Wettability of nickel coated graphite by aluminum

Graphite is a very attractive candidate for aluminum–metal matrix composites. However, aluminum does not wet graphite, which makes the production of aluminum–graphite composites difficult. Nickel is a material known to be wetted by aluminum. In the presence of a nickel intermediate layer between the aluminum and graphite, wetting of the graphite by aluminum was expected to improve. To determine the wettability of aluminum on nickel coated graphite, the sessile drop technique along with a high temperature X-ray setup was used. Aluminum drops on substrates of graphite, electrolytic nickel, and nickel coated graphite were studied. Contact angles determined for these samples showed that graphite is non-wetting while the nickel coated graphite provided better wetting than electrolytic nickel. The aluminum/substrate interface of the samples was examined microscopically using scanning electron microscopy.