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In order to adapt to the development of lightweight equipment, and further improve the wear resistance of ZL109 aluminum alloy, the influence of nickel-coated carbon nanotubes as an electrolyte additive on the preparation and wear resistance of microarc oxidation ceramic coatings on ZL109 aluminum alloy surface was investigated. In this work, 0.4 g/L, 0.8 g/L, 1.2 g/L, 1.6 g/L, and 2 g/L nickel-coated carbon nanotubes were added to the electrolyte respectively. The microarc oxidation ceramic coatings were prepared under bipolar pulse constant pressure mode, which were analyzed from the aspects of morphology, chemical composition, and wear resistance property. The results show that the nickel-coated carbon nanotubes possess a great influence on ceramic coatings. The morphology of ceramic coatings was significantly changed. In this work, the coating prepared by 1.2 g/L nickel-coated carbon nanotubes exhibits excellent wear resistance property. [ABSTRACT FROM AUTHOR]

The purpose of this work was to improve reliability and durability of high-silicon aluminum alloy piston skirts for diesel engines. Novel ceramic matrix composites were fabricated on ZL109 aluminum alloy substrates by two steps combining microarc oxidation (MAO) with electrophoresis deposition (EPD). MoS 2 is incorporated into an aluminum oxide matrix during processing. The effects of the ceramic matrix composites on anti-wear and self-lubricating were investigated using a reciprocating test method and cylinder liner samples (boron copper cast iron) as the sliding partner. Compared to the high-silicon aluminum alloys substrate, the friction coefficient of ceramic matrix composites against the liner material was reduced by 35% under dry sliding, the wear loss was decreased by 95%, the worn surfaces were flat and smooth, and friction coefficient was relatively stable. The mechanisms by which the observed advantages were produced are discussed. [ABSTRACT FROM AUTHOR]

A surface texture produced by three-step microarc oxidation (MAO) was optimized to improve the tribology performance of a self-lubricating composite coating for diesel engine piston skirts. WS 2 was introduced into the self-lubricating composite coating as a self-lubricating additive. The effects of MAO's varying electrical parameters in terms of stages and action time on the microstructure and chemical composition of the coatings were analyzed by XPS mapping, micron CT, SEM, XRD, and EDS mapping. Furthermore, friction-wear tests under dry lubricating were employed to evaluate the self-lubricating property of the composite coating. Compared to the bare ZL109 aluminum alloy, the optimized composite coating's friction coefficients were reduced by 60%. Notably, the wear loss of cylinder liner samples matched with the optimized composite coating was almost zero under this work condition. Image 1 • An optimized self-lubricating coating for Al–Si piston skirts was fabricated. • The surface texture was optimized for the self-lubricating coating. • Varying electrical parameters and action time were analyzed for the texture. [ABSTRACT FROM AUTHOR]

Ceramic based self-lubricating coating was successfully fabricated on Al-based plasma electrolytic oxidation (PEO) ceramic coating in this work. The coating was reinforced with thermosetting polyimide (PI) containing tungsten disulfide (WS 2) fillers. The morphology, chemical composition and phase structure of the PEO, PEO/PI and PEO/PI/WS 2 coatings were observed by SEM, EDS and XRD, respectively. Tribological properties of the coatings were comparatively investigated using a reciprocating pin-on-block tribotester under different conditions. Under dry sliding conditions, the friction coefficient of PEO/PI/WS 2 coating was about 0.4, which was 50% lower than that of PEO coating. Meanwhile, the wear rate of counter pin cooperated with PEO/PI/WS 2 coating was only 0.04 mg min−1, which was 90.9% lower than that of PEO coating. Under step loading conditions, the load was ultimately increased to 70 N and the total duration time was about 35 min, while the corresponding values of PEO coating were 30 N and 13 min, respectively. These are owed to the hard ceramic coating and the soft self-lubricating coating, which can improve the load capacity and decrease the friction, of the ceramic based self-lubricating coating. Image 1 • A self-lubricating coating was successfully fabricated on ZL109 aluminum alloy. • The introduction of WS 2 in the self-lubricating coating shows excellent tribological properties. • The combination of soft lubricating coating and hard supporting ceramic coating is the main anti-friction mechanism. [ABSTRACT FROM AUTHOR]