Title:
【発明の名称】無圧焼結法または低圧気体焼結法により製造した高密度の自己強化性窒化ケイ素セラミック
Document Type and Number:
Japanese Patent JPH06505225
Kind Code:
A
Abstract:
A dense, self-reinforced silicon nitride ceramic prepared by pressureless sintering or low pressure gas sintering. The composition comprises (a) silicon nitride, at least 20 percent of which is in the form of beta -silicon nitride whiskers having a high average aspect ratio, (b) from about 2 to about 10 weight percent of a glassy grain boundary phase containing magnesium oxide, yttrium oxide, silica, zirconia, and optionally, one oxide selected from the group consisting of calcium, gallium, indium and hafnium oxides, and (c) a second crystalline phase in an amount ranging from 0.5 to about 5.0 weight percent comprising zirconium oxide, and (d) optionally, crystalline phases of metal zirconium silicide and/or metal zirconium silicon nitride in a combined amount from 0.1 to 3.0 weight percent, wherein the metal is tantalum, calcium, hafnium, gallium or indium, and wherein when the metal is calcium, hafnium, gallium or indium, the same metal occurs as the metal oxide in the glassy phase. The ceramic exhibits high fracture toughness and high fracture strength and has a density of at least 98 percent of theoretical.
Inventors:
Pikiku, Alexander Jei
Application Number:
JP50529492A
Publication Date:
June 16, 1994
Filing Date:
January 06, 1992
Export Citation:
Assignee:
The Dow Chemical Company
International Classes:
C04B35/584; C04B35/593; C04B35/645; C04B35/80; (IPC1-7): C04B35/58; C04B35/58
Attorney, Agent or Firm:
Heiyoshi Odashima