Si_3N_4 Al_2O_3 MgO厚肉焼結体の焼結過程における気孔の形成機構

概要

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Massive Si_3N_4 Al_2O_3 MgO ceramics 50 min in outer diameter and 50 mm high were sintered to study the formation mechanism of pores which were produced in the inner part of sintered bodies. Sintering was per formed at temperatures of 1600, 1700, 1750 and 1800℃ under nitrogen gas flow. The sintered bodies consisted of dense surface and porous interior. Pores formed at temperatures above 1700℃. As temperature increased, the size of pores increased. Pores seem to be produced by trapping CO gas in the sintered body. CO gas is generated by the following chemical reaction of SiO_2 and C (carbon) , which are contained in the Si_3N_4 green body; Si0_2 + 3C SiC + 2CO . Non porous and homogenious Si_3N_4 ceramics can be obtained by the use of raw Si_3N_4 powders containing less than 0.2wt% car bon, and firing at the temperature range from 1400 to 1600℃ with a heating rate of less than 1.7 K/min.
社団法人日本セラミックス協会の論文
1994-03-01