Compositions: ceramic – Ceramic compositions – Refractory
Patent
1990-08-24
1992-06-02
Group, Karl
Compositions: ceramic
Ceramic compositions
Refractory
501 98, 501 95, 264 65, C04B 3558
Patent
active
051186454
ABSTRACT:
A process for preparing a self-reinforced silicon nitride ceramic body of high fracture toughness comprising hot-pressing a powdcer mixture containing silicon nitride, a densification aid such as sodium oxide, a conversion aid such as lanthanum oxide and a compound, such as gallium oxide, which enhances growth of .beta.-silicon nitride whiskers-under conditions such that densification and the in situ formation of .beta.-silicon nitride whiskers having a high aspect ratio occur. A novel silicon nitride ceramic of high fracture toughness and high fracture strength is disclosed comprising a .beta.-silicon nitride crystalline phase wherein at least about 20 volume percent of the phase is in the form of whiskers having an average aspect ratio of at least about 2.5; a glassy second phase containing the densification aid, the conversion aid, the compound which enhances growth of .beta.-silicon nitride whiskers, and an amount of silica; and not greater than about 10 weight percent of the total weight as other phases. The glassy phase may also include a minor amount, e.g., up to 5.0 weight percentg, based upon total weight of the ceramic, of aluminum nitride or boron nitride. The glassy phase optionally includes an amount of a secondary reinforcing material such as silicon carbide whiskers.
REFERENCES:
patent: 3950464 (1976-03-01), Masaki
patent: 4004937 (1977-02-01), Masaki
patent: 4025351 (1977-01-01), Masaki
patent: 4046580 (1977-02-01), Ishii et al.
patent: 4097293 (1978-09-01), Komeya et al.
patent: 4119689 (1978-10-01), Prochazka et al.
patent: 4179301 (1979-04-01), Buljan
patent: 4218257 (1980-11-01), Oda
patent: 4227842 (1980-09-01), Samanta et al.
patent: 4279657 (1981-11-01), Greskovich
patent: 4296065 (1981-07-01), Ishii et al.
patent: 4323325 (1982-09-01), Samanta et al.
patent: 4406668 (1983-04-01), Sarin et al.
patent: 4407970 (1983-05-01), Komatsu et al.
patent: 4511525 (1985-06-01), Tsuge et al.
patent: 4543345 (1985-08-01), Wei
patent: 4603116 (1986-08-01), Smith et al.
patent: 4609633 (1986-06-01), Fukuhara
patent: 4652276 (1987-01-01), Burden
patent: 4699890 (1987-04-01), Matsui
patent: 4717693 (1988-01-01), Wittmer
patent: 4734234 (1988-04-01), Sterzel
patent: 4753764 (1988-02-01), Kamijo et al.
patent: 4879263 (1989-11-01), Kemeya et al.
patent: 4883776 (1989-09-01), Pyzik et al.
patent: 4919689 (1990-02-01), Pyzik et al.
patent: 4923829 (1990-03-01), Yasutomi
Akihiko Tsuge et al., Journal of The American Ceramics Society, 58 323-326 (1975).
F. F. Lange, Journal of The American Ceramics Society 62, 1369-1374 (1983).
Chemical Abstract 105:157787w (1986).
Beaman Donald R.
Dubensky William J.
Pyzik Aleksander J.
Pyzik Barbara M.
Rossow Harold E.
Group Karl
Howard D. R.
The Dow Chemical Company
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