WOLLASTONITE CERAMICS FROM CHALK AND DIATOMITE FOR REFRACTORY INSULATION

Abstract

Wollastonite ceramics was obtained from chalk and diatomite by the method of solid-phase synthesis of components. The influence of charge composition, modes of its mechanochemical activation and temperature-time modes of heat treatment on the phase composition, physical-mechanical and thermophysical properties of ceramic materials is studied. As a result of the joint mechanochemical activation of the charge components (chalk + diatomite), the temperature of the solid-phase synthesis of wollastonite ceramics was reduced to 900 °C. After firing for 2 hours, ceramic samples were obtained almost 90 % consisting of the mineral wollastonite. The compressive strength of the samples is 22 – 23 MPa at an average density of 1270 – 1300 kg/m3. The material has a stable thermal coefficient of linear expansion (TCLE) under 7.76?10–6 K–1. It can be operated at temperatures up to 1100 °C inclusively. Thermal insulation samples with an average density of 435 kg/m3, compressive strength of 2.2 MPa, thermal conductivity of 0.099 W/(m °C) and the limiting operating temperature under 1050 °C were obtained from the prepared charge mixture and foamed perlite. The resulting materials can be used as thermal insulation for industrial and civil facilities, refractory insulation of industrial furnaces, equipment, etc.