Hot isostatic pressing of BeO

The experimental procedure using glass containers and the properties of products were studied by the hot isostatic pressing of BeO powder. The BeO powder obtained by the thermal decomposition of beryllium sulfate at 1,1000C for 2 hours in air was pressed to pellets at room temperature. After firing at 1,1000C for 3 hours, the pellets were enclosed in glass tubes. The glass tubes were evacuated to 10-3mm Hg and were sealed. The sealed specimens were inserted in alumina tubes. The above-mentioned assembly was introduced into a molybdenum furnace placed in a high pressure vessel, and then the hot isostatic pressing experiment was performed by using argon gas as pressure-transmitting medium. The specimens were heated up to the softening point of glass under the relatively low pressure of 200 bar, and then temperature and pressure were raised up to the desired condition of above 1,0000C and 2,000 bar. The experiment revealed that the specimens with theoretical density can be obtained under the condition of relatively low temperature and short pressing time, and that grains were unifromly distributed, and abnormal grain growth was not recognized, but only partly took place at higher temperature under pressure. Consequently, slightly translucent products were obtained. (Iwakiri, K.)