| abstract |
A low thermal expansion ceramic composition having a predominant Al 2 TiO 5 phase along with zirconium titanate and zirconia phases. The final overall ceramic composition after firing has a low thermal expansion between 24°-1000° C. of not greater than 1.5×10 -6 ° C. -1 and a thermal stability in air such that (a) upon heating to 1200° C. for at least 4 hours there is substantially no decomposition of the Al 2 TiO 5 phase to rutile or alumina as measured by X-ray diffraction, (b) physical growth after thermal cycling between 200° and 1150° C. for 300 cycles does not exceed 1.5%, and (c) the composition maintains a low average thermal expansion between 24°-1000° C. of not greater than 1.5×10 -6 ° C. -1 after the isothermal heating or cycling conditions. The composition is preferably made by forming a mixture of the equivalent of 50-90 volume percent Al 2 TiO 5 or a solid solution having a substantial amount of Al 2 TiO 5 in the solid solution, and zirconium titanate and then heating the mixture at a temperature of 1250° C. or higher. |