Silicon nitride sintered body and its manufacturing method

文件类型：PDF文档
文件大小：198K
PURPOSE : To obtain a dense high strength silicon nitride sintered compact as well as to shorten nitriding time and to enhance productivity by subjecting Si powder having a specified concn. of unpaired electrons to reactive sintering in a nitrogen atmosphere. CONSTITUTION : A compd. of at least one kind of element among rare earth element, Al, Mg, and Ca is added as a sintering aid by 0.1-15mol% (expressed in terms of the element) to Si powder having 10 -10 /cm concn. of unpaired electrons. An element whose valence is +1 to +3 other than Al, Mg and Ca or a compd. of the element is further added as a nitrogen hole forming agent by 0.5-15mol% (expressed in terms of the element). The covalent bond radius RM of the element whose valence is +1 to +3 and the covalent bond radius RSi of Si satisfy the relation of (RM-RSi)/RSi -10 /cm concn. of unpaired electrons, >=99% relative density and >=800MPa three-point bending strength.