| 摘要 |
1296049 Magnesium aluminate spinel W R GRACE & CO 11 Dec 1969 [16 Dec 1968] 60620/69 Heading C1A Magnesium aluminate spinel is prepared by feeding a mixture of magnesium and aluminium salts and/or oxides at an atomic ratio of Mg : Al of 1À001 : 2 to 1À217 : 2 to a fluid energy mill maintamed at a temperature above 700‹ C. The feed to mill may be in the form of a dry mixture, or aqueous solution, or an aqueous slurry. Suitable feedstocks include a dry mixtureof Al(OH) 3 and Mg(NO 3 ) 2 .6H 2 O, solutions of nitrates, nitrites, formates and acetates, or a slurry of oxides formed by precipitation from a solution of salts with ammonia may be included as part of the feedstock. The spinel powder recovered from the milling process may be calcined at a temperature 650‹ to 1100‹ C., pressed at a pressure of at least 10,000 p.s.i. and sintered at 1450‹ to 1650‹ C. to form ceramic bodies having 97 to 99% of theoretical density. |
