The Wettability of Copper-Manganese Alloys on Alumina and Their Potential as Direct Brazing Filler Metals

The wetting and spreading of copper-manganese alloys on alumina was studied using a sessile drop technique. The contact angle, solid-liquid interfacial energy and the work of adhesion values were calculated based on the experimentally measured spreading radius in the temperature range of 1100 to 1300°C. Using an in situ measurement technique, the spreading radius could be continuously monitored as a function of time. The results were compared to similar work on the copper-titanium/alumina system. Similar spreading behavior was observed for both systems and it is proposed that spreading occurs by the same interfacial reaction product nucleation and growth mechanism. While the maximum work of adhesion was lower for copper-manganese alloys on alumina relative to that for copper-titanium alloys on alumina (1425 versus 2800 mJ.m 2 ), the copper-manganese/alumina adhesion values are sufficient for many direct bonding applications. The potential for improving interlayer mechanical properties for alumina brazed with copper-manganese alloys is also discussed.