Investigation of characterization and tribological behavior of composite oxide coatings doped with h-BN and graphite particles on ZA-27 alloy by micro-arc oxidation

This paper investigates the tribological effects of composite oxide coatings grown on ZA-27 surfaces under dry sliding condition. Coating processes were conducted using three different electrolytic solutions through micro-arc oxidation (MAO) method. The base electrolytic solution without any particles as additives was labeled as MAO-Coated, whereas electrolytic solution labeled as Coated-A contained graphite particles and Coated-B contained hexagonal boron nitride (h-BN) particles incorporated into base solution. The morphology of each coated samples were analyzed using a Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The friction and wear tests were conducted using a pin-on-disc tester in order to evaluate the tribological behavior. Results indicated the friction coefficients of both Coated-A and Coated-B samples were lower when compared to that of uncoated ZA-27 alloy. Further comparative studies showed Coated-A samples containing graphite particles resulted in the lowest friction coefficient.