Seizure and Friction Properties of the DLC Coated Journal and Aluminum Alloy Bearing

Using a bearing tester that can control the relative positional relationship between the shaft and the bearing in parallel, the seizure and friction property of the combination of a-C:H:Si DLC coated journal and the aluminum alloy bearing were verified. In case of the shaft rotation speed was 5200 rpm under the commercial 0W-20 engine oil at 110°C lubrication, the coefficient of friction of the steel journal rose sharply and seizure occurred when the pressure reached 113 MPa. In contrast, no seizure occurred with DLC journal at 121 MPa of the upper limit of the device. As a result of the observation of the sliding surface after the seizure, the large wear and the deposition of Sn which was seemed to be melted were confirmed for the bearing combined with the steel journal. The surface roughness of the DLC journal and bearing was not changed clearly after the test. This is probably due to the poor affinity with aluminum of DLC. Also, the EPMA result showed that Mo, Zn and P elements in lubricant were clearly not detected in both steel and DLC journal. Also, in the EHL region, the friction coefficient of DLC journal was reduced up to 10% co MPared with that of the steel journal.