TA15钛合金高温摩擦磨损性能研究

Tribological Properties of TA15 Titanium Alloy at Different High Temperatures

目的 为探究TA15钛合金高温耐磨性能的潜力,研究了TA15钛合金在室温~800℃下的摩擦磨损性能。方法 利用Rtec摩擦磨损试验机(Rtec,San Jose,USA)进行TA15钛合金的摩擦磨损性能测试,通过激光共聚焦显微镜、JSM-7800F扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)等手段,分析了TA15钛合金在不同温度下的磨痕形貌、成分变化以及磨损机理。结果 在不同试验温度下,微观组织没有出现明显变化,主要为等轴α相和β相;不同温度下的摩擦因数波动不大,从室温的0.279下降到600℃的0.224,而在800℃时,表面严重氧化导致摩擦因数增大到0.309;在室温~400℃时,试样表面磨痕不断变窄变浅,犁沟和磨屑不断减少,而到400℃以上时磨痕逐渐变宽,比磨损率也大幅增大,且在600℃时的磨损量最大;在600℃时,以氧化磨损为主,并伴随着磨粒磨损和黏着磨损,且表面磨痕形貌和宽度比较均匀;在800℃时磨损表面以黏着磨损和氧化磨损为主,并伴随着高温焊接的发生。结论 TA15合金表面的O元素含量随温度的升高而逐渐升高,并且氧化反应主要发生在β相内。随着试验温度的升高,TA15钛合金磨损表面的氧化磨损现象也更加明显。

To investigate the high-temperature wear resistance potential of the TA15 titanium alloy,its tribological properties were studied at various temperatures,ranging from room temperature to 800 ℃.The Rtec Universal Tribometer(Rtec,San Jose,USA) equipped with a high-temperature furnace capable of reaching 1 000 ℃,with a heating rate of 100 ℃/min,was used to conduct friction and wear property tests on the TA15 titanium alloy.The impact of temperature on the friction coefficient and wear rate was analyzed.The wear morphology,composition changes,and wear mechanism of the TA15 titanium alloy at different temperatures were analyzed with a laser confocal microscope,a JSM-7800F scanning electron microscope(SEM),energy dispersive spectrum(EDS),and X-ray diffraction(XRD).The study showed that there were no significant changes in the microstructure at different test temperatures,and the microstructure was primarily composed of equiaxed α and β phases.As the test temperature increased,the O element content on the surface of the TA15 titanium alloy continuously increased,and the oxidation wear phenomenon on the wear surface became more apparent.The wear width varied significantly at 200 ℃ and 400 ℃,owing to the small average width and depth at these temperatures.Although the wear width error was the smallest at 600 ℃,the wear depth error was the highest due to too deep partial scratches,indicating that abrasive wear was the primary factor.At 800 ℃,the specimen was extruded and deformed,resulting in a significantly increased wear width(about 2 300 μm).Furthermore,increased adhesive wear caused noticeable local tearing.At temperatures below the service temperature of 500 ℃,wear losses only slightly varied from 0.005 1 g to 0.004 3 g.However,at 600 ℃,the wear loss abruptly increased to 0.019 1 g,which was mainly due to TA15's excellent plasticity at that temperature.Additionally,the high temperature microhardness affected the wear loss and mechanism.Unexpectedly,at a test temperature of 800 ℃,the total mass increased by 0.019 4 g due to the softened TA15's compaction and obvious adhesive wear.The wear mechanism of TA15 at room temperature was primarily abrasive wear.At 200 ℃ and 400 ℃,the wear was mainly stripping wear and adhesive wear,accompanied by minor abrasive wear and oxidation wear.At 600 ℃,the wear was primarily oxidized,accompanied by abrasive wear and adhesive wear,with uniform surface wear morphology and width.At 800 ℃,the wear surface was mainly affected by adhesive wear and oxidation wear,accompanied by high temperature welding.At high temperatures,TA15's surface wear is mainly influenced by high temperature softening and surface oxidation.Worn surfaces are distributed with various particles of different morphologies,with Ti as the main element and N element detected at various spots,indicating that grinding ball particles are embedded in the substrate regardless of test temperature.Owing to Ti's high chemical activity,oxidation is inevitable,and the content of O element increases gradually with the rise in test temperature.