EP0328805A1 - Herstellung von Verbundwerkstoffen mit Metallmatrix - Google Patents

Herstellung von Verbundwerkstoffen mit Metallmatrix Download PDF

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Publication number
EP0328805A1
EP0328805A1 EP88304238A EP88304238A EP0328805A1 EP 0328805 A1 EP0328805 A1 EP 0328805A1 EP 88304238 A EP88304238 A EP 88304238A EP 88304238 A EP88304238 A EP 88304238A EP 0328805 A1 EP0328805 A1 EP 0328805A1
Authority
EP
European Patent Office
Prior art keywords
preform
metal
die
die cavity
cavity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP88304238A
Other languages
English (en)
French (fr)
Inventor
David James Lloyd
Willard Mark Truman Gallerneault
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcan International Ltd Canada filed Critical Alcan International Ltd Canada
Publication of EP0328805A1 publication Critical patent/EP0328805A1/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/02—Pressure casting making use of mechanical pressure devices, e.g. cast-forging
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
    • C22C47/02—Pretreatment of the fibres or filaments
    • C22C47/06—Pretreatment of the fibres or filaments by forming the fibres or filaments into a preformed structure, e.g. using a temporary binder to form a mat-like element
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1036—Alloys containing non-metals starting from a melt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
    • C22C47/08—Making alloys containing metallic or non-metallic fibres or filaments by contacting the fibres or filaments with molten metal, e.g. by infiltrating the fibres or filaments placed in a mould

