Structural determination of wear debris generated from sliding wear tests on ceramic coatings using Raman microscopy

In order to address the important interest in wear debris and associated we ar mechanisms, we have studied a series of physical-vapor deposition cerami c hard coatings (CrN/NbN, CrN, NbN, TiAlN/VN, and TiCN) using a ball-on-dis k sliding configuration against corundum. The debris generated were charact erized using Raman microscopy to identify compounds, especially oxides, gen erated during the wear process to gain a better understanding of tribochemi cal reactions. The high spatial resolution (2 mu m), sensitivity to structu ral changes, and nondestructive nature make this technique ideal for the st udy of such small amounts of wear debris. This article examines binary, mul ticomponent, multilayered, and superlattice coatings. Under dry sliding con ditions of 5 N normal load and 10 cm/s speed, titanium-based alloy coatings were found to provide TiO2 (rutile) debris. However, the addition of thin layers of VN to the TiAlN system provided a lower friction coefficient, and much less debris through the possible formation of a lubricious surface ox ide. CrN-and NbN-based coatings were also found to produce debris with Rama n bands corresponding to oxides. Contact temperatures were also estimated b y comparison of the tribochemical products generated during sliding wear wi th the formation temperatures of oxides detected from static oxidation. (C) 2000 American Vacuum,? Society. [S0734-2101(00)16604-7].