JPH06505198A - Continuous manufacturing equipment for castable metal matrix composites - Google Patents

Abstract

A method and apparatus for preparing a continuous flow of castable composite materials of nonmetallic particles in a metallic matrix, wherein particles are mixed into a molten metallic alloy to wet the molten metal to the particles, and the particles and metal are sheared past each other to promote wetting of the particles by the metal. The mixing occurs while minimizing the introduction of gas into the mixture, and while minimizing the retention of gas at the particle-liquid interface. Mixing is done at or below a maximum temperature whereat the particles do not substantially chemically degrade in the molten metal during the time required for processing, and casting is done at a temperature sufficiently high that there is no solid metal present in the melt.

Description

[Detailed description of the invention] Continuous manufacturing equipment technology for castable metal matrix composites The present invention relates to metal matrix composite materials, and more particularly to metal matrix composite materials produced by continuous flow mixing. Concerning the manufacture of such materials.

Metal matrix composites are becoming increasingly accepted as structural materials. There is. Metal matrix composites are typically embedded in a metal matrix. It consists of reinforcing particles such as fibers, coarse particles, and powders. Strength and rigidity due to reinforcement material and other desired properties to the composite material, while the matrix protects the fibers and Transfer the load within the composite material. These two components, the matrix and the reinforcement, are work together to achieve improved results over what could be achieved alone. I can do that.

Background technology Twenty years ago, these materials were so expensive to manufacture that designers had little choice. Because it was not recognized, it was little more than a curiosity in the laboratory. recently, Many applications for such materials are being discovered and they are being used in increasing amounts.

The high cost of producing composite materials remains an issue and therefore slow to be applied and compete with more common alternatives such as high-strength alloys A manufacturing method for producing composite materials having an acceptable quality and at an acceptable price. There is an increasing need for

Unreinforced metal alloys are typically produced by melting and casting procedures. Melting and casting Because the reinforcing particles can chemically react with the molten metal during melting and casting, It is not easily applicable in the production of reinforced composite materials. Another problem is melting. The problem is that metals often cannot wet the surface of the particles immediately, so The two mixtures separate immediately after casting or have poor mechanical properties. That will happen.

In the past, particulate material was added to the molten alloy and the resulting mixture was Attempts to produce metal alloy-particulate composites by fabrication have not been particularly successful. won. The main difficulty with such an approach is that the molten metal alloy is It was assumed that any desired particles could not be easily wetted.

As a result, if it is not possible, the introduction of particles into the liquid matrix and It was very difficult to hold.

The ability to produce such composite materials by melting and casting would be an important technology As a result, the production of such composite materials will have physical and economic advantages. Many attempts have been made to achieve waterlogging properties by coating the particles with nickel. It has been suggested that

Another technique involves saturating the melt with anions of refractory particles. This includes promoting wetting of the refractory particles. In other methods, refractory particles Melt elements such as lithium, magnesium, silicon and calcium before adding Contains additions to. Yet another method involves the presence of solid metal particles. An alloy in which silicon carbide particles are kept at a temperature below the liquid temperature of the alloy. to a vigorously stirred, partially solidified slurry of Ru. Yet another attempt to improve the wettability of microparticles involves the use of water, oxygen, adsorbed gases, and Mixing large particulate material and fibers in the melt with the molten alloy to remove skins Prior treatment includes ion bombardment, mechanical agitation, vacuum and heat exposure.

In one approach to manufacturing aluminum alloy-alumina fiber composites, A paddle-shaped stirring blade is used, which moves the fibers into the melt. to induce high shear forces to be introduced into the crucible wall to form a vortex. Designed to always move close together. This process also requires baffles. This baffle is inclined at an angle of approximately 45° towards the direction of flow, and the surface of the melt is It is immersed in the lower position without being soaked. The role of baffles is to control the flow pattern in the melt. , and to help the fibers become trapped below the surface of the melt.

Yet another approach is to use composite materials such as aluminum-silicon carbide particle composites. is produced using hot water washing of the particle dispersion. The particles are added to the melt before they are added to the melt. Preheat at 900° C. for 60 minutes to aid introduction into the melt. The vortex is a machine The melt is rapidly stirred using an impeller, which forms a deep vortex. It is generated by Fine particles are immediately mixed into the melt and are removed by the molten metal. Particles are added through the side of the vortex to promote wetting of the particles. This person Composite materials manufactured by this method are resistant to fine particles as well as trapped gases. Poor metal bonding.

In a variant of the melting and casting technique, the reinforcement is provided as a mat of filler material and is melted The metal alloy is forced under pressure into the residual space. infiltration ) or compression casting, this method uses composites that are not well bonded internally. A composite material is generated. Furthermore, this method is expensive and difficult to use. That's what I mean This is because devices specific to each individual part must be manufactured.

All of these traditional melting and casting techniques mainly focus on the production of grains in order to obtain complete wettability. for special and costly changes that must be made to the child or molten alloy. , has disadvantages. Moreover, the technology is complex for large-scale, industrial applications. There has been no success in producing composite materials.

