Investigation of a self-lubricating coating for diesel engine pistons, as produced by combined microarc oxidation and electrophoresis

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). MoS2 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.