Massachusetts Institute of Technology

Metal Matrix Cast Composites, Inc.

Avco Corporation

H.c. Starck Gmbh

James A Cornie

Stephen S Cornie

Prabhat Kumar

Merton C Flemings

Raymond J Suplinskas

Andreas Mortensen

John E Shields

Richard Wu

Thomas W Henze

Richard R Malen

Albert W Hauze

Mark A Ryals

Ralph P Mason

Hank Breit

Eric M Klier

Larry Ballard

Robert Desberg

Himanshu Pokharna

Maxim Seleznev

Harold E Debolt

Sjur Vidar Velken

Harold E DeBolt

Shiyu Zhang

Donald R Gorsuch

Christopher K Knapp

Brent V Chambers

Theodoulos Kattamis

Brett M Schulz

Raul H Varela

Mark Montesano

Bruce E Bond

Embodiments of the present invention provide composite bodies having a discontinuous graphite preform and at least one silicon-bearing metal alloy infiltrant. Embodiments of the present invention also provide methods for producing such composite bodies. The metal alloy is preferably comprised of aluminum, copper, or magnesium, or combinations thereof. Certain preferred embodiments provide at least one aluminum alloy having from about 5% silicon to about 30% silicon, more preferably from about 11% to about 13% silicon, as an alloying element. Certain presently preferred embodiments provide an aluminum-silicon eutectic composition having about 12.5% silicon. Embodiments of the invention provide composite materials be 'tuned' to more closely match thermal expansion characteristics of a number of semiconductor or integrated circuit materials such as, but not limited to, silicon, alumina, aluminum nitride, gallium nitride, and gallium arsenide while also providing high thermal conductivity. Embodiments of the present invention are especially suited for use as a heat sink, a heat spreader, or both.

Thermally conductive graphite reinforced alloys

The invention relates to a method that involves (a) removing graphite from at least one surface of a metal graphite composite material; (b) chemically cleaning or plasma etching the surface of the metal graphite composite material; (c) applying a metal-containing material to the surface of the chemically cleaned or plasma etched metal graphite composite material, and thereby forming an intermediate layer; (d) applying a metal coating on the intermediate layer, and thereby forming a composite material. The invention also relates to a composite material comprising (a) a metal graphite composite substrate having at least one surface that is substantially free of graphite; (b) a metal-containing intermediate layer located on a surface of the substrate; and (c) a metal coating on the intermediate layer.

Pre-plating surface treatments for enhanced galvanic-corrosion resistance

Methods and materials for preparing investment molds useful in pressure infiltration casting of near net-shape metal or metal matrix composite (MMC) components. One embodiment of the invention includes disposing a slurry of an appropriately sized refractory material and a vehicle around a preform or fugitive pattern, removing the bulk of the vehicle, then curing/drying the refractory material to create an investment mold of the invention. Subsequently, pressure infiltration casting with a molten infiltrant using the investment mold permits infiltration of the mold cavity and/or preform without infiltration of the investment mold. As a result, the investment mold readily is removed to provide the near net-shape metal or MMC component. In other embodiments of the invention, a non-fugitive pattern is used, typically with a modified refractory cement of the invention. In these embodiments, the non-fugitive pattern is removed after formation of the investment mold to provide a suitable mold cavity which may be used to produce near net-shape metal or MMC components.

Castable refractory investment mold materials and methods of their use in infiltration casting

Disclosed are economical methods and apparatus for high throughput pressure infiltration casting. Methods of the invention use a mold vessel as an evacuation chamber along with an evacuation cap to produce superior quality near-net shape finished cast parts with low porosity. Other methods of the invention use an improved heat transfer technique for directionally solidifying molten infiltrant at an increased rate to increase further the throughput of the pressure infiltration casting cycle. The invention also provides apparatus for practicing methods for high throughput pressure infiltration casting. One embodiment of an apparatus of the invention is a removable evacuation cap, often used in conjunction with a fill tube. Another apparatus embodiment is an evacuation cap coupled to a mold vessel which is used as an evacuation chamber.

