ENGINEERED NANOMATERIAL HARD COATINGS ON METAL AND POLYMER SUBSTRATES

摘要

A great deal of emphasis has been placed recently on developing nanostructured films and coatings on metallic and polymeric substrates to impart improved wear properties. The interest stems from the fact that the mechanical behavior of nanostructured materials appears to be significantly different from its coarse grained counterpart. Our recent work shows that the maximum benefit is achieved when the structure of the coating is a composite of micron and nano scale features, and is suitably tailored for any given application. We have successfully applied this concept to two classes of protective coatings: (1) tungsten carbide-cobalt coatings on metal substrates, wherein the agglomerated powder, used as feedstock material in a high velocity oxy-fuel thermal spray gun, is composed of a mixture of micron and nanoscale WC grains, and (2) optically transparent hard coatings on polycarbonate substrates, wherein the coating is composed of relatively large ceramic particles dispersed in a polymer nanocomposite matrix. It is clearly demonstrated for both types of coatings that the addition of large particles of hard materials in a nanostructured matrix substantially improves wear properties of the matrix.