Deposition of Coatings of Waste Marble Dust Pre-Mixed with Nickel Chrome Powder by High-Velocity Oxy-Fuel Spraying Route

Abstract

We have explored the coating potential of waste marble dust on metal substrates by the high-velocity oxy-fuel spraying route. To improve the deposition rate and overall coating quality, a conventional spray-grade powder, nickel chrome, is premixed with marble dust in limited proportions prior to coating deposition. Mild steel, aluminum, inconel, and copper are taken as the substrates and liquefied petroleum gas is used as the fuel for the spraying. The deposition of overlay coating is performed by varying the spray distance and the resulting coatings are characterized in terms of their deposition efficiency, thickness, adhesion strength, and microhardness. The coating microstructures are studied using a scanning electron microscope and the phases present in the coating are identified using an X-ray diffractometer. It is observed that the coatings exhibit fairly good interfacial adhesion, hardness, and thickness values that vary significantly with the spray distance. A maximum deposition efficiency of about 78% is obtained for the copper substrate at a spray distance of 100 mm, whereas, for aluminum, Inconel, and mild steel substrates, these values are 74.88%, 66.08%, and 60.84%, respectively. Similarly, appreciably good interfacial adhesion strength and thickness of the coatings on all the substrates are recorded.