The reduction of frictional power losses in power transmitting gears takes a crucial role in the design of energy- and resource-efficient drivetrains. Water-containing lubricants like glycerol and polyalkylene glycols have shown great potential in achieving friction within the superlubricity regime with coefficients of friction lower than 0.01 under elastohydrodynamic lubrication. Additionally, a bio-based production of the base stocks can lead to the development of green lubricants. However, one challenge associated with the application of water-containing lubricants to gearboxes is the evaporation of water and its impact on the lubricant properties. In this study, the influence of water evaporation on elastohydrodynamic friction and film thickness was investigated for three water-containing polyalkylene glycols. Two nominal water contents of 20 wt% and 40 wt% and two viscosities were considered. The results show that the friction increases continuously with higher evaporated water content, while the overall friction level remains low in nearly water-free states. A similar trend is observed for film thickness, where the strong increase in viscosity results in a notable increase in film thickness. Nevertheless, the sensitivity of friction and film thickness to water evaporation is low for small amounts of evaporated water. This allows generous thresholds for permissible variations in water content.

减少动力传输齿轮中的摩擦功率损失在能源和资源高效型传动系统的设计中起着至关重要的作用。甘油和聚亚烷基二醇等含水润滑剂在超润滑状态下实现摩擦方面显示出巨大的潜力，在弹流润滑下摩擦系数低于 0.01。此外，基础油的生物基生产可以促进绿色润滑油的开发。然而，与将含水润滑剂应用于齿轮箱相关的一项挑战是水的蒸发及其对润滑剂性能的影响。在本研究中，研究了水蒸发对三种含水聚亚烷基二醇的弹性流体动力摩擦和膜厚度的影响。考虑了 20 wt% 和 40 wt% 的两种标称水含量以及两种粘度。结果表明，随着蒸发水含量的增加，摩擦力不断增加，而在接近无水状态下，总体摩擦力水平仍然较低。薄膜厚度也观察到类似的趋势，其中粘度的强烈增加导致薄膜厚度显着增加。然而，对于少量蒸发的水，摩擦力和膜厚度对水蒸发的敏感性较低。这为水含量的允许变化提供了很大的阈值。