- Thermal Spray Coatings for Aeronautical and Aerospace Applications

Abstract

Advancements in surface modification technologies have led to the development of various thin coatings aimed at improving the tribological properties of materials in order to reduce losses due to friction and wear. Lubrication is indispensable for achieving reduced friction between two moving surfaces. The increasing demand for low friction and wear in aerospace and other tribological applications which involve severe sliding conditions and the limitations of fluid lubricants at extreme environmental conditions such as high vacuum, low and high temperature, radiation, etc. gave rise to the need for solid lubricant coatings. Solid lubricants such as transition metal dichalcogenides, soft metals, diamond like carbon films, polymers, etc. have been successful in providing low friction at a sliding interface. However, the use of these coatings is restricted to certain areas of application conditions and environments due to issues related to their structure and properties. In recent years, development of nanostructured coatings has received great attention since they exhibit exotic properties due to nano-scale engineering. Novel coating architectures such as nanocomposites and multilayered coatings have been areas of intense research since these nanostructured solid lubricant coatings exhibit improved tribological properties in combination with other desirable properties such as improved adhesion and hardness over a wide range of environmental conditions. In this review, we have described the deposition and characterization of nanostructured solid lubricant coatings which have great potential for enhancing the properties of traditional solid lubricant coatings. Various methods used for the preparation of the nanostructured solid lubricant coatings have been described in brief. We describe in detail, the structure, microstructure, adhesive strength, mechanical and tribological properties, and thermal stability of sputter deposited nanostructured solid lubricant coatings. We also present the potential applications of nanostructured solid lubricant coatings in aerospace, automotive and other engineering sectors.