Development and characterisation of high performance ceramic-metal composites

Ceramic-metal composites, or cermets, are used in a wide variety of industrial applications where toughness, high strength, and resistance to corrosion and wear are required, notably in the petroleum, mining, chemical processing, transportation, and pulp and paper industries. There is consequently a continuing drive to develop improved materials for use in these demanding environments, either in bulk or coating form. For approaching 100 years, materials based on tungsten carbide/cobalt (WC/Co), have been the cermet of choice. However, WC/Co actually exhibits relatively poor corrosion and oxidation resistance, while the mechanical properties are severely degraded above ~500°C. A family of novel cermets, co-developed by the applicant, utilising ductile nickel aluminide (Ni3Al) alloys, eliminate many of the problems associated with WC/Co and other cermet systems, and offer the notable benefit that strength actually increases with temperature, up to ~1,000°C. The present application builds extensively on our prior program of research into the development and characterisation of high performance cermets. We plan to prepare nano-structured materials, based on titanium carbide and carbonitride, utilising a variety of Ni3Al-based binders. Mechanical properties, such as strength and hardness, will be assessed. Fracture behaviour will be evaluated through in-situ crack growth observation. Our ongoing Hertzian contact damage studies (simulating spherical bearing conditions) will be expanded, notably to include assessment of strength degradation, cyclic indentation response and elevated temperature damage (where specific benefits are expected when using Ni3Al). In addition, the oxidation response of these materials needs to be more fully assessed, which will be achieved through thermogravimetric analysis and static oxidation trials. The successful outcome of this research will be new generations of high performance cermets for a variety of industrial applications, which will lead to improved component lifetimes and increased safety tolerances. Ultimately, the materials that are produced may also be adapted for use as coatings, further increasing their operational scope.