POLISHING RATE OF BAO-B2O3-SIO2, PBO-SIO2 AND PBO-B2O3 GLASSES

BaO-B2O3-SiO2, PbO-SiO2 and PbO-B2O3 glasses were polished using a pit ch polisher and cerium oxide dispersed in distilled water. The factors affecting the polishing rate at initial stage were discussed in terms of glass properties: Vickers microhardness, chemical water durability and bulk modulus. The polishing rate of BaO-B2O3-SiO2 glasses depends mainly on the hardness of the hydrated layer formed; this factor is c onsistent with Izumitani proposal. The polishing rates of PbO-SiO2 and PbO-B2O3 glasses increase with increasing PbO content up to 50 mol% P bO and then decrease remarkably. The polishing rates of PbO-SiO2 and P bO-B2O3 glasses are apparently affected by the bulk modulus which is r elated to the product of the ratio of plastic strain to elastic strain (c/a) and the indentation hardness H using Hill's theory on plastic-e lastic materials.