Published online by Cambridge University Press: 21 February 2011
There are several possible descriptions of the nature of the adhesion between an oxide and a metal substrate, some of which are formally equivalent. These include electrostatic interactions connected with the development of space charge regions, chemical bonding across the interface, van der Waals forces, and mechanical interactions associated with a nonplanar interface. However, the detailed mechanism must also be consistent with the growth process and the associated evolution of the interface for an oxide growing on a metal substrate. The problem is further complicated by the nature of the failure at or near the interface which leads to a phenomenological definition of adhesion which is not necessarily identical to the formal definition, and involves other parameters such as the growth stresses in the oxide, the plasticity of the oxide or the surface metal, and the effect of thermal cycling when the coefficients of thermal expansion of the two phases differ. In this paper, an attempt is made to describe these different aspects of the problem, and to refer to some of the more important ways of modifying the adhesion of an oxide, including the reactive element effect and the segregation of impurities to the interface and the modification of the morphology of the interface.