction material). Yet further embodiments have larger or more numerous pores on both of these surfaces, compared to pores on the interior of the 'preform.' Alternatively, the pore size could be substantially consistent throughout the preform, but larger than normal prior art pore sizes to assist in smoothing of CTE transitions within the selectively reinforced matrix composite. Selective Particle Enhancement ("SPE"). In particularly preferred aspects, the properties of the porous 'preform' (inner liner or member), with or without functional gradient porosity (or with or without functional gradient stepped porosity layers) may be modified and substantially enhanced by the use of selective particle enhancement ("SPE") or selective particle gradient enhancement ("SPGE") to provide for deposition/impingement of selected particles into the porous 'preform' to a desired depth prior to infiltration casting (e.g., by insertion into a high-pressure die casting mold). Preferably, SPE and/or SPGE is accomplished by such means as low or high velocity impingement/ 'spray' techniques using one or more particle types that impart particular desired properties to the final casting (FIGURE 5 showing use of a spray gun 18 ). In particular aspects, the application of multiple particle types to a wear surface can be accomplished by sequential SPE, or by the use of a multiple head apparatus 20 (FIGURE 6), which can be adjusted to place specific types of particles in the exact region or pattern desired or required for such particle properties. In particular aspects, selective particle gradient enhancement (SPGE), is used to create a particle gradient within the 'preform' (e.g., creating particle gradient distribution at the wear surface similar to those made by prior art centrifugal casting methods to create a 'preform' or a casting from MMC ingot). According to aspects of the present invention, SPE and/or SPGE can be applied to essentially any type of 'preform,' including but not limited to ceramic, carbon graphite foam, ceramic matrix composite, metal matrix composite inner members, etc. In particular aspects, SPE or SPGE can be used to impinge particles 22, 24, 26 into wear surface side of the porous 'preform' 2 (FIGURES 7A and 7B), into interior postions/patterns within the porous 'preform' 2 (FIGURE 8A and 8B), into the matrix material interface surface of the 'preform,' or into both the wear surface, and the matrix material interface surface of the 'preform.' Combinations of different types of particles 22, 24, 26 can be used with SPE and/or SPGE (FIGURES 7A, 7B, 8A and 8B).

According to preferred embodiments, SPE is used to impinge/integrate/deposite particles to a functionally significant depth within the porous 'preform,' such as the effective 'wear depth' of the friction surface, to provide for continued functional presentation of selected particles throughout the service/wear life of the selectively reinforced composite brake drum. Alternately, or additionally, particles have intermediate CTE values (of intermediate value between that of the infiltrated 'preform' and that of the non-reinforced matrix material) can be impinged/integrated on the matrix interface side of the 'preform' to a depth sufficient to effectively smooth any differential CTE that would otherwise be present absent such SPE treatment. Particle sizes for SPE and SPGE applications may vary and, for example, may range from about 10 um to about 75 um or greater. Alternatively, smaller particles could be used to improve machineability of the final casting. Copper, or some other suitable material, could be used not only assist in friction material effectiveness, but also as an element of magnetic brake or Eddy current brakes aspects that can be built into the drum (see, e.g., FIGURE 8A and 8B, where symbolic 'square symbols' 26 could represent elements of a magnetic or conductive brake aspect). Metallic particles will assist in providing an optimal wear surface to assist in creating a higher friction coefficient with optimized friction material. Exemplary SPE and/or SPGE materials for particles include, but are not limited to: Silicon Carbide (SiC); Silicon; Alumina Oxides (A12O3); Mangesium oxide; Tungsten Carbides; Chromium Carbide; Carbon Diamond; Polycrystalline Diamond; Nickel; Copper; Zinc; Titanium Boride; fibrous material (e.g., acrylic fibers, aramid fibers, glass fibers, silica fibers, carbon fibers, metallic fibers, mineral fibers and mixtures thereof); carbonaceous material (e.g., petroleum coke, metallurgical coke, natural carbon, synthetic carbon and mixtures thereof); iron powder; inert fillers (e.g., whiting, talc, barytes, clays and mixtures thereof) and binders (e.g., resinous binders); metal sulfide-iron powder alloy; metal sulfides, including but not limited to ZnS, FeS, MoS₂, CuS₂, TiS, CdS, Sb₂S₃, MnS, CoS, Co₃S₄, CaS, BaS, SrS, FeS₂, ZrS₂, Cu₂S, Ni₃S₂, NiS, Ni₃S₄, MnS₂, CoS₂, Co₂S₃, SnS; etc. For example, according to particular aspects of the present invention SPE, of 'preform' surfaces that represent operational friction surfaces (e.g., friction surfaces in brake drums and disc brake rotor embodiments), using metal sulfides or metal sulfide-iron powder alloys will provide for enhanced functional communication between the selectively reinforced matrix composite friction surface and the friction material of typical brake pads, resulting in substantially decrease stopping distances In particularly preferred embodiments, to increase the operational strength of the final matrix composite brake drum, the porous 'preform' inner member is secured or wound (e.g., at the open end; the end facing the open side of the drum) with a reinforcement wrapping 8 or material of greater strength than the inner liner/member to prevent expansion¹ of the inner member during operation of the drum. Preferably, the reinforcement material exhibits minimum shrinkage during the manufacturing process. In particular embodiments, the reinforcement wrapping/winding(s) 8 are located on the exterior side of the tubular 'preform'2 (the side opposite the wear surface) and extend from the open end of the brake drum inward, and may extend partially across (FIGURES 9A and 9B), fully across (FIGURES 1OA and 10B), and even in multiple layers across (FIGURES 1 IA and 1 IB) the outer diameter of the inner liner/member 2. In alternate embodiments, the reinforcement wrapping 8 or material may be integrated, at least to some extent within the porous 'preform' 2 (FIGURES 12 and 13), for example by integration during fabrication of the porous perform to produce an integral reinforcement porous perform. The number of windings 8 and the location of the windings 8 are selectable, being determinable, based on the type of application the brake drum 10 will be used for, and depending on the stress loading the drum will undergo. For example, for any given reinforcement support/wrapping material, more windings may me required for heavy uses such as buses, garbage trucks, logging trucks, maximum load haulers such as cement transit mixers or aggregate haulers, etc. The thickness of the windings may vary, and may range, for example, in particular embodiments from about lmm to about 1.254 cm.

Suitable reinforcement support/wrapping materials include, but are not limited to alumina fiber such as Nextel fibers (e.g., Nextel 610 fibers), Saffil fiber, alumina-silicate fibers, coated or uncoated carbon fibers, Basalt fiber, steel, stainless steel, Aluminum MMC cable, or any other high strength durable fibers.

As discussed herein above, suitable infiltration casting methods include, but are not limited to high pressure vacuum die casting, squeeze casting, or any other method that can result in complete infiltration of the inner member. In preferred embodiments, the infiltration casting method comprises indirect squeeze infiltration of porous rigid preforms on a shot- control high-pressure die casting machine.

For example, according to preferred aspects of the present invention, the production of high quality selectively reinforced aluminum based metal matrix composite reinforced composite brake drums, brake rotors, clutch wear plates, cylinder liners, commercial wheels or other components, where high wear resistance or high strength are required, can be reproducibly and efficiently produced via indirect squeeze pressurized liquid metal infiltration of ceramic or carbon graphite foam 'preforms' on a shot-control commercial die casting machine. Preferably, to best accomplish this, the processes of a shot-control commercial die-casting machine are optimized. Typical exemplary processing parameters to be optimized are as follows: preform preheat and melt superheat are preferably adjusted to preclude premature melt solidification before and during infiltration; infiltration speed is preferably controlled to avoid permanent deformation of the ceramic, carbon graphite foam, or other preforms; the maximum pressure available on the die caster is preferably deployed to minimize non-infiltration defects; the gating system is preferably designed to ensure feeding of the solidification shrinkage in the composite casting, etc.

A 'preform' with optimized properties is preferred to provide for complete metal infiltration. For a finished component where repeated thermal cycling occurs, the coefficient of thermal expansion differential between the selectively reinforced area of the component and the unreinforced area could result in component failure. Therefore, in preferred embodiments, the forming of a preform with larger pores at the reinforced and unreinforced interface will assist in providing for a better transition for gradual decrease in thermal expansion within the reinforced area, and is preferred for long-term part integrity. Preferably, such porosity gradient preforms are used in combination with the disclosed SPE and SPGE aspects to substantially further improve smoothing of differential CTE values at the interface. Therefore, a functionally gradient porosity 'preform,' and in particular such a preform in combination with SPE and/or SPGE treatment is a particularly preferred component of such parts as brake drums, brake rotors, clutch plates, and other parts subject to large variations in operating temperatures during initial fabrication and/or service conditions. In additional SPE and/or SPGE aspects, an increase in the quantity of reinforcement particles (e.g., silicon carbide, alumina, titanium oxide, etc., towards the wear surface of the part provides for optimal wear characteristics, because the wear resistance particles are selectively applied and concentrated at/deposited in/integrated into (preferable to a depth equal to the effective service wear depth of the part) the wear surface/working surface.

EXAMPLE 2

Disk Brake Rotors. In additional selective reinforcement matrix composite embodiments, the present inventive compositions and methods provide for selectively reinforced disk brake rotors comprising infiltration cast porous 'preforms' (with or without porosity gradients). Preferably, such disk brake rotor 12 embodiments (FIGURES 14A and 14B) further comprise SPE and/or SPGE to provide for enhanced wear, CTE smoothing, etc., in analogy with the above-described brake drum embodiments. Preferred embodiments comprise two annular porous preforms 2, one on each side of a center rotor 14), and further comprise cooling channels 16 (e.g., radial cooling passages for air) within the center rotor portion 14. The types of suitable matrix materials, 'preforms' and SPE/SPGE particles are as describe above, in analogy with the above-described brake drum embodiments.

