The authors report on surface modification by laser-induced periodic surface structures of different periodicities and modulation depths to modify dry and lubricated tribological properties. Using 220 fs laser pulses in the infrared ( λ 1 = 1030 nm), visible ( λ 2 = 515 nm), and ultraviolet ( λ 3 = 343 nm) spectral regions, the authors periodically structure two-dimensional areas with periodicities in the range between 300 and 950 nm and modulation depths between 30 and 180 nm, respectively. The coefficient of friction is measured by performing a linear reciprocating ball-on-disk test with polytetrafluoroethylene balls on such structured 100Cr6 bearing steel. This configuration reveals a modified friction behavior using load forces between 50 and 1000 mN and a translation speed of 4 mm/s. In general, the results show an increased coefficient of friction in the presence of the applied periodic structures. In particular, in the case of dry environmental conditions, laser-induced periodic surface structures with an increasing spatial period lead to an increase in the coefficient of friction. In addition, for a sliding direction perpendicular to the alignment of the periodic structures, a higher coefficient of friction is found in comparison to a parallel movement. While in the case of lubricated friction, an increased coefficient of friction is also found; yet, it reveals a less pronounced dependency of the sliding direction as compared to dry conditions. For lubricated linear reciprocating movements, the coefficient of friction decreases under increasing load forces, which results in a load depended friction reduction.

中文翻译：

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激光波长对飞秒激光诱导周期性表面结构改性100Cr6钢与聚四氟乙烯摩擦的影响

作者报告了通过激光诱导的不同周期和调制深度的周期性表面结构进行表面改性，以改变干燥和润滑的摩擦学特性。使用红外 ( λ 1 = 1030 nm)、可见光 ( λ 2 = 515 nm) 和紫外 ( λ 3 = 343 nm) 光谱区域中的 220 fs 激光脉冲，作者周期性地构建具有周期性的二维区域300 到 950 nm 之间，调制深度分别在 30 到 180 nm 之间。摩擦系数是通过使用聚四氟乙烯球在这种结构化的 100Cr6 轴承钢上进行线性往复式球盘试验来测量的。这种配置揭示了使用 50 到 1000 mN 之间的负载力和 4 mm/s 的平移速度的改进摩擦行为。一般来说，结果表明，在应用周期性结构的情况下，摩擦系数增加。特别是在干燥的环境条件下，随着空间周期的增加，激光诱导的周期性表面结构会导致摩擦系数的增加。此外，对于垂直于周期性结构排列的滑动方向，与平行运动相比，发现更高的摩擦系数。而在润滑摩擦的情况下，也发现摩擦系数增加；然而，与干燥条件相比，它揭示了滑动方向的不太明显的依赖性。对于润滑的线性往复运动，摩擦系数随着负载力的增加而降低，这导致负载依赖的摩擦减少。