Evaluation on tribological design coatings of Al2O3, Ni–P–PTFE and MoS2 on aluminium alloy 7075 under oil lubrication

The current work evaluated the friction and wear properties of tribological design surface coatings on aluminium alloy 7075 under various speed and nominal contact pressure. Hard-anodized Aluminium Oxide (Al2O3), burnished Refractory Metal Sulfide (MoS2) and composite electroless nickel coatings with polytetrafluoroethylene (Ni–P–PTFE) particles were subjected to pin-on-disc sliding test against grey cast iron (GCI) under Mach 5 SL SAE 10 W-30 lubrication. The results indicated that Ni–P–PTFE composite coating possessed excellent friction–reduction capability but limited wear resistance due to low mechanical strength. Al2O3 coated sample showed outstanding wear resistance with high friction characteristic leading to high surface contact temperature. Furthermore, MoS2 coating improved the wear resistance of the aluminium alloy.

► Ni–P–PTFE shows excellent friction-reduction but limited wear resistance on Al-7075.
► Al2O3 shows outstanding wear resistance but high friction characteristic on Al-7075.
► Burnished MoS2 improved wear resistance of the Al-7075.