Alumina-zirconia ceramic

Abstract

A ceramic consisting essentially of from 1 to 15 percent of glass and 99 to 85 percent of a mixture of particulate Al 2 O 3 and particulate ZrO 2 is disclosed. ZrO 2 is present in a sufficient amount, usually from 1/4 to 6 percent based on the weight of the ZrO 2 and Al 2 O 3 , to strengthen the ceramic significantly, by comparison with an otherwise identical ceramic where the particulate ZrO 2 is replaced either by the glass or by particulate Al 2 O 3 . The glass constitutes a vitreous phase bonding the particulates into a dense, gas impervious structure, and can be a calcium magnesium silicate glass containing from 45 to 80 percent of SiO 2 , from 8 to 55 percent of CaO and MgO, and not more than 15 percent of Al 2 O 3 .

What I claim is: 
     
       1. A ceramic consisting essentially of from .[.1.]. .Iadd.5 .Iaddend.to 15 percent and .[.99.]. .Iadd.95 .Iaddend.to 85 percent of a mixture of particulate Al 2  O 3  and particulate ZrO 2 , the particulates all being finer than 15 microns in ultimate particle size, ZrO 2  constituting from 1/4 to 4 percent based upon the weight of ZrO 2  and Al 2  O 3  in the ceramic, and said glass constituting a vitreous phase bonding the particulates into a dense, gas impervious structure, and being a calcium magnesium silicate glass containing from 45 to 80 percent of SiO 2 , from 8 to 55 percent of CaO and MgO, and not more than 15 percent of Al 2  O 3 . .[. 
     
     
       2.  A ceramic as claimed in claim 1 wherein the glass constitutes from 3 to 12 percent thereof..]. 
     
     
       3. A ceramic as claimed in claim 1 wherein the glass constitutes from 5 to 12 percent thereof. 
     
     
       4. A ceramic as claimed in claim 1 wherein particulate Al 2  O 3  constitutes more than 99 and not more than 991/2 percent, based upon the weight of the ZrO 2  and Al 2  O 3  in the ceramic. .[.5. A ceramic as claimed in claim 2 wherein particulate Al 2  O 3  constitutes more than 99 and not more than 991/2 percent, based upon the 
     
     
        weight of the ZrO 2  and Al 2  O 3  in the ceramic..]. 6. A ceramic as claimed in claim 3 wherein particulate Al 2  O 3  constitutes more than 99 and not more than 991/2 percent, based upon the weight of the ZrO 2  and Al 2  O 3  in the ceramic.