Oxidation Behavior of Silver- and Copper-Based Brazing Filler Metals for Silicon Nitride/Metal Joints

The oxidation behavior of reactive-element-containing brazing filler metals at 600°C was studied. Weight-gain measurements coupled with scanning electron microscopy and energy dispersive X-ray analysis indicated the formation of a nonprotective oxide on the following three ternary alloys: (i) Cu-80%, Sn-10%, Ti-10%; (ii) Ag–Cu eutectic + 5% Ti; and (iii) Ag–Cu eutectic + 5% Zr. Additions of Ni and Si to these alloys failed to reduce spallation. However, a protective oxide was formed by adding Al. The resultant quaternary alloys possessed excellent flow properties on silicon nitride.