EXAMPLE 3 Cylinder Liners and/or Cylinder Blocks Comprising Cylinder Liners. In additional selective reinforcement matrix composite embodiments, the present inventive compositions and methods provide for selectively reinforced cylinder liners 16 and/or cylinder blocks comprising infiltration cast porous 'preforms' 2 (with or without porosity gradients). Preferably, such cylinder liners 16 and/or cylinder blocks embodiments (FIGURE 15) further comprise particles (e.g., 22, 24, 26) applied by SPE and/or SPGE to provide for enhanced wear, CTE smoothing, etc., in analogy with the above-described brake drum and disk embodiments. Preferred embodiments comprise a cylindrical porous preform 2, and further comprise fluid cooling channels 28 within the porous 'preform' 2. The types of suitable matrix materials, 'preforms' and SPE/SPGE particles are as describe above, in analogy with the above-described brake drum and disk brake rotor embodiments. Additionally, particles (e.g. Paladium and/or functional equivalents) suitable to enhance fuel combustion, or to minimize undesired emissions can be applied to the inner surface of the 'preform' of the cylinder liner using SPE and/or SPGE.

EXAMPLE 4

Brake Drums. With reference to Figures 16-22, particular embodiments of the present invention are directed to a brake drum which meets the above-described needs. In one embodiment, the brake drum includes a tubular inner member 2 (wear liner) having an interior surface suitable for contacting a brake pad and an exterior surface, a length of reinforcement wrapping 8 (e.g., wire, cable, array (mesh), etc.) snugly wrapped around a portion of the exterior surface of the wear liner, and at least one fastener for securing at least a portion of a wheel assembly to the brake drum. Preferably, the brake drum includes a tubular outer shell molded over and substantially covering the length of reinforcement wrapping 8 to protect the wrapping and provide additional support to the brake drum. Preferably the outer shell and the inner member 2 are integrated by using infiltration casting of a porous 'preform' inner member, and in such cases the reinforcement wrapping 8 is optional, and may be present when additional strength is desired.

As described in detail below, the length of reinforcement wrapping 8 (e.g., single strand, cable, mesh, fiber(s), etc.) wrapped around the tubular inner member 2 supports (strengthens) the inner member. Thus, the inner member and the outer shell of the brake drum can be made from similar, lightweight materials having lower internal yield strengths than the prior art steel brake drums. The term 'internal yield strength' as used in this application means the amount of internal pressure which the brake drum can withstand without failing.

Preferably, the inner member 2 and the outer shell are made of similar materials with compatible rates of thermal expansion, and the outer shell can be molded over the reinforcement wrapping, so there is no requirement for ridges or cast spines to interface between the inner member (wear liner) and the outer shell, although retention patterns (e.g., groove) may be desirable to localize the reinforcement wrapping 8 on the inner member 2 during drum fabrication.

In particular embodiments, multiple layers (see Figures 18-20) of the length of reinforcement wrapping are wrapped around substantially the entire exterior surface to support the entire inner member 2. Preferably, where the wrapping is, for example, wire, the length of wire has a diameter of between about 0.1 inches and about 0.4 inches, has a tensile strength of at least 180,000 psi, and is wrapped at a tension of at least about 25 foot-pounds to provide tight, consistent wrapping of the length of wire around the exterior surface and sufficient support of the inner member. Alternatively, pre-tensioned wrapped multi-strand wire (e.g., cable), or fiber can be used for this purpose. Preferably, cable or fiber is used. Preferably, a single layer of cable winding or fiber winding is used.

In alternative preferred embodiments, the length of reinforcement wrapping comprises high-strength fibers, such as composite fibers, cable of mesh, including, but not limited to fibers, cables and arrays (e.g., mesh) comprising: carbon fibers, vitreous glass fibers (Basalt wool, comprising SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃), alumina oxide fibers and e-glass (e.g., fiber glass), and combinations thereof. According to the present invention such fibers are used in, for example, wire, cable, and other arrays (e.g., mesh, or woven arrays) to provide reinforcement wrapping to support the inner member. Preferably, the reinforcement wrapping comprises material that is not flammable, and is not irritating to the eyes, skin and respiratory tract. Preferably, the fibers of the reinforcement wrapping are non-respirable, and non-hazardous. Preferably, reinforcement wrapping comprises vitreous glass (Basalt wool) or Nextel fiber (e.g., Nextel 610). Preferably, the vitreous fibers are amorphous comprising, as main constituents, SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃, and no carcinogens are present in amounts above 0.1%. Preferably, the vitreous glass melts at about 2400 degrees Fahrenheit. Alternatively, the function of the reinforcement wrappings can be met by distribution of a reinforcing fiber network within the preform (e.g., an integrated reinforcement matrix of short and/or intermediate and/or longer fibers.

Since the length of reinforcement wrapping 8 supports the inner member 2 and inhibits expansion of the inner member, the inner member and the outer shell can be made from lightweight materials having a density of less than about 0.15 pounds per cubic inch, such as aluminum and aluminum alloys. For example, the inner member can be made of an alloy which includes at least about seventy-five (75) volume percent aluminum and between about ten percent (10%) and about twenty-five percent (25%) abrasive material so that the brake pads can grip against the brake drum. I n alternative preferred embodiments, the percentage of abrasive material is at least 10%. Preferably the percentage of abrasive material is between about 10% and about 50%, or between about 10% and about 30%, or between about 10% and about 28%, or between about 15% and about 28%. Preferably, mixed metal composite (MMC), or ceramic metal composite (CMC) is used to form the inner member (wear plate). Preferably, porous 'preforms' as describe herein above are used.

A particular embodiment (see Figures 23, 24 A and 24B) of the invention comprises a generally continuous, circular, (e.g., helical) wire alignment groove 30 cast into the outer surface of the inner member 2. Preferably, the groove 30 is in the shape of a uniform helix. Alternatively, circular or spiral grooves with non-uniform pitch could be substituted for the generally circular, uniform helical groove. The cast groove has two ends. The groove is shaped such that the wire or cable fits snugly within the groove. The cast grooves comprise 'walls' of inner member material that separate the groove troughs. By attaching, or tucking the wire to the inner member at each end of the groove, it is possible to create a single-layer wire (e.g., cable) wrapping covering a substantial portion of the exterior surface of the inner member.

The cast alignment groove, or other suitable retention pattern, facilitates keeping the wire in a fixed position relative to the inner member. By varying the pitch of the groove relative to a facial plane of the inner member, or by changing how tightly the groove is wound, it is possible to use wires or cables of different length to substantially cover the exterior surface of the inner member.

In other embodiments comprising an inner member with a cast alignment groove, multiple layers of wire are wrapped around the inner member with the first layer of wire fitting within the grove and later layers crossing (e.g., criss-crossing) over previous layers. By attaching, or tucking the ends of the wire to the inner member or the wire, the wire can be held at a constant tension, covers a substantial portion of the exterior surface of the inner member, and provides rigidity and strength to the inner member.

In particularly preferred embodiments, at least one of the tubular inner member, the bonding layer, and the outer shell comprises 'carbon graphite foam' . Preferably, infiltration casting is used in such embodiments. For example, an aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a 'preform' of porous 'carbon graphite foam^'' (with or without particulate reinforcement, such as silicon carbide). Carbon graphite foam (developed at Oak Ridge National Laboratory, USA) has high thermal conductivity and also acts as super-conductor (see, e.g., U.S. Patent Nos.: 6,673,328, 6,663,842, 6,656,443, 6,398,994, 6,387,343 and 6,261,485, all of which are incorporated by reference herein in their entirety). Preferably the silicon carbide volume should be from about 10% to 35% to provide desired friction at wear plate rubbing surface. Infiltration of un-reinforced or reinforced alloy into carbon graphite foam 'preform' is during a suitable casting procedure including, but not limited to die casting, high- vacuum permanent mold casting, squeeze casting, or centrifugal casting. According to the present invention, carbon graphite foam can be included in the compositions of at least one of the tubular inner member, and any bonding layers, or other member or parts in contact therewith. Significantly, according to the present invention, inner members comprised of carbon graphite foam are more cost effective that CMC versions, and are environmentally favored because they are produced from a by-product of coal production.

In alternative embodiments with reinforcement wrapping comprising fiber arrays (e.g., carbon fibers, vitreous glass fibers(Basalt wool comprising SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃), alumina oxide fibers and e-glass (e.g., fiber glass), Nextel fibers, and combinations thereof), the outer surface of the inner member may have a suitable alignment pattern cast into the outer surface thereof to facilitate keeping the fiber arrays in a fixed position relative to the inner member. Alternatively, the reinforcement wrapping are integrated onto, or into porous 'preforms' that serve, after infiltration casting, as inner members.

Additional embodiments comprise sensor materials or devices (e.g., magnetic resistive devices, or thermal transfer materials such as sodium metal) placed in recessed cavities in the walls formed by the generally continuous, circular, helical groove on the outer surface of the inner member, or placed in recessed cavities in the outer surface of the inner member that are positioned in areas not covered by the groove.