Another industrial use for producing composite materials with metal matrix and particulate reinforcement Approaches have used powder and whole techniques. In the powder and gold method examples, Carefully sized aluminum powder is injected into silicon carbide in the presence of an organic solvent. Mix with particles. Solvent avoids pyrophoric reaction between aluminum and oxygen in air It is necessary to The mixture is poured into a drying dish and the solvent is allowed to evaporate over a period of time. It will be done. Dry, unconsolidated sheets approximately 1 mm thick are stacked, Form a plate of desired thickness. This flimsy stack of sheets is placed in a press, The matrix is heated to a liquid-solid state, where the metal becomes liquid. after that, The stack is pressed to consolidate the particles and form a solid plate.

In another powder or gold method, silicon carbide particles and aluminum are mixed as described above. However, the mixed powder is poured into a cylindrical mold and molded into a circular shape using a vacuum hot press. It is solidified into a cylindrical billet. The cost of raw materials, especially aluminum powder, is high ( , due to the complexity of the manufacturing process, the current cost of composite materials does not allow for large-scale production in many regions. It is discouraged from being used. In the powder method, the alloying elements in the metal matrix material are This results in considerable segregation, which has an adverse effect on mechanical and physical properties. undesirable.

Both of the above industrial powder and metal methods have high bow 1 tension stress and sufficient strength. , a composition with low ductility and formability is obtained. required in these methods The combined heating and deformation cycles lead to extensive elemental segregation in the matrix, which This reduces ductility and prevents maximum matrix and composite strength from being achieved. .

Another problem is the retention of surface oxides that coat the original aluminum powder particles. I have it. This oxide further acts to reduce the ductility of the matrix. acid The carbide coating prevents complete wetting of the carbide particles, thus making it even more ideal for composites. It will also be clear that the material properties are limited.

Melting and casting approaches to produce metal composites with good properties Further improvements are needed. Both the method and apparatus produce the composition Composite materials can be manufactured relatively cheaply compared to other methods of manufacturing and competing materials. It must be suitable for manufacturing. This invention satisfies this requirement. and provides further related benefits.

Disclosure of invention The invention has a wetted non-metallic refractory ceramic particle reinforcement dispersed throughout. The present invention provides a method and apparatus for manufacturing a metal matrix composite material. . The process is continuous, reducing manufacturing costs below the high costs of batch manufacturing. It has the potential to increase Continuous flow processes are suitable for manufacturing composite materials for casting and smelting applications. are doing. In the former, composite materials are used in a wide range of conventional and non-conventional technologies. It can be cast using In the latter, the composite material is rolled into semi-finished products. and can be formed by standard industrial procedures such as extrusion.

According to the invention, a composite of metal alloys reinforced with non-metallic particles in a preselected volume The method of manufacturing the material is that the metal material is continuously fed into a mixer and the molten composite material melts the metal alloy in a continuous flow system where the metal alloy is continuously drawn from the mixer. and adding a stream of non-metallic particulate material to the mixer; The relative flow velocity of the metal material and the particulates is preselected by the volumetric part of the particles in the composite material. adjusted to become something. Molten metal alloys containing particulate material are The particles are dispersed throughout the volume of the molten mixture to promote wetting of the particles and the molten The metals are mixed in a mixer under conditions where they are sheared together and the melt on the particles is Improves wetting of molten metal. Mixing involves the introduction of gas into a mixture of particles and molten metal. mixing stage while minimizing gas retention within the mixture. No substantial chemical degradation of the particles in the molten metal during the time required to complete the step It happens with temperature. The mixed material drawn from the mixer is cast by suitable technology. It will be done.

The method of the invention produces composite materials by mixing molten metal alloys with reinforcing particles. It is a continuous flow method for manufacturing. A stream of molten alloy and particles is introduced into a mixer where it Mixing under suitable conditions results in a homogeneous mixture of wet particles in the melt.

The flow rate of the molten alloy and particles is determined by the preselected total flow rate and the molten metal of the preselected particles. The final solid composite material is preselected so that the final solid composite is will have a selected volume of particles.

The metal material is preferably an aluminum alloy, but magnesium alloys etc. Other materials can also be used. Non-metal particle materials include metal oxides, metal nitrides, Preferably, it is a metal carbide, metal silicide, or glass. The most preferred combination The composite material is silicon carbide or aluminum oxide grains in an aluminum alloy matrix. It is a child reinforcement.

Traditional casting methods reduce the viscosity of the metal, making it easier to cast. It is usually desirable to cast the molten metal at a high temperature so that it can be cast. however, The temperature of the method of the invention is selected taking into account the reaction of the particles with the molten alloy. mixture and during the casting stage, the molten metal must not be heated to too high a temperature or and between the particles and the molten metal, degrading the strength of the particles and the properties of the final composite material. Undesirable reactions may occur. Therefore the highest temperature will complete the process to ensure that no appreciable degree of reaction occurs between the particles and the metal melt in the time required for selected. For the present approach, the highest mixing and casting temperature is For metal alloys containing alloying elements with high reactivity, temperatures above the liquidus temperature of 20°C, maximum For common metal alloys, the temperature is 70°C above the liquidus, which promotes interference with the reaction. For metal alloys containing alloying elements, from 100°C to 125°C above the liquidus line, It is. However, due to the short duration of mixing, under some circumstances more High temperatures are acceptable.

