Spinel Ceramics Via Edge Bonding

Abstract

A spinel ceramic made from the process comprising the steps of polishing one edge of a first spinel part to a surface roughness of less than 1 nm, polishing one edge of a second spinel part to a surface roughness of less than 1 nm, joining the polished edge of the first spinel part to the polished edge of the second spinel part, heating the first and second spinel parts to about 1000-1200° C., and maintaining said heating for about 3-6 hours resulting in bonded spinel parts.

What we claim is: 
     
         1 . A spinel ceramic made from the process comprising the steps of:
 polishing one edge of a first spinel part to a surface roughness of less than 1 nm;   polishing one edge of a second spinel part to a surface roughness of less than 1 nm;   joining the polished edge of the first spinel part to the polished edge of the second spinel part;   heating the first and second spinel parts to about 1000-1200° C.; and   maintaining said heating for about 3-6 hours resulting in bonded spinel parts.   
     
     
         2 . The spinel ceramic of  claim 1  wherein the bonded spinel parts form a spinel ogive dome. 
     
     
         3 . The spinel ceramic of  claim 2  wherein the spinel ogive dome is a monolithic part with an almost invisible bondline. 
     
     
         4 . The spinel ceramic of  claim 1  wherein said spinel ceramic comprises a monolithic spinel ogive dome with a nearly invisible bondline wherein said spinel (MgAl 2 O 4 ) is a rugged, hard and strong ceramic material which transmits from the UV to the infrared in the range of from about 0.2 to about 5 μm. 
     
     
         5 . A spinel ceramic made from the process comprising the steps of:
 polishing a first edge of a first spinel transparent tile, having dimensions of about 3″×3″×½″ thick, wherein said polishing results in less than 1 nm surface roughness;   polishing a first edge of a second spinel transparent tile, having dimensions of about 3″×3″×½″ thick, wherein said polishing results in less than 1 nm surface roughness;   joining the polished edges;   applying a load to the tiles;   heating the tiles up to 1100° C. at 5° C./min and holding for 6 hours; and   cooling slowly to room temperature at 1° C./min resulting in bonded spinel tiles.   
     
     
         6 . The spinel ceramic of  claim 5  wherein the spinel ceramic exhibits optical transparency from the UV to 5 μm, similar to the first spinel transparent tile and the second spinel transparent tile prior to bonding. 
     
     
         7 . A spinel ceramic made from the process of  claim 5  wherein said spinel ceramic comprises a monolithic spinel ogive dome with a nearly invisible bondline wherein said spinel (MgAl 2 O 4 ) is a rugged, hard and strong ceramic material which transmits from the UV to the infrared in the range of from about 0.2 to about 5 μm.