Definitions

  • This invention relates to the production of metal matrix composites, and more particularly to methods of producing cast metal matrix composite articles, as well as to the products of such methods.
  • Metal matrix composites are articles constituted of a metal matrix, e.g. aluminum or alloys thereof, having distributed therein a divided solid filler, viz. a fibrous or particulate material which is capable of being incorpo­rated in and distributed through such metal matrix and which at least substantially maintains its integrity as thus incorporated rather than losing its form or identity by dissolution in or chemical combination with the metal.
  • a divided solid filler viz. a fibrous or particulate material which is capable of being incorpo­rated in and distributed through such metal matrix and which at least substantially maintains its integrity as thus incorporated rather than losing its form or identity by dissolution in or chemical combination with the metal.
  • the present invention provides a new and improved method of producing a composite cast article comprising a metal matrix and a divided solid filler.
  • a melt of the metal matrix is provided in a die cavty and a preheated preform of a divided solid filler is placed on top of the melt in the die cavity.
  • Pressure is exerted on the preform in a direction parallel to the cavity axis for pushing the preheated preform into the molten metal and forcing the molten metal to fully infiltrate the preform filler, after which the resultant cast article is solidified.
  • preform refers to an effectively integral, porous compacted body of divided solid filler fibers or particles which has been subjected to sufficient compacting pressure to develop green strength, viz. strength such that the compacted body is self-sustaining in shape and dimensions when handled.
  • a melt of the metal matrix is provided in the die cavity. Then a preheated preform is placed on the surface of the melt and pressure is applied thereon by a ram to push the preform downwardly into the melt until it is fully impregnated with molten metal.
  • spacers are provided between the top of the preform and the ram to assist infiltration of the preform.
  • This procedure of pushing the preform through the melt has important advantages.
  • the melt is quescient and when a preheated preform is pushed through it, metal flashing is avoided because hot metal is not hitting cold surfaces. Also, heat flow is more uniform as convection can be eliminated.
  • the solidifying step is performed by controlling heat flow within the die cavity in such manner that a solidification front advances unidirectionally, along the cavity axis, entirely through the metal-infiltrated preform layer, while the metal ahead of this front within and at least immediately beyond the preform layer remains molten; and the metal layer disposed beyond the preform layer (with respect to the direction of advance of the aforementioned solidification front) contains metal in excess of the amount which infiltrates the preform from that metal layer during the pressure-exerting step. It is found that this combination of features enables production of composite articles which are advantageously free of porous zones and which, in consequence, are characterized by fully adequate mechanical properties throughout.
  • contraction-created pores cannot be enclosed between converging solidification fronts in a filler layer because there is only a single solidification front advancing unidirectionally through the entire preform layer; and ahead of this front there is a continuing supply of molten metal, which fills any contraction-vacated space, under the continuing applied infiltration pressure.
  • the requisite control of heat flow within the die cavity during the pressure-exerting step is preferably effected by establishing a temperature differential between opposite ends of the die cavity, as for example by selectively heating or cooling one end of the die; by selectively thermally insulating one end of the die, so that heat is preferentially transferred from the other end of the cavity; or by an appropriate combination of these techniques.
  • a temperature differential two opposed solidification fronts may nevertheless advance toward each other along the cavity axis from the opposite ends of the cavity, but with different initiation times and/or rates of advance, so that they meet within the zone or layer of excess metal beyond the preform layer rather than within the preform layer itself, and only one of the solidification fronts passes through the preform.
  • the die cavity may be heated by moving an external source of heat progressively and unidirectionally along the die from one end of the die to the other and parallel to the axis thereof as infiltrating pressure is exerted endwise on the metal-preform within the cavity.
  • a unidirectionally advancing solidification front in this case, follows the heat source along the cavity axis.
  • the invention will be described as embodied in methods of producing cast compo­site billets of aluminum (matrix metal) and discontinuous reinforcing fibers of a refractory material such as SiC or Al2O3.
  • Such composites have utility for structural and other purposes, being characterized by light weight and high strength.
  • a die 10 fabricated of a suitably thermally conduc­tive material (e.g. steel), defining an axially vertical and upwardly opening cylindrical die cavity having its lower end closed by a metal or like die plate 11.
  • the die plate is supported on a steel base plate 12 and is sepa­rated therefrom by a layer 14 of compressible thermal insulation, e.g. Fibrefrax R .
  • a quantity of matrix metal 16 and a disc-shaped preform 18 of a refractory fiber material which is to be impregnated with the matrix metal to produce a composite metal-fiber article are disposed within the die cavity.
  • suitable fiber materials for the preform include articles of alumina, zirconia, silica, silicon carbide, silicon nitride or titanium diboride, in particular alumina in the form of chopped fibers, and silicon carbide or silicon nitride in the form of either whiskers or chopped fibers.
  • the preform 18 is preferably provided with spacer strips 30 across the top face thereof; and these spaces 30 may be fixed to the preform, e.g. by means of a bead 31 of sodium silicate around the lower peripheral edge of each spacer.
  • the spacers preferably cover no more than about 10% of the area of the top of the preform and preferably the sodium silicate does not migrate into the horizontal interface between a spacer and the preform.
  • the die is heated, e.g. by means of a conventional induction or resistance heater 24 surrounding the die and arranged to minimize heating of the base plate 12.
  • Molten metal is added to the heated die, resting on a layer 20 of thermal insulaion which in turn rests on the die plate 11.
  • the insulating layer is made of fibrous or like material (e.g., Fibrefrax R aluminum silicate fiber).
  • a vertically movable ram 26, positioned in register with the die cavity, is advanced downwardly to bear against preform 18. With the metal fully molten, the ram is operated to exert pressure in a downward vertical direction.
  • Fig. 1 illustrates that point in the performance of the method at which the matrix metal is entirely molten, heating has been discontinued, and the ram has just come into contact with the preform 18. Thereafter, pressure exerted by the ram forces the preform downwardly to the position shown in Figure 4 and forces the molten matrix metal into the insulation layer 20 and the preform 18, and also compresses the insulation layer 14.
  • the insulation layer 20 is of coarser weave than the preform 18, so that this layer becomes infiltrated in advance of the preform.
  • the preform has a compressive strengh sufficient to withstand the pressure applied by the ram, and hence substantially retains its initial shape and dimensions.
  • the amount of superheat in the metal varies with die temperature.
  • a larger offset is necessary between the preform and the die wall to prevent modifying metal tacking to the die wall and the preform. This offset is typically from about 2.5 mm to about 12.5 mm with a 75 mm diameter die.
  • the preform is preferably preheated to a high temperature, e.g. in the order of 700°C.
  • the spacers attached to the preform serve two func­tions. Firstly, they provide space for the infiltrating liquid metal, nominally hydrostatic infiltration. Secondly, they are used to concentrate residual gas from the preform. Thus, if the spacer has a higher fibre loading than the preform, its metal breakthrough pressure and pressure gradient will be higher than in the preform and will tend to infiltrate less readily.
  • the preform may have a typical volume fraction of fibers (V f ) of about 0.15 while the spacers may have a V f of about 0.25.
  • V f volume fraction of fibers
  • the spacers may have a V f of about 0.25.
  • the spacers infiltrate last.
  • the matrix metal cools and solidifies since heat is no longer being supplied to the system. Finally, the ram is withdrawn upwardly, and the formed composite product may be removed from the die.
  • the ram 26 is preferably fabricated of a metal of high thermal conductivity such as die steel (which may also be the material of the base plate 12) or copper bronze and is "cold," i.e., unheated, as introduced to the die cavity; if desired for expedited matrix metal solidification, the ram may be internally cooled, but such positive cooling is not required in all instances.
  • the die plate 11 is heated by the resistance or induction heater 24 before the ram is introduced, it being noted that the peripheral portion of this plate is in direct contact with the heated die and that the plate is initially well insulated by layer 14 from the relatively unheated base plate 12, so as to minimize heat losses.
  • the ram begins to press against the upper end of the die cavity contents, its relatively low temperature, and the relatively high temperature of the die plate 11 at the lower end of the cavity contents, cause the lower end of the cavity to be hotter than the upper end.
  • the cool ram abstracts heat from the top end of the die cavity, initiating a first solidification front that moves downwardly through the cavity.
  • a first solidification front that moves downwardly through the cavity.
  • the ram compresses the insulation layer 14 between the die plate 11 and the base plate 12, reducing the insulating effect of the layer 14 and enhancing the thermal contact between the initially heated die plate and the initially cool base plate, heat is abstracted from the lower end of the die cavity.
  • solidification of the contained metal commences at that locality, sealing any escape paths for molten metal at the bottom of the die and initiating a second, upwardly moving solidification front.
  • the effect of the initial heat differential between the top and bottom of the die cavity is to retard the upward advance of the second front relative to the downward advance of the first front; hence the fronts ultimately meet at a level, in the cavity, which is substantially below the midpoint between their respective starting levels.
  • the relative thicknesses of the preform itself and the metal below the preform are so chosen that the two solidification fronts thus respectively advancing from the upper and lower ends of the cavity meet below the preform.
  • the preform preferably has a thickness of no more than 25 mm in order to assure rapid heating of the fibers.
  • the lower metal layer thickness as seen in Figure 4 is sufficient so that, when impregnation of the preform is complete, there will remain a layer of excess metal below the preform in which the solidification fronts can meet.
  • the provision of excess molten metal in the pool below the preform is important to ensure a continuing supply of molten metal for infiltration of the preform at all times as the first solidification front advances downwardly through the preform.
  • the die 10 has a wall thickness of 25 mm. and an internal diameter of about 75 mm., this being also the approximate diameter of the ram 26, which however can enter the die cavity with slight clearance.
  • the central portion of the die plate 11 has a vertical thickness of 6 mm., and its thinner edge portion has a vertical thickness of 3 mm., while the base plate 12 has a vertical thickness of 25 mm.
  • Both the base plate and the ram are fabricated of die steel.
  • the insulating layers are constituted of "Fibrefrax" refractory fibers; layer 14 has an uncompressed vertical thickness of 3 mm., and the vertical thickness of layer 20 is 1.5 mm.
  • the heater 24 is a resistance heater.
  • a refractory fiber preform 18 having a diameter of 70 mm. and a vertical thickness of 30 mm. is infiltrated with molten metal. After infiltration, the vertical thickness of matrix metal below the preform is 30 mm. A ram pressure of 20-200 mPa is applied for 240 seconds.
  • V f volume fraction of fibers