In a preferred approach, a vacuum is applied to the molten mixture of metal and particles during the mixing stage. It will be done. Vacuum reduces atmospheric gases that can be introduced into the melt and also tends to extract dissolved, trapped and adsorbed gases from the melt during be. The size of the vacuum is made of metals that do not contain volatile components such as zinc or magnesium. Not important for alloys. However, if volatile elements are present, the vacuum is selected so that its volatile elements are not extracted from the alloy at an unacceptably high rate. be done. The preferred vacuum reduces gas favorably but minimizes the loss of volatile elements. It has been found that it is possible to reduce the

Composite materials produced by the method of the invention have particles that are generally uniform throughout the casting volume. It has a cast microstructure of metal matrix in which potash is uniformly distributed. Matri The particles are manufactured in such a way that they are wetted during manufacturing, so the particles are well absorbed into the matrix. is combined with An important oxide layer is inserted between the particles and the metal matrix. Not yet. Cast composites are particularly suitable for cast composites where the matrix alloy has a castable composition. suitable for casting and casting applications. For composite materials using refined alloy matrices, Processing is completed by known elementary forming operations such as rolling and extrusion.

Continuous preparation of composites of metal alloys reinforced with non-metallic particles in pre-selected volumes The device that produces the flow allows the particles to flow through the mixture in such a way as to promote wetting of the particles by the metal. The molten metal is dispersed throughout the volume and under conditions where the particles and molten metal are sheared together including means for mixing the flow of alloy with the flow of particulate material and wetting the particles with molten metal; The mixing is such that the introduction of gas into the mixture of particles and molten metal is minimized and necessary to complete the mixing step while minimizing retention of gas within the mixture. occurs at a temperature at which substantial chemical degradation of the particles does not occur in the molten metal for a reasonable amount of time. molten gold a metal supply means for introducing a stream of particulates into the mixing means; and a metal supply means for introducing a stream of particulates into the mixing means. A particle supply means is also provided, and the metal flow rate of the metal supply means and the particles of the particle supply means are also provided. The flow rate of the child can be controlled. Remove the flow of mixed composite material from the mixing means. It also includes the means to remove the

Preferably, the equipment uses single-stage or multi-stage mixing. Use multi-stage mixing If so, they can be carried out in one or many chambers. . At each stage, the molten metal and particulates are mixed together to wet the metal into particulates. dispersion impeller or other techniques to achieve sufficient shear of the molten metal. mixed together using a technique. Air or other adversely reacting gases may interfere with the wetting process. Although care must be taken to prevent the can be introduced inside.

The method and apparatus of this invention represents an important and significant advance in the art of manufacturing composite materials. It is clear that it provides a step forward. Composite materials are made with particles before mixing. using conventional metal alloys without coating or otherwise treating Produced economically by equipment that incorporates the particle reinforcement directly into the molten metal. This person The method is economically competitive with methods of producing unreinforced alloys and is significantly more effective than other techniques. and economically produce composite materials. Other features and advantages of this invention can be found below, in the appendix. The invention is explained in more detail by way of example in conjunction with the drawings, and the more detailed description provides a clear explanation of the invention. It will become clear.

Brief description of the drawing FIG. 1 is a schematic side cross-sectional view of the melt in the crucible before, during, and after conventional impeller mixing. ; Figure 2 is a front view of the distributed impeller; Figure 3 is a side sectional view of a mixing device using a dispersion impeller, with some parts cut away for clarity. Figure 4 shows another mixing device. FIG. 5 is a side sectional view of another mixing device; FIG. 6 is a side sectional view of another mixing device. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION This invention involves mixing particulate nonmetallic reinforcement into a melt volume of matrix material. The present invention is embodied in a method and apparatus for manufacturing a composite material. standard In order to produce composite materials that are suitable for There must be. If wetting is not achieved, the particles will be moved below the surface by the mixer. Even after being pushed away by It is difficult to do so. Non-wetting particulates also reduce the ability of cast solid composite materials. Mechanical properties become insufficient. In particular, the ratio of length to thickness, also called aspect ratio. This is true for particulate matter where the distance between the two ends is relatively short. Short on the order of 1-5 For particles with aspect ratios, in order to obtain good strength and stiffness values, There must be good bonding at the particle-matrix interface. A good bond is This cannot easily be achieved in the absence of wetting of the molten matrix to the particles. I can't.

