The effect of diamond like carbon coating on the wear resistance at dry sliding conditions

Abstract

Abstract Wear due to sliding is an inevitable problem in many engineering applications. Protective surface coating is usually used to mitigate this problem. The development in this field is continuous and consistent. There are many types of coatings according to their compositions and the deposition methods. One of the coatings with the most promising properties, such as the hardness, is the Diamond-Like Carbon (DLC) coating. The tribological properties of this coating generated by Plasma-Assisted Chemical Vapor Deposition (PACVD) and applied on bearing steel 52100 ASTM are not available. In this study, the wear resistance of the DLC coating applied to bearing steel 52100 ASTM, was evaluated. The coating method employed was PACVD, which is regarded as one of the most distinctive coating techniques due to the unique tribological properties imparted to the coating. The pin-on-disc tribometer was used to examine the coefficient of friction and mass losses for samples of (steel disc against steel ball) and (DLC coated disc against DLC coated ball) under constant sliding velocity and constant sliding distance with four different loads (2, 5, 10 and 20 N) that results in maximum contact pressure below and higher than the maximum shear stress of the bearing steel. The wear coefficient was calculated using Archard’s equation based on the experimental results. It was found that the DLC coating may result in significant reduction, reaching 93.5%, in weight loss and 83% in COF at low contact pressure (less than the maximum shear stress). However, at high contact pressure (equals to or higher than the maximum shear stress) the weight loss and the COF for the DLC coating are higher than those of the bearing steel. This behavior indicates that the DLC coated pair may not be suitable at high loads. The wear coefficient is calculated for each testing condition and it is found to be affected by the applied load. The average wear coefficient for the DLC coating is provided which can be used with the Archared wear model to predict the wear rate within the range of the parameters used in this study.