Controlled synthesis of microarc oxidation coating on Ti6Al4V alloy and its antifriction properties

AbstractCeramic coatings were fabricated on a Ti6Al4V alloy surface by microarc oxidation (MAO) in Na2 SiO3 – (NaPO3)6 aqueous solutions with and without NaAlO2 additive using an AC power supply. The effect of NaAlO2 on microstructure, composition, and homogeneity of ceramic coatings were characterised using SEM, XRD, and EPMA. The antifriction property of the coatings with optimised microstructure sliding against SAE 52 100 steel ball was investigated on a pin-on-disc friction and wear tester. The results show that the addition of NaAlO2 into Na2 SiO3 – (NaPO3)6 solution assists the formation of more dense, uniform, and thicker coatings and increases rutile TiO2 content in the coatings. The optimised coating sliding against the steel has a friction coefficient as low as 0.2 – 0.3 at an applied load of 0.5 N and sliding cycle below 2500, which is much smaller than that of uncoated Ti6Al4V against the same counterpart. The transferring of material from the softer steel ball onto the coating surface is the ...