Synthesis and characterization of low density calcia stabilized zirconia ceramic for high temperature furnace application

Five weight percent calcia stabilized zirconia (CSZ) low density ceramic material was synthesized from zirconia and calcia powder by solid state reaction. Powder specimens were sintered at various temperatures for different time durations in air and argon atmosphere. Physico-chemical properties such as thermal stability, purity, crystalline phases identification, particle size, particle size distribution, specific surface area and porosity of CSZ were measured by thermogravimetry and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Taller (BET) and particle size analyzer (PSA). Total relative shrinkage and coefficient of thermal expansion were estimated by dilatometry. The density and Vicker's microhardness were measured in order to evaluate the material performance. A combination of cubic zirconia and calcium zirconium oxide (Ca_0.15Zr_0.85O_1.85) phases were found when specimen sintered at 1500 °C in air while under argon atmosphere at 1750 °C and 1850 °C, the ZrO and Ca_0.15Zr_0.85O_1.85 phases were established. At higher sintering temperature (1950 °C) for 4 h in argon medium three phases ZrO, CaZrO₃ and Ca_0.15Zr_0.85O_1.85 were observed. It was found that with the increase of sintering time these phases convert into a single cubic phase Ca_0.15Zr_0.85O_1.85. Pellets sintered at different temperatures and duration were also studied by scanning electron microscopy showing that the grain structure becoming fine with increase of temperature and duration.