Synthesis of Si3N4 using Residual Organics Trapped in the Silica Gel by Sol-Gel Method

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J. Korean Ceram. Soc. > Volume 29(5); 1992 > Article

Journal of the Korean Ceramic Society 1992;29(5): 357.

졸-겔법으로 제조된 실리카겔중의 잔류유기물을 이용한 $Si_3N_4$의 합성

김병호, 신현호, 이재영

고려대학교 공과대학 재료공학과

Synthesis of Si3N4 using Residual Organics Trapped in the Silica Gel by Sol-Gel Method

ABSTRACT

Residual organics were considered as impurity in Sol-Gel method. The purpose of this study was to find the conditions to contain as much residual organics as possible in silica gel prepared from TEOS(tetraethylortho-silicate) by Sol-Gel method. Residual organics are to be expected to have reduction effect on synthesizing Si3N4 from silica gel. The results of this study are follows: 1) The maximum content of entrapped carbon was 19.8 wt.%(C/SiO2=0.25 wt.ratio) in silica gel synthesized under the conditions 1.5 fold mole water for incomplete hydrolysis, 2.5 fold mole phenol as a solvent and 0.1 fold mole HCl as a catalyst to TEOS. 2) Silica gel with organics entrapped by Sol-Gel method had a positive effect on the formation of Si3N4 compared with commercial silica gel. 3) Sintered body of synthesized $alpha$-Si3N4 with Y2O3 and Al2O3 as additives at 175$0^{circ}C$ in N2 atmosphere showed bending strength, 602$pm$20 MPa and frature toughness 4.45$pm$0.15 MPa.m1/2.