| Despite their use in a variety of applications, the fundamental properties of metal-ceramic interfaces are still poorly understood. Historically, this has been due to experimental complications associated with the study of a buried interface, and to theoretical difficulties caused by complex interfacial bonding interactions. However, the advent of first-principles techniques based on Density Functional Theory (DFT) has led to new opportunities for highly-accurate computer simulations of the atomic and electronic structure of interfaces.; In this study we present a series of DFT calculations on a broad class of Al/ceramic interface systems, with the goal of explaining and predicting the nature of metal-ceramic adhesion. Since the strength of interfacial bonding, as quantified by the ideal work of adhesion , plays a crucial role in determining the mechanical properties of an interface, we have systematically calculated for 20 different interface geometries including oxide (α-Al 2O3), carbide (WC, VC), and nitride (VN) ceramic compounds with the goal of identifying trends. In order to identify the optimal atomic structures we consider the effects of several stacking sequences, interface terminations (both polar and non-polar), and allow for full atomic relaxations. For each system we use a variety of methods to carefully analyze the interfacial electronic structure in order to determine the nature of the metal-ceramic bonding.; Although we find significant differences in both the interfacial bonding and the inherent electronic structures of the bulk ceramics, our calculations reveal a trend in with respect to the summed surface energies of the interfaced materials (σAl + σceramic). Specifically, we find that surfaces having larger σ's adhere at interfaces more strongly than those with small σ's. We argue that this behavior is consistent with the intuitive notion of the surface energy being a measure of surface reactivity, and hence it could be used as a guide in the design of interfacial properties. |
