ホットフォージ法で作製したマグネシア焼結体の微構造と機械的性質

抄録

Ultra fine MgO powder prepared by oxidation of Mg vapor was encupslated in a Mo mold with dimensions of O.D.30φ-I.D.10φ×30^hmm. The mold was preheated at 1300°C for 10 minutes, and then, immediately press-forged under uniaxial compressive load. The particle size of the starting powder (0.001μm) grew to 0.3-0.4μm during the preheating, but the grown particles were broken down by the mechanical fracture effect in the press-forge process and a dense polycrystal with smaller grain size (0.1-0.15μm) was obtained by a masstransport mechanism. However, the polycrystalline MgO obtained did not show satisfactory mechanical properties, because of some stored internal stress around the grain boundary. A polycrystalline MgO with good mechanical properties was obtained after annealing the press-forged body at a relatively low temperature of 800-1000°C for few hours to remove the strain. An attempt was made to understand clearly the above experimental results. It was also emphasized the importance to develope a new technique for sintering the ultra fine ceramic powders.