Pressureless sintering of La-Y-Sialon ceramics and grain growth in later period of sintering

The pressureless sintering process of Sialon ceramics added with (1.5%La2O3+4.5%Y2O3) as sintering aids was studied. It is found that a β'-Sialon with relative density over 99% is obtained by sintering at 1750°C for 1 h. The crystal grain growth was observed at room temperature by SEM for the samples sintered at 1800°C holding for different times. It is proved that the grain-growth along the c-axis of β'-phase is a first priority, since (210) and (001)lattice plans have different activation energies. On the present condition, the logarithm of grain aspect ratio L¯/W¯ of average grain length L¯ to average width W¯ is in proportion to the sintering time because of the proportion of lgL¯ to sintering time and the proportion of W¯ to the sintering time.