Sensitivity of Process Parameters in Atmospheric Plasma Spray Coating

Atmospheric plasma spraying (APS) is one of the most widely used thermal spraying technique which finds a lot of applications due to its versatility of spraying a wide range of materials from metallic to nonmetallic and hence more suitable for spraying of high melting point materials like refractory ceramics material, cermets etc. In recent era,any material can be used for plasma spraying on almost any type of substrate. Process parameters are the key factor that affects the formation of microstructures, bonding of coating with substrate and mechanical strength of coating. In this paper, the process parameters and their sensitivity towards the plasma modified structural elements are discussed.The microstructure of thermally sprayed coatings, which results from the solidification and sintering of the particles, frequently contain pores, oxides and cracks. The amount and distribution of these defects, as well as other coating properties as for instance thickness, hardness and bond strength, will be defined by the selected spray parameters. Therefore, the correct choice of the spray process as well as respective parameters (particle size, particle velocity, spray distance, plasma gun power, working pressure, substrate roughness, substrate temperature and so on) is very important for the deposition of good coatings and, consequently, to enlarge the useful life in service of the components.