W. R. Grace Co.-conn.

USA As Represented by Secretary of the Navy

Other

Piezo Electric Products, Inc.

Roy W Rice

John W Lau

Jack H Enloe

Craig P Cameron

Robert C Pohanka

Jacob Block

Philip L Berneburg

Tariq Quadir

Basil E Walker

William J McDonough

Charles R Morgan

Kenneth Joseph Wynne

Awdhoot V Kerkar

Paul D Smith

Christian B Lundsager

Rasto Brezny

Manfred Kahn

Robert M Spotnitz

Leonard E Dolhert

Jyoti P Chakraverty

William S Coblenz

Anthony J Colageo

William B Fox

John J Mecholsky, Jr

Stephen W Freiman

Damian E Shadwell

The invention encompasses a method of forming a composition containing an AlN-SiC composite and/or solid solution, the method comprising:

Reaction processing of AlN/SiC composites and solid solutions

Transformation-toughened material bodies such as transformation-toughened zirconia may be strengthened by grit blasting the body surface. Grit blasting of the surface with a grit material such as alumina or silicon carbide can result in flexural strength increases of at least about 10-20% compared to the body prior to blasting. The method of the invention provides strength increases comparable or better than those resulting from surface grinding and may be used for a broader variety of body shapes.

Non-machining surface strengthening of transformation toughened materials

The invention encompasses a method of forming a densified ceramic part comprising the steps:

Manufacture of optical ferrules by electrophoretic deposition

Thermoplastic rubber is used as part of a thermally conductive electrically insulating filled elastomer composition. The filler may be any conventional filler such as hexagonal boron nitride or alumina. The thermoplastic rubber may be crosslinked. The filled elastomer can be molded or pressed into desired shapes.

Thermally conductive elastomer

Low sodium hollow glass microspheres containing less than about 3 wt. % Na.sub.2 O are produced from aqueous precursors. The method comprises

Method for making low sodium hollow glass microspheres

A boron compound, capable of forming boron oxide on hot pressing in an oxygen-containing atmosphere, is used as a densification aid for hot pressing of alumina-containing ceramics in oxygen-containing atmospheres. The boron compound may be incorporated into the material to be hot pressed or may be applied to the surface of that material. Air may be used as the hot pressing atmosphere. The alumina-containing ceramic to be hot pressed may be formed by reaction processing techniques. Boron nitride is a preferred boron compound.

Hot pressing densification aid for alumina

Monolithic bodies of sinterable materials are formed by a sintering process in which little or no shrinkage of the body occurs during sintering. In the method, large particles are placed in particle-to-particle contact with finer size powder particles at the interstices to form a molded shape which is then fired. During firing, the large particles are substantially stable, but the fine powder particles sinter to bond the large particles together. The method is especially useful for producing large and/or intricately shaped bodies. The method is also especially useful for making monolithic bodies using large hollow spherical particles.

Method for making sintered bodies

The processes of the invention involve the formation of an initial reactant mixture by combining sources of SiO.sub.2, B.sub.2 O.sub.3, aluminum, and carbon. The mixture may then optionally be shaped or compacted. The reactant mixture is then heated to start a reaction which is described by the formula:

Al.sub.2 O.sub.3 /B.sub.4 C/SiC composite

The invention encompasses unsintered and sintered compositions comprising boride and alumina. A sintered material containing boride and alumina may be produced by a method comprising:

Rare earth boride/alumina composites and methods of making

Low cost sintered silicon nitride suitable for use as a structural ceramic is provided. Certain low grade silicon nitride powders can be used to produce low cost sintered silicon nitride bodies having good mechanical properties. Compositions using such silicon nitride powders in combination with various sintering aids are also disclosed.

Sintered silicon nitride

An electronic package comprising dielectric layers including a densified aluminum nitride (AlN) base layer and at least one densified AlN-borosilicate glass composite layer bonded thereto is described. Any of the dielectric layers may be metallized with conductive circuit patterns and can contain conductive vias. Production of this package is accomplished by hot pressing a greenware laminate comprising a densified base (e.g., AlN); at least one green sinterable sheet(e.g., AlN-borosilicate glass composite); and a green sheet of non-sinterable material (e.g., boron nitride [BN]. The respective green sheets comprise homogeneous mixtures of the ceramic powders and a binder, e.g., polyethylene. The polyethylene is burnt off during the hot press operation. Residual BN is removed by brushing and/or grit blasting, leaving the finished electronic package, all ceramic elements of which are densified. The package provides superior thermal conductivity, strength, dielectric properties, and silicon-compatibility.

Electronic package comprising aluminum nitride and aluminum

An electronic package comprising dielectric layers including a densified aluminum nitride (AlN) base layer and at least one densified AlN-borosilicate glass composite layer bonded thereto is described. Any of the dielectric layers may be metallized with conductive circuit patterns and can contain conductive vias. Production of this package is accomplished by hot pressing a greenware laminate comprising a densified base (e.g., AlN); at least one green sinterable sheet (e.g., AlN-borosilicate glass composite); and a green sheet of non-sinterable material (e.g., boron nitride [BN]). The respective green sheets comprise homogeneous mixtures of the ceramic powders and a binder, e.g., polyethylene. The polyethylene is burnt off during the hot press operation. Residual BN is removed by brushing and/or grit blasting, leaving the finished electronic package, all ceramic elements of which are densified. The package provides superior thermal conductivity, strength, dielectric properties, and silicon-compatibility.

An improved welding cup is made from graphite or ceramic fiber composites, coated with silicon nitride, sialon, boron nitride, or silicon carbide. The cup shows superior resistance to erosion, slagging, and thermal fracture.

Coated welding cups

A sintered silicon nitride product is made having a high flexural strength by sintering a mixture of silicon nitride and a sintering aid containing alumina and at least a three component rare earth oxide mixture which does not contain yttria. Based on the weight of the final sintered nitride product, the three component rare earth oxide mixture comprises about 3 to 6% La.sub.2 O.sub.3, 2 to 5% Nd.sub.2 O.sub.3, and 1 to 4 CeO.sub.2. An additional fourth component, Pr.sub.6 O.sub.11, can be added in an amount of 0.5 to 1.1%.

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Alexandria, VA, United States of America

Roy W Rice