Effect of Addition of Divalent Metal Oxides on the Crystallization, Thermal Expansion, and Surface Roughness of Alkali-Free Porcelain Enamel in the

Abstract

The effect of addition of CaO, SrO BaO and ZnO on the crystallization, thermal expansion, and surface roughness of alkali-free porcelain enamel in the MgO-ZrO2-P2O5-SiO2-B2O3 system was investigated by means of DTA, XRD, SEM observations, thermal expansion measurements, and surface roughness observations. The addition of CaO, SrO and BaO in frit affected the temperature of crystallization in DTA, while the addition of ZnO did not affect the temperature. CaO and BaO raised the thermal expansion coefficient, while ZnO lowered it. The surface of porcelain enamel was smoother in the frit containing CaO than in the frit containing BaO.