CHEMICAL MODIFICATION OF POROUS-GLASS USING ZIRCONIUM PROPOXIDE

A porous glass specimen, having a mean pore diameter of 10 nm, was pre pared from fluorine containing sodium borosilicate glass, Two types of specimens (PG-S and PG-B) were impregnated with Zr-propoxide by the s ol-gel method, PG-S had larger pores containing less residual silica-g el. PG-B had larger and smaller pores containing less and larger amoun ts of residual silica-gel, respectively, Zr-propoxide in pores was con verted into Zr-oxide by drying at room temperature and heating at 500 degrees C. These treatments of impregnation and conversion were repeat ed up to 5 times. ZrO2 was identified as tetragonal zirconia, The amou nt of anchored ZrO2 in pores increased with increasing number of the t reatment. ZrO2 precipitated mainly in the larger pores and these large r pores decreased in pore size, Therefore, the inhomogeneous pore size distribution was adjusted to become homogeneous by the treatment with Zr-propoxide. The alkali resistance of porous glass specimens was imp roved by this chemical modification to some extent.