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US 5,394,015 AGranted
Method of producing sintered silicon nitrides
AssigneeSumitomo Electric Industries, Ltd.
InventorsYasushi Tsuzuki, Tomoyuki Awazu, Akira Yamakawa
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AssigneeSumitomo Electric Industries, Ltd.
InventorsYasushi Tsuzuki, Tomoyuki Awazu, Akira Yamakawa
Estimating the term…
The invention provides a method of producing sintered silicon nitrides having such strength characteristics as are sufficient to insure satisfactory reliability of the sintered silicon nitride for use in applications such as automotive engine parts and bearings. The method comprises preparing a sintering aid by blending yttrium oxide, spinel, and aluminum oxide and/or aluminum nitride together in such proportions in terms of molar ratios of metal elements that Y/(Al+Mg) is 0.23 to 0.85 and Al/Mg is 2.1 to 5.2, mixing 5.0 to 13.0% by weight of the sintering aid with 87.0 to 95.0% by weight of a silicon nitride powder having an .alpha. crystallinity of not less than 60%, and, after the resulting powder mixture is molded into shape, sintering the molded piece at temperatures of 1400 to 1650.degree. C. in a nitrogen gas atmosphere or in an inert gas atmosphere containing nitrogen gas.
A method of producing a sintered silicon nitride which comprises preparing a sintering aid by blending yttrium oxide, spinel, and aluminum oxide and/or aluminum nitride together in such proportions in terms of molar ratios of metal elements that Y/(Al+Mg) is 0.23 to 0.85:1 and Al/Mg is 2.1 to 5.2:1 mixing 5.0 to 13.0% by weight of the sintering aid with 87.0 to 95.0% by weight of a silicon nitride powder having an a crystallinity of not less than 60%, and, after the resulting powder mixture is molded into a molded piece, sintering the molded piece at temperatures of 1400 to 1650.degree. C. in a nitrogen gas atmosphere or in an inert gas atmosphere containing nitrogen gas.
Dependencies are inferred from the claim text.