Ti-6Al-4V热浸镀铝涂层干滑动磨损行为的实验研究

An experimental investigation on dry sliding wear behavior of hot-dip aluminized Ti-6Al-4V alloy

摘要:

Ti-6Al-4V合金经热浸铝并在650℃下进行高温扩散退火处理，获得TiAl3涂层。采用销-盘式磨损试验机研究铝化后的Ti-6Al-4V合金与GCr15钢对磨的干滑动磨损行为。通过SEM、XRD、EDS和XPS等微观分析手段测试热浸镀铝涂层磨面的形貌、物相和成分，并且探讨其磨损机制。研究结果表明：随着滑动速度的增加，当滑动速度为0.75m/s时，铝化后的Ti-6Al-4V合金的磨损量先减小到最小值，然后在2.68m/s时增加到最高值，最后在4m/s时降至最低值。在不同的滑动速度下，磨损量随着载荷的增加而增加。研究发现，摩擦层结构对磨损的行为和机制有显著的影响。在4m/s时，含氧的摩擦层(TiO和TiO2)具有明显的减磨性能；相反地，在2.68m/s时，没有氧化物的摩擦层并未显示出对磨损具有保护作用。与未经热浸镀处理的Ti-6Al-4V合金相比，在不同工况下，铝化后的涂层提高了钛合金的耐磨性，尤其速度为4m/s。耐磨性得到提高是由Ti-Al涂层和摩擦氧化物层所引起的。

Abstract:

An aluminized coating of TiAl3 was prepared on Ti-6Al-4V alloy by hot-dip aluminizing and subsequently high-temperature diffusion at 650 ℃. Dry sliding wear behavior was conducted for the aluminized Ti-6Al-4V alloy against GCr15 steel on a pin-on-disc wear tester. The morphology, phase and composition of worn surface of the HDA coatings were characterized by SEM, XRD, EDS and XPS. The wear mechanism was also explored. The research result demonstrated that with an increase of sliding velocity, the wear loss of the aluminized Ti-6Al-4V alloy decreased to a lower value at 0.75 m/s, then increased to the highest at 2.68 m/s and finally decreased to the lowest at 4 m/s. At different sliding velocities, the wear loss increased with an increase of load. Tribo-layers were identified to notably affect the wear behavior and mechanism. At 4 m/s, oxide-containing tribo-layers (TiO and TiO2) possessed an obvious wear-reduced function; conversely at 2.68 m/s, no-oxide ones did not show the protection from wear. Compared with uncoated Ti-6Al-4V alloy, the aluminized coating improved the wear resistance of the titanium alloy under various conditions, especially 4 m/s. The improved wear performance was suggested to be attributed to Ti-Al coating and tribo-oxide layer.