Production and characterization of Al2O3 macromolecularfoams for application in radiant burners

Abstract

From time to time the industries present an interest on reducing the pollution generated by its processes, searching for alternatives which provide equal or better efficiency in its activities. A very promising alternative for the application of processes which need heating by radiation in related to the porous radiant burners (SCHEFFLER, COLOMBO, 2004; CATAPAN, 2007). The radiant burners should be porous and consist of a ceramic to resist at high temperatures (> 1500°C) and to provide high resistance to thermal shock. In this work, the replication method was used to obtain alumina foams. Polyurethane foams were impregnated with aqueous suspensions of 50-70% wt. solid (Al2O3) and additives (binders). The viscosity of the suspension was evaluated and adjusted to an appropriate impregnation. The impregnated foams were heat treated for degradation of polyurethane at 400°C/1h and subsequently sintered (between 1500°C and 1600°C/3h) for densification of the cell walls. Permeability and compressive strength of the foams were correlated to the microstructure and cellular morphology (size and geometry of the cells). The sintering temperature, which promoted greater densification and increase in mechanical strength, was 1600°C.