The effects of calcium oxide on fluorapatite crystal morphology and mechanical property of functional glass-ceramics

Abstract

The roles of calcium oxide on fluorapatite crystal morphology, crystallization kinetics behavior and mechanical property of functional glass-ceramics in the SiO2-Al2O3-K2O-CaO-P2O5 system were investigated. Glass compositions with calcium oxide content (in wt%) of (1) 3.8, (2) 4.2, (3) 5.3, (4) 6.0, and (5) 6.9 were fabricated by sintering method. Different heat treatments were carried out at the temperature of 930 °C for 30 min, 1100 °C for 30 min and 1100 °C for 120 min, respectively. The results showed that the length of fluorapatite crystal increased with temperature and heating time, however, the length increased firstly and then decreased dramatically with the increase of calcium oxide content. Meanwhile, the minor crystalline phase changed from low albite to anorthite. The microhardness was also influenced by different crystal morphologies. The results revealed that it was possible to control crystalline phase and mechanical property of fluorapatite glass-ceramics by changing calcium oxide content and heat treatment regime.