還元窒化法によるAlN粉末合成反応に及ぼすCa化合物添加の影響
1994 年 102 巻 1187 号 p. 670-674
詳細
1994 年 102 巻 1187 号 p. 670-674
Effect of Ca-compound addition on synthesis of AlN powder by carbothermal reduction-nitridation method was investigated, in which CaF2, CaCl2, CaCO3, Ca(OH)2, Ca(CH3COO)2 and CaC2 were selected as additives. Each compound promoted the nitridation, and CaF2 and CaCO3 were the most excellent reaction promoters achieving full nitridation even at 1300°C. In case of CaF2 addition, it was estimated that the reduction-nitridation proceeds through the formation of an intermediate compound, CaF2⋅5Al2O3. In case of other additives, Ca-aluminates, CaO⋅xAl2O3 (x=1, 2, 6), were formed as intermediates. The value x in the aluminates was dependent on the chemical species of additives. The grain morphology of synthesized AlN varied with the species of additives; addition of CaF2 and CaCl2 resulted in spherical AlN particles. The reduction-nitridation behavior of CaO⋅Al2O3 and CaO⋅2Al2O3 was also investigated. The Ca-aluminates changed through the reaction step; CaO⋅2Al2O3→CaO⋅Al2O3→12CaO⋅7Al2O3→CaO, finally yielding AlN.
