Al2(SO4)3용액의 가수분해에 의해 얻어진 Aluminum Hydroxides Gel의 pH가 판상 α−Al2O3의 결정성장에 미치는 영향

Abstract

To precipitate the complex gels of the pH 6, 7, 8, 9 included in a flux and an aluminum hydroxides gel, an aqueous solution of a mixture of Na₂CO₃ and Na₂PO₄ㆍ12H₂O was added with stirring in an aqueous solution of a mixture of Al₂(SO₄)₃ㆍ18H₂O, Na₂SO₄ and K₂SO₄, and then the complex gels were aged in ₂0 h at 90℃. As the hydrolysis pH changed, it had an effect on the physical properties such as the crystal structure, crystal morphology and a phase transition temperature of the AlO(OH) gel, and also on the crystal structure, crystal morphology, particle size and particle size distribution of the α-Al₂O₃ platelets prepared by molten-salt precipitation. Also, in this study, the complex gels were crystallized at 1,200℃ and thereafter dried at 110℃, and then it was investigated to effect of the hydrolysis pH on the crystal structure, morphology and particle size distribution of the α-Al₂O₃ platelets crystals using XRD, DTA, SEM and particle size analyzer.