Sintering Behavior of Beryllium Oxide

The sintering behavior of beryllia in a reducing atmosphere was studied between 1500° and 2100°C. Above 1700°C. the firing temperature had only a small effect on the density after heating for 24 hours. Examination of the time dependence of sintering showed that at 1700°C. during the first 3 to 5 hours there was a large increase in the density of the body accompanied by a simultaneous rapid rate of grain growth. Firing for longer times resulted in more moderate increases in both density and grain growth. The grain-growth characteristics of beryllia were unchanged by most oxide additions although compacts of higher density resulted. Oxide additives which formed a liquid phase at the sintering temperature enhanced both the sinterability and grain growth of beryllia.