No abstract

In present paper the influence of the post spray heat treatment on microstructure, microhardness and abrasive wear behaviour of flame sprayed Ni-Cr alloy (EWAC 1004) coatings deposited on mild steel has been reported. Coatings were deposited by oxy-acetylene flame spraying torch. The post spray heat treatment of the coatings was done at 800°C for 2 h. Wear behaviour of coatings was evaluated using pin on disc wear system against 120 and 600 grades SiC abrasive medium at 5 N, 10 N, 15 N and 20 N normal load. Results showed that the influence of normal load on wear rate is governed by the microstructure, hardness and abrasive grit size. Heat treatment increased average microhardness of the coating. Heat treatment of these coatings deteriorated the abrasive wear resistance against both fine and coarse abrasive mediums. In general, increase of normal load increased the wear rate. SEM study showed that wear is largely taken place by plowing, micro-cutting and crater formation mechanisms.KEY WORDS: Ni-Cr coating; flame thermal spraying; mild steel; abrasive wear; post spray heat treatment; microhardness and microstructure.