Study on Evaluation of the Mechanical Property in TiCN Single-layer and Multi-layer Coatings by a Micro Slurry-jet Erosion (MSE) Method

—Variation of the Erosion Rates as a Function of Depth from the Surface—

Abstract

Commercial TiCN coatings generally consist of various multi-layer structures to improve their performance, and thus a technique to measure the mechanical properties of the TiCN multi-layer coating should be developed. In the present study, the micro slurry-jet erosion (MSE) test, developed by the authors, was applied to evaluate the properties of TiCN single-layer and multi-layer coatings. Specimens of TiCN single-layer and multi-layer coatings with a varying C content were deposited on high speed steel substrate by a cathodic arc method. The TiCN multi-layer coating was made with a stepwise increasing C content toward to the surface, by means of controlling the flow rate of N₂ and CH₄ during the deposition. The MSE tests were conducted by impacting slurry-jet containing 1.2 μm alumina particles perpendicular to the specimen surface, the erosion depth variation on the eroded surfaces was measured, and finally the erosion rates were calculated from the measured data. The most important findings in the present study: for the TiCN s ingle-layer coatings, their erosion rates became remarkably smaller with increasing C content due to the increase of hardness; for the TiCN multi-layer coating, the variation of the erosion rate as a function of depth from the surface was similar but more gradual than the expected stepwise variation based on the measured data of TiCN single-layer coatings with varying C contents.