The relation between wetting and interfacial chemistry in the CuAgTi/alumina system

From results obtained over the last 10 years from simple reactive metal/ceramic model systems, a concept of reactive wetting has been formulated which suggests a direct relation between wetting and the physicochemical properties of the interfacial reaction products. The aim of this study is to examine whether this concept can help to understand and rationalise the sometimes conflicting results for the CuAg–Ti/alumina system, which is more complex but important in brazing. This was done using new wetting data generated by sessile drop experiments performed by varying the Ti content in the alloy and the furnace atmosphere (neutral gas and two levels of high vacuum). Experiments were carried out on monocrystalline alumina and also on polycrystalline alumina substrates of varying purity and roughness.