Bioactivity and mechanical properties of SiO2-CaO-P2O5 glass-ceramics

摘要

Glass-ceramics in the system SiO2-CaO-P2O5, with 55 mol% of silicon content, with and without phosphorus, were obtained by thermal treatment of sol-gel glasses as the precursors. The influence of the composition of the precursor glass on the crystallisation, bioactive behaviour and mechanical properties of these glass-ceramics was investigated. An interesting result is that when phosphorus was not present in the precursor glass, the biaxial flexural strength of the glass-ceramics increased by one order of magnitude.The crystalline phases obtained were similar in both glass-ceramics, although when phosphorus was present the crystallisation of tricalcium phosphate and the stabilisation of the Wollastonite phase at high temperature in the glass-ceramic took placeBoth glass-ceramics, without and with phosphorus, showed a fast in vitro bioactive response; a new apatite-like layer fully covered the surface of both materials after soaking in simulated body fluid for a short time. The rate of the apatite layer formation mainly depended on the sintering process, which took place at lower temperatures in the glass-ceramics without phosphorus.The glass-ceramics containing phosphorus showed a decrease in the values of the Weibull coefficient, an increase of porosity and pore size, and a heterogeneous microstructure, worsening their mechanical properties.