1984 Volume 25 Issue 3 Pages 187-196
The volatilization in the Al–O–C(–Si–Fe) system have been investigated mainly by thermal gravimetry in vacuum for four cases; (1) aluminum oxycarbides, (2) mixtures of alumina and carbon with and without additives (iron oxide, silicon nitride and silicon carbide), (3) mixtures of alumina and aluminum carbide or silicon carbide and (4) mixtures of alumina, silica (mullite), iron oxide and carbon. Al2OC evaporated essentially congruently, whereas Al4O4C evaporated incongruently; α-Al2O3 was formed in addition to vapors. The volatilization reaction between alumina and carbon was found to be enhanced remarkably when iron was added, unchanged by SiC addition and prevented slightly in the presence of Si3N4. The mixtures of alumina and carbide volatilized at lower temperatures than did those of alumina and carbon. These features are discussed in terms of the equilibrium pressure in the light of previous results of reaction experiments focussed upon the oxycarbide formation.
