Low-temperature densification sintering and properties of CaAl2Si2O8 ceramics with MeO•2B2O3 (Me = Ca, Sr, Ba)

Dense CaAl2Si2O8 ceramics were prepared via a two-step sintering process at temperatures below 1000 degrees C. First, pre-sintered CaAl2Si2O8 powders containing small amounts of other crystal phases were obtained by sintering a mixture of calcium hydroxide and kaolin powders at 950 degrees C for 6 h. Subsequently, the combination of the pre-sintered ceramic powders with MeO center dot 2B(2)O(3) (Me = Ca, Sr, Ba) flux agents enabled the low-temperature densification sintering of the CaAl2Si2O8 ceramics at 950 degrees C. The sintering behavior and phase formation of the CaAl2Si2O8 ceramics were investigated in terms of the addition of the three MeO center dot 2B(2)O(3)flux agents. Furthermore, alumina and quartz were introduced into the three flux agents to investigate the sintering behaviors, phase evolvements, microstructures, and physical properties of the resulting CaAl2Si2O8 ceramics. The results showed that, because of their low-melting characteristics, the MeO center dot 2B(2)O(3)(Me = Ca, Sr, Ba) flux agents facilitated the formation of the CaAl2Si2O8 ceramics with a dense microstructure via liquid-phase sintering. The addition of alumina and quartz to the flux agents also strongly affected the microstructures, phase formation, and physical properties of the CaAl2Si2O8 ceramics.