Wetting of metal particles occurs when the adhesive force between the two phases is greater than the cohesive force within the liquid. It is a phenomenon involving a solid and a liquid in perfect contact. aluminum and Under suitable conditions, molten metals such as aluminum alloys can form poly(typical non-metallic particles) It has wettability and spreads on the child reinforcement material. However, on the surface between the metal and the particle The presence of contaminants interferes with wetting. In particular, gases and oxides attached to the surface Prevents wetting of molten metal onto its surface. Therefore, the molten metal may wet the surface. The presence and effectiveness of gases and oxides inserted between the molten metal and the particles to It is necessary to minimize the effects of This allows the particles to remain within the molten metal during mixing and casting. retention, promoting good interfacial bonding properties after casting and solidification.

There are metals and fine particles in the molten metal that can interfere with the wetting of the metal particles. There are several sources of gas. The gas is initially adsorbed onto the surface of the provided particles. ing. Even after thorough cleaning, the gas immediately removes particles, even in high vacuum. Redeposit on surfaces. These layers prevent further wetting. Bubbles easily melt It adheres to the surface of fine particles after being immersed in metal. The surface area may have air bubbles attached or This is because it tends to be most favorable for aggregation.

Gases are present in molten metal in a dissolved or physically entrained state. There is. Gaseous species are also present as oxides on metal surfaces. used in this invention Aluminum is the preferred metal for liquid or solid metal surfaces. is well known for forming oxides that directly interfere with wetting. .

Gases are also used to mix metals and particulates together to promote wetting. can be introduced into the molten mixture of metal and particulates by mixing techniques. Previously carried out During mixing, paddle-type or A Ships Blobera type mixed impeller was used. Stir the melt at high speed. A vortex is formed at the top of the impeller, and then particulates are added to the side or bottom of the vortex. Ru. It was thought that the flow of metal along the sides of the vortex facilitated mixing.

Instead, now wetting the gas by mixing it into the mixture when a vortex is present. , which has been found to interfere with the ultimate purpose of the mixing procedure.

This is most noticeable when there is a gaseous atmosphere above the melt, but when mixing is done in a vacuum. Also, the gas is physically drawn into the molten mixture by the vortex.

Figure 1 graphically illustrates the effect of vortex mixing and the incorporation of gas into the composite melt. There is. Experiments were conducted to determine the extent of gas incorporation into the molten mixture.

A mixture of aluminum and silicon carbide particles was melted in a crucible. Line A is the melt shows the surface of The melt is then immediately stirred by a conventional mixing impeller in argon. It is smeared and generates vortices on the surface. Line B shows the shape of the surface during mixing and shows the rapid There is a deep vortex characteristic of stirring. When mixing is stopped, the surface of the melt shown by line C The level was much higher than before mixing as shown by line A. This difference is melted by the vortex. This was due to gases drawn into the material and trapped during the mixing process. this Physical entrainment is particularly important for melts containing solid particles. melt Is the gas drawn in preferentially retained at the surface between the particulate and the melt? It is et al. Thus, mixing promotes the dispersion of particles in the melt and increases wettability. While it can have beneficial effects, mixing the wrong type will eventually interfere with grooves. .

Mixing action also creates unwanted gases in the melt, in a manner similar to cavitation. May cause foam to clump. Dissolved or trapped gases may be A low-pressure area just behind the metered mixing impeller blades, where the reduced pressure causes air bubbles to It is aggregated into. Air bubbles preferentially attach to the particulate surface and also impede wetting.

The mixing process of the present invention involves the incorporation of gas into the melt, adsorption into the melt, and dissolution of the gas. Minimizes the retention of trapped gases, resulting in less wetting of metal particles. The level of gas in the melt that interferes with the flow is reduced.

The mixing process also involves high shear rates and high shear rates between the molten metal and solid particles in the melt. A state of force is generated. In shear conditions, molten metal rubs against a solid surface. Removal of adsorbed gases and air bubbles from particulate surfaces by physical mechanism of polishing is promoted, so contaminants such as gases and oxides are washed away. By shearing There is also a tendency for the metal to stretch over the surface, so that the applied shear force is Helps overcome forces that prevent metal from spreading on solid surfaces. new effect does not deform or fracture the particles, but instead causes the liquid metal to pass rapidly through the particles. and shear.

In a preferred approach, a vacuum is applied to the surface of the melt. Due to vacuum, gas contamination through the surface into the melt during mixing is reduced. Vacuum also gas is removed from the melt. Minimizes the introduction of gas into the molten metal , if other techniques are employed to minimize gas retention in the molten metal. There is no need to use a vacuum. One such approach within the scope of this invention No. 5,028,392, granted July 2, 1991, be.

A metal alloy, preferably a metal alloy, reinforced with particles of a non-metallic material, preferably silicon carbide. Manufacture of composite materials of aluminum or aluminum alloys Start with melting. For example, 6061.2024.7075.7079 and A35 Uses a wide range of standard wrought, cast or other aluminum alloys, such as 6 can do. Alloy type limitations are unknown.