Particular embodiments of the invention include a bonding layer between the exterior surface of the inner member (including over the reinforcement wrapping) and the outer shell. Preferably the inner member and the outer shell are made of conventional aluminum, aluminum alloy, or an aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALCAN^®, containing silicon carbide; manufactured by Alcan Aluminum Limited). Preferably, the outer shell and the inner member comprise at least one member of the 535-alloy family (ALCAN aluminum) selected from the group consisting of 535.0, 535.2, A535.0, A535.1, B535.0, B535.2. Preferably, an essentially Be (beryllium)-free alloy, such as A535 and B535 (low Mn) are used. Preferably, A535.1 is used. Alternatively, the inner member consists of, or comprises ceramic matrix composite (CMC); 'carbon graphite foam'; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%). Preferably, the inner member comprises an infiltration cast porous 'preform,' and thus does not require a bonding layer for optimal integration with the outshell; that is the inner member and the outer shell are integral, by virtue of infiltration casting of the porous 'preform.'

Preferably, the bonding layer, when desired, comprises a metal alloy (e.g., 1100 aluminum) having a melting temperature lower than that of either the material from which the inner member and the outer shell are made of or the material from which the wire is made of, and is fused, for example, between the wire wrapped around the inner member and the outer shell. Preferably, the bonding layer is applied by flame spraying. Preferably the bonding layer is applied to the exterior surface of the inner member (including over the cast grooves), prior to wrapping of the wire or cable into the grooves. Alternatively bonding layers are applied to the exterior surface of the inner members, both before and after wrapping of the wire or cable.

Preferably, for bonding layers comprising 1100 aluminum and the like, the bonding layer also comprises an amount of zinc or tin suitable to confer enhanced bonding (most likely by lowering the melting temperature of the bonding layer). In alternative embodiments, the boding layer is an adhesive (e.g., high-temperature adhesive). Preferably, such adhesives are used in combination with, for example, ceramic matrix composite (CMC) wear plates. Preferably, the bonding layers, whether fused aluminum based or high- temperature adhesive comprise one or more additional materials to enhance thermal conduction. Preferably, the material comprises 'carbon graphite foam.'

Yet further embodiments provide a method for making a brake drum. The method includes manufacturing a tubular inner member and wrapping a length of reinforcement wrapping (e.g., wire, cable, fiber array (mesh)) tightly around an exterior surface of the tubular inner member. In preferred embodiments, the inner member comprises or consists of MMC. In particularly preferred embodiments, the inner member comprises or consists of a porous 'preform' that is infiltration cast, and thus does not require a bonding layer, and the wrapping is optional and added when more strength is desired.

The method also can include molding (e.g., casting) an outer shell that substantially or completely covers the length of wire around the exterior surface to provide additional support to the brake drum. In particular embodiments, an alignment groove is cast into the exterior surface of the inner member, for alignment of the wrapped wire.

In particular embodiments, the MMC inner member is initially cast as MMC.

In alternative preferred embodiments, the MMC inner member is provided by infiltration casting of molten aluminum alloy (the outer shell material) into a porous preform positioned within a die cast mold cavity for in situ casting. Preferably, the porous 'preform' comprises or consists of silicon carbide and/or aluminum oxide that has been cast to form the porous 'preform.' Preferably, the porous 'preform' has the dimensions of the inner member, and has a porosity percentage of about 72% (corresponding to a. particle percentage of about 28% in the final MMC inner member). Alternatively, the porosity percentage can vary between about 75% and about 50% (corresponding to a particle percentage of about 25% to about 50% in the final MMC inner member).

In particular embodiments, the method of making the brake drum can incorporate an intermediate stage. After manufacturing a tubular inner member (by either direct MMC casting or using the above-described perform approach) and wrapping a length of wire or cable tightly around, for example, an exterior surface of the tubular inner member, a bonding layer comprising a metal alloy (e.g., 1100 aluminum) is optionally applied over the wire wrapping. The method can also include molding an outer shell that substantially covers the length of wire around the exterior surface to provide additional support to the brake drum.

In an alternate embodiment, the method of making the brake drum can incorporate a bonding layer comprising a thin shell of metal alloy (e.g., 1100 aluminum) that is cast over a wire wrapping an inner tubular member. This shell bonds to the wire wrapping under the heat and pressure of molding an outer shell that substantially covers the length of wire around the exterior surface.

In embodiments where the reinforcement wrapping comprises basalt fibers alumina oxide fibers, e-glass, composite fibers, etc., that are made into wire, cable or arrays (e.g., mesh), the reinforcement wrapping is preferably impregnated with 1100 aluminum dust to improve 'wetting' during the casting process. Preferred embodiments comprise spraying, applying, dusting or casting a bonding layer of metal alloy (e.g., 1100 aluminum) over the exterior surface of the inner member (including over the optional grooves or retaining patterns thereof) before the reinforcement wrapping is wrapped around the inner member. This bonding layer bonds to the inner member and the wrapping (e.g., wire) under the heat and pressure of molding an outer shell that substantially covers the length of wire around the exterior surface.

One skilled in the art would recognize that two separate bonding layers — one between the inner member and the wire and the second between the wire wrapping and the outer shell - of metal alloy (e.g., 1100 aluminum) could also be employed. The two bonding layers are preferably of the same material in order to facilitate a stronger bond between the bonding layers as well as between the bonding layers, the inner member, the wire wrapping, and the outer shell. The two separate bonding layers would bond to each other and the other components under the heat and pressure of molding the outer shell.

In alternate embodiments, particularly those having inner members comprising or consisting of CMC, the bonding layer may comprise or consist of epoxy. In additional preferred embodiments, a wire or cable comprising copper, or comprising one or more other low-impedance materials is used to wrap and support the inner member. Preferably, such copper-containing wire, cable or mesh also comprises another material (e.g., steel, basalt fibers, etc.) to maintain the strength of the reinforcement wrapping. According to the present invention, such wrappings (with copper or low- impedance material) are operable to interact with external activatable magnetic elements (e.g., electromagnets), fixed at one or more positions within a vehicle (e.g., truck) so as to be in electromagnetic association with the inventive drums to provide, for example, for additional braking (drag braking or Eddy current braking) when needed. The present invention provides a strong, lightweight brake drum which can be manufactured relatively inexpensively, because the inner member and the outer shell can be made from similar materials and there is no need for ridges and spines between the inner member since the outer shell can be molded over the wire. Additionally, the presence of the optional inventive bonding layer or layers provides for improved thermal and acoustic transfer between the inner member and the outer shell of the drum. Alternatively, particularly preferred embodiment involve the use of reinforced porous 'preforms' and infiltraion casting, and in particular, such use in combination with SPE and/or SPGE methods are describe herein. The inventive drums provide for optional sensor means, and means for optional electromagnetic mediated braking (e.g., drag braking, Eddy current-mediated braking).

Particular embodiments of the present invention provide a novel lightweight, reinforced brake drum comprising an inner member (wear plate), a length or amount of reinforcement wrapping or material (e.g., wire, cable, fiber or mesh), and an outer shell. Preferably, the inner member comprises a generally helical groove, or other reinforcement or wrapping retention pattern or means on the exterior surface thereof. Preferably, a bonding layer is also present to enhance thermal and/or acoustical transfer. Preferably, the generally tubular inner member (wear plate) consists of or comprises at least one material selected from the group consisting of: aluminum-based metal matrix composite (MMC), comprising a particulate reinforcement; ceramic matrix composite (CMC); 'carbon graphite foam'; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%).

The following discussion describes in detail particular embodiments of the invention and several variations thereof. This discussion should not be construed as limiting the invention to that particular embodiment or to those particular variations. Practitioners skilled in the art will recognize numerous other embodiments and variations, as well.

With reference to Figures 25, 26 and 27, the present invention is directed to a lightweight, reinforced brake drum 10 for use with vehicles requiring brakes (e.g., trucks, cars, etc.), for example, as part of a wheel assembly 13. The lightweight, reinforced brake drum 10 comprises (i) an inner member (wear plate) 14 (equivalent to 2), (ii) a length of reinforcement wrapping or material (e.g., wire, cable, fiber or mesh) 16 (equivalent to 8), and (iii) an outer shell 18.

The inner member (wear plate) 14 is tubular or generally tubular and has an interior surface 20 and an exterior surface 22. The interior surface 20 has a surface finish which is suitable for contacting brake pads 24. Preferably, the surface finish is at least about one hundred twenty-five (125) microinches RMS.

Preferably, the inner member 14 comprises or is composed of a lightweight material having a density of less than about 0.15 pounds per cubic inch and having a high resistance to corrosive road conditions. Typically, the inner member 14 is composed of an aluminum or an aluminum alloy. Other lightweight materials and alloys, such as ceramic, magnesium and tinsalloy, can also be used in the invention, as can composite materials such as carbon fiber epoxy resin composites. For example, an alloy which includes at least about seventy-five (75) volume percent aluminum makes an excellent inner member 14. Preferably, the inner member (wear liner) comprises or consists of MMC₅ or the like. Preferably the inner member and the outer shell are made of conventional aluminum, aluminum alloy, or an aluminum- based metal matrix composite (MMC), comprising a particulate reinforcement (e.g., DURALC AN^®, containing silicon carbide; manufactured by Alcan Aluminum Limited). Preferably, the outer shell and the inner member comprise at least one member of the 535-^' alloy family (ALCAN aluminum) selected from the group consisting of 535.0, 535.2, A535.0, A535.1, B535.0, B535.2. Preferably, an essentially Be (beryllium)-free alloy, such as A535 and B535 (low Mn) are used. Preferably, A535.1 is used. Alternatively, the inner member consists of, or comprises ceramic matrix composite (CMC); 'carbon graphite foam'; or manganese-bronze having a particulate reinforcement such as, but not limited to silicon carbide (e.g., from about 10% to about 35%).

