Application of wetting research to joining and to fabrication of composite materials

Abstract

To assist in selection of suitable wetting materials and control of wetting in various situations, previous results for ceramic–aluminium systems have been readdressed. Wetting systems can be categorised into three types (A, B, and C), characterised by original wettability and equilibrium wettability. In pure systems at 1373 K, AlN–Al and Si3 N4–Al are categorised as system A, a non-wetting system, and Al2O3–Al as system C, a wetting system. However, h-BN–Al, graphite–Al, MgO–Al, and SiC–Al belong to system B, changing from a non-wetting to a wetting system through interfacial reactions. From the present results, it was found that the contact angle for h-BN is far lower than the contact angles for typical ceramics. In fact, the contact angle decreased to 0° in phase IV (equilibrium phase) at and above 1273 K. This indicates that, from the viewpoint of wetting, h-BN and aluminium are an ideal combination for joining and, even more so, for the manufacture of a metal matrix composite. To demon strate the efficiency of joining or fabricating a composite material using this combination, a simple experiment was set up. The composite material is expected to have high wear resistance and good lubricating properties.