硫酸钠熔盐制备片状α-Al2O3的研究

分别以十八水合硫酸铝和氢氧化铝为γ-Al2O3源,以硫酸钠为熔盐,干法混合熔盐和γ-Al2O3,采用熔盐法制备片状氧化铝.结果表明:以氢氧化铝为γ-Al2O3源,由于氢氧化铝为母盐分解后仍保留球形多面体的母盐假相,熔盐只能溶解球形多面体表面的氧化铝,经过溶解-沉淀过程生长出少量镶嵌于球形多面体的片状氧化铝,不能制备片状氧化铝;以十八水合硫酸铝为氧化铝源,分解后形成的分散程度良好的γ-Al2O3与硫酸钠熔盐摩尔比γ-Al2O3∶Na2SO4=1∶4时能够充分溶解于熔盐中,可制备出分散的片状氧化铝.

Preparation of Alpha-alumina Platelets by Sodium Sulfate Molten Salt

The alpha-alumina platelets were prepared in sodium sulphate molten salt by dry method mixing molten salt and different source γ-Al2O3 respectively.The γ-Al2O3 was prepared with aluminum sulfate octadecahydrate and aluminum hydroxide respectively.The results indicate that the alumina platelets cannot be prepared in sodium sulphate molten salt with aluminum hydroxide as the source of γ-Al2O3.The decomposed aluminum hydroxide remaine pseudomorph of the spherical polyhedron.A small amount of alumina platelet is grown and inserted in the spherical polyhedron through dissolution-precipitation due to molten salt could only dissolved alumina in the spherical polyhedron surface.The dispersed alumina platelets could be obtained in sodium sulphate molten salt with aluminum sulfate octadecahydrate as the source of γ-Al2O3.The well dispersed γ-Al2O3, decomposed from aluminum sulfate octadecahydrate, completely dissolve in molten salt, then alumina platelets precipitated out in molten salt when the molar ratio of γ-Al2O3∶Na2SO4 is 1∶4.