Preferably, the inner member comprises, or is substantially comprised of a friction material being a ceramic matrix composite ("CMC") having a two- or three-dimensionally interconnected crystalline ceramic phase, and a non-contiguous metal phase dispersed within the interconnected ceramic phase (see, e.g., U.S. Patent Nos. 5,620,791, 5,878,849 and 6,458,466, incorporated herein by reference in their entirety). The ceramic phase of the CMC may be a boride, oxide, carbide, nitride, suicide or combination thereof. Combinations include, for example, borocarbides, oxynitrides, oxycarbides and carbonitrides. The ceramic may include various dopant elements to provide a specifically desired microstructure, or specifically desired mechanical, physical, or chemical properties in the resulting composite. The metal phase of the CMC may be a metal selected from the Periodic Table Groups 2, A- 11, 13 and 14 and alloys thereof. In particular embodiments, the CMC is produced by infiltrating a porous ceramic body with a metal, thus forming a composite. Such infiltration involves, for example, forming a porous ceramic 'preform' prepared from ceramic powder, such as in slip casting (e.g., a dispersion of the ceramic powder in a liquid, or as in pressing (e.g; applying pressure to powder in the absence of heat), and then infiltrating a liquid metal into the pores of said 'preform.' In particular embodiments, the friction material comprises a ceramic-metal composite comprised of a metal phase and a ceramic phase dispersed within each other, wherein the ceramic phase is present in an amount of at least 20 percent by volume of the ceramic-metal composite. In particular embodiments, the braking component is a metal substrate, such as aluminum, having laminated thereto a ceramic metal composite of a dense boron carbide-aluminum composite having high specific heat and low density.

In particularly preferred embodiments, at least one of the tubular inner member, the bonding layer, and the outer shell comprises 'carbon graphite fo an? . Preferably, the inner member comprises 'carbon graphite foam. ^'1 Preferably, infusion casting is used in such embodiments. For example, an aluminum-based alloys (e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a 'preform' of porous 'carbon graphite foam' (with or without particulate reinforcement, such as silicon carbide). Carbon graphite foam (developed at Oak Ridge National Laboratory, USA) has high thermal conductivity and also acts as super-conductor (see, e.g., U.S. Patent Nos.: 6,673,328, 6,663,842, 6,656,443, 6,398,994, 6,387,343 and 6,261,485, all of which are incorporated by reference herein in their entirety). Preferably the silicon carbide volume should be from about 10% to 35% to provide desired friction at wear plate rubbing surface. Infiltration of un-reinforced or reinforced alloy into carbon graphite foam 'preform' is during a suitable casting procedure including, but not limited to die casting, high- vacuum permanent mold casting, squeeze casting, or centrifugal casting. According to the present invention, carbon graphite foam can be included in the compositions of at least one of the tubular inner member, and any bonding layers, or other member or parts in contact therewith. Significantly, according to the present invention, inner members comprised of carbon graphite foam are more cost effective that CMC versions, and are environmentally favored because they are produced from a by-product of coal production.

Preferably, if the material predominantly forming the inner member 14 is relatively lightweight and soft (e.g., aluminum alloy), it is mixed with an abrasive so that the interior surface 20 of the inner member 14 has a coefficient of friction and wear resistivity similar to that of prior art brake drums 10 made from iron and steel. Typical abrasives usable in the invention are silicon carbide and carborundum. Where the inner member 14 is composed of an aluminum or aluminum alloy, the composition preferably includes between about ten (10) and about fifty (50) volume percent abrasive, or between about ten (10) and about thirty (30) volume percent abrasives, or between about ten (10) and about twenty-eight (28) volume percent abrasives. In preferred embodiments, the inner member 14 material contains between about fifteen (15) and about twenty-eight (28) volume percent abrasives. An excessive amount of abrasive material tends to make the inner member 14 brittle, while an insufficient amount of abrasive material causes the interior surface 20 to be slippery when engaging the brake pads 24 and the interior surface 20 tends to wear too quickly. Where the abrasive material consists of or comprises silicon carbide particles, the particle size distribution preferably has a median diameter of between about ten (10) and about twenty (20) micrometers with less than about five percent (5%) of the particles larger than twenty-five (25) micrometers and with no more than about ninety percent (90%) of the particles larger than about five (5) or larger that about eight (8) micrometers. Silicon carbon particles which meet FEPA Standard 42-GB-1984 for F500-grit powders are preferably used in the invention.

Preferably, the inner member is comprises or consist of MMC, CMC or 'carbon graphite foam' . A commercially available material known as "Duracon.RTM.", marketed by Alcon Aluminum, Ltd., Duralcon U.S.A. of San Diego, Calif., is an excellent material for the inner member 14. Duracon.RTM. is a mixture of aluminum/ceramic and about eighteen- twenty-two volume percent (18-22%) of silicon carbide.

Casting embodiments Preferably, the inner member 14 (which can be a preform) is formed by a casting process and the interior surface 20 is optionally machined to obtain a finish suitable for contacting a brake pad(s) 24.

In particular embodiments, the MMC inner member is initially cast as MMC.

The outer member 18, and/or the inner member(s) (wear plates) 14 are preferably cast in a mold(s). The casting process is performed by any suitable casting process, including but not limited to die casting, sand casting, permanent mold casting, squeeze casting, or lost foam casting. Preferably, casting is by die-casting. Alternatively, casting of the outer member 18, and/or the inner member(s) (wear plates) 14 is by spin-casting, such as that generally described in U.S. PATENT 5,980,792 to Chamlee (incorporated herein by reference in its entirety). For example, aluminum-based metal matrix composite (MMC) comprising a particulate reinforcement {e.g., Duralcan®) containing silicon carbide) is centrifugally spin- casted to cause and create functionally beneficial particulate (sic) distributions (gradients). In the present instance such casting methods increase particle density at friction surfaces. Alternatively, aluminum-based alloys, including eutectic and hypereutectic alloys such as 380, 388, 398, 413, or others such as 359-356-6061, optionally containing particulate reinforcement such as silicon carbide, or aluma oxides, ceramic powders or blends, can be cast into {e.g., by infiltration casting) a ceramic fiber-based, or a carbon graphite foam-based porous 'preform' of desired specification using discontinuous alumina-silicate {e.g., Kaowool Saffil Fibers), silicon carbide, ceramic powders, or blends of the preceding. Reinforced or non-reinforced aluminum-based alloys infiltrate the 'preforms' during the casting procedure, making, for example, a MMC with selective reinforcement. Preferably, casting process is performed by a suitable method, including, but not limited to die casting. Alternatively, permanent mold high-vacuum, squeeze casting, lost foam, or centrifugal casting {e.g., U.S. 5,980,792) can be employed.

In alternative preferred embodiments, the MMC inner member is provided by infiltration casting of molten aluminum alloy (the outer shell material) into a porous preform positioned within a die cast mold cavity for in situ casting. Preferably, the porous perform comprises or consists of silicon carbide and/or aluminum oxide that has been cast to form the porous preform. Preferably, the porous perform has the dimensions of the inner member, and has a. porosity percentage of about 72% (corresponding to & particle percentage of about 28% in the final MMC inner member). Alternatively, the porosity percentage can vary between about 75% and about 50% (corresponding to a particle percentage of about 25% to about 50% in the final MMC inner member). The MMC in such embodiments is produced upon infiltration of the molten aluminum alloy into the pores of perform to provide for an MMC having the desired particle composition.

In alternate preferred embodiments, infusion casting is preferred where the inner member comprises ''carbon graphite foam. For example, an aluminum-based alloys {e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into (e.g., infiltration casting) a 'preform' of porous 'carbon graphite foam' (with or without particulate reinforcement, such as silicon carbide).

For typical brake drums 10 for use on a heavy-duty truck, the inner member 14 has an internal diameter 26 of about 161/2 inches, and a width 28 of about 7 inches. For the material sold under the Duracon.RTM. mark, a thickness 30 of the inner member 14 of between about 0.35 inches to about 0.60 inches provides sufficient internal yield strength and wear life when manufactured in accordance with this invention.

Reinforcement Material or Wrapping

The length of the reinforcement material or wrapping (e.g, mesh, wire or multifilament cable) 16 is wrapped around a portion of the exterior surface 22. In particular embodiments, multiple layers of the length of reinforcement wrapping (e.g., wire) 16 (equivalent to 8) are wrapped around the entire exterior surface 22 to provide support for the inner member 14. As shown in FIGS. 18-20, multiple layers of a length of wire 16, for example, can be crisscrossed across the exterior surface 22 to provide better support to the inner member 14. With reference to FIG. 17, a first layer of wire 16 is wrapped substantially straight around the inner member 14. With reference to FIG. 18, a second layer of wire 16 is wrapped at about a ten (10) to thirty (30) degree angle from the first layer. With reference to FIG. 19, a third layer of wire 16 is wrapped at about a twenty (20) to sixty (60) degree angle from the second layer. With reference to FIG. 20, a fourth layer is wrapped substantially similar to the first layer. The required overall thickness of layers of wire 16 depends upon the tensile strength of the length of reinforcement wrapping (e.g., wire cable, mesh, etc.) 16.

