Ceramic disc of aluminium oxide-rich material

摘要

A ceramic disc consists of an aluminium oxide material which has the composition (by wt.) 91.6-98.2% Al2O3, 1.5-3.8% SiO2, 0.2-0.9% CaO, 0.1-0.6% MgO and 0-2.5% ZrO2 and which contains baddeleyite and/or zircon in addition to corundum. Also claimed is a process for producing a ceramic disc from an aluminium oxide material with an Al2O3 content of 91.6-98.2 wt.% by shaping and firing of a ceramic material formed by mixing (i) 91.0-97.6 wt.% alumina which has a specific surface of 0.4-2 m<2>/g and a particle size distribution of d50 = 10 to 100 microns (exclusive) and d100 = 60 to 400 microns (exclusive) and which contains <= 0.2 wt.% Na2O, <= 0.2 wt.% SiO2, <= 0.1 wt.% CaO and <= 0.1 wt.% Fe2O3 as impurities with (ii) 2.4-8.8 wt.% additives of overall composition (by wt.) 1.5-3.8% SiO2, 0.2-0.9% CaO, 0.1-0.6% MgO, 0.6-1.0% Al2O3 and 0-2.5% ZrO2.