| 摘要 |
1,131,486. Synthetic diamonds. TOKYO SHIBAURA ELECTRIC CO. Ltd. 8 Nov., 1966 [13 Nov., 1965], No. 49898/66. Heading C1A. Synthetic diamonds are prepared by heating a carbonaceous material to at least 1200‹ C. under a pressure of at least 50,000 atmospheres in the presence of a catalyst which includes at least one of the elements vanadium, molybdenum and tungsten and at least one of the elements copper, silver and gold and does not contain iron, nickel, cobalt, platinum, palladium, ruthenium, osmium, iridium, rhodium, chromium, manganese or tungsten. The carbonaceous substance may be, for example, graphite, amorphous carbon, coal, coke, charcoal or an organic substance such as coal tar, pitch, wood, paper, naphthalene or paraffin, and the catalyst may contain several metals or metal compounds such as carbides, the elements being in a mixture or alloyed. The reaction time is between 5 and 20 minutes. The diamonds formed are colourless and have a grain size ranging from tens of microns to 0.4 mm. They are substantially free from crystallites. |
