EXPERIMENTAL INVESTIGATION OF THE STRUCTURE, ELASTIC, AND STRENGTH CHARACTERISTICS OF POROUS CORUNDUM CERAMICS

This paper aims to investigate the internal structure and to evaluate the elastic and strength characteristics of the corundum ceramic samples sintered at different temperatures. The average value of porosity of the sintered samples at the temperatures of 1400, 1500, and 1600 degrees C is 33, 26, and 17%, respectively. Mechanical tests of the ceramic samples are performed using the threepoint bending method. The ultimate bending strength varies from 135 to 265 MPa in the studied sintering temperature range. The elastic moduli of the sintered samples are found to be in the range of 58 - 113 GPa. An analysis of the ceramic samples' microstructure is performed using a scanning electron microscope. The dependence of the porosity, pore size, and grain size on the sintering temperature is indicated. The values of strength and elastic modulus of the samples increase nonlinearly with rising sintering temperature in the experiment. Statistical behavior of mechanical properties of the ceramic samples is described using the Weibull analysis. The strength data for the sintering temperatures of 1500 and 1600 degrees C are well described by the Weibull distribution, and the strength values for a sintering temperature of 1400 degrees C are described with a significant scatter.