Chemistry of inorganic compounds – Nitrogen or compound thereof – Binary compound
Patent
1991-06-17
1993-03-02
Langel, Wayne
Chemistry of inorganic compounds
Nitrogen or compound thereof
Binary compound
4285395, 501 96, C01B 21072
Patent
active
051907380
ABSTRACT:
A process for producing unagglomerated single crystals of aluminum nitride of low oxygen content having a size of at least 10 microns suitable for the reinforcement of metal, ceramic and polymeric matrix composite materials, and especially metal matrix materials. The process involves producing a reaction mixture of alumina (or a precursor), carbon (or a precursor), and an alkali metal oxide (or precursor such as a carbonate) as a crystal growth promoter or catalyst. The alkali metal oxide is present in an amount required for the formation of crystals of the required size, preferably in the range of 10-60 microns. The reaction mixture is subjected to a preheating step under nitrogen at a temperature in the range of 1600.degree.-1700.degree. and is then subjected to a heating step under nitrogen at a temperature in the range of 1800.degree.-1950.degree. C. This two-stage heating process ensures that the resulting crystals are of low oxygen content and thus good thermal conductivity. Particularly desirable crystals are produced if electrostatic precipitator dust is used as a source of the alumina, if petroleum coke or calcined anthracite coal is used as a source of the carbon and if the reaction is carried out in the presence of a porosity enhancer for the reaction mass, especially short cellulose fibres. The particles produced by the invention are in the form of large single crystals for good matrix reinforcement and have low oxygen and carbon contents. The invention extends to the particles produced by the process and to matrix composites reinforced with the particles.
REFERENCES:
patent: 1094171 (1914-04-01), Serpek
patent: 2962359 (1960-11-01), Perieres et al.
patent: 3032398 (1962-05-01), Clair
patent: 3477812 (1969-11-01), Huml et al.
patent: 3607014 (1971-09-01), Huml et al.
patent: 3933573 (1976-01-01), Dugger
patent: 4322395 (1982-03-01), McHenry et al.
patent: 4481300 (1984-11-01), Hartnett et al.
patent: 4528119 (1985-07-01), Barnes
patent: 4540673 (1985-09-01), Takeda et al.
patent: 4615863 (1986-10-01), Inoue et al.
patent: 4618592 (1986-10-01), Kuramoto et al.
patent: 4650777 (1987-03-01), Kurokawa et al.
patent: 4693989 (1987-09-01), Sane
patent: 4806330 (1989-02-01), Melling et al.
patent: 4812425 (1989-03-01), Walker
patent: 4869925 (1989-09-01), Hiai et al.
patent: 4908173 (1990-03-01), Schwetz et al.
patent: 4977113 (1990-12-01), Phelps et al.
patent: 5096860 (1992-03-01), Nadkarni
P. B. Perry et al, "The optical absorption edge of single-crystal AIN prepared by a close-spaced vapor process", Appl. Phys. Lett. 33 (4), Aug. 15, 1978, pp. 319-21.
K. M. Taylor et al, "Some Properties of Aluminum Nitride", Journal of the Electrochemical Society (Apr. 1960), pp. 308-314.
Hirai et al-Nippon Kinzoku Gakkaishi, 54(2), 181-5 (1990) English Abstract.
Alcan International Limited
Langel Wayne
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