ESTIMATING THE METAL-CERAMIC VAN-DER-WAALS ADHESION ENERGY

We invoke the Lifshitz theory of van der Waals forces to derive a simp le, analytical expression for the adhesion across a planar metal-ceram ic interface. The van der Waals energy is conveniently expressed as a function of readily accessible bulk properties of the respective mater ials. Application to several non-reactive metal-sapphire systems shows the predicted van der Waals energy to provide a good lower-bound esti mate of the measured adhesion energy. Apart from platinum and palladiu m, where strong metal-aluminium interactions have been predicted, adhe sion energies in noble-metal systems are well accounted for by van der Waals interactions alone. Not surprisingly, adhesion in the more chem ically active metals exceeds the van der Waals energy.