The tribological properties of polyimide/polyamide imide/epoxy coating filled by WS 2 and ZnO under dry, water, and sediment conditions

ABSTRACTThree types of polyimide/polyamide imide/epoxy resin (PI/PAI/EP) coating materials filled with different amounts of WS2 and ZnO were designed, and the coatings were prepared on the surface of 1010 steel substrates using liquid spray coating technology. The mechanical and tribological characteristics of these coatings were investigated. The CoFs (coefficients of friction) of these coatings were lower than those of the copper alloy proposed to be replaced under dry sliding wear and water lubrication. The lowest CoF of 0.237 was achieved with 7.35 wt% WS2, and the highest CoF of 0.251 was observed for 4 wt% ZnO. However, the coating with 7.35 wt% WS2 had the lowest hardness and poorest load-bearing capacity under water lubrication. The coating with 4wt % ZnO had the best load-bearing capacity and the lowest wear rate. The agglomeration of the coating on the substrate was influenced by the content of ZnO. The CoF of the coating was influenced by both the transfer film formed by WS2 and the amount of ZnO floating on the surface of the coating. The embedding of sand into the coating surface during friction increased the surface roughness, which led to an increase in the CoF.Keywords: —Polymer coatingDry sliding wearWater lubricationSediment wearCoefficients of frictionDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. AcknowledgementsThis research was supported by the National Nature Science Foundation of China (52005273), the Natural Science Foundation of Zhejiang Province (LQ20E050007), the Ningbo Key Research and Development Program (2022Z050, 2023T010, 2023T013), and the Hunan Science and Technology Innovation Project (2022RC4016). This research was also supported by Yongsheng Jin (Ningbo Silver-ball Technology Co.; Ltd.; Ningbo 315207, China), and Jinxing Wu (Hunan Zhuoer Bearing Tech. Co.; Ltd.; Loudi 417000, China).Declaration of Interest StatementThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.Table 1 Composition and addition amount of coatingsDownload CSVDisplay TableTable 2 CoFs between copper alloy and different composite coatingsDownload CSVDisplay TableFigure 1. Coating preparation processDisplay full sizeFigure 2. The polished cross-section microstructure of polished composite coating: (a) T1 coating; (b) T2 coating; (c) T3 coatingDisplay full sizeFigure 3. Distribution of Zn, W, and S elements in composite coatings: Zn element distribution in T1 (a1), T2 (b1), and T3 (c1) coatings; S element distribution in T1 (a2), T2 (b2), and T3 (c2) coatings; W element distribution in T1 (a3), T2 (b3), and T3 (c3) coatingsDisplay full sizeFigure 4. Hardness and elastic modulus of coatingsDisplay full sizeFigure 5. CoFs and wears of the various coatings after 30 min of testing: (a) CoFs curves; (b) wear rate and scar widthDisplay full sizeFigure 6. Wear surface morphology of composite coatings under dry sliding wear for 30 min: (a) T1 coating; (b) T2 coating; (c) T3 coatingDisplay full sizeFigure 7. Wear mechanism of coatings under dry sliding wear: (a) Schematic diagram of the frictional movement of the ball on the surface; (b) T1 coating; (c) T2 coating; (d) T3 coatingDisplay full sizeFigure 8. CoFs and wears of the various coatings under water lubrication after 30 min of testing: (a) CoFs curves; (b) wear rate and scar widthDisplay full sizeFigure 9. Wear surface morphology of composite coatings under water lubrication for 30 min: (a) T1 coating, (b) T2 coating, (c) T3 coating.Display full sizeFigure 10. Wear mechanism of coatings under water lubrication: (a) Schematic diagram of the frictional movement of the ball on the surface; (b) T1 coating; (c) T2 coating; (d) T3 coatingDisplay full sizeFigure 11. CoFs and wears of the various coatings under sediment conditions after 30 min of testing: (a) CoFs curves; (b) wear rate and scar widthDisplay full sizeFigure 12. Wear surface morphology of composite coatings under sediment conditions for 30 min: (a) T1 coating; (b) T2 coating; (c) T3 coating. The larger SiO2 particles in Fig. 12c are due to accumulation in larger peeling pits.Display full sizeFigure 13. Wear mechanism of coatings under sediment conditions: (a) Schematic diagram of the frictional movement of the ball on the surface; (b) T1 coating; (c) T2 coating; (d) T3 coatingDisplay full size