Copper wettability on tungsten carbide surfaces

The wetting behavior of copper on tungsten carbide surfaces was investigated through the sessile drop method, at 1080 °C, in vacuum atmosphere. Tests were performed on three different types of substrates: (i) commercial sample of WC-Co with 3.5 wt% of cobalt; (ii) WC thin film sputter-deposited on the aforementioned commercial WC-Co sample and (iii) WC sample processed by hot pressing. The lowest final contact angle was achieved on the WC-Co surface (6°), followed by those of WC thin film (13°) and WC (25°). The contact angle values were inversely correlated with the wetting behavior, i.e. the highest wettability was found for the WC-Co and the lowest for the WC surfaces. Structural, microstructural and elemental characterizations of the interface region between the molten copper and the substrate were performed, using low angle X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). The wettability behavior was discussed taking into consideration the effect of minor phases, such as cobalt.