Development of super-tribological duplex coatings due to 3-dimensional femtosecond-laser processing

(1)飞秒激光诱导的纳米结构上形成的TiN和DLC的硬薄膜的TiN和DLC的摩擦学硬涂层被照射800-和267-nm，飞秒（fs）激光脉冲在空气中的能量通量略高于烧蚀阈值。在烧蚀的薄膜表面上，线偏振fs脉冲产生几乎与激光偏振方向垂直的精细周期结构阵列，而圆偏振光形成精细的点结构。这些表面结构的尺寸是激光波长的1/10 ~ 1/5，并且随着激光波长的减小而减小。此外，这些结构的大小随着注量的增加而增加。结果表明，飞秒激光的偏振态、波长和能量密度可以精确控制表面形貌。(2)DLC-MoS_2复合薄膜的研制及微槽对摩擦学性能的影响在DLC薄膜上，利用机械方法在球盘摩擦试验机的滑动轨迹中心形成微槽，然后用溅射法沉积一层厚度约为3 μm的MoS_2固体润滑膜。由于微槽的存在，使摩擦系数从0.16降低到0.09。这些结果表明，微槽作为MoS_2润滑剂的水库。应采用飞秒激光加工，以形成更细的微槽。(3)飞秒激光诱导纳米结构对DLC膜摩擦学性能的影响我们利用飞秒激光脉冲在DLC膜上形成了纳米结构区域（10 mm × 10 mm）。结果表明，纳米结构的类金刚石表面对轴承钢球表现出改善的摩擦学性能。

(1) Femtosecond-laser-induced nanostructure formed on hard thin films of TiN and DLCTribological hard coatings of TiN and DLC were irradiated by 800- and 267-nm, femtosecond (fs) laser pulses in air at an energy fluence slightly above the ablation threshold. On the ablated thin-film surfaces, the linearly-polarized fs pulses produce arrays of fine periodic structures that are almost oriented to the direction perpendicular to the laser polarization, while the circularly-polarized light forms fine dot structures. The size of these surface structures is 1/10 〜 1/5 of the laser wavelength and decreases with a decrease in the laser wavelength. Furthermore, the size of these structures increased with an increase in the fluence. The results suggest that the surface morphology can be controlled precisely with the fs-laser polarization and wavelength and fluence.(2) Development of DLC-MoS_2 duplex thin films and the influence of micro grooves against the tribological propertyMicro-sized grooves were mechanically created in the center of the sliding path of a ball-on-disk friction testing machine on a DLC coating and then deposited with a solid lubricant film of MoS_2 with a thickness of about 3 μm utilizing a sputtering method. The friction coefficient was lowered from 0.16 to 0.09 due to the micro-grooves against the bearing steel ball. These results suggest that the micro-grooves act as MoS_2 lubricant reservoirs. The fs-laser processing should be applied to create the more fine micro-grooves.(3) The influence of femtosecond-laser-induced nanostructure against the tribological propertyWe developed the technique to create a nanostructured area (10mm X 10mm) on a DLC film utilizing the fs-laser pulses. It was found that the nanostructured DLC surface showed the improved tribological properties against the bearing steel ball.