Mechanical Properties of Porous Alumina at High Temperature

Abstract

Porous alumina was prepared with fine alumina powder and fine PMMA particles. Porous alumina of 1.5 to 10 μm in diameter was obtained with up to 40% porosity after sintering at 1600 K. After being characterized, the microstructure and air permeability, Young's modulus, fracture strength and toughness were measured up to 1273 K. Air permeability of porous alumina increased drastically above 20% porosity because of the formation of continuous pores. Young's modulus and fracture strength of porous alumina was lower than that of dense alumina and decreased gradually above 1000 K. However, the rate of decrease of porous alumina was lower than that of dense alumina. A similar decrease was observed for fracture toughness. Fracture toughness also decreased above 1000 K, however, the rate of decrease was small for porous alumina with large porosity and pore size. The frontal process zone size elongated at high temperatures, contributing to the prevention of the decrease in fracture toughness at room temperature.