In a particular embodiment, a length of wire (or cable) 16 made of a steel alloy having a tensile strength of between about 180,000-240,000 psi and having a diameter 32 of between about 0.05 inches to about 0.25 inches is preferred since this wire can be tightly and consistently wrapped around the inner member 14. For the type of wire detailed above, multiple layers of wire (or cable) 16 having a combined thickness 34 of between about 0.1 inches to about 0.4 inches provides sufficient support for the brake drum 10. If an insufficient amount of wire 16 is wrapped around the inner member 14, the internal yield strength of the brake drum 10 is too low and the brake drum 10 tends to rupture from internal pressures exerted by the brake pads 24. If too many layers of wire are wrapped around the inner member 14, the internal yield strength is large, the brake drum 10 will be heavier than necessary. Preferably, cable (wrapped multi-stranded wire) is used and only a single layer of wrappings is required.

Additional embodiments comprise a composite wire 16 consisting of an inner core and outer cladding with the core and cladding made of two different metals or metal allows. Preferably, one of the metals or metal alloys has low impedance (e.g., copper or copper alloy) and the other metal or metal alloy is one having high tensile strength (e.g., steel or steel alloy). In preferred embodiments the core is made of the metal or metal allow with high tensile strength and the cladding is made of the metal or metal alloy with low impedance.

According to particular aspects of the present invention, such wrappings are operable to interact with external activatable magnetic elements (e.g., electromagnets), fixed at one or more positions within a vehicle (e.g., truck) so as to be in electromagnetic association with the inventive drums to provide for additional braking (drag braking and/or Eddy current- mediated braking) when needed.

A different embodiment comprises a length of multi-stranded wire (preformed cable) 16, such as preformed aircraft cable or commercial grade low stretch cable having (7 X 19) seven bundles of nineteen separate wire strands, having a diameter between 0.062 inches to about 0.562 inches. Preferably, when cable is used, only a single layer of wrappings is required to support for brake drum 10.

The length of wire or multi-wire, preformed cable 16 is wrapped tightly around the exterior surface 22. Typically, the length of wire or multi-wire, preformed cable 16 is wrapped tightly to have a tension of at least five (5) foot-pounds. Preferably, the length of wire or multi-wire, preformed cable 16 is wrapped to have a tension of at least about twenty (20) to forty-five (45) foot-pounds to obtain the desired internal yield strength of the brake drum 10. Alternately, for a wire or multi-wire, preformed cable 16 having a tensile greater than 240,000 psi, the wire or multi-wire, preformed cable 16 can be wrapped to have a tension which approaches or exceeds about seventy-five (75) foot-pounds.. The ends (not shown) of wire or multi-wire, preformed cable 16 can be welded (not shown) to the inner member 14 or to wire or multi-wire, preformed cable 16 to retain the tension on the wire or multi-wire, preformed cable 16. In alternative preferred embodiments, the length of reinforcement wrapping comprises high-strength fibers, such as composite fibers, cable or mesh, including, but not limited to fibers, cables and arrays (e.g., mesh) comprising: carbon fibers, vitreous glass fibers(Basalt wool, comprising SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃), alumina oxide fibers and e-glass (e.g., fiber glass), and combinations thereof. According to the present invention such fibers are used in, for example, wire, cable, and other arrays (e.g., mesh, or woven arrays) to provide reinforcement wrapping to support the inner member. Preferably, the reinforcement wrapping comprises material that is not flammable, and is not irritating to the eyes, skin and respiratory tract. Preferably, the fibers of the reinforcement wrapping are non-respirable, and non-hazardous. Preferably, reinforcement wrapping comprises vitreous glass (basalt wool). Preferably, the vitreous fibers are amorphous comprising, as main constituents, SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃, and no carcinogens are present in amounts above 0.1%. Preferably, the vitreous glass melts at about 2400 degrees Fahrenheit. Some advantages of Basalt-based fibers (vitreous glass, or pseudo-glass) are that they are relatively inexpensive, are approximately five-times stronger that steel on a weight basis, and have relatively lower thermal expansion coefficient — retaining strength above 400 degrees Centigrade. Additionally, and significantly, the Basalt-based fibers are much safer to work with, being non-carcinogenic and non-respirable.

With reference to Figures 23 through 27, particular embodiments incorporate a generally continuous, circular, helical groove 60 on the exterior surface 22 of the inner member 14. Preferably, the groove 60 has depths ranging from 0.100 inches to 0.350 inches, as measured from the exterior surface 22 of inner member 14 to the bottommost point of groove 60. Preferably, groove 60 has widths generally ranging from 0.015 inches to 0.650 inches. Groove 60 forms spaces (or walls) 62 on the exterior surface 22 of the inner member 14, which run between the groove 60 and between the groove and the edges of inner member 14. Preferably, these spaces (or walls) 62 have widths ranging between 0.025 inches and 0.500 inches. By varying the pitch (see FIG. 23) of groove 60, groove 60 can run over different percentages of the exterior surface of inner member 14. With reference to Fig. 24A and 24B, it is well-known in the art that the "pitch" of a circular helix refers to the angle 84 that a helix makes with the plane perpendicular to the axis of the helix. The winding number is the number of turns a helix makes for a given interval along its axis. For a helix with a uniform pitch, the pitch and winding number are inversely proportional, that is, the lower the pitch (i.e., closer the pitch is to zero degrees) the higher the winding number. The helix 82 and helix 86 have different pitches 84 and 88. Because helix 86 has a lower pitch 88 than the pitch 84 of helix 82, helix 86 has a higher winding number than helix 82.

In alternative embodiments with reinforcement material or wrapping, comprising fiber arrays (e.g., carbon fibers, vitreous glass fibers (basalt wool comprising SiO₂, AI₂O₃, CaO, MgO and Fe₂O₃), alumina oxide fibers and e-glass (e.g., fiber glass), and combinations thereof), the outer surface of the inner member may have a suitable alignment pattern cast into the outer surface thereof, the cast alignment pattern operatively complementary with the reinforcement material or wrapping to facilitate, for example, keeping the fiber arrays in a fixed position relative to the inner member.

Sensor Materials

Further embodiments incorporating a groove 60 or other alignment pattern on the exterior surface 22 of inner member 14, additionally incorporate sensor materials or devices (β-g-, magnetic resistive devices or means, or heat transference devices or materials such as sodium metal) placed within receiving means such as, for example, recessed cavities 64 in the spaces (or walls) 62 between the groove 60 on the exterior surface 22 of inner member 14.

These recessed means or cavities are suitably sized to accommodate sensor materials or devices. Preferably, the sensor material or device is at least one of a heat sensing material or device, a speed or motion sensing material or device, a vibration sensing material or device, or a pressure sensing material or device. Preferably, the heat sensing device or material is a thermal voltaic cell, or a thermal voltaic material, respectively.

In additional embodiments, the inner member 14 further comprises at least one recessed means or cavity 64 on its outer surface 22, wherein the cavity is sized to hold a heat transfer-enhancing material. Preferably, the heat transfer-enhancing material is metallic sodium.

In particular embodiments comprising a groove 60, a wire or multi-wire preformed cable 16 is wrapped tightly around inner member 14 such that the wire or multi-wire, preformed cable 16 lies within grove 60. By welding the ends of the wire or multi-wire, preformed cable 16 to the inner member 14, it is possible to get a single-layer wire wrapping that covers a substantial portion of the exterior surface 22 of inner member 14 and provides added strength to inner member 14.

In other embodiments, a reinforcement material or wrapping (e.g., a wire or multi- wire, preformed cable or mesh 16) is wrapped tightly around the inner member 14 such that the reinforcement wrapping lies within the groove 60. The wrapping (e.g., wire) is continued to be wrapped in a crisscross manner over previous layers. With reference to Figures 17-20, a first layer of wire or multi-wire, preformed cable 16 is wrapped around inner member 14 so as to fit within a groove (not shown). With reference to FIG. 18, a second layer of wire 16 is wrapped at about a ten (10) to thirty (30) degree angle from the first layer. With reference to FIG. 19, a third layer of wire 16 is wrapped at about a twenty (20) to sixty (60) degree angle from the second layer. With reference to FIG. 20, a fourth layer is wrapped substantially similar to the first layer.

Other embodiments comprise a plurality of generally continuous, circular, helical grooves 60 on the exterior surface 22 of inner member 14 arranged generally parallel to one another. In these embodiments, multiple lengths of reinforcement wrapping (e.g., wire 16, multi-wire, preformed cables, mesh, etc., 16), or a combination thereof can be wrapped tightly around inner member 14 in a one-to-one correspondence with grooves 60 such that each separate length of reinforcement wrapping is contained within a groove 60 and each groove 60 contains, for example, a wire or multi-wire preformed cable 16.

After the reinforcement material or wrapping (e.g., mesh, wire, cable, etc.) 16 is wrapped around the inner member 14, the outer shell 18 is placed (e.g., cast) over the wire 16 to protect, for example, the wire 16 and provide additional strength to the brake drum 10. Typically, the reinforced inner member 14 is placed in a mold (not shown) and the outer shell 18 is molded around the exterior surface 22 and the reinforcement wrapping 16.

As described in more detail herein above, the outer shell 18 can be made from a number of lightweight materials such as 356-355 aluminum (see herein above for more detailed list). Alternately, the outer shell can be comprised of a lightweight material having a density of less than about 0.15 pounds per cubic inch with a high resistance to corrosive road conditions. For example, aluminum or aluminum alloys or other lightweight materials and alloys such as magnesium, tinsalloy can be used in the invention as well as composite materials such as carbon fiber epoxy resin composites. In particular embodiments, an MMC inner member is initially cast as MMC.

