The dependence of the elastic properties of silica/alumina materials on the conditions used for firing

The dependence of the elastic properties of a range of powder compact samples has been measured as a function of firing variables. It was found that both Youngʹs modulus and Poissonʹs ratio are particularly sensitive to the peak temperature and the time for which the peak temperature is maintained, over a range of these variables for which density is not significantly affected. The material investigated is used industrially for the manufacture of wall tiles. Firing trials conducted in an industrially operated tunnel kiln have indicated that sufficient variation in firing conditions exists, in the cross-section of the tunnel kiln, to cause significant variation in the values of Youngʹs modulus and Poissonʹs ratio of bodies fired in different positions in the kiln. Microstructural examination of bodies produced to have very similar densities but vastly different values of Youngʹs modulus and Poissonʹs ratio has indicated that the dependence of Youngʹs modulus and Poissonʹs ratio on firing conditions can be explained by the extent of sintering within the ceramic matrix.