Abstract: 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.

Key words: 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.