Low-temperature Sintering of CaZnSi2O6 Glass Ceramics with Machinable Precursor Based on Silicone Rubber and Enhanced Mechanical Strength by Bi2O3

Machinable precursors were prepared using methyl vinyl silicone rubber, kilchoanite, fluxing agents, and nano silica. CaZnSi2O6 glass ceramics were sintered using machinable precursors at temperatures ranging from 600 to 1000 degrees C. The microstructure and crystal phase during the heating process were analyzed by SEM and XRD. The flexural strength and linear contraction of the ceramics were measured. The results showed that Bi2O3 improved the flexural strength above 800 degrees C. When the sintering temperature was 1000 degrees C, Bi2O3 improved the flexural strength by 22%, from 90.54 to 110.48 MPa. Furthermore, the linear contraction increased by 1.88%, from 15% to 16.88%. Bi2O3 provided more liquid phase above 800 degrees C, which connected the grains more tightly and caused the ceramics to shrink further, so that the ceramics with Bi2O3 had a denser microstructure and higher flexural strength.