Studies on Al₂O₃ used for Radio Recieviug Tubes

Abstract

1. A sort of methods of refining of Alundum powders were studied. Four methods were tried and it became clear that half of the Na₂O contained in Alumdum as the form of β-Al₂O₃ could be removed briefly.
2. Electrical properties of Alundum were studied. It became clear that the breakdown voltage of Alundum was independent on temperature below 1050°C, but dependent on temperature higher than this temperature and also be increased by pre-heating at high temperature. It was because of the evaporation of impurities.
Varieties of sizes and purities of Alundum powders show no difference in their electrical properties if they were pre-heated at high temperature.