MODIFICATION OF THE GOLD GRAPHITE INTERFACIAL ENERGY BY INTERFACIAL ADSORPTION OF NICKEL

The effects of nickel additions on the energy of gold/graphite interfaces was investigated. Nickel was found to segregate to the interface forming an adsorbed layer. Solid-state wetting measurements showed that the contact angle of gold on graphite was decreased by 7.8 degrees by the addition of 15 at % Ni. The corresponding decrease in interfacial energy, determined from the Young-Dupre equation was found to be similar to 112 mJ m(-2). The interfacial excess of nickel corresponding to 15 at % Ni in the bulk was calculated by means of the Gibbs adsorption isotherm to be about 0.45 equivalent monolayers of gold. The presence of nickel at the interface was further confirmed by crater-edge profiling studies performed in a scanning Auger microprobe.