Thermal and Mechanical Properties of High Thermal Expansion ZrO2-CaF2 Composite Ceramics

Thermal and mechanical properties of two-phase composite sintered-materials consisting of ZrO2 with 3mol% Y2O3 and various volume fractions of CaF2 were measured. The composites were made by hot-pressing micronized powders at 1300°C under 30MPa pressure. No phase except ZrO2 and CaF2 was observed by the X-ray diffraction method in the composites, and no crack in sintering bodies was observed by scanning electron microscope. Thermal expansion coefficient increased with increasing CaF2 content, in agreement with the prediction obtained by the Turner's equation for thermal expansion coefficients of composites. Bending strength decreased with increasing CaF2 content. The composite containing 50vol% CaF2 showed a high thermal expansion coefficient of 15×10-6/°C and a bending strength was approximately 350MPa. These properties are similar to that of stainless steel and Al2O3, respectively.