Effects of Direct Current on the Wetting between Molten Al and a Graphite Substrate

Graphite fiber attracted much attention in the area of aluminum based composite due to its low density and high strength. However, one of the major drawbacks in fabricating graphite reinforced metal matrix composites (MMCs) is that aluminum generally does not wet graphite. Therefore, it is difficult to impregnate the graphite fiber in molten aluminum. The application of external electric power has been recently reported as a promising way to improve the wettability. The effect of an electric current on the wettability of molten Al on graphite has not been investigated. The effects of electric current, density of sample and heating time on wettability, thickness of product, and microstructure were investigated. The wettability remarkably improved utilizing electric current due to a larger formation of Al4C3 per unit time from electromigration. The wettability of molten Al on graphite substrate is better with an applied negative current and with lower relative density of sample.