Functionally Graded Material Coatings (FGMC) - A Review

Abstract

The coatings are substances that are applied over the surface of an object to prevent it from wear, tarnish and corrosion. Coatings maintain the properties of base metals (thermal, optical and electrical) over a long duration of time. The coatings are generally characterized by the properties like good adhesion, low porosity and substrate compatibility that include geometry and temperature. Coatings often suffer from problems like variable thermal expansion coefficient compared to their base metals. To overcome the variable thermal expansion issue, the functionally graded material (FGM) layers may be imposed. Present work aims to study the FGM coatings capable of enhancing the mechanical, thermal and tribological properties of base metals by providing scratch resistance. An attempt has been made to present a comprehensive review of high-velocity-oxy-fuel, plasma spray and other techniques adopted by industries and other groups. The effects of applying FGM coatings on the operating conditions and the performance of the base metals are also covered in detail.