Ti6Al4V微弧氧化TiO2/W复合膜的制备及摩擦学性能

目的提高Ti6Al4V合金的摩擦学性能。方法在硅酸盐-磷酸盐电解液中添加不同浓度的纳米W粉,利用微弧氧化技术在Ti6Al4V基体表面制备出氧化陶瓷膜。利用FE-SEM、EDS和XRD研究了在不同浓度W粉参与下的微弧氧化膜表截面微观形貌、元素分布及膜层相组成。通过旋转摩擦磨损试验评估了膜层的摩擦学性能。结果电解液中加入纳米W粉可以促进膜厚增长,尤其在含0.5～2 g/L纳米W粉时,膜厚呈近似线性增长;但W粉在膜层表面的附着会导致粗糙度的增大。在纳米W粉参与下,微弧氧化膜中除了锐钛矿、金红石和Al_2TiO_5相之外,W含量也随电解液中颗粒含量的增加而提高。在6 g/L纳米W粉复合下,微弧氧化膜的摩擦系数、比磨损率分别减小了约13.33%和3.53%。结论 W粉颗粒以机械啮合附着在氧化膜表面,部分颗粒随熔融氧化物包裹进入膜层并发现熔化迹象。W粉含量为6 g/L时,制备的氧化膜表面质量有所改善,即微孔和裂纹等有所减少,耐磨性较佳,摩擦系数和比磨损率较不含W粉的膜层均有所减小。

Preparation and Tribological Property of TiO2/W Composite Coating on Ti6Al4V by Micro-arc Oxidation

The work aims to improve the tribological properties of Ti6Al4V alloy. Oxidation ceramic coatings were prepared on the surface of Ti6Al4V substrate by micro-arc oxidation treatment in silicate-phosphate electrolyte with different concentrations of tungsten nano-powder. Micro-morphology of surface and cross section element distribution, phase constituents of the micro-arc oxidation coatings with different concentrations of tungsten nano-powder were analyzed by FE-SEM, EDS and XRD. Tribological properties were evaluated by rotational wear test. The addition of tungsten nano-powder in electrolyte could promote the growth of the coating, especially the approximate linear growth within the range of 0.5~2 g/L tungsten nano-powder in electrolyte, but the adhesion of tungsten nano-powder on the surface of the coating could increase roughness. Except rutile, anatase and Al2TiO5 in the micro-arc oxidation coatings, the content of tungsten nano-powder also increased as the particles in the electrolyte grew. The friction co-efficiency and specific wear rate of the composite coating prepared in the electrolyte with 6 g/L tungsten nano-powder reduced by 13.33% and 3.53% respectively. Tungsten nano-powder exists on composite coating surface by mechanical entrapment. Parts of particles enter the membrane with molten oxide and show signs of melting. The quality of the micro-arc oxidation coating surface prepared in electrolyte with 6 g/L tungsten nano-powder is improved, e. g. reduction of the micro-pores and cracks, and better wear resistance. Friction co-efficiency and specific wear rate are both lower than that of coating without tungsten nano-powder.