| 摘要 |
1,203,441. Treating surfaces of alumina crystals. POST OFFICE. 2 Feb., 1968 [3 Feb., 1967], No. 5347/67. Heading CIA. A depth of the surface of a crystalline aluminium oxide member is removed by contact with molten vanadium pentoxide. The crystalline member may first be polished, and then at least one surface is contacted with molten V 2 O 5 , preferably at a temperature of 800- 1000‹ C., for from 15 minutes to 2 hours. The crystal is preferably kept stationary. The contacting with molten V 2 O 5 may be carried out in a plurality of stages. When sufficient depth has been removed to give a uniform surface, any residual V 2 O 5 is removed by immersion in hot, concentrated HCl, and the surface then washed in distilled water and alcohol, and dried in air. This treatment gives a smooth polished surface free from damage suitable, e.g. for deposition of thin Si films on to the Al 2 O 3 member. The Al 2 O 3 member may be of α-corundum or in a form which contains small quantities of metal oxide, as do ruby and sapphire. A pale violet film may appear on some surfaces, after immersion in the melt, which is resistant to chemical attack, although some changes occur on treatment with cone. HCl, HNO 3 or catechol in hydrazine hydrate. The films disappear after prolonged heating in air at 1200‹ C. |