Before adding particles, remove oxides, particles, dissolved gases and other impurities that interfere with wetting. It is preferred, but not necessary, to wash the melt to remove materials.

One approach uses a non-reactive gas such as argon gas, argon and chlorine, etc. The mixture of non-reactive and reactive gases is allowed to cool for example for 15 minutes before the particles are added. In a holding tank for a certain period of time, the melt is foamed through. Air bubbles that reach the surface At the same time, hydrogen gas, etc. that diffuses into the bubbles as it rises, dissolves and travels. - Carry knobbed gas. It also pushes the dross floating in the metal to the surface. Ru.

Particles of non-metallic ceramic material are added to the molten metal and mixed. particles mixed and under casting conditions, deterioration due to chemical reaction with molten metal is sufficiently low. There must be. i.e. fine particles that dissolve in molten metal under all known conditions. No particles are perceivable and may form undesirable reaction products when in contact with molten metal. No fine particles could be detected. On the other hand, most nonmetals change into molten metal at high temperatures. Although the reaction occurs on a large scale, the reaction often requires the temperature of the molten metal to process. by controlling the temperature to a point where no substantial degree of reaction occurs for a period of time. can be reduced to the lowest possible level.

Preferred non-metallic reinforcement materials include metal oxides, metal nitrides, metal carbides, metal silicides. objects and glass. Among these, there are those that are easily available and not expensive. , the physical properties and characteristics that allow the formation of desired composite materials using this approach. Silicon carbide and aluminum oxide are of particular interest because they exhibit the necessary combination of reactivities. Deep taste.

The amount of fine particles added to the melt is determined by the ability to stir the particle-containing melt and obtain uniformity. It can be varied substantially by a maximum amount that depends on the force. Amount of particulates As , the melt becomes more viscous and more difficult to stir. fine particles The higher the amount, the more surface area for gas retention and stabilization within the melt, The ability to produce stable, wet materials is limited. Fine particles in aluminum alloy The maximum amount of is found to be about 35% by volume. Particle size and shape It can also be changed.

The combination of molten metal and particles is formed by any convenient method prior to mixing.

Particles are added to the surface or subsurface of the melt, in the latter case partially or completely. If mixing is not done simultaneously to achieve complete wetting, the particles typically will not reach the surface. It's coming up. Particles can also be added with metal pieces before melting the metal. , because of this, the particles coexist with the metal pieces as they are melted to form a melt. Continue. This latter option is desirable since it is desirable to clean the melt before adding the particulates. This procedure is not recommended. If particulates are present during cleaning of the melt, they will It may be carried to the surface along with the gas.

The particulates and molten metal are mixed together for a sufficient time to wet the molten metal to the particles. It will be done. Mixing is done at a high temperature to remove gas from the surface of the particulates and promote wetting. Performed under conditions of shear strain rate and force. Mixing technology allows gas to melt The introduction of molten gas already trapped in the melt must also be avoided. Stabilization of the system must also be avoided.

One approach to mixing involves immersing the mixture in the melt and applying high shear within the melt. dispersion vanes actuated to induce small vortices at the surface of the melt. car is used. A distributed impeller meeting these requirements is illustrated in FIG.

This distributed impeller 100 has a distributed impeller shaft having a plurality of flat blades 104. 102. The blade 104 is not placed at an appropriate position with respect to the direction of rotation. but at an angle of approximately 45 degrees from a line perpendicular to the shaft 102. be done. This design minimizes the appearance of surface vortices and eliminates air bubbles in the melt. It acts to draw fine particles into the melt while minimizing agglomeration. This te Due to the strike, this impeller can rotate up to at least 2500 revolutions per minute (rpm). At the surface of the aluminum alloy melt, which can rotate at high speeds, significant vortices are induced It is explained that it is not done. induces the highest shear rates and forces in the molten mixture , high speed rotation is desirable as it reduces the time required to achieve wetting.

Wetting of the melt onto the fine particles of metal is achieved and the fine particles are dispersed throughout the metal. The mixture is mixed in the dispersion impeller for a sufficient period of time. In my experience, batch processing systems A total mixing time of about 70 minutes has been found to be sufficient. continuous flow system In the system, substantially all of the molten mixture is present at least once under a high shear state. must be exposed to In a preferred approach, the molten composite flow chamfer has a mixing impeller sized to the channel, so that the Substantially all of the composite material to be used is agitated by the impeller. Reliably melts the material Multi-stage mixing can be performed so that all the materials are mixed.

The mixing temperature is carefully controlled to avoid reverse chemical reactions between particles and molten metal. must be The maximum temperature of the metal when in contact with the particles is the temperature at which the particles are in the molten metal. Do not exceed temperatures at which chemical deterioration occurs. The maximum temperature depends on the type of alloy used. and can be determined for each individual alloy. While the molten alloy is in contact with the particulates , the maximum temperature must not be exceeded for any period of time.