In alternative preferred embodiments, an MMC inner member is provided by infiltration casting of molten aluminum alloy (the outer shell material) into a porous preform positioned within a die cast mold cavity for in situ casting. Preferably, the porous perform comprises or consists of silicon carbide and/or aluminum oxide that has been cast to form the porous preform. Preferably, the porous perform has the dimensions of the inner member, and has a porosity percentage of about 72% (corresponding to & particle percentage of about 28% in the final MMC inner member). Alternatively, the porosity percentage can vary between about 75% and about 50% (corresponding to a particle percentage of about 25% to about 50% in the final MMC inner member). The MMC in such embodiments is produced upon infiltration of the molten aluminum alloy into the pores of perform to provide for an MMC having the desired particle composition. Some substantial advantages of the perform method disclosed herein is that there is no problem of keeping particles (e.g., silicon carbide and/or aluminum oxide) suspended during casting of the inner member, and the provision of uniformity of particle distribution during casting. Preferably, the outer shell and the inner member comprise at least one member of the

535-alloy family (ALCAN aluminum) selected from the group consisting of 535.0, 535.2, A535.0, A535.1, B535.0, B535.2. Preferably, an essentially Be (beryllium)-free alloy, such as A535 and B535 (low Mn) are used. Preferably, A535.1 is used. 535 alloys retain a bright physical appearance without deterioration in outdoor service. 535 alloys have high corrosion resistance and have superior aging properties (less fatigue).

In preferred embodiments, infusion casting is preferred where the inner member comprises 'carbon graphite foam. For example, an aluminum-based alloys {e.g., eutecic, hypereutectic, or otherwise), with or without particulate reinforcement are cast into {e.g., infiltration casting) a 'preform' of porous 'carbon graphite foam^'' (with or without particulate reinforcement, such as silicon carbide).

Preferably, the inner member 14 and the outer shell 18 are made of a material having similar rates of thermal expansion so that the inner member 14 and the outer shell 18 expand at the same rate to prevent separation of the inner member 14 and the outer shell 18.

Similar to prior art brake drums, the outer shell 18 is typically cylindrical shaped. For the version described herein, an outer shell 18 having a thickness 44 of between about 0.75 inches to about 1.25 inches is sufficient.

With reference to Figures 25-27, other embodiments comprise a bonding layer 66 preferably made of a metal alloy {e.g., 1100 aluminum) having a melting temperature lower than that of the material comprising either the inner member 14 or the outer shell 18.

Bonding layer 66 is fused between the inner member and the layers of wire, or multi-wire, preformed cable 16. In other embodiments, a bonding layer (not shown) is fused between the layers of wire, or multi-wire, preformed cable 16 and outer shell 18. In yet other embodiments, a bonding layer 66 is fused between the inner layer and the wire wrapping and a second bonding layer (not shown) is fused between the layers of wire, or multi-wire, preformed cable 16 and the outer shell 18.

According to the present invention, the fused bonding layer permeates, at least to some extent into each of the first and second materials, thereby enhancing thermal conductivity between first and second materials.

Preferably, the bonding layer is 1100 aluminum of a thickness from about 0.005 to about 0.035 inches. Preferably, the bonding layer comprises a metal alloy {e.g., 1100 aluminum) having a melting temperature lower than that of either the material from which the inner member and the outer shell are made of or the material from which the wire is made of, and is preferably fused between the wire wrapped around the inner member and the outer shell. Preferably, the bonding layer is applied by flame spraying. Preferably the bonding layer is applied to the exterior surface of the inner member (including over the cast grooves), prior to wrapping of the wire or cable into the grooves. Alternatively bonding layers are applied to the exterior surface of the inner members, both before and after wrapping of the wire or cable.

Preferably, for bonding layers comprising 1100 aluminum and the like, the bonding layer also comprises an amount of zinc or tin suitable to confer enhanced bonding (most likely by lowering the melting temperature of the bonding layer). In alternative embodiments, the boding layer is an adhesive {e.g., high-temperature adhesive). Preferably, such adhesives are used in combination with, for example, ceramic matrix composite (CMC) wear plates or carbon graphite foam-based wear plates. Preferably, the bonding layers, whether fused aluminum based or high-temperature adhesive comprise one or more additional materials to enhance thermal conduction. Preferably, the material comprises ' carbon graphite foam. '

In particular embodiments, the bonding layer 66 is spray coated or dipped onto the wrapped layer or layers of reinforcement wrapping (e.g., wire or multi-wire, preformed cable, mesh, etc.,) 16. In other embodiments, the bonding layer 66 is cast as a thin shell over the layer or layers of, for example, wire or multi-fire, preformed cable 16, and is fused to the layer or layers of wire or multi-wire, preformed cable 16 and the outer shell 18, by casting the outer shell 18 in situ in a mold containing the inner member 14 tightly wrapped in wire or multi-wire, preformed cable 16 and a thin shell of the bonding layer 66.

Similarly, in embodiments comprising a bonding layer 66 between inner member 14 and the wire wrapping 16, the bonding layer 66 is spray coated or dipped onto the inner member 14 before the wire or multi-wire, preformed cable 16 is wrapped around inner member 14 (over bonding layer 66). In these embodiments, the bonding layer 66 could also be cast as a thin shell around inner member 14, which bonds to inner member 14 and wire wrapping 16 under the pressure of wrapping wire 16 around inner member 14 and from the additional heat and pressure of casting outer shell 18 in situ in a mold containing the inner member 14 with the thin shell of the bonding layer 66 and the wire 16 wrapped around both.

In embodiments where the reinforcement wrapping comprises Basalt fibers alumina oxide fibers, e-glass, composite fibers, etc., that are made into wire, cable or arrays (e.g., mesh), the reinforcement wrapping is preferably impregnated with 1100 aluminum dust to improve 'wetting' during the casting process.

In embodiments comprising a groove 60 or a plurality of grooves 60 on the exterior surface of inner member 14 and, for example, wire(s) or multi-wire, preformed cable(s) 16 tightly wound around inner member 14 so that they are contained with the groove(s) 60, the bonding layer 66 can be spray coated or dipped onto both the wire(s) or multi-wire, preformed cable(s) and the spaces (or walls) between the groove(s) 60.

In other embodiments, the bonding layer 66 can preferably be cast as a thin shell around an inner member 14 comprising a groove or plurality of grooves 60 containing, for example, wire 16; multi-wire, preformed cables 16; or a combination thereof, and fused into place by casting the outer shell 18 in situ in a mold containing the inner member, wires or multi-wire, preformed cables, and the thin shell of bonding layer 66 material.

In preferred embodiments, the bonding layer is preferably sprayed or dipped on to the outer surface 22 of the inner member 14 that incorporates a groove or plurality of grooves, or other reinforcement wrapping retention pattern 60 before the, for example, wire or multi- wire, preformed cable 16 is wrapped around the inner member 14 so as to fit within the groove or plurality of grooves 60.

In yet other embodiments, the bonding layer preferably comprises a thin shell 66 cast around the inner member 14, which has, for example, a groove or plurality of groove 60, before the wire or multi-wire, preformed cable 16 is wrapped around the thin shell 66 and the inner member 14. In these embodiments, the bonding layer 66 bonds to the inner member 14 and the wire 16 because of the pressure generated in wrapping the wire snuggly around the shell 66 and inner member 14 so that the wire fits within the groove or plurality of grooves 60. Bonding is further facilitated by casting the outer shell 18 in situ in a mold containing the inner member 14 which is surrounded by the thin shell bonding layer 66 and the wire wrapping 16.

Embodiments comprising a groove or plurality of grooves, or other reinforcement wrapping retention pattern cast 60 on the exterior surface 22 of inner member 14 have certain advantages. These include, without limitation, the wire or multi-wire, preformed cable 16 being securely held in place without the need for multiple layers of wire or multi-wire, preformed cable as illustrated in Figures 2 - 5. This allows for the use of less wire or multi- wire, preformed cable in the manufacture of the brake drums and also helps decrease the weight of the brake drum. For example, by allowing the wire or multi-wire, preformed cable 16 to be held in position by the groove or plurality of grooves 60 with gaps between the wire or multi-wire, preformed cable 16, the groove or plurality of grooves allow for a more uniform contact between the outer surface 22 of inner member 14 and inner surface 68 of the outer shell 18. More uniform contact facilitates greater thermal and acoustic transfer between inner member 14 and outer shell 18, which in turn reduces brake noise and helps prevent degradation of the inner member 14 from overheating.

