Aluminum Company of America

David I Yun

Ralph R Sawtell

M K Premkumar

Warren H Hunt

Eric T Streicher

Mosur K Premkumar

H Robert Baumgartner

Michael F Ehman

Frankie E Phelps

Jan H Van Linden

Gerald E Carkin

Que-Tsang Fang

Robert A Marra

Caroline Wei-Berk

Thomas B Gurganus

Douglas E Marinaro

Brijmohan J Roopchand

James A DerKacy

P Victor Kelsey, Jr

Mary E Hyland

A method of fabricating a metal matrix composite containing electrically isolated areas and the MMC formed from the method. The method comprises: (a) providing a liquid pool of unreinforced aluminum alloy; (b) infiltrating the unreinforced aluminum alloy into a stack comprising upper and lower porous preforms and an electrical insulator material placed between the preforms; (c) solidifying the liquid-phase metal to form a metal matrix composite product that completely surrounds the stack; and (d) forming at least one groove in the solidified metal, the groove extending downward to the insulating substrate so as to electrically isolate at least one region on the surface of the metal matrix composite.

Metal matrix composites containing electrical insulators

A method of fabricating MMCs having high thermal conductivity coupled with coefficient of thermal expansion (CTE) values which approximates the CTE of ceramics and semi-conductor materials typically used in electronic packaging. The method comprises preparing a formed agglomeration of powder particles (preform); partially sintering the preform; placing the partially sintered preform into a forming chamber; infiltrating the preform with liquid-phase metal; and allowing the liquid-phase metal to solidify and form an MMC around and through the preform. In a preferred embodiment, the preform is constructed from silicon carbide, and the metal matrix is an aluminum-silicon alloy.

Incorporating partially sintered preforms in metal matrix composites

Metal matrix composites are manufactured in a vacuum die casting machine. Solid aggregate material is placed in a die, the die is evacuated, and molten metal is driven by a piston to infiltrate the solid aggregate material where it subsequently solidifies to form a metal matrix composite.

Monolithic metal matrix composite

A method of fabricating a metal matrix composite containing electrically isolated areas and the MMC formed from the method. The method comprises: (a) providing a liquid pool of unreinforced aluminum alloy; (b) infiltrating the unreinforced aluminum alloy into a stack comprising upper and lower porous preforms and an electrical insulator material placed between the preforms; (c) solidifying the liquid-phase metal to form a metal matrix composite product that completely surrounds the stack; and (d) forming at least one groove in the solidified metal, the groove extending downward to at least one insulating substrate so as to electrically isolate at least one region on the surface of the metal matrix composite.

Fabricating metal matrix composites containing electrical insulators

Lightweight composite armor comprising a plurality of ceramic bodies embedded in a metal matrix. The ceramic bodies are preferably generally spherical alumina balls coated with a binder and ceramic particles. A particularly preferred coating comprises titanium dioxide and barium sulfate particles suspended in an aqueous sodium silicate solution at a thickness of about 0.76-1.5 mm.

Coated ceramic bodies in composite armor

Metal matrix composites are manufactured in a vacuum die casting machine. Solid aggregate material, at least 65 volume percent, is placed in a die, the die is evacuated and heated, and molten metal is driven by a piston to infiltrate the solid aggregate material where it subsequently solidifies to form a metal matrix composite.

Fabrication of metal matrix composites by vacuum die casting

Controlling the linear velocity of melt discharge from the discharge outlets of a melt distribution device so as to essentially negate reverse flow from the walls of the mold has been found to produce less oxides and less surface defects in an ingot, particularly an aluminum ingot. This discharge is controlled from the outset of the casting of an ingot because it has been found most defects occur within the initial phase of a cast. A melt distribution device, referred to as a 'bag-in-a-bag', is provided which is a pressureless interiorly partitioned receptacle. The partitioning of the receptacle provides an outer bag and a melt-impermeable inner bag in which a pool of melt collects. The pool is deep enough to submerge the discharge end of a spout, to dissipate the kinetic energy of the incoming melt, and to distribute melt from a central zone to discharge zones on either side of the central zone. The discharge zones are provided with outlets through which the melt is discharged at a velocity in the range from about 40 in/min to about 100 in/min depending in part upon the drop rate and the size of the ingot to be cast. Desirable drop rates are in the range from about 2-10 in/min, preferably in the range from 3-7 in/min. A novel starting block is provided which confines the flow of melt so as to form a pool of melt in the center of the mold cavity before the rest of the ingot is cast.

Partitioned receptacle for distributing molten metal from a spout to

Controlling the linear velocity of melt discharge from the discharge outlets of a melt distribution device so as to essentially negate reverse flow from the walls of the mold has been found to produce less oxides and less surface detects in an ingot, particularly an aluminum ingot. This discharge is controlled from the outset of the casting of an ingot because it has been found most defects occur within the initial phase of a cast. A melt distribution device, referred to as a 'bag-in-a-bag', is provided which is a pressureless interiorly partitioned receptacle. The partitioning of the receptacle provides an outer bag and a melt-impermeable inner bag in which a pool of melt collects. The pool is deep enough to submerge the discharge end of a spout, to dissipate the kinetic energy of the incoming melt, and to distribute melt from a central zone to discharge zones on either side of the central zone. The discharge zones are provided with outlets through which the melt is discharged at a velocity in the range from about 40 in/min to about 100 in/min depending in part upon the drop rate and the size of the ingot to be cast. Desirable drop rates are in the range from about 2-10 in/min, preferably in the range from 3-7 in/min. A novel starting block is provided which confines the flow of melt so as to form a pool of melt in the center of the mold cavity before the rest of the ingot is cast.

A method of forming a ceramic-metal composite including steps of providing a body of ceramic material; infiltrating molten metal into open spaces of the body at an elevated pressure; cooling the metal to form a solid composite; and reacting a portion of the metal in the composite at an elevated temperature with an oxidizing gas. A particularly preferred composite is made by infiltrating an alumina body with an aluminum alloy and then oxidizing in air at an elevated temperature. The composite is useful for making armor plate and other products where a combination of high hardness, good strength, and light weight are needed.

Formation of ceramic-metal composite by pressure casting and oxidation

A method of manufacturing a metal matrix composite material containing high thermal stability polymer fibers, comprising the steps of: (1) providing high thermal stability polymer fibers; (2) providing a liquid-phase metal; (3) mixing the liquid-phase metal and the high thermal stability fibers; and (4) allowing the liquid-phase metal to solidify and form a metal matrix composite.

Production of metal matrix composites reinforced with polymer fibers

In a system for treating and managing hot aluminum dross, the dross is compacted and delivered by a pair of 'squeeze' rolls in a continuous semi-solid sheet, readily broken up for further treatment or disposal. The rolls may be cooled or heated as required to condition the dross appropriately, for storage or immediate further treatment. Ribs on the rolls and/or a stepped 'break' chute downstream of the rolls may be used to break the compacted dross into 'patties' for convenient handling.

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Murrysville, PA, United States of America

David I Yun