For example, the highest temperature can activate reactive components such as magnesium, zinc or lithium. The alloy liquidus temperature of the silicon carbide fine particle alloy containing the same amount is 20°C or more. The maximum temperature is For normal alloys without quantitative reactions or stabilizing elements, temperatures below the alloy liquidus temperature The temperature is 70℃ above. The maximum temperature stabilizes the melt against reactions such as silicon For alloys containing large amounts of elements, the temperature should be 100 to 125°C above the alloy liquidus temperature. Ru. If a temperature higher than the above temperature is used, the viscosity will increase due to the presence of dissolved substances. It is difficult to melt, mix, and cast composite material mixtures because of the increased or It may be impossible.

The maximum temperature also depends on the reactivity of the particulate, which is primarily determined by its chemical composition.

Silicon carbide is relatively reactive and the above principles apply. aluminum oxide is Relatively unreactive in aluminum and aluminum alloys, and therefore highly different temperatures can be used.

In an earlier approach called flow casting, the metal and particulates were mixed between the solidus and liquid phases of the alloy. mixed in the range between the lines. In this range, the solid metal forms in equilibrium with the liquid metal. The solid metal also increases viscosity and shear forces, making mixing more effective.

However, using temperatures substantially below the liquidus will cause the composite to solidify. Extensive and undesirable segregation of alloying elements in the metallic phase can occur after It has now been found. The material is also easily cast using traditional casting procedures Can not do it.

Therefore, the molten mixture is in equilibrium with the liquid metal without the formation of a substantially solid metal phase. The temperature range ranges from the lowest temperature at which the particles are not chemically degraded in the molten metal. maintained within the The lowest temperature is around the liquidus line of molten metal, but it remains for a while. However, it can also be maintained at a lower temperature. Fluctuations in temperature to lower temperatures are It is not harmful as long as the melt is cast without any metal phase present. For example, fine particles There is usually an interim temperature drop when additives or alloying additives are added to the melt. It is possible. The temperature must be raised above the liquidus temperature before the melt is cast. . Although acceptable for short periods of time, the energy required to return to steady state temperature For cost reasons, such temperature fluctuations are preferably avoided. Maximum temperature is liquid gold Limited by the onset of degradation of particulates in the genus. for a while to a higher temperature (between Variations are acceptable as long as they do not cause significant particle degradation; Higher temperatures should not be maintained for long periods of time.

After mixing is complete and the molten composite mixture is withdrawn from the mixing device, the composite material is It can be cast using any casting technique. After composite material or mixed, The melt is essentially homogeneous, and the particles are wetted by the metal, so that they stick to the surface. Does not float immediately. When the composite material is held for a substantial period of time, the difference in density causes the particles to can be stirred to avoid segregation of shall not be introduced into Casting must be completed immediately or by rapid casting procedure There isn't.

The resulting casting material can be manufactured into products using conventional procedures. composite material The material can be annealed or heat treated. It can be rolled in conventional equipment, e.g. It can be processed at high heat using extrusion or extrusion. The final composite material also Recasting is not possible in foundry operations by any acceptable casting procedure. I can do that.

Figure 3-6 shows three implementations of an apparatus for manufacturing composite materials by the continuous flow method of the present invention. This is an example. With respect to FIG. 3, the apparatus 10 includes a mixer 12, a melt Molten metal supply means 1 for supplying the trix alloy and fine particles to the mixer 12, respectively 4 and the particle feeder 16, and receives the mixed composite material from the mixer 12. It includes a holding furnace 18 in which it is held before casting.

The mixer 12 has at least one, here shown two, stages of molten metal. and mixtures of particulates. The molten metal is passed from the molten metal supply means 14 to the heating conduit 20. Pass and be accepted. The molten metal supply means 14 is used as a composite material matrix. It includes a furnace 15 for melting the metal alloy used. The molten metal in the furnace 14 is Which inert gases or mixtures of inert and reactive gases, such as argon and chlorine, are listed By foaming through the molten metal using a lance 22 inserted below the surface. It is preferable to wash continuously. The bubbled gas is present in the melt. Collects dissolved or trapped gases such as hydrogen and oxygen, removes them to the surface, and removes them from the solution. Dross particles present below the surface of the melt are also suspended. Is the molten metal below the surface of the furnace 150? to the evacuated degassing unit 17, where it is exposed to the vacuum applied to the surface. Trapped gases remaining from processing in the furnace 15 are removed. molten metal Continuously from below the melt surface of the degassing unit 17, through the conduit 20, the mixer 1 Flows up to 2.

Also, since the vacuum and metal levels can vary, the metal flow rate can vary considerably. Since precision control is desirable, a metal pump 24 is placed within the metal conduit 20. It will be done. Pump 24 can have various speeds and pumps molten metal to mixer 12. Acts as both a pump and a valve in controlling flow rate.

