Evaluation of Tribological Properties of Bearing Materials for Marine Diesel Engines Utilising the Contact Voltage Method

The contact voltage (CV) method, which can detect miniature failures, has been tested under laboratory conditions to monitor the condition of bearings. In this study, the bearing materials for marine diesel engines, aluminium and copper alloy, were tested on a bearing fatigue wear test bench in the boundary lubrication state, which was found through tests of the different parameters. The frictional torque, the oil film thickness and the bearing temperature were measured, as well as the CV signals. The possibility of using the CV technique to monitor the condition of the bearings was also assessed by evaluating the tribological properties. After 10 h of the test, the aluminium alloy bearing was worn to the alloy layer. Then, the wear-reducing layer on the surface of the bearing slowly peeled off, and the wear was intensified. Due to its higher wear-resisting property, the amount of wear on the copper alloy bearing increased slowly. After 20 h of the fatigue wear test, the aluminium alloy bearing became severely worn, the CV characteristic was up to 81% of the initial value, the bearing temperature increased by 6.3%, and the torque value increased by 32%. This indicates that the CV method is more sensitive to wear failure. Due to better wear resistance, the copper alloy bearing showed only slightly wear and a small increase in its CV value. The main contribution is that the CV method is useful for monitoring the lubricated condition and for evaluating the tribological properties of bearings. This research has laid technical foundations for the engineering of the sliding bearing wear monitoring system based on the CV method.