Wollastonite Ceramic from Chalk and Diatomite for Refractory Heat Insulation

Wollastonite ceramic was obtained from chalk and diatomite by solid-phase synthesis of the components. The influence of the batch composition, regimes of mechanochemical activation, and thermophysical properties of the ceramic materials were investigated. As a result of the combined mechanochemical activation of the batch components (chalk + diatomite), the temperature of the solid-phase synthesis of wollastonite ceramic was lowered to 900°C. After 2-h firing, the mineral wollastonite comprised almost 90% of the ceramic samples. The compressive strength of the samples is 22 – 23 MPa at an apparent density of 1270 – 1300 kg/m³. The material has a stable linear thermal expansion coefficient (CLTE) not exceeding 7.76 × 10 ^–6 K^–1. It can operate at temperatures up to 1100°C inclusively. Samples of heat-insulating material with an average density of 435 kg/m³, compressive strength 2.2 MPa, coefficient of thermal conductivity 0.099 W/(m ∙ K) and limiting operating temperature up to 1050°C inclusive were obtained from the developed batch and expanded perlite. The developed materials can be used as refractory heat insulation for industrial furnaces, equipment, and elsewhere.