METAL CERAMIC COHESION AND THE IMAGE INTERACTION

A detailed understanding at the microscopic level of the strength of bonding at metal ceramic interfaces, including its dependence on the crystallographic structure and chemical nature of the components, requires a model of the interatomic forces. Interatomic force models and computer simulation are widely used in the study of metal-metal and ceramic-ceramic boundaries but have not yet been applied to metal-ceramic. Recently however improvements in the microscopic modelling of metallic and ceramic cohesion together with the development of more powerful computers have opened possible ways of simulating the metal-ceramic interface which we are currently investigating. A particularly important component of the adhesive interaction across a metal-ceramic interface is believed to be the electrostatic image interaction which has no place in simple models of adhesion based on chemical bonding. This paradoxical situation is resolved. The image interaction is really a classical concept in the continuum electrostatics of point charges near a conducting surface, and makes no reference to discrete atoms. Nevertheless its equivalent attractive force close to a real metal surface can be calculated quantum mechanically for simple geometries. Fortunately, the results of these quantum mechanical calculations can be simulated by a classical interatomic force model, suggesting a way forward for atomistic simulation.