电解液Ca/P比对微弧氧化钛合金涂层结构及性能的影响

Influence of electrolyte Ca/P ratio on microstructure and properties of micro-arc oxidation titanium alloy coatings

摘要:

本文采用微弧氧化技术在Ti-13Nb-13Zr合金表面制备HA/TiO2复合涂层。通过改变电解液中Ca/P比值，研究不同Ca/P比对微弧氧化涂层的相组成及组织变化，以及对耐磨性、耐蚀性与体外生物活性的影响。 结果表明： 随着电解液Ca/P比增大，涂层粗糙度及孔隙率增大。涂层相组成以锐钛矿及金红石为主，金红石相含量随着电解液Ca/P比增大而增大。乙酸钙含量为35g/L的电解液制备的CA35涂层厚度达80.59 μm，表面Ca/P比为1.98，表现出最好的耐磨耐蚀性能。与基体相比，CA35涂层平均摩擦系数约为0.19，下降了43%。采用Pt参比电极和0.9 wt% NaCl测试溶液对涂层的耐蚀性进行检测。CA35涂层的腐蚀电流密度为4.94 μA/cm2，腐蚀电位为-221.71 mV。CA35涂层在Kokubo 溶液中产生矿化产物的速度最快。 研究发现适当提高电解液Ca/P比能有效促进HA的形成，提高涂层的耐磨耐蚀性能，过高的Ca/P比会导致涂层性能下降。此外，本文对Ca/P比对涂层性能的影响机理进行了探讨。

Abstract:

HA/TiO2 composite coatings were prepared on Ti-13Nb-13Zr alloy by micro-arc oxidation. By changing the Ratio of Ca/P in the electrolyte, the phase composition and microstructure changes, as well as the effects of different Ca/P ratios on the wear resistance, corrosion resistance and in vitro biological activity of micro-arc oxidation coating were studied. The results show that the coating roughness and porosity increase with the increase of electrolyte Ca/P ratio. The coating phase is mainly composed of anatase and rutile, and the rutile phase content increases with the increase of Ca/P ratio of electrolyte. The coating thickness of CA35 prepared with 35g/L calcium acetate electrolyte is 80.59 μm and the surface Ca/P ratio is 1.98, showing the best wear and corrosion resistance. Compared with the substrate, the average friction coefficient of CA35 coating is about 0.19, which decreases by 43%. The corrosion resistance of the coating was tested by Pt reference electrode and 0.9 wt % NaCl test solution. The corrosion current density of CA35 coating is 4.94 μA/cm2, and the corrosion potential is -221.71 mV. The CA35 coating produced the fastest mineralized products in Kokubo solution. It is proved that increasing the Ca/P ratio of electrolyte can effectively promote the formation of HA and improve the wear resistance. In addition, the influence mechanism of Ca/P ratio on coating properties was discussed.