Novel microporous MgO-based high-temperature thermal insulator

Abstract

This paper addresses the development of a novel microporous MgO-based (MPMB) thermal insulator whose temperature-resistant microporous structure was engineered for the introduction of controlled packing flaws amongst their highly asymmetric and porous particles during compacting by uniaxial pressing. Hard-burnt MgO, dolomite, and TiO2 particles were dry-mixed with expanded aluminum phyllosilicate and fibers before being sprayed with a colloidal silica dispersion. The mixture was uniaxially pressed as 400 × 100 × 20 mm boards and dried at 120 °C. Samples were thermally treated at different temperatures (120-1100 °C) for the evaluation of their physical properties (compression strength, rigidity, permanent dimensional thermal variation, solid density, total porosity, pore diameter distribution, and thermal conductivity), crystalline phases, and microstructure. The microporous microstructure generated during pressing was not significantly affected by thermal treatments up to 1100 °C and the samples’ thermal conductivity, total porosity, and compression strength varied between 0.20 and 0.14 W (m K)−1, 54–56%, and 29-15 MPa in the 200-1000 °C temperature range.