| 摘要 |
PURPOSE:To obtain uniform particle shape with small particle size and small dispersion of the particle size, and to facilitate sintering without using a sintering flux by calcining a powder mixture comprising alumina powder, carbon powder, and specified oxide powder in nitrogen-contg. nonoxidizing atmosphere. CONSTITUTION:Powder of alumina or of a compd. generating alumina powder by heat treatment, powder of carbon or of a compd. generating carbon powder by heat treatment, are mixed with powder of oxide of group IIa element of the Periodic Table or of a compd. generating the same powder by heat treatment. Obtd. powder mixture is calcined (at ca. 1,400-1,850 deg.C) in N2-contg. nonoxidizing atmosphere. Preferred proportion of the above described components is 0.35-2pts.wt. carbon powder and 0.005-1.0pts.wt. oxide of the group IIa per 1pt.wt. alumina powder. (When compds. generating alumina, carbon, or said oxide by heat treatment are used, the proportion means the proportion of the heat-treated products). |
