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. 2024 Aug 1;17(15):3802.
doi: 10.3390/ma17153802.

Wear Performance Evaluation of Polymer Overlays on Engine Bearings

Ismail Ozdemir  1 , Bahattin Bulbul  2 , Ugur Kiracbedel  2 , Thomas Grund  1 , Thomas Lampke  1
Affiliations

Wear Performance Evaluation of Polymer Overlays on Engine Bearings

Ismail Ozdemir et al. Materials (Basel). .

Abstract

Modern engine bearing materials encounter the challenge of functioning under conditions of mixed lubrication, low viscosity oils, downsizing, start-stop engines, potentially leading to metal-to-metal contact and, subsequently, premature bearing failure. In this work, two types of polymer overlays were applied to the bearing surface to compensate for extreme conditions, such as excessive loads and mixed lubrication. Two different polymer overlays, created through a curing process on a conventional engine bearing surface with an approximate thickness of 13 µm, were investigated for their friction and wear resistances under a 30 N load using a pin-on-disc setup. The results indicate that the newly developed polymer overlay (NDP, PAI-based coating) surface has a coefficient of friction (COF) of 0.155 and a wear volume loss of 0.010 cm3. In contrast, the currently used polymer overlay (CPO) in this field shows higher values with a COF of 0.378 and a wear volume loss of 0.024 cm3, which is significantly greater than that of the NDP. It was found that, in addition to accurately selecting the ratios of solid lubricants, polymer resins, and wear-resistant hard particle additives (metal powders, metal oxides, carbides, etc.) within the polymer coating, the effective presence of a transfer film providing low friction on the counter surface also played a crucial role.

Keywords: copper-based bimetal; pin-on-disc; plain bearing; polymer overlay; wear.

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Conflict of interest statement

Authors Bahattin Bulbul and Ugur Kiracbedel were employed by the company Eksel Bimetal Sintering and Casting Factory. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
(a) Schematic illustration of the bearing structure of a conventional electroplated coated bearing and (b) the investigated type of polymer-coated bearing.
Figure 2
Figure 2
Copper-Based Sintering Bimetal production system.
Figure 3
Figure 3
SEM images of the polymer overlay microstructure on the bronze bearing (a) at low (500×) and (b) high (2500×) magnifications.
Figure 4
Figure 4
Wear test setup for a polymer-coated bearing segment.
Figure 5
Figure 5
Macroscopic view of the tested polymer overlays: (a) the reference material (commercial), and (b) the newly developed material sprayed onto the bronze bearing surface.
Figure 6
Figure 6
The variation in the coefficient of friction for the reference coating (a) and the newly developed polymer overlay coating (b) under a 20 N applied wear load for a longer sliding distance.
Figure 7
Figure 7
The variation in the coefficient of friction and ECR measurement (indicated by the red arrow) for the reference coating (a) and the NDP overlay (b) material tested under 30 N load.
Figure 8
Figure 8
The macroscopic appearance of the worn surfaces of the reference polymer (a) and the NDP overlay (b) after the wear test under a 30 N load.
Figure 9
Figure 9
Three-dimensional wear track images of the reference polymer (a) and the NDP overlay (b) after wear tests under 30 N also displaying the depth of worn surfaces at (c) and notable breaks in the side walls of the wear path (red arrows) (d), respectively.
Figure 10
Figure 10
The variation in the COF values (a) and linear wear loss (b) tested under 30 N.
Figure 11
Figure 11
The change in the COF as a function of wear distance when the reference polymer coating initially comes into contact with a ball under a 30 N load (1st zone), depicting the region where it functions in harmony with the ball (2nd zone) and the point at which it completely separates from the wear surface (3rd zone).
See this image and copyright information in PMC

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