Preparation and tribological properties of MAO-PVA/PTFE self-lubricating composite coating on aluminum alloy surface

In order to enhance the wear resistance of 6061 aluminum alloy, the MAO-PVA/PTFE self-lubricating composite coating was prepared on the surface of aluminum alloy using microarc oxidation (MAO) technology and solgel technique. Scanning electron microscopy and X-ray diffraction were employed to analyze the morphological properties and structures of the single MAO coating and the composite coating. Energy-dispersive spectroscopy was utilized to examine the elements present on the surface and within the wear track. Ball and disk friction tests were conducted to evaluate the wear resistance of the composite coating. Furthermore, the comprehensive friction performance of the composite coating was investigated across a range of speed variations (1 to 2.5 cm/s) and load variations (1 to 7 N). The test results revealed that the PVA-PTFE film covered the surface of the MAO coating, effectively sealing the micropores. Compared to the single MAO coating, the average coefficient of friction (COF) of the composite coating decreased significantly from 0.549 to 0.139, resulting in improved wear resistance. Moreover, the COF of the composite coating decreased with increasing velocity and load. Subsequently, the wear mechanisms of both the single MAO coating and the composite coating were discussed. The main wear mechanisms observed in the MAO coating were adhesive wear and abrasive wear, while the MAO-PVA/PTFE composite coating exhibited minimal fatigue and oxidation wear. Consequently, the composite coating effectively enhanced the wear resistance of the aluminum alloy, leading to an improved service life.