Methods and apparatus for high throughput pressure infiltration casting

A method of high throughput pressure casting involving the steps of providing a mold vessel containing an infiltrant and a mold cavity; evacuating the mold cavity, and heating the infiltrant to form a molten infiltrant which isolates a reduced pressure in the mold cavity; transferring the mold vessel containing the molten infiltrant to a pressure vessel; applying pressure to the molten infiltrant to move it into the mold cavity; and cooling the molten infiltrant in the mold cavity to solidify the molten infiltrant. The mold cavity may contain a preform to produce a metal matrix composite.

Method of high throughput pressure casting

A mold cavity in a mold vessel is evacuated. A charge of molten infiltrant is transported into the mold vessel while the vacuum is maintained in the mold cavity. Pressure is applied to the molten infiltrant to move the molten infiltrant from the mold vessel into the mold cavity. The molten infiltrant is cooled in the mold cavity to solidify the infiltrant. A fill tube can be used to transport the infiltrant to the mold vessel.

Methods of high throughput pressure infiltration casting

A mold vessel having a mold cavity is heated and evacuated. A charge of molten infiltrant is provided into the mold vessel from a source not in vacuum communication with the mold vessel while a reduced pressure is maintained in the mold cavity. Pressure is applied to the molten infiltrant to move it into the mold cavity. The molten infiltrant in the mold cavity is cooled to solidify the molten infiltrant. The mold cavity may contain a preform to produce a metal matrix composite.

Method for high throughput pressure casting

The invention provides methods for producing semi-permanent casting tooling, as well as semi-permanent casting tooling apparatus. Casting tooling including a blend of high char resin and refractory powder; casting tooling prepared from a blend of sol-gel ceramic precursor and refractory powder; and a preform including a leachable core as well as methods for their production are provided. The casting tooling of the invention can be used in casting processes including die casting, permanent mold casting and pressure infiltration casting. Also provided is an investment mold casting technique compatible with a pressure infiltration process.

Casting tooling

A method for producing semi-permanent casting tooling, including the steps of blending a high char resin with a refractory powder to form a plastic moldable material; shaping the plastic moldable material to form a green tooling body; and heating the green tooling body to convert the high char resin into carbon char to form reusable casting tooling. The casting tooling can be used in casting processes including die casting, permanent mold casting and pressure infiltration casting.

Method for preparation of casting tooling

A method for pressure infiltration casting is provided wherein steps of preheating and evacuating a mold cavity and infiltrant charge are carried out in a separate vessel from a pressure vessel wherein the mold cavity is filled, allowing for rapid finished article throughput. An apparatus for pressure infiltration casting is also provided.

Method and apparatus for casting

Composites of materials in which the matrix material does not spontaneously or readily wet the disperse phase and in which the volume fraction of the disperse phase is less than that formed in a packed bed of dispersate particles can be made effectively by an indirect method of infiltrating a packed bed of dispersate particles, using pressure or other mechanical force as needed to overcome poor wetting and form an intermediate concentrated composite. The concentrated composite is then mixed with additional matrix-forming material to produce the finally desired composite. The technique is particularly valuable for composites with ceramic dispersates and metal or alloy matrixes.

Composites and method therefor

A method for pressure infiltration casting is provided wherein steps of preheating and evacuating a mold cavity and infiltrant charge are carried out in a separate vessel from a pressure vessel wherein the mold cavity is filled using a vent tube, allowing for rapid finished article throughput.

Method for pressure infiltration casting using a vent tube

The continuous manufacture of a composite in which dispersates are mixed within a matrix material is set forth. Molten metal alloy and concentrated dispersion containing a particulate ceramic dispersate in a precurser dispersion material are continuously fed into a chamber where the mixture is first blended, then agitated to shear both the particulate and matrix. Well dispersed slurry is then fed into a crucible for solidification processing, or is continuously cast into a billet.

Method and apparatus for continuous casting of composites

Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

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Cambridge, MA, United States of America

James A Cornie