Aluminum titanate-calcium dialuminate composites with low thermal expansion and high strength

Aluminum titanate (Al2TiO5, AT) has many advantages, such as high melting point, low thermal expansion and low thermal conductivity, but its industrial applications are hindered by phase decomposition at high temperature and low mechanical strength. This paper reports the properties of calcium dialuminate (CaAl4O7, CA2) reinforced AT matrix composites. With the aid of Fe and Mg doping, the phase decomposition of AT is prevented. The three point bending strength of the composites is enhanced remarkably with increasing CA2 content. After sintering at 1400 °C, the AT-40wt%CA2 sample had a bending strength of 35 MPa about two orders of magnitude higher than that of the pure AT sample (∼0.3 MPa). The well sintered AT-CA2 composites also exhibit low thermal expansion coefficient, especially for the 1400 °C sintered AT-20wt%CA2 sample (0.23 × 10−6/°C). The AT-CA2 composite with high mechanical strength and low thermal expansion is promising candidate in high temperature applications.