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
EP88304238A 1988-02-18 1988-05-11 Herstellung von Verbundwerkstoffen mit Metallmatrix Withdrawn EP0328805A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA559212 1988-02-18
CA559212 1988-02-18

Publications (1)

Publication Number Publication Date
EP0328805A1 true EP0328805A1 (de) 1989-08-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP88304238A Withdrawn EP0328805A1 (de) 1988-02-18 1988-05-11 Herstellung von Verbundwerkstoffen mit Metallmatrix

Country Status (4)

Country Link
EP (1) EP0328805A1 (de)
JP (1) JPH01210166A (de)
KR (1) KR890012725A (de)
BR (1) BR8802319A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0460987B1 (de) * 1990-05-23 1997-04-09 Elf Atochem S.A. Keramische Vorformen, ihre Herstellung und ihre Verwendungen
CN108380845A (zh) * 2018-05-30 2018-08-10 滁州市锴模装备模具制造有限公司 一种冰箱接水铝盘模具

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3913657A (en) * 1974-07-17 1975-10-21 Us Energy Method and apparatus for fabricating a composite structure consisting of a filamentary material in a metal matrix
US3970136A (en) * 1971-03-05 1976-07-20 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Method of manufacturing composite materials
GB1567328A (en) * 1975-09-30 1980-05-14 Honda Motor Co Ltd Method for producttion of fibre-reinforced composite material
DE3525122A1 (de) * 1985-07-13 1987-01-15 Iwan Dr Kantardjiew Verfahren zur herstellung eines verbundwerkstoffes aus metall und kurzfasern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970136A (en) * 1971-03-05 1976-07-20 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Method of manufacturing composite materials
US3913657A (en) * 1974-07-17 1975-10-21 Us Energy Method and apparatus for fabricating a composite structure consisting of a filamentary material in a metal matrix
GB1567328A (en) * 1975-09-30 1980-05-14 Honda Motor Co Ltd Method for producttion of fibre-reinforced composite material
DE3525122A1 (de) * 1985-07-13 1987-01-15 Iwan Dr Kantardjiew Verfahren zur herstellung eines verbundwerkstoffes aus metall und kurzfasern

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0460987B1 (de) * 1990-05-23 1997-04-09 Elf Atochem S.A. Keramische Vorformen, ihre Herstellung und ihre Verwendungen
CN108380845A (zh) * 2018-05-30 2018-08-10 滁州市锴模装备模具制造有限公司 一种冰箱接水铝盘模具

Also Published As

Publication number Publication date
JPH01210166A (ja) 1989-08-23
KR890012725A (ko) 1989-09-19
BR8802319A (pt) 1989-12-05

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