Brush Wellman, Inc.

Materials and Electrochemical Research (Mer) Corporation

Juan L Sepulveda

David E Jech

Anthony B Traversone

Raouf Loutfy

Sekyung Chang

Sharly Ibrahim

Mark Opoku-Adusei

Richard H Sworden

Ricardo Ramos

Jordan P Frazier

A freeze-forging method for producing sintered three-dimensional ceramic bodies, particularly magnesium aluminate spinel domes. The method comprises forming a ceramic mix of a ready-to-sinter ceramic powder and a nonaqueous liquefied sublimable vehicle having a solidification temperature from room temperature to below 200&#xb0; C.; reducing the temperature of the ceramic mix to below the vehicle's solidification temperature to freeze the mix; crushing the frozen mix into powdered form; molding the frozen powder into net shape by cold forging in a mold to form a net-shaped green body preform of the desired three-dimensional shape; and densifying the green body into a sintered three-dimensional ceramic body.

Production of sintered three-dimensional ceramic bodies

An in-situ method for nanomixing magnesium aluminate spinel nanoparticles with a uniformly distributed controlled concentration of nanoparticles of an inorganic sintering aid, such as LiF, to produce ready-to-sinter spinel powder. The spinel-sintering aid nanomixture is formed by induced precipitation of the sintering aid nanoparticles from a dispersion of the spinel nanoparticles in an aqueous solution of the sintering aid, followed by separation, drying and deagglomeration of the spinel-sintering aid nanomixed product.

Ready-to-sinter spinel nanomixture and method for preparing same

The thermal conductivity, thermal conductivity, of a sintered copper/refractory metal composite having a maximum porosity of about 1% is greatly improved when the composite contains phosphorus and sintering aid in a specified weight ratio, &ldquo;phosphorus/sintering aid ratio.&rdquo; The copper/refractory matrix composite herein comprises, by weight, from about 5% to about 30% copper, from about 0.2% to about 0.6% sintering aid, from about 0.08% to about 0.3% phosphorus, the remaining metal is refractory metal. The phosphorus to sintering aid ratio ranges from about 0.25 to about 0.55. In one embodiment of the invention the sintering aid contains cobalt and the refractory metal is tungsten.

High conductivity copper/refractory metal composites and method for making same

The invention provides for a functionally-graded metal substrate that is made of at least two metal compositions, a functional insert and a surrounding body that surrounds the functional insert. In a preferred embodiment of the invention a functional insert powder composition of loose powder metal is placed in a compact of a surrounding body powder composition and both metal compositions are sintered in a sintering furnace to form a sintered part. The sintered part is infiltrated in part or in whole with a molten metal compound to produce a functionally graded metal substrate having a density of at least 90% of theoretical. A heat-generating component such as a chip can be attached to the metal substrate for use in microelectronic packaging. When the functionally-graded metal substrate has two discrete compositions of copper/tungsten the surrounding body which has a CTE that ranges from about 5.6ppm/.degree. C. to about 7 ppm/.degree. C. constrains the expansion of the functional insert which has a thermal conductivity that ranges from about 200 W/mK to about 400 W/mK.

Functionally graded metal substrates and process for making same

The process for producing net shape or near net shape metal parts is improved by sintering a compact in a reducing atmosphere where the compact contains a metal and chemically-bound oxygen in the form of a metal oxide, for example, and the chemically-bound oxygen is in an amount sufficient to improve the sintering of the compact. Improved sintering is facilitated when the metal oxide forms a metal/metal oxide eutectic during reduction of the chemically-bound oxygen in a reducing atmosphere during the sintering process. The compact can contain a metal oxide and a solution compound to produce an alloy part, provided the chemically-bound oxygen is present in an amount sufficient to improve sintering. In a preferred embodiment, the compact also contains a reinforcement compound and is sintered to make a metal matrix composite. The resultant density of the near net shape metal parts made by the improved sintering process is preferably about 97% or more of the theoretical density.

Process for making improved net shape or near net shape metal parts

The sinterability of a copper/tungsten green compact is improved by using copper oxide, tungsten oxide or both as the copper and/or tungsten source. Sinterability is further enhanced by including steam in the sintering atmosphere. Spontaneous combustion of the source powders used to form the sintering compacts can be reduced or eliminated by including corrosion inhibitor in the powders.

Process for retarding spontaneous combustion of powdery mixtures

The sinterability of a copper/tungsten green compact is improved by using copper oxide, tungsten oxide or both as the copper and/or tungsten source. Sinterability is further enhanced by including steam in the sintering atmosphere.

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Tucson, AZ, United States of America

Juan L Sepulveda