The effect of TiN coating on erosion-corrosion resistance of alpha-Ti alloy in saline slurry

The slurry erosion-corrosion behaviour of TiN coated alpha-Ti alloy in aque ous silica slurry containing 3.5% NaCl has been investigated using a jet-in -slit rig. Erosion-corrosion tests were performed with slurry having jet ve locity range 4.8-12.8 m s(-1) and at normal impact angle. Because of synerg istic effects between erosive wear and flow-induced corrosion, the erosion- corrosion rates of the TiN coating and alpha-Ti substrate were higher than the sum of erosive wear rates and flow-induced corrosion rates. At the lowe r slurry velocity, the TiN coating deposited on the alpha-Ti substrate pres ented better slurry erosion-corrosion resistance. With increasing slurry ve locity, however, perforating, cracking and fragmenting of the hard TIN coat ing occurred and the protection effect of the coating layer reduced with th e erosion-corrosion duration. And then the volume loss of the alpha-Ti subs trate was enhanced through cracking of flakes induced by stress and corrosi on. (C) 1999 Elsevier Science Ltd. All rights reserved.