シリコン粒子の窒化機構に関する考察

概要

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Si_3N_4 ceramics can be obtained by nitridation of Si powder compact accompanying a little volume change. Elucidating the nitridation mechanism of Si particle is important to control the form of Si_3N_4 particle. In this work, TEM analysis of the initial stage of nitridation of Si particle was conducted, and following are concluded ; (a)at the initial stage of nitridation of Si particle, at temperature between 1100 to 1250°C, 10 nm to 50 nm thickness of Si_3N_4 layer is formed between the Si body and the surface oxide layer, which indicates the nitriding velocity is low. (b)the Si_3N_4 layer becomes thinner with decreasing the radius of Si particle. (c)The nitridation mechanism of Si particle can not be explained by linear-parabolic model, and it suggests that not only the diffusion velocity of N_2 and the reaction velocity of Si and N_2. (d)The volume expansion of Si_3N_4 shell leads a radius compressive stress and circumferential tensile stress, which are proportional to the third power of a particle radius. The radius compressive stress increases with decreasing the radius of Si particle, and it controls a nitriding velocity.
社団法人日本セラミックス協会の論文
1997-07-01