Adhesion at ceramic interfaces
Many of the properties associated with ceramic materials such as high hardness, high dielectric constant, refractoriness, and good optical properties will play a critical role in the development of devices for new and emerging technologies. In many cases, the combination of properties that is required demands that a composite material be designed to fulfill these complex materials needs. The increasing emphasis upon composite materials design and performance necessarily focuses greater attention upon the structure and properties of interfaces in ceramic materials. One on the most important aspects of interfacial behavior is the adhesive stability. As an example, high hardness ceramic coatings for tribological applications require a high degree of interfacial adhesion with the underlying substate material. Alternatively it has been shown that fiber reinforced ceramic composites that are designed for high fracture toughness must contain weak interfaces that allow for fiber pull-out to toughen the instrinsically brittle ceramic matrix. Our ability to design ceramic interfaces for specific interfacial adhesive behavior dictates that we develop a full understanding of the factors that control the adhesive bond in these systems. We report on the use of continuum fracture mechanics techniques to identify the molecular source of adhesion between oxide surfaces and introduce a new approach to measuring interfacial adhesive forces using an Interfacial Force Microscope.