| 摘要 |
PURPOSE:To obtain a sintered chromium oxide having isotropic texture and high quality, by putting metallic chromium in an inorganic acid having a specific mole concentration, sealing the mixture in a capsule made of a noble metal, inserting the capsule in an autoclave, and carrying out hydrothermal synthesis and sintering of the titled oxide. CONSTITUTION:An inorganic acid 3 such as hydrochloric acid having a concentration of 0.01-1mol and powder of metallic chromium 5 are put into the capsule 1 made of a noble metal such as platinum, and the top 7 of the capsule 1 is sealed. The capsule is placed in an autoclave and heated at 800-1,400 deg.C under a pressure of 1-1,000 mega-bar to effect the hydrothermal synthesis and sintering. The metallic chromium is oxidized by the reaction to sintered chromium oxide. After the reaction, the produced H2 is diffused through the wall of the capsule 1 into the autoclave, and the capsule is shrunk to the form 1' leaving the sintered chromium oxide 9 at the bottom. A hard and strong chromium oxide can be produced by this process.
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