CHEMICAL-REACTION ASSISTED TRANSIENT LIQUID-PHASE BONDING OF ALUMINA IN COMBINATION WITH COLD ISOSTATIC PRESSING

A new method of transient liquid phase (TLP) bonding of alumina specim ens has been developed rising a mixture of aluminium powder and silica powder as insert materials. A chemical reaction of aluminium with sil ica occurs in the interlayer to produce alumina and silicon. Some of t he specimens were subjected to cold isostatic pressing (cipping) befor e bonding to improve the bonding strength. Specimens with an interlaye r of powder mixture were joined for Al/SiO2 ratios of 1:0.84 and 1:0.4 2, but did not join for an interlayer with a theoretical ratio of 1:16 7. When specimens were subjected to cipping before bonding, bonds were far stronger than bonds without cipping in a temperature range from r oom temperature to elevated temperatures above the melting point of al uminium. In the mechanical test (bending test), fracture occurs at the boundary between the alumina matrix and the interlayer at room temper ature, and in the interlayer at temperatures above the melting point o f aluminium. MST/3817.