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

Abstract

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.

Excellent Seizure and Friction Properties Achieved with a Combination of an a-C:H:Si DLC-Coated Journal and an Aluminum Alloy Plain Bearing

“…The specifications of the bearings used are shown in Table 5. In a previous study [12,13], 17 mm wide bearings were used, but in the present study the bearing width was narrowed by 31% to 11.4 mm. That was done to make the difference in seizure properties clearer by increasing the contact pressure at the maximum load level of the bearing tester.…”

“…The specifications of the bearings used are shown in Table 5. In a previous study [12,13], 17mm wide bearings were used, but in the present study the bearing width was…”

“…The evaluations were performed using a bearing test rig as specified in ISO 21866-1 for automotive journal bearings [11], which makes it possible to examine the properties under fluid, mixed, and boundary lubrication regions. The friction and seizure properties of DLC-coated journals in a specific load range up to a maximum specific load of 121 MPa have previously been reported along with the related influence of surface roughness and engine oil additives [12,13]. In the present study, friction and seizure properties were investigated under specific load as high as 181 MPa, along with analyzing the sliding part surfaces and conducting acoustic emission (AE) tests to analyze the phenomena involved.…”

“…The highly rigid connecting rods apply the load to the journal in a step-like manner via the plain bearings by means of a hydraulic vibration generator (iv). It also has a tilting device (v) that adjusts the parallelism between the journal and the bearing [12,13]. The applied load is measured with a load cell (vi).…”

The effects of DLC-coated journal on improving seizure limit and reducing friction under engine oil lubrication

“…Tests were conducted at a relatively high oil temperature of 110°C. In order to verify the friction properties of the DLC coating with a low-viscosity lubricating oil, 0W-8 viscosity grade oil without MoDTC 9 was also used as shown in Table 3.…”