The objective of this research was to develop a novel self-lubricating coating on an AA6061 aluminum alloy. Three coatings were prepared by the plasma electrolytic oxidation (PEO) process using 50-, 500-, and 1000-Hz pulsed direct current, respectively. The as-deposited coatings were then post-treated using two different methods, viz., ultrasonic vibration-aided vacuum oil impregnation (UVOI) and oil impregnation under ambient pressure (OIAP). After posttreatment, an oil-containing, self-lubricating top layer was formed on the coatings. The effects of the coatings' surface morphologies and structures on their oil-holding capabilities were discussed. The results revealed that coatings prepared with higher frequency had a greater oil-holding capacity using OIAP post-treatment, while those prepared with lower frequency had a greater oil-containing capability using UVOI post-treatment. These phenomena are related to the morphologies of the coatings produced with various current modes. The tribological properties of the coatings before and after post-treatments were investigated by pin-on-disc sliding wear tests. Due to the formation of a lubricant-containing top layer, the post-treatment coatings had a lower friction coefficient and improved wear resistance compared with the asdeposited coatings. In addition, the coatings after UVOI treatment had better wear performance than those post-treated using the OIAP process. Among all coatings, the coating produced with a 50-Hz pulsed current followed by UVOI posttreatment achieved the lowest friction coefficient (0.03) and best wear resistance when sliding against a Si 3 N 4 ceramic counterface. This study indicates that a novel self-lubricating coating can be prepared by a PEO process combined with vacuum oil impregnation post-treatment.
The corrosion behavior of galvanic couples covered by a 0.5 mm thick film using a homemade electrochemical measurement device has been researched in this work. The potential distribution and current density of lap joints (bare and coating damaged) in the thin layer electrolyte have been calculated using the boundary element method (BEM). The results show that the potential of 2A12 aluminum alloy plates as an anode shifted positively after lapping. The degree of anodic polarization and the corrosion rates reached the highest values in the regions around the bolts and then decreased on either side. The corrosion rate is closely related to the coating damage area; the smaller the damage area is, the larger the corrosion rate in the region of coating damage. The results of simulations conform to reality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.