Micro-nanostructured cermet coatings

A cermet is a composite material consisting of ceramic (cer) and metallic (met) materials. The ceramic in general has high temperature resistance and hardness, and the metal has the ability to undergo plastic deformation. A cermet is ideally designed to have the combined optimal properties of a ceramic and a metal. Metals such as cobalt and nickel and their alloys are usually used as a binder for an oxide, boride, nitride, or carbide. The binder material itself can also contribute to the corrosion resistance because of its excellent intrinsic anticorrosion performance. Due to the combined properties, cermet materials have been widely used as machining and cutting tools, extrusion dies, wear-resistant coatings, and so on. Nanostructured cermet materials have aroused much interest in past decades due to the improved hardness, while the decrease in toughness is a challenge for most industry applications. Multiscaled micro-nano cermet coatings present high hardness and simultaneously high toughness, and thereby provided an impressive improvement of service performance, especially in harsh wear or erosion environments. This chapter is organized as follows: the mechanisms governing the mechanical properties of the cermet, thermal spray techniques to deposit nanostructured cermet, microstructure and properties of various cermet coatings, and finally status quo and prospects.