コンヴァージョン法によるSiC層の形成機構と微細構造
1997 年 61 巻 11 号 p. 1228-1233
詳細
1997 年 61 巻 11 号 p. 1228-1233
As an oxidation protection system for C/C composites, SiC coating by conversion method (conv-SiC layer) is very important. In order to obtain a clear understanding of SiC conversion mechanisms, microstructure of the conv-SiC layers on carbon substrates was inspected and microstructural evolution process was discussed from a thermodynamical point of view. As carbon substrates, isotropic graphite and C/C composites were selected. conv-SiC is formed through a reaction between C of the substrates and SiO gas. SiO gas is mainly produced through reaction between Si in a raw material for SiC conversion and CO gas from SiC formation reaction. A dominant transportation mechanism of SiO gas and CO gas during SiC conversion is assessed to be gaseous diffusion through micropores with a diameter of about 200 nm in the growing conv-SiC region or surface diffusion on the wall of the micropores instead of solid-state diffusion. A precise microstructural analysis of the conv-SiC layer and SiC/C interface suggested its excellent adhesion characteristics with the substrates.
