| Titanium and titanium alloys with a strong medium-temperature stability, biocompatibility and high specific strength have widely been applied in the aerospace, navigation, sports and other fields. However, titanium alloys are vulnerable to fail and cause a threatening risk to the security in practical applications because of its poor wear resistance. In addition, the requirement to the corrosion resistance of titanium alloys is improved with the expansion of application fields. Nowadays, there are a variety of methods to improve the wear resistance and corrosion resistance of titanium alloys, and micro-arc oxidation is widely used in surface modification of titanium for the higher adhesion and hardness. In this toptic, MAO films on Ti6Al4V alloys were prepared in Na2SiO3solution using a pulsed power supply with constant current mode, and the influence of current density、duty ration、oxidation time and SiC nano particle on micro-arc oxidation process and performance of MAO films were studied.(1) For all micro-arc oxidation processes, the voltage curve can be divided into three stages. Initially, the voltage of micro-arc oxidation increases rapidly, leading to the rapid growth of the oxide film. In the second stage, the oxidation voltage increases continuously to a stable value, but the growth speed reduces significantly. In the last stage, the voltage keeps at a high value which increases with the improvement of the current density and duty ration.(2) With the increase of current density and oxidation time, the thickness, surface roughness and pore diameter of the oxidation film increase accordingly. The titanium oxide film is mainly composed of rutile and anatase phases, and the rutile proportion increases with the increase of the current density, and the duty ration or the extension of the oxidation time.(3) With the increase of current density and the oxidation time, the friction coefficient of the oxidate film increases, while the wear rate increases after decreases firstly. When the current density and oxidation time are low, the corrosion resistance and the wear resistance of the oxidation film improve with the increase of current density and extension of the oxidation time. However, when the current density and oxidation time are lager, the influence of current density and oxidation time is not obvious to the corrosion resistance and wear resistance. In contrast, the duty ration has little effect on the wear resistance and corrosion resistance of the oxidate film.(4) The addition of the nano-SiC particle makes the oxidation voltage and the thickness of the oxidate film correspondingly increase, and makes the pores diameter reduce. Also, the friction coefficient of the oxidate film increases and the wear rate decreases after adding the nano-SiC particle, which is beneficial to improve the wear resistance and corrosion resistance of the film. In addition, a SiC phase exists in oxidation film. |
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