気相反応法によるSiC-Si_3N_4系複合粉体の合成(2. 気相反応法)(<特集>新技術によるセラミックスの合成と評価(I))

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The formation of SiC-Si_3N_4, composite particles by the vapor phase reaction of Si(CH_3)_4-NH_3-H_2 system at 1200℃ was investigated with emphasis on the effect of m mixing temperature of Si(CH_3)_4 and NH_3 streams. Powders produced were amorphous. When Si(CH_3)_4 was mixed with NH_3 in a low temperature zone below 900℃, the particle size was 0. 05 to 0. 07μm and decreased with an increase in NH_3 concentration. When the mining temperature was 1100℃, the particle size was nearly 0. 02 μm regardless of NH_3 concentration. The amorphous powders crystallized into β-SiC and α-Si_3N_4 (partially including β-Si_3N_4) by the heat treatment at 1 550℃ in Ar- N_2 atmosphere. The crystallized phase from amorphous powder produced dueed in low temperature mixing was SiC phase, SiC-Si_3N_4 composite and Si_3N_4 phase depending on the NH_3, concentration used, among which the composite particles had hybrid structure consisting of Si_3N_4 core and SiC shell. On the other hand, SiC-Si_3N_4 composite particles were obtained even at a high NH_3 concentration in high temperature mixing, and they consisted of SiC core and Si_3N_4 shell. The following formation processes of composite particles in the vapor phase reaction were proposed : in low temperature mixing (T_m=700°-900℃) , nitride particles were produced at first by the reaction between Si (CH_3)d and NH_3 immediately after the mixing and then carbide layer deposited on their surfaces from the unreacted Si(CH_3)_4, while in high temperature mixing (T_m = 1100℃), Si(CH_3)_4 polymerized and decomposed into SiC particles in a low temperature zone and then the SiC particles were nitrided with NH_3 in a high temperature zone.
社団法人日本セラミックス協会の論文
1987-01-01

気相反応法によるSiC-Si_3N_4系複合粉体の合成(2. 気相反応法)(<特集>新技術によるセラミックスの合成と評価(I))

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