石墨对TA7钛合金表面微弧氧化涂层组织及耐蚀性的影响

Effects of Graphite on Microstructure and Corrosion Resistance of Microarc Oxidation Coatings on Surface of TA7 Titanium Alloy

为提高TA7钛合金的耐腐蚀和耐磨损性能,在钛合金表面制备了微弧氧化涂层,研究了石墨颗粒对微弧氧化涂层组织结构及耐蚀性的影响。结果表明,在基础电解液中加入石墨颗粒能够显著提高TA7钛合金微弧氧化涂层的厚度,降低微弧氧化涂层的表面粗糙度和显微硬度,且随着石墨含量的升高,微弧氧化涂层的厚度增大,但显微硬度减小,表面粗糙度基本保持不变;微弧氧化涂层的物相主要有高温稳定相金红石及锐钛矿;微弧氧化处理提高了TA7钛合金的自腐蚀电位,降低了腐蚀电流密度,石墨颗粒的加入进一步提高了自腐蚀电位,降低了腐蚀电流密度,显著提高了微弧氧化涂层的耐蚀性。

In order to improve the anti-corrosion and anti-wear properties of TA7 titanium alloy,microarc oxidation(MAO)coatings were prepared on the surface of the alloy.The effects of graphite particles on the microstructure and corrosion resistance of the MAO coating were investigated.The results show that the addition of graphite particles into basic electrolyte increased the coating thickness,and decreased the surface roughness and micro-hardness.With the increase of graphite concentration,the MAO coating increased in thickness and decreased in micro-hardness,but remained the same in surface roughness.The phases of the MAO coating were high-temperature stable rutile phase and anatase phase.MAO treatment made the free corrosion potential increase and made the corrosion current density decrease for TA7 titanium alloy.The addition of graphite particles further increased the corrosion potential and decreased the corrosion current density,resulting in the significant increase of corrosion resistance of the MAO coating.