Wear of chromium nitride coating under high loads and speeds

摘要

This paper investigates the effect of high loads (up to100 N) and high speeds (up to 3 m/s) on wear and friction behaviour of PVD deposited CrN coatings on cast iron substrate. Uncoated substrate materials were also tests under identical test parameters to compare the friction coefficient, wear rate, temperature generation accompanied with wear mechanism. With the increase of normal loads from 50 N to 80 N the wear rate of coated sample increases from 4.59 x 10(-5) mm(3)/Nm to 6.86 x 10(-5) mm(3)/Nm, while the sliding speed remains constant. Temperature rise due to friction was monitored in wear tracks, and higher wear track temperature (from 65 degrees C to 178 degrees C) simulates higher coating wear as well as degradation of materials. The wear mechanisms of the CrN coatings involve pull out of nitride particles, oxidation of wear particles, adhesive wear and a combination of fatigue delamination as evident from wear track morphology investigated by scanning electron microscope.