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

(1)用飞秒激光在空气中以略高于烧蚀阈值的能量，分别用800 nm和267 nm飞秒激光脉冲照射TiN和DLC的摩擦硬膜，形成飞秒激光诱导的纳米结构。在烧蚀的薄膜表面，线偏振的fs脉冲产生了几乎垂直于激光偏振方向的精细周期结构阵列，而圆偏振光形成了精细的点结构。这些表面结构的尺寸为激光波长的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影响的增加而增加。结果表明，激光的偏振、波长和通量可以精确地控制表面形貌。(2) DLC-MoS_2双相薄膜的制备及微沟槽对DLC涂层摩擦学性能的影响。在球盘式摩擦试验机的滑动路径中心机械地形成微沟槽，然后用溅射法在DLC涂层上沉积厚度约为3 μm的MoS_2固体润滑膜。由于微沟槽与轴承钢球的摩擦，摩擦系数从0.16降低到0.09。这些结果表明，微槽具有MoS_2润滑储层的作用。为了制造出更精细的微沟槽，应采用光纤激光加工。(3)飞秒激光诱导纳米结构对摩擦学性能的影响我们开发了利用fs激光脉冲在DLC薄膜上创建纳米结构区域（10mm X 10mm）的技术。结果表明，纳米结构DLC表面对轴承钢球的摩擦学性能有明显改善。

(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.