STUDY OF WEAR BEHAVIOUR OF CHROME-NITRIDE COATING USING PHYSICAL VAPOR DEPOSITION

Abstract

ABSTRACT In the present investigation, Wear behaviour of chrome coating was examined using PVD (Ion Plating) in dry and flooded condition. The PVD having 93.7% Cr and 6.3% Nitrogen is used. The cast iron substrate of same composition as of piston rings was used to get the similar result as in the engine cylinder piston combination. After preparation of the coating, the plate (90×90×2 mm) was prepared with the help of a surface grinder and further wear test were performed on a pin-on disc configuration. The load and velocity range varies from (50, 60, 70, 80, 90 & 100 N), and Speed (319, 764, & 1433 rpm) keeping the sliding distance 2500 m. The wear rate was calculated using mass loss methods on an electronic balance having least count of 0.0001g. The morphology of worn surface was analysed with SEM & EDS which allow to elucidating the mechanism of wear and chemical composition of the tribo-film formed during the pin and disc sliding contact. The main wear mechanisms observed by SEM were adhesion, deformation, microcutting and erosion. There was a significant decrease in the specific wear rate of coated sample compared to uncoated and large reduction of coated sample in flooded condition compare to dry condition of test. The wear rate of the coating was found to be increased with increase in load as well as sliding speed for the Ion Plating with the counter body that is material of Cylinder liner which is alloy of cast iron. However, The Coefficient of friction was found to be decreased with the increase of load of 50 to 70 N and sliding speed from 1 m/s to 3 m/s. In these conditions chrome coating shows the better tribological behaviour.