EFFECT OF ADDITIVES ON THE MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF COMMERCIAL ALUMINA CERAMICS

The effect of impurities or additives on the microstructure of some co mmericial alumina ceramic samples have been characterized by scanning electron microscope-energy dispersive x-ray spectrometer and the mecha nical properties investigated. Both the hardness and the toughness hav e been found to increase as the SiO2 content decreases, and the theore tical density is reached in these materials. Grain size and distributi on seem to be important factors in the mechanical properties of alumin a ceramics. If the additives are controlled carefully, finer grain siz e and distribution can be obtained, together with a high relative dens ity in terms of pore distribution characteristics and consequently enh anced mechanical properties.