系统研究不同等离子渗氮温度对Ti-6Al-4V合金显微组织、硬度、耐磨性和腐蚀性能的影响

Systematic Study on the Roles of Different Plasma Nitriding Temperatures on the Microstructure, Hardness, Wear Resistance and Corrosion Performance of Ti-6Al-4V Alloys

摘要: 本研究对Ti-6Al-4V钛合金(TC4)分别在600℃、700℃和800℃等离子体渗氮处理15小时。以上不同温度对元素分布、相组成、硬度、耐磨性的作用(三种不同工况：空气；水；3.5wt% NaCl溶液)和腐蚀性能进行了深入分析。实验结果表明，渗氮处理后，表面形成以Ti₂N和TiN为主的硬质涂层。随着处理温度的逐渐升高，涂层表面氮含量呈上升趋势，钛(Ti)、铝(Al)等元素含量相应下降。氮处理后TC4钛合金基体硬度由376.88 HV显著提高到519.88 HV。在一定的渗氮时间下，随着渗氮温度的升高，渗氮层的厚度显著增加，从2.483 µm增加到5.141 µm。随着渗氮温度的升高，渗氮试样的平均摩擦系数由0.31增加到0.41，但磨损痕迹逐渐变细变浅。具体而言，TC4合金基体的体积磨损降低了约500倍(从2.614 × 10⁻⁵ mm³·N⁻¹·m⁻¹降低到5.497 × 10⁻⁸ mm³·N⁻¹·m⁻¹)。TC4钛合金的主要磨损机制是磨粒磨损和粘着磨损。此外，对比不同样品的自腐蚀电流，TC4-700 (5.157 × 10⁻⁸ A/cm²)的耐蚀性能最好，TC4 (1.910 × 10⁻⁷ A/cm²)的耐蚀性能最差。几乎是原来的4倍。这一结果对材料在恶劣环境(如海洋环境)中的应用具有重要意义。

Abstract: In this study, Ti-6Al-4V titanium alloy (TC4) was treated by plasma nitriding at 600˚C, 700˚C, and 800˚C for 15 hours, respectively. The roles of above different temperatures on the element distribution, phase composition, hardness, wear resistance (three different condition: air, water, 3.5wt% NaCl solution) and corrosion performance were in-depth analyzed. The experimental results show that a hard coating consisting primarily of Ti₂N and TiN phases forms on the surface after nitriding treatment. As the treatment temperature gradually rises, the nitrogen content on the coating surface shows an increasing trend, while the content of elements like titanium (Ti) and aluminum (Al) decreases correspondingly. The hardness of the TC4 titanium alloy substrate notably increases from 376.88 HV to 519.88 HV after nitrogen treatment. Under a constant nitriding duration, the gradual increase in nitriding temperature leads to a significant thickening of the nitrided layer, increasing from 2.483 µm to 5.141 µm. With the increase of nitriding temperature, the average friction coefficient of the nitriding sample increased from 0.31 to 0.41, but the wear marks gradually became thinner and shinier. Specifically, the volume wear of the TC4 alloy matrix is reduced by about 500 times (from 2.614 × 10⁻⁵ mm³·N⁻¹·m⁻¹ to 5.497 × 10⁻⁸ mm³·N⁻¹·m⁻¹). The main wear mechanism of TC4 titanium alloy is abrasive wear and adhesive wear. In addition, comparing the self-corrosion currents of different samples, TC4-700 (5.157 × 10⁻⁸ A/cm²) has the best corrosion resistance, and TC4 (1.910 × 10⁻⁷ A/cm²) has the worst corrosion resistance. A nearly fourfold improvement. This result has important implications for the application of materials in harsh environments, such as Marine environments.