| 摘要 |
<p>The present invention relates to a coarse crystalline aluminium oxide, hereafter also referred to as technical aluminum oxide, as well as a process for its preparation. In certain fields of application in grinding and lapping, aluminum oxides are required having an average primary crystal coarseness greater than 6 .mu.m. The production of such aluminum oxides is the object of the present invention. It has been found out that aluminum oxides having an average primary crystalline coarseness of 6 - 25, particularly 8 - 16 .mu.m, can be produced such that the calcination of the aluminum hydroxide is carried out in the presence of at least one fluorine salt and of vanadium salt. The specification discloses coarsely crystalline aluminum oxide, characterized in that it contains, as trace elements: V2O5 > 0,005 wt.% P2O5 > 0.005 wt.% Na2O > 0.8 wt.%.</p> |
