Preparation and characterization of novel environmentally friendly Al2O3/SiO2/CaO ceramic foams

摘要

Low-cost Al2O3-SiO2-CaO ceramic foams were prepared using a novel and simple reactive foaming process. The foamed green bodies were produced by mixing aluminium powder and calcium hydroxide in an aqueous solution of sodium silicate and sintered in an argon atmosphere using a pressureless electric current assisted process (T = 800 C). An additional thermal treatment was performed in air using a conventional furnace (T = 1050 degrees C) in order to oxidize the residual metallic phases. The resulting foams exhibited open porosity, densities ranging from 0.50 to 0.65 g/cm(3) and wide pore size distribution (0.04-400 mu m). The compressive strength and thermal diffusivity of these foams ranged from 2.12 to 1.01 MPa and from 0.27 to 0.45 mm(2)s(-1), respectively, which indicate their suitability as thermal insulator materials.