Slurry erosion characteristics or TiN coatings on alpha-Ti and plasma-nitrided Ti alloy substrates

The slurry erosion behavior of TiN coatings on alpha-Ti and plasma-nitrided Ti alloy substrates in aqueous silica slurry has been investigated using a jet-in-slit rig. Erosion tests were performed with slurry jet velocities b etween 6.4 and 15.2 m s(-1). At the lower slurry velocity, pitting was caus ed by the slurry impact, and there was little volume loss for each of the c oatings. The TiN coatings deposited on the alpha-Ti and nitrided Ti alloy s ubstrate presented high slurry erosion resistance. With increasing slurry v elocity, however, perforation and fragmentation of the hard TiN coatings oc curred and the protection effect of the coating layer reduced with the eros ion duration. The erosion rates for the coatings deposited on the nitrided Ti substrate were slightly lower than those for the coatings deposited on t he alpha-Ti substrate under the same test conditions. After coating perfora tion, the surfaces of the substrates were eroded by crater formation and fl aking on the center section of the erosion scars while cutting and plowing occurred at the outer regions of the erosion scars. (C) 1999 Elsevier Scien ce S.A. All rights reserved.