| 摘要 |
<p>The invention relates to a ceramic protective layer whose base material consists of pure aluminium oxide or predominantly of aluminium oxide. In order to improve said protective layer, its base material is admixed with oxides of the metals from the groups IIA, IIIA, IIIB, VB, VIB, VIIB or VIII of the Periodic Table of the Elements, prior to application of the protective layer. This results in the formation of a corundum structure in the aluminium oxide. Particularly suitable for producing such a corundum structure are gallium oxide, vanadium oxide, chromium oxide and iron oxide. The formation of the corundum structure increases the stability of the protective layer with respect to corrosive effects of vanadium pentoxide and sodium sulphate. By adding a defined amount of magnesium oxide it is possible both to promote the formation of corundum and to reduce grain growth in the aluminium oxide. The other metal oxides promote, in particular, the formation of the corundum structure, and therefore magnesium oxide is preferably admixed in addition to said metal oxides in order to reduce grain growth.</p> |
