Fabrication and Characterization of Isostatically Hot‐Pressed MgO

Isostatic hot-pressing was used to fabricate solid MgO bodies of high purity (with respect to metallic impurities) to 90 to 95y0 density with high translucency and a grain size of approximately 0.2μ. The densified material contained significant amounts of brucite as a result of water in the starting material which was not removed during vacuum baking. The fabricated pieces showed many cracks which were apparently introduced into the compacts before densification. When the hot-pressed pieces were reheated, the brucite decomposed, the density increased, and the porosity coalesced while grain growth occurred. The general technique appears to be usable for fabricating finely divided powders if powder degassing and predensification procedures are improved.