# US 5,710,382 A · Aluminum nitride, aluminum nitride containing solid solutions and aluminum nitride composites prepared by combustion synthesis and sintered bodies prepared therefrom

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- Number: US 5,710,382 A
- Document ID: US5710382A
- Status: Granted
- Kind: A
- Application number: 08/593,310
- Filed: 1996-01-31
- Granted: 1998-01-20
- Earliest claimed: 1995-09-26
- Assignees: The Dow Chemical Company
- Inventors: Stephen D. Dunmead; William G. Moore; Kevin E. Howard; Kevin C. Morse; Theresa A. Guiton
- Web page: https://patentgrep.com/patent/US5710382A

## CPC

- C01B 21/072: with aluminium
- C04B 35/581: based on aluminium nitride
- C04B 35/80: Fibres, filaments, whiskers, platelets, or the like
- C01P 2004/10: extending in one dimension, e.g. needle-like
- C01P 2004/20: extending in two dimensions, e.g. plate-like
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2006/10: Solid density
- C01P 2006/12: Surface area
- C01P 2006/80: Compositional purity
- Y10T 428/12042: Porous component
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Aluminum nitride powder, aluminum nitride platelets, powdered solid solutions of aluminum nitride and at least one other ceramic material such as silicon carbide, and composites of aluminum nitride and transition metal borides or carbides are prepared by combustion synthesis at low gaseous nitrogen pressures. Porous bodies of aluminum nitride or composites of aluminum nitride and transition metal borides or carbides are also prepared by combustion synthesis at these pressures. The porous bodies are suitable for infiltration, either as formed or after being coated with at least one layer of a silicate material, by polymers or metals. The powders are also suitable for preparing dense sintered bodies. The aluminum nitride powder is also used to prepare AlN sintered bodies.

## Claims

### Claim 1

Aluminum nitride platelets, prepared by combustion synthesis comprising:
a) igniting, in the presence of gaseous nitrogen at a pressure of from 0.75 to 30 atmospheres (0.075 to 3 MPa), a particulate material that is a metal selected from aluminum and aluminum alloys in admixture with carbon and
b) allowing the combustion wave to pass through substantially all of the admixture to convert at least 10 percent by weight of the aluminum in the particulate material to aluminum nitride.

### Claim 2

A sintered AlN body formed by sintering, an aluminum nitride powder prepared by a method comprising,
a) igniting, in the presence of gaseous nitrogen at a pressure of from 0.75 to 30 atmospheres (0.075 to 3 MPa), a particulate material that is a metal selected from aluminum and aluminum alloys, optionally in admixture with an inert solid diluent, the particulate material having a bulk density and an aluminum metal content sufficient to establish and maintain a self-propagating combustion wave that passes through the admixture and
b) allowing the combustion wave to pass through substantially all of the admixture to convert the aluminum in the particulate material to aluminum nitride powder,
in an inert atmosphere at a temperature and pressure sufficient to densify the aluminum nitride powder to form the AlN sintered body, said body having a density of at least about 98% of theoretical, thermal conductivity of at least about 100 W/m-K and metal impurity concentration of at least about 200 ppm to at most about 20,000 ppm by weight, wherein the metal impurity is in the form of a metal silicide, a metal boride, or a metal boron silicide.

### Claim 3 (depends on 2)

The AlN sintered body of claim 2 wherein the sintered body has a metal impurity concentration of at least about 200 ppm but less than about 10,000 ppm.

### Claim 4 (depends on 3)

The AlN sintered body of claim 3 wherein the metal impurity is iron.

### Claim 5 (depends on 2)

The sintered AlN body of claim 2 wherein the AlN body contains a compound of a rare earth metal, yttrium, alkaline earth metal, boron or combination thereof.

### Claim 6 (depends on 5)

The sintered body of claim 5 wherein the compound is an oxide.