HVOF sprayed Ni3Ti and Ni3Ti+(Cr3C2+20NiCr) coatings: Microstructure, microhardness and oxidation behaviour
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Date
2018
Journal Title
Journal ISSN
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Publisher
Elsevier Ltd
Abstract
This paper reports the development of Ni<inf>3</inf>Ti and Ni<inf>3</inf>Ti+(Cr<inf>3</inf>C<inf>2</inf>+20NiCr) coatings on AISI 420 stainless steel (MDN-420) and titanium alloy ASTM B265 (Ti-15) by HVOF technique. Microstructure, microhardness and high temperature oxidation behaviour of coatings were investigated. Microstructure of coatings was dense and displayed layers depicting lamellar structure. The microhardness of coatings was significantly higher than that of substrate owing to higher density and cohesive strength between individual splats of coating materials. Cyclic oxidation studies conducted on Ni<inf>3</inf>Ti and Ni<inf>3</inf>Ti+(Cr<inf>3</inf>C<inf>2</inf>+20NiCr) coatings showed oxide scale was composed of various oxides like NiO, NiCr<inf>2</inf>O<inf>4</inf> and Cr<inf>2</inf>O<inf>3</inf> phases. The formation of compact and protective NiO phase in case of Ni<inf>3</inf>Ti coatings; NiO and Cr<inf>2</inf>O<inf>3</inf> phases in Ni<inf>3</inf>Ti+(Cr<inf>3</inf>C<inf>2</inf>+20NiCr) coatings stabilised the weight gain exhibited slow oxidation rate at higher temperatures. © 2017 Elsevier B.V.
Description
Keywords
Alloy steel, Binary alloys, Chromium alloys, Chromium compounds, Coatings, Electron microscopy, Fuels, Hardness, HVOF thermal spraying, Lamellar structures, Microhardness, Microstructure, Nickel compounds, Oxidation, Scale (deposits), Sprayed coatings, Stainless steel, Thermooxidation, Titanium alloys, Titanium compounds, X ray diffraction, Coating material, Cohesive strength, Cyclic oxidation, High temperature, High velocity oxy fuel, Oxidation behaviours, Slow oxidation, Weight gain, Nickel alloys
Citation
Journal of Alloys and Compounds, 2018, 736, , pp. 236-245