Richardson A D, Evans M-H, Wang L, Wood R J K, Ingram M
1nCATS, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.
Afton Chemical Corporation, Bracknell, UK.
Tribol Lett. 2018;66(1):4. doi: 10.1007/s11249-017-0947-0. Epub 2017 Nov 25.
Hydrogen diffusion during rolling contact fatigue (RCF) is considered a potential root cause or accelerator of white etching cracks (WECs) in wind turbine gearbox bearing steels. Hydrogen entry into the bearing steel during operation is thought to occur either through the contact surface itself or through cracks that breach the contact surface, in both cases by the decomposition of lubricant through catalytic reactions and/or tribochemical reactions of water. Thermal desorption analysis (TDA) using two experimental set-ups has been used to measure the hydrogen concentration in non-hydrogen-charged bearings over increasing RCF test durations for the first time. TDA on both instruments revealed that hydrogen diffused into the rolling elements, increasing concentrations being measured for longer test durations, with numerous WECs having formed. On the other hand, across all test durations, negligible concentrations of hydrogen were measured in the raceways, and correspondingly no WECs formed. Evidence for a relationship between hydrogen concentration and either the formation or the acceleration of WECs is shown in the rollers, as WECs increased in number and severity with increasing test duration. It is assumed that hydrogen diffusion occurred at wear-induced nascent surfaces or areas of heterogeneous/patchy tribofilm, since most WECs did not breach the contact surface, and those that did only had very small crack volumes for entry of lubricant to have occurred.
滚动接触疲劳（RCF）过程中的氢扩散被认为是风力涡轮机齿轮箱轴承钢中白色蚀刻裂纹（WECs）的潜在根本原因或加速因素。运行期间氢进入轴承钢被认为是通过接触面本身或通过穿透接触面的裂纹发生的，在这两种情况下都是通过润滑剂通过水的催化反应和/或摩擦化学反应分解而实现的。首次使用两种实验装置的热脱附分析（TDA）来测量未充氢轴承在增加的RCF试验持续时间内的氢浓度。两台仪器上的TDA均显示氢扩散到滚动体中，试验持续时间越长测量到的浓度越高，同时形成了大量的WECs。另一方面，在所有试验持续时间内，滚道中测量到的氢浓度可忽略不计，相应地也没有形成WECs。在滚子中显示了氢浓度与WECs形成或加速之间关系的证据，因为随着试验持续时间的增加，WECs的数量和严重程度都增加了。假设氢扩散发生在磨损诱导的新生表面或异质/片状摩擦膜区域，因为大多数WECs没有穿透接触面，而那些穿透的WECs裂纹体积非常小，以至于润滑剂无法进入。
