1997 Volume 105 Issue 1221 Pages 401-405
Phase-separated glass specimen was prepared from a fluorine containing sodium borosilicate glass by heat treatment at 500°C, which consisted of borate-rich glass phase and silica-rich glass phase. For this phase-separated glass specimen, the leaching process was investigated. The leaching process consisted of two stages. In the first stage, soluble components of B2O3, Na2O and NaF were leached out from the borate-rich phase and this leaching proceeded in a diffusion-controlled process. In the second stage, silica-gel which precipitated in pores during leaching was leached out and this leaching proceeded in a reaction-controlled process. Activation energies were calculated for the first stage as 33.5kJ/mol and 32.7kJ/mol from the data of thickness of leached layer and weight loss, and for the second stage as 22.6kJ/mol, 24.5kJ/mol and 29.1kJ/mol from the data of pore size distribution, weight loss and Si content of leaching solution.
