PREPARATION OF POROUS SILICA GLASS AND CONTROL OF ITS PORE-SIZE DISTRIBUTION

Porous silica glass was prepared by phase separation of Na2O-B2O3-CaO-SiO2 glass. After homogeneous glasses were heated between 652 degrees C and 732 degrees C for several hours, they were immersed in 1 M nitric acid for 8 h at 85 degrees C. Then the silicate gel that remained in the pore was removed by 0.1 M sodium hydroxide solution. The pore size distribution was determined by a mercury intrusion method. Specific surface area was determined by the BET method. The pore size of the porous glass was uniform and could be changed between 40 nm and 260 nm. From the result of elemental analysis, the main component was found to be silicate whose silica content was more than 99%. It was confirmed also that pore size was affected by the addition of B2O3 to the starting glasses.