Thermal insulators made with rice husk ashes: Production and correlation between properties and microstructure

Extruded and pressed thermal insulators were obtained with the utilization of rice husk ashes, which is a residue from the beneficiation process of rice with high silica content. The thermal insulators were characterized both chemically (composition) and physically (particle size, porosity, density and thermal conductivity), and their properties were correlated to their microstructure. The thermal conductivity of these insulators was determined by the hot plates method, according to the ASTM-E 1225-87 Standard, and the measured values were then compared to a commercial thermal insulator made from diatomaceous silica. The morphology of the preset phases (solid and porous), as well as their distribution, was determined by means of scanning electron microscopy.