The particle feeder 16 is a commercially available vacuum extruder or vacuum locked hopper. It is. The particulates are typically carefully dried in feeder 16 to ensure moisture content. is prevented from reaching the mixer 12. The fine particles come from the feeder 16. It is conveyed through conduit 26 to mixer 12. The flow rate of fine particles is determined by screw extrusion. controlled by a machine 28 or similar device operated by a variable speed motor. . By varying the operating speed of the extruder 28 and pump 24, the mixer A preselected total flow rate to 12 and a preselected relative amount of particulates and metals are achieved. can. If necessary, conduit 28 may be heated, but in most implementations, Since the amount of fine particles is relatively small compared to the amount of metal supplied to the mixer 12, the No heating of tube 28 is required.

In the embodiment of Figure 3, the mixer has two stages, each with a separate channel. 30 and 32. One chamber 30 has a cylindrical refractory lining. It is a steel container and the cylindrical axis is vertical. The top of each chamber 30 and 32 is vacuum It is connected to a pump 34 and pumped to a vacuum of about 30-50 torr.

The vacuum reduces the likelihood of introducing gas into the molten composite as it is mixed.

Molten metal enters from metal conduit 20 near the top of first chamber 30 . Fine particles are It is introduced through tube 26 just above or below the surface of the metal. first chan Bar 30 includes a vertically mounted impeller 36, generally of the type illustrated in FIG. this The impeller enters the chamber 30 through a rotating vacuum fitting 38 and an external variable It is driven by a high speed motor 40. Fine particles are drawn into the molten metal by the impeller 36. The mixture is stirred to form a first type of composite material. The vortex generated by the impeller 36 Throughout, care is taken to avoid introducing gas into the molten material. Fine particles of molten metal Wetting is achieved by high shear mixing action.

The outer diameter of the blades of impeller 36 is slightly smaller than the inner diameter of the cylinder of chamber 30 .

The relatively small gap between the impeller 36 and the inner wall of the chamber 30 ensures that the first All metals flowing downward through the chamber will be subjected to a mixing action. .

Almost no metal reaches the bottom of the chamber 30 without passing through the blades of the impeller 36. stomach. To reduce the likelihood that metal will pass directly along the inner wall within the interstitial gap, A baffle 42 extends inwardly from the inner wall of chamber 30. Baffle 42 is Blocking the flow along the inner wall and directing the metal and particulate mixture towards the center of the chamber 30 This is a protrusion that pushes the mixture back, allowing the mixture to be mixed by the impeller blades of the next stage. will be combined.

The mixed composite material passes from the bottom end of the first chamber 30 through the composite metal conduit 44. drawn out. A commercially available eddy current conductivity monitor 46 is placed within conduit 44 and The volume fraction of particulates in the feed stream is monitored. This information is used in the final composite material In order to achieve the desired volume of particulates in the particulate feeder 16 and the molten metal used in the feedback sense to control the flow rate of the metal supply means 14. Ru.

The composite material enters second chamber 32 through conduit 44 . The second chamber 32 The chamber 30 is configured in a similar manner to the chamber 30 of The same numbered elements are used, except rather towards the top. (This style The direction of flow in the second chamber is not critical; the direction of flow within the second chamber can be changed using different conduit arrangements. If there is, it can be the same as the first chamber. ) At this stage, a large portion Several particles are wetted by the molten metal, but there is a possibility that some particles are not yet wetted. Ru. Passing the composite material axially through the impeller 36 of the second chamber 32 By further mixing the composite material, the proportion of the wetted surface of the microparticles is increased. 2nd stage If mixing by floor is insufficient for some special composite materials, This principle can be extended to additional stages.

The mixed composite material is drawn from second chamber 32 through conduit 48 and stored. It is guided to the holding furnace 18. Conduit 48 also includes an eddy current device 50 to Measuring the amount of particles.

The apparatus of Figure 3 has a two-stage mixer in which both stages use impeller mixing. . A pond type device is also possible and such an alternative embodiment is shown in FIG.

The apparatus 60 in FIG. 4 includes a molten metal supply means 14, a particulate feeder 16, and a holding furnace. 18 is as described above. However, here the molten metal and fine particles are It is introduced into a mixer 62 whose cylindrical axis is horizontal and which is essentially straight cylindrical. Mi Walls 64 of kisser 62 are constructed of a non-conductive material such as aluminum oxide. high frequency A wave induction coil 66 is wound around the outside of the cylindrical mixer 62. when activated In this case, the induction coil 66 mixes the molten metal and the particles flowing from left to right in FIG. Manufacture composite materials. A plurality of fixed baffles 68 extend inwardly from the inner wall of the mixer 62. It is a region where the mixing produced by the induction coil is low, and the complex mixing This prevents stratification of the compound. mixer 62 The inside of is pumped by vacuum line 70 and gas accumulates in the system and ' This reduces the possibility of contamination in molten composite materials. of particles in the molten composite material An eight current monitor 72 is also provided to quantify the amount of current. In Figure 4;'・Drawing related Although the relatively short length of mixer 62 is shown, mixer 62 is approximately 6-9 mm long. -Torme length, has multiple induction coils and multiple sets of bafflesG,)jJ −,17′□゛−゛′A device 80 employing a similar horizontal linear mixer 82 is shown in FIG. It is written as F. This mixer 82 configuration is such that the mixer 82 As previously described, except that one or more impellers 82 are operated within the It is on the same line. The impeller is used for side impact as shown. act) for mixing, axial mixing (axia In this example, multi-stage mixing is possible. , may be used in a single mixing chamber.゛Combination of impeller and induction mixing, Or you can use a mixture of other names. A further advantageous device 90 is shown in FIG. There is. The device 90 includes an impeller □94 and a 202, which uses induction mixing. You could also do that. In the apparatus 90, the metal supply means 14 physically mixer. 92 and thus imposes a hydrostatic head on the metals and composites within the mixer 92. ostatic) is applied. Since gas cannot enter the system, Vacuum pumping of mixer 92 is not required. However, gas is a particulate feeder. Great care must be taken not to enter through the door 16.

