Ceramic Composites Based on Zircon and Hafnium Oxide

By sintering nanosized powders in air in the range of 1000–1300°C, ceramic composites (1 – x)ZrSiO₄–xHfO₂ with low thermal conductivity are obtained. It is shown that at a temperature of 1300°C the composites are a mixture of monoclinic solid solutions of Hf_xZr_1 – xO₂ and SiO₂. For the first time, the temperature–concentration dependencies of the thermal conductivity of the obtained ceramic samples are presented. Using electron microscopy, the fracture surface of ceramic samples after sintering at 1300°C is investigated, their thermal behavior is studied using dilatometry, and the temperature coefficient of linear expansion is estimated.