方向性珪素鋼に対する Si-SiC 系酸化防止剤の酸化防止機構

概要

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Antioxidation mechanism of a newly developed oxidation inhibitor of refractory powder mixture composed of SiO_2, Si, SiC, synthetic mica, colloidal silica, surface active agent, and coking bond has been investigated. During heating, Al_2O_3 is formed as a result of the decomposition by Si (metallic silicon) of mullite (3Al_2O_3・2SiO_2) contained in refractory powder. Furthermore, the fine SiC powder is oxidized and changes gradually to a protective cristobalite-SiO_2 (C-SiO_2) layer which acts as an excellent diffusion barrier to oxygen from atmosphere. The protective C-SiO_2 is not formed from the C-SiO_2 which is added in the oxidation inhibitor but is formed through the oxidation process of the SiC. On the other hand, Al_2O_3 which is formed by the decomposition of mullite becomes Al_2O_3・SiO_2 in combination with SiO_2. On the steel surface, however, Al_2O_3 becomes highly protective FeO・Al_2O_3 or 3FeO・Al_2O_3・3SiO_2 layer and, at the same time, it prevents the formation of a low melting point material such as fayalite (2FeO・SiO_2). It has been clarified that this oxidation inhibitor exhibits the excellent antioxidability due to superposed effect of above-mentioned reactions.
社団法人日本鉄鋼協会の論文
1988-05-01