Depending on your needs, different implementations of continuous flow equipment, e.g. impeller and inductive mixing, etc. Examples can be used in combination.

The method and apparatus of this invention provide an economical, melting and casting technique for producing high quality materials. According to the order, it will be recognized that it is for producing particulate reinforced composite materials. . Wetting minimizes the effects of gases in the matrix and allows them to mix at high shear rates. This is achieved by For purposes of illustration, specific embodiments of the invention will now be described in detail. However, various improvements can be made within the spirit and scope of the invention.

Accordingly, the invention is not limited except as by the appended claims.

Submission of translation of written amendment (Article 184-8 of the Patent Act) September 10, 1993 i

Claims (16)

[Claims] 1. Manufacture composites of metal alloys reinforced with non-metallic particles in pre-selected volumes A method, the method comprising: The metal material is continuously fed into the mixer, and the molten composite material is continuously fed from the mixer. The process of melting metal alloys in a continuous flow system drawn by adding the flow of child material to the mixer, and adding the flow of the metal material to the particulate The flow rate is adjusted to provide a preselected volume fraction of particles in the composite; moreover The particles are dispersed throughout the volume of the molten mixture to promote wetting of the particles by the metal. , the molten metal alloy in a mixer under conditions where the particles and molten metal are sheared together. The process involves mixing the particles with particulate material and wetting the particles with molten metal; The introduction of gas into the melted metal mixture is minimized and the gas is retained within the mixture. particles in the molten metal for the time required to complete the mixing step while minimizing occurs at a temperature at which the child is not substantially chemically degraded, and further removed from its mixer. A manufacturing method comprising the step of casting the composite mixture produced. 2. A method according to claim 1, wherein the metal material is an aluminum alloy. 3. Non-metallic materials consist of metal oxides, metal nitrides, metal carbides and metal silicides The method of claim 1, wherein the refractory ceramic is selected from the group consisting of: 4. Non-metallic materials include silicon carbide, aluminum oxide, boron carbide, silicon nitride and nitride. The method of claim 1, wherein boron is selected from the group consisting of boron. 5. 2. The method of claim 1, wherein the non-metallic material is glass. 6. 2. The method of claim 1, wherein the mixing step uses a rotary impeller. 7. The mixing step may be performed using a vacuum applied to the mixture of molten metal and particles. The method described in claim 1. 8. The mixer includes at least two separate chambers through which the particulate 2. The method of claim 1, wherein the molten composite material flows and mixing occurs while the molten composite material is added. 9. The casting step must be carried out at a sufficiently high casting temperature that substantially no solid metal is present. The method described in claim 1. 10. A series of composite materials of metal alloys reinforced with non-metallic particles in a preselected volume. an apparatus for producing a continuous flow, the apparatus promoting wetting of particles by metal; The particles are dispersed throughout the volume of the mixture so that the particles and molten metal are sheared together. A flow of molten metal alloy is mixed with a flow of particulate material under conditions of The mixing includes means for wetting the particles and the molten steel in a manner that minimizes the introduction of gas into the mixture of particles and molten steel. The mixing step is carried out while minimizing gas retention within the mixture. temperature at which the particles do not substantially chemically deteriorate in molten steel during the time required to complete and a metal supply means for introducing the flow of molten metal into the mixing means. a particle supply means for introducing a stream of particulates into the mixing means; The flow rate of metal in the supply means and the flow rate of particles in the particle supply means can be controlled and further To, Apparatus including means for removing a stream of mixed composite material from the mixing means. 11. 10. The mixing means includes an impeller for mixing the molten metal and particulate material together. The device described. 12. 11. Apparatus according to claim 10, wherein the mixing means is evacuated by a vacuum pump. 13. The mixing means may include multiple components to assist in mixing the molten metal and particulate material together. 11. The apparatus of claim 10, including several baffles. 14. The mixing means includes at least two stages of mixing, each stage of mixing with the molten metal. 11. The apparatus of claim 10, including means for mixing the particulates together. 15. 15. The apparatus of claim 14, wherein the individual stages are contained in separate chambers. 16. 15. The apparatus of claim 14, wherein said stage is within a single chamber.