Effect of Current Density on the Structure and Properties of Micro-arc Oxidation Coatings on Titanium Alloy Drill Pipe

Abstract

TiO2 ceramic coatings were prepared on the surface of titanium alloy drill pipe with different current density by pulsed DC micro-arc oxidation. The morphology, structure, composition, hardness, friction and wear properties and corrosion resistance of the coatings were analyzed by SEM, XRD, micro-sclerometer, ball-on-disk wear tester and electrochemical workstation respectively. The results show that with the increase of current density, the thickness and hardness of the coating increasing, the wear resistance and corrosion resistance first increase and latter reduce. At different current density, the phase structure of the film is mainly composed of rutile TiO2 and anatase TiO2, and also contains a small amount of Al2TiO5 crystal and amorphous SiO2. The microstructure analysis shows that with the increase of current density, the density of the film increases and the roughness decreases, but when the current density continues to increase, the hole increases and the roughness increases. Under the experimental conditions, when the current density is 10 A/dm2, the combination property of the micro-arc oxidation layer is better.