ISSN   1004-0595

CN  62-1224/O4

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微织构F-DLC涂层表面润湿与摩擦学性能研究

Wettability and Tribological Performances of the Textured F-DLC Coating Surface

  • 摘要: 采用激光织构技术对304不锈钢表面进行微织构处理,并利用等离子体增强化学气相沉积(PECVD)工艺在其表面制备氟掺杂类金刚石(F-DLC)涂层,构建疏水表面,研究了微织构处理和F-DLC涂层对304不锈钢表面润湿性和摩擦学性能的影响. 结果表明:氟元素掺杂可以降低类金刚石碳(DLC)涂层的表面能,使得304不锈钢表面的静态水接触角由57°提高至107°,实现由亲水性表面到疏水性表面的转变;而在沉积涂层之前进行激光织构,激光织构的图案和织构过程中激光烧蚀形成的纳米小颗粒在沉积涂层后形成的团簇结构,使得接触角达到144°;通过设计不同微织构图案,可实现对涂层摩擦学性能的调控,其中以0.1 mm (间距)× 0.1 mm (直径)激光点阵处理的F-DLC织构涂层具有最优的摩擦学性能,圆孔型织构形成的凹坑可以储存摩擦磨损产生的磨屑,从而降低涂层的摩擦系数,使涂层的稳定摩擦系数仅为0.2. 因此,通过优化激光点阵结构进行微织构处理,结合氟掺杂DLC涂层技术,可以显著提高304不锈钢表面的疏水性能和摩擦学性能.

     

    Abstract: At low temperatures, the surface of the substrate is prone to freezing, resulting in losses