Makoto Katsumata

Fabrication of hollow alumina microspheres via core/shell structure of polymethylmethacrylate/ alumina prepared by mechanofusion

Core/shell microspheres of polymethylmethacrylate coated with Al2O3 or a mixture of Al2O3 and SiO2 nanoparticles have been successfully prepared by a mechanofusion system. The microspheres were then subjected to removal of PMMA by firing in air, followed by sintering at 1600°C for 3 h. The shell structure was destroyed after the sintering when the shell layer consisted of only Al2O3. The addition of SiO2 was found to be effective for maintaining the original shell structure, while the shell size expanded slightly and a hole was formed in each hollow microsphere during the removal process of PMMA.

Preparation of Core/Shell Microspheres of Polymethylmethacrylate/Alumina by Mechanofusion as a Precursor of Hollow Alumina Microspheres

Core/shell microspheres of polymethylmethacrylate (PMMA) coated with Al 2 O 3 were successfully fabricated by a mechanofusion system. The microshperes were subjected to calcination to give hollow Al 2 O 3 microspheres. The Al 2 O 3 shell structure was destroyed during a pre-firing or sintering process without the addition of fine SiO 2 powder. In contrast, addition of 5.0 or 10.0 wt% SiO 2 was found to be effective for maintaining the original shell structure, while the size of hollow Al 2 O 3 microspheres increased slightly and a small hole formed in each microsphere during the removal process of PMMA.