Plasma Spray Coating of Fly Ash on Metals for Tribological Application

Abstract

Thermal spray coating of fly-ash was deposited on various substrate viz. copper, mild steel, stainless steel and aluminum by plasma spraying (atmospheric plasma spraying) at at Laser & Plasma technology Division, BARC-Mumbai. Subsequently, coatings were evaluated for deposition efficiency, adhesion strength (coating to substrate), microhardness of different phases. Phase composition analysis was made using XRD technique.Deposition efficiency up to ~60 % was achieved. The quality of the coatings has a strong dependence on input power to the plasma torch and particle size of the feed material. Adhesion strength of 7-12 MPa was obtained.. The hardness measured on the polished cross-section of the coating on optically distinguishable phases, varies between 800-1000 Hv for different phases. Phase composition analysis was done using XRD technique and reveals that, along with silica, α-γ Alumina and Mullite phases are present in the coatings. The surface and interface morphology of the coatings are examined with SEM.