Microstructure and Adhesion Strength of Ni3Ti Coating Prepared by Mechanical Alloying and HVOF

Abstract

In the present work we report the development of Ni<inf>3</inf>Ti intermetallic compound by high energy ball milling of Ni and Ti powders. The ball milled powders were taken at various intervals (4, 6, 8, 10, and 11 h) to analyze the formation of Ni<inf>x</inf>Ti<inf>x</inf> intermetallic compounds. The ball milled powders were analyzed using scanning electron microscopy and X-ray diffraction. The layered shaped powder particles of Ni<inf>3</inf>Ti phase were formed after 11 h of ball milling, which was confirmed by X-ray peaks. Further High-Velocity Oxy-Fuel (HVOF) process was used to coat Ni<inf>3</inf>Ti and Ni<inf>3</inf>Ti + (Cr<inf>3</inf>C<inf>2</inf> + 20NiCr) on MDN 420 steel. Both the coated materials displayed excellent cohesion with minimal porosity less than 2%. The tensile adhesion strength test was carried out on these coatings to check the bond strength. Out of the two the Ni<inf>3</inf>Ti coating showed excellent bond strength of 41.04 MPa compared to that of Ni<inf>3</inf>Ti + (Cr<inf>3</inf>C<inf>2</inf> + 20NiCr) coating. © 2018, Pleiades Publishing, Ltd.