The grooves or plurality of grooves, or other reinforcement material/wrapping retention patterns 60 also aid in the even spacing of wire 16; multi-wire, preformed cable 16; or a combination thereof. Even spacing aids in ease of manufacture of the brake drums. The uniform spaces between the wires or multi-wire, preformed cables 16, also facilitates thermal and acoustic transfer. In particular embodiments, the depth of the groove or plurality of grooves 60 and the diameter of the wire or multi-wire, preformed cable 16 is suitably adjusted so that some portion of the wire or multi-wire, preformed cable 16 extends beyond the outer surface 22 of inner member 14. This arrangement helps the outer shell 18 to "grip" the inner member 14 and prevents the inner member 14 slipping or turning within the outer shell, without the need for cast interfacing ridges or spines to lock the inner member 14 to the outer shell 18 {see, e.g., U.S. Pat. No. 1,989,211). The use of grooves 60 and wire or multi- wire, preformed cable 16 to help "lock" the inner member 14 and outer shell 18 together, leads to much simpler and cost-effective methods of manufacture than when the inner member and outer shell have ridges and spines. Embodiments incorporating a bonding layer 66 of some metal alloy (e.g., 1100 aluminum) that has a lower melting temperature than the material used to manufacture inner member 14 and outer shell 18 have certain advantages. The advantages include, without limitation, increased thermal and acoustic transfer from the inner member 14 to the outer shell 18. This aids in decreasing brake noise and helps prevent the degradation of the inner member 14 due to overheating. The use of a bonding layer 66 also enhances the bond between the inner member 14 and outer shell 18, thus negating the need for ridges and spines to "lock" the inner member 14 and outer shell 18 together. This allows for simpler and more cost-effective methods of manufacturing these brake drums. Preferably, the bonding layer comprises or is formed of 1100 aluminum. Preferably the thickness of the 1100 aluminum bonding layer is from about 0.005 to about 0.035 inches. In alternate embodiments, particularly those having inner members comprising or consisting of CMC (or carbon graphite foam), the bonding layer may comprise or consist of epoxy. The brake drum 10 includes at least one fastener 42 for securing the brake drum 10 to a portion of the wheel assembly 13. In FIG. 21, each wheel assembly 13 includes a wheel 46, a brake assembly 48, and an axle 50 and a wheel mounting pad 52 having a guidance ring 54 and a plurality of wheel bolts 56. Similar to prior art brake drums, the outer shell 18 can include a front surface 36 having a plurality of guidance bolt apertures 38 and a guidance ring aperture 40 extending there through. The wheel bolts 56 extend through bolt apertures 38 and a guidance ring 54 extends through the guidance ring aperture 40 to secure the brake drum 10 to the wheel assembly 13. Alternatively, the front surface 36 could be manufactured as an integral part of the inner member 14 or the brake drum 10 could be attached to the wheel assembly 13 in another fashion. The invention provides an unusually light brake drum 10 which is comparable to typical brake drums made of steel in terms of internal yield strength, durability and braking power. Compared to typical heavy-duty truck brake drums which weight approximately one hundred twenty (120) pounds, an equivalent brake drum embodiment of the present invention having an inner member 14 made of an aluminum alloy/abrasive composition having a thickness of about 0.50 inches, multiple layers of wire 16 having an overall thickness 34 of about 0.3 inches and an aluminum alloy outer shell 18 having a thickness of about 1.25 inches weighs between about forty (40) pounds and about seventy-five (75) pounds. Accordingly, with a heavy-duty semi trailer rig, having four brake pads on the cab and four brake drums on the trailer, an increase in cargo handling capability of between about three hundred sixty (360) pounds and about six hundred forty (640) pounds can be realized. Such increase in cargo capacity can greatly affect the trucker's net profit.

Different sized brake drums are within the scope of the present invention, including those suitable for automobiles, SUVs, light trucks, medium duty trucks (e.g., class 7) and heavy duty trucks (e.g., class 8), and larger. In preferred embodiments the drums are sized to be used in association with lift-axels.

Secondary Brakes (e.g., drag-type brakes)

Compression brake means (e.g., 'Jake' brakes, and exhaust compression brakes) are known in the art as secondary engine brakes, but are disfavored because they are noisy and can produce a stand-off condition with exhausted unburned fuel (exhaust valves are held open in the case of Jake brakes). Such means are relatively heavy.

Additionally, electromagnetic drive-line break means, or magnetic brakes, are known, where such breaks comprise mounted magnetic means placed, for example, behind a transmission and in communication with iron plates spinning at drive shaft speed. Such means are also relatively heavy.

A fundamental disadvantage of Jake breaks, exhaust compression brakes, or magnetic drive-line devices (aside from excessive weight, complexity and in some instances pollution), is that any drag produced thereby is transferred only to the drive axel, or to a set of dual drives, and not to all wheels. Therefore, there is a pronounced need in the art for additional means to provide secondary braking in the trucking industry.

Electromagnetic Damper Brake for Commercial Truck and Trailers.

Unlike conventional brakes which operate by causing friction between moving parts, in an electromagnetic damper brake kinetic energy is converted to heat without contact between the moving parts. With reference to Figures 28 and 29, in preferred embodiments of the present invention, electromagnetic means are used to produce/induce a pattern field or Eddy current in optimally arrayed communication with (e.g., placed 'in shear' with) the rotating inventive drum, disk, etc., so that the induced field current opposes the motion direction of the brake drum (or a brake disk) providing a drag brake (e.g., secondary drag- brake). Such means are relatively light. Such means would not be possible using conventional iron drums. Preferably, the rotating drums 92, discs, etc., are composed of a metal (e.g., aluminum) matrix composite with a conductive, specific resistance material. Such rotating members, for example, shaped and configured as a drum or disc (rotor) are attached to a rotating axis and electromagnets 90 are positioned normal to the rotating member, and on both sides thereof, to generate a magnetic field intersecting the rotating dram or disc (rotor). The electromagnets 90 allow for control (see electronic control module (EMC) 93) of the damper brake by varying the strength of the magnetic field. Electric current is passed through the electromagnets 90 by means of a controller 93 located between the power source (e.g., battery) and electromagnets 90. As the metal (e.g., aluminum) matrix composite drum 92 or disc (rotor) rotates inside the magnetic field, electric currents (Eddy currents) are induced inside it. Those currents then produce a magnetic field in opposition to the original field creating a force which acts to decelerate the metal (e.g., aluminum) matrix composite rotating brake drum 92 or disc (rotor). The induced current is proportional to the surface speed of the metal (e.g., aluminum) matrix composite brake drum 92 or disc (rotor), and increases as surface speed increases, also decreases brake torque as surface speed decelerates. The interaction of the two magnetic fields causes a force that resists the change in magnetic flux.

In particular embodiments, the drum additionally comprises magnetic elements or particles, and the pattern field is in communication with said magnetic elements or particles to provide for an enhanced drag brake (e.g., secondary drag-brake).

Preferably, the present inventive Eddy current brakes and drag breaks are positioned on each wheel end, and have independent control as to the amount of drag provided for each brake, and additionally interface with the ABS system (e.g., advanced ABS) of the vehicle (e.g., car, truck, trailer, etc.), providing an increased level of safety from skids, jackknifϊng, etc, and providing enhanced control.

In particular Eddy current brake embodiments, such as those shown in Figures 28 and 29, each of an opposed pair of electromagnets is positioned on one arm of a C-shaped fixture held in proximity to the drum but without touching (e.g., at the outer drum edge (Figure 28) or at the noise band area (Figure 29)) such that the rotating edge of the brake drum (or rotor) passes between the two intersecting magnetic fields generated by the opposed electromagnets, thereby placing the magnetic field generated by the induced Eddy current in the rotating drum in 'shear' with the magnetic fields generated by the opposed electromagnets. In alternate embodiments, such as that shown in figure 30, one electromagnet 90 of a pair of electromagnets is mounted in or on a brake shoe fixture 96 (e.g., including brake pads 98), while the opposed magnet of the pair is mounted at a stationary generally opposed position outside the drum, such that the rotating brake drum (e.g., a central annular portion of drum or rotor) passes between the two intersecting magnetic fields generated by the generally opposed electromagnets, thereby placing the magnetic field generated by the induced Eddy current in the rotating drum in 'shear' with the magnetic fields generated by the opposed electromagnets.

In certain embodiments, the Eddy current brakes, either alone or augmented by inductive means designed to be 'regenerative' to provide a source of electricity for vehicular reuse, and reduction of parasitic alternator drag, etc., to enhance efficiency and economy.

While the present invention has been described in considerable detail with reference to certain preferred versions, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of preferred versions contained herein.

Claims

1. A selectively reinforced composite, comprising a matrix material and an integral porous preform having one or more reinforcement constituents and having an internal porous preform portion defined by at least one porous external preform surface portion, wherein the porous preform is infiltrated by the matrix material, and wherein the at least one porous preform surface portion or at least one portion thereof has been subjected, prior to infiltration by the matrix material, to selective particle enhancement comprising directed deposition or impingement of selected enhancement particles onto the porous surface and/or penetrating further into the porous preform to provide for selected particle deposition into and integration within the porous preform.

2. The reinforced composite of claim 1, wherein the at least one porous external preform surface portion that has been subjected to selective particle enhancement or a portion thereof is coincident with at least one external surface portion or a portion thereof of the reinforced composite.

3. The reinforced composite of any one of claims 1 or 2, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, wherein at least one of the two opposed porous external preform surface portions or at least one portion thereof has been subjected to selective particle enhancement and is coincident with at least one external surface portion or a portion thereof of the reinforced composite, and wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in a direction toward the porous preform surface portion that opposes the coincident porous external preform surface portion or portion thereof.

4. The reinforcement composite of any one of claims 1, 2 and 3, wherein the reinforcement composite is a brake drum, and wherein the coincident surface of the preform is configured within the drum to provide a wear-resistant surface at a friction material- contacting position thereof.

5. The reinforcement composite of any one of claims 1, 2 and 3, wherein the reinforcement composite is a disk brake rotor, and wherein the coincident surface of the preform is configured within the rotor to provide a wear-resistant surface at a friction material-contacting position thereof.

6. The reinforcement composite of any one of claims 1, 2 and 3, wherein the porous preform is a cylinder liner, wherein the reinforcement composite is a cylinder block or a cylinder liner-containing portion thereof, and wherein the coincident surface of the preform is configured within the cylinder block or a cylinder liner-containing portion thereof to provide a wear-resistant surface at a friction material-contacting position thereof.

