GRAZING OF ZRO2 TOUGHENED AL2O3 TO STAINLESS-STEEL

In the present investigation ZrO2 toughened Al2O3 (ZTA) has been blaze d to AISI 316 stainless steel using Ag-4Ti (CB2) and Ag-26.5Cu-3Ti (CB 4) filler metals along with nickel and copper interlayers respectively . It is shown that the best proper ties are achieved with the CB2 fill er material and nickel interlayer. Under optimum blasing conditions, t his contribution provides an average four point bending strength of si milar to 150 MPa, which is only 20% lower than that observed for plain ZTA-ZT4 joints. In contrast, the high yield strength and strain harde ning coefficient of the CB4 filler metal makes it less suitable for br azing of ZTA-steel joints, where bending strengths below 25 MP are att ained because of a high residual stress level. These results are not s ignificantly improved by the use of a ductile copper interlayer since copper partly dissolves in the filler metal during the brazing operati on.