Anorthite and Thermal Expansion of CaO-Al₂O₃-SiO₂-B₂O₃ Ceramics

Abstract

The relationship between the amount of anorthite (CaO⋅Al₂O₃⋅2SiO₂) formed in the sintering process of the CaO-Al₂O₃-SiO₂-B₂O₃ ceramics and the thermal expansion coefficients was studied. The results obtained are as follows: (1) The thermal expansion coefficient decreased with increasing the amount of anorthite. (2) In the case of 890°C-30min sintering, the maximum anorthite amount of 30% was produced by using a small particle α-Al₂O₃ of 0.9μm in size. The thermal expansion coefficient of the ceramics containing 30% anorthite was 4.7×10^-6/°C, which was comparatively lower than the value of 6.2×10^-6/°C for the ceramics containing no anorthite.