7. The reinforcement composite of any one of claims 1, 2 and 3, wherein the reinforcement composite is a clutch pressure plate or clutch center plate, and wherein the coincident surface of the preform is configured within the clutch pressure plate or clutch center plate to provide a wear-resistant surface at a friction material-contacting position thereof.

8. The reinforcement composite of any one of claims 1, 2 and 3, wherein the reinforcement composite is armor, and wherein the coincident surface of the preform is configured within the armor to provide a wear-resistant surface at a friction material- contacting position thereof.

9. The reinforced composite of any one of claims 1-7 and 8, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, and wherein the porous preform comprises a porosity gradient of pore size, pore number or both, increasing in opposite directions from a position between the opposed surface portions towards each of the opposed porous external preform surface portions.

10. A selectively reinforced composite, comprising a matrix material and an integral porous preform having one or more reinforcement constituents and having an internal porous preform portion defined by at least one porous external preform surface portion, wherein the porous preform is infiltrated by the matrix material, and wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in an direction away from the at least one porous external preform surface portion.

11. The reinforced composite of claim 10, wherein the at least one porous preform surface portion or at least one portion thereof has been subjected, prior to infiltration by the matrix material, to selective particle enhancement comprising directed deposition or impingement of selected particles onto the porous surface and/or penetrating further into the porous preform to provide for selected particle deposition into and integration within the porous preform.

12. The reinforcement composite of any one of claims 10 or 11, wherein the at least one porous external preform surface portion or the at least one portion thereof is coincident with at least one external surface portion or a portion thereof of the reinforced

\ composite.

13. The reinforcement composite of any one of claims 10, 11 or 12, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, wherein at least one of the two opposed porous external preform surface portions or the at least one portion thereof has been subjected to selective particle enhancement and is coincident with at least one external surface portion or a portion thereof of the reinforced composite, and wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in a direction toward the porous preform surface portion that opposes the coincident porous external preform surface portion or portion thereof.

14. The reinforcement composite of any one of claims 10, 11, 12 and 13, wherein the reinforcement composite is a brake drum, and wherein the coincident surface of the preform is configured within the drum to provide a wear-resistant surface at a friction material-contacting position thereof.

15. The reinforcement composite of any one of claims 10, 11, 12 and 13, wherein the reinforcement composite is a disk brake rotor, and wherein the coincident surface of the preform is configured within the rotor to provide a wear-resistant surface at a friction material-contacting position thereof.

16. The reinforcement composite of any one of claims 10, 11, 12 and 13, wherein the porous preform is a cylinder liner, wherein the reinforcement composite is a cylinder block or a cylinder liner-containing portion thereof, and wherein the coincident surface of the preform is configured within the cylinder block or a cylinder liner-containing portion thereof to provide a wear-resistant surface at a friction material-contacting position thereof.

17. The reinforcement composite of any one of claims 10, 11, 12 and 13, wherein the reinforcement composite is a clutch pressure plate or clutch center plate, and wherein the coincident surface of the preform is configured within the clutch pressure plate or clutch center plate to provide a wear-resistant surface at a friction material-contacting position thereof.

18. The reinforcement composite of any one of claims 10, 11, 12 and 13, wherein the reinforcement composite is armor, and wherein the coincident surface of the preform is configured within the armor to provide a wear-resistant surface at a friction material- contacting position thereof.

19. A method for making a selectively reinforced composite, comprising: obtaining a porous preform having one or more reinforcement constituents and having an internal porous preform portion defined by at least one porous external preform surface portion; subjecting the at least one porous preform surface portion or at least one portion thereof to selective particle enhancement comprising directed deposition or impingement of selected enhancement particles onto the porous surface and/or penetrating further into the porous preform to provide for selected particle deposition into the porous preform; and infiltrating, subsequent to the selective particle enhancement, the porous preform with a matrix material to provide for a selectively reinforced composite casting.

20. The method of claim 19, wherein infiltrating is by at least one means selected from the group consisting of centrifugal casting; high pressure die casting; vacuum die casting; squeeze casting; high vacuum permanent mold casting; low vacuum permanent mold casting; vacuum riserless/pressure riserless casting, surface spray, and deposition methods.

21. The method of any one of claims 19 and 20, wherein the at least one porous external preform surface portion that has been subjected to selective particle enhancement or a portion thereof is coincident with at least one external surface portion or a portion thereof of the finished reinforced composite.

22. The reinforced composite of any one of claims 19, 20 and 21, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, wherein at least one of the two opposed porous external preform surface portions or at least one portion thereof has been subjected to selective particle enhancement and is coincident with at least one external surface portion or a portion thereof of the reinforced composite, and wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in a direction toward the porous preform surface portion that opposes the coincident porous external preform surface portion or portion thereof.

23. The reinforcement composite of any one of claims 19, 20, 21 and 22, wherein the reinforcement composite is a brake drum, and wherein the coincident surface of the preform is configured within the drum to provide a wear-resistant surface at a friction material-contacting position thereof.

24. The reinforcement composite of any one of claims 19, 20, 21 and 22, wherein the reinforcement composite is a disk brake rotor, and wherein the coincident surface of the preform is configured within the rotor to provide a wear-resistant surface at a friction material-contacting position thereof.

25. The reinforcement composite of any one of claims 19, 20, 21 and 22, wherein the porous preform is a cylinder liner, wherein the reinforcement composite is a cylinder block or a cylinder liner-containing portion thereof, and wherein the coincident surface of the preform is configured within the cylinder block or a cylinder liner-containing portion thereof to provide a wear-resistant surface at a friction material-contacting position thereof.

26. The reinforcement composite of any one of claims 19, 20, 21 and 22, wherein the reinforcement composite is a clutch pressure plate or clutch center plate, and wherein the coincident surface of the preform is configured within the clutch pressure plate or clutch center plate to provide a wear-resistant surface at a friction material-contacting position thereof.

27. The reinforcement composite of any one of claims 19, 20, 21 and 22, wherein the reinforcement composite is armor, and wherein the coincident surface of the preform is configured within the armor to provide a wear-resistant surface at a friction material- contacting position thereof.

28. The reinforced composite of any one of claims 19-77 and 28, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, and wherein the porous preform comprises a porosity gradient of pore size, pore number or both, increasing in opposite directions from a position between the opposed surface portions towards each of the opposed porous external preform surface portions.

29. A method for making a selectively reinforced composite, comprising: obtaining a porous preform having one or more reinforcement constituents and having an internal porous preform portion defined by at least one porous external preform surface portion, wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in an direction away from the at least one porous external preform surface portion; and infiltrating the porous preform with a matrix material to provide for a selectively reinforced composite casting.

30. The method of claim 29, wherein the at least one porous preform surface portion or at least one portion thereof has been subjected, prior to infiltration by the matrix material, to selective particle enhancement comprising directed deposition or impingement of selected particles onto the porous surface and/or penetrating further into the porous preform to provide for selected particle deposition the porous preform.

31. The reinforcement composite of any one of claims 29 or 30, wherein the at least one porous external preform surface portion or the at least one portion thereof is coincident with at least one external surface portion or a portion thereof of the reinforced composite.

32. The reinforcement composite of any one of claims 29, 30 or 31, wherein the internal porous preform portion comprises two generally opposed porous external preform surface portions, wherein at least one of the two opposed porous external preform surface portions or the at least one portion thereof has been subjected to selective particle enhancement and is coincident with at least one external surface portion or a portion thereof of the reinforced composite, and wherein the porous preform comprises at least one porosity gradient of pore size, pore number or both, increasing in a direction toward the porous preform surface portion that opposes the coincident porous external preform surface portion or portion thereof.

33. The reinforcement composite of any one of claims 29, 30, 31 and 32, wherein the reinforcement composite is a brake drum, and wherein the coincident surface of the preform is configured within the drum to provide a wear-resistant surface at a friction material-contacting position thereof.

34. The reinforcement composite of any one of claims 29, 30, 31 and 32, wherein the reinforcement composite is a disk brake rotor, and wherein the coincident surface of the preform is configured within the rotor to provide a wear-resistant surface at a friction material-contacting position thereof.

35. The reinforcement composite of any one of claims 29, 30, 31 and 32, wherein the porous preform is a cylinder liner, wherein the reinforcement composite is a cylinder block or a cylinder liner-containing portion thereof, and wherein the coincident surface of the preform is configured within the cylinder block or a cylinder liner-containing portion thereof to provide a wear-resistant surface at a friction material-contacting position thereof.

36. The reinforcement composite of any one of claims 29, 30, 31 and 32, wherein the reinforcement composite is a clutch pressure plate or clutch center plate, and wherein the coincident surface of the preform is configured within the clutch pressure plate or clutch center plate to provide a wear-resistant surface at a friction material-contacting position thereof.

37. The reinforcement composite of any one of claims 29, 30, 31 and 32, wherein the reinforcement composite is armor, and wherein the coincident surface of the preform is configured within the armor to provide a wear-resistant surface at a friction material- contacting position thereof.

38. A reinforcement composite made by using the method of any one of claims 19-22, 29-31 and 32.

39. A brake drum or brake rotor system, comprising: a selectively reinforced aluminum or magnesium brake drum or brake rotor according to any one of claims 4, 5, 14 and 15; and a pair of generally opposed magnetic field-generating means, suitably configured and operatively to induce an Eddy current within the rotating drum or rotor.

40. The system of claim 39, wherein the pair of generally opposed magnetic field- generating means is positioned proximate to the outer edge of the drum or rotor, or proximate to the noise band area of the drum.