Surface modification of CaO–Al2O3–SiO2 glass by dissolution of aluminum and silicon components into alkali hydrothermal medium

CaO–Al2O3–SiO2 glass (36:11:53 in molar ratio as a batch composition) was subjected to a hydrothermal treatment in 2 M NaOH at 120 °C for 24 h for making surface-porous glass. The surface-porous structure of the glass with the thickness of about 12 μm was formed by dominant aluminum and small silicon dissolutions to the hydrothermal medium. The porous surface consisted of solid substances with a size of several micrometers connected with each other and spaces with a size ranging from 0.2 to 3 μm. Furthermore, the dispersion of TiO2 particles on this surface-porous glass by a sol–gel dipping process was successful. It was concluded that the alkaline hydrothermal treatment was effective for the formation of surface-porous glass as a potential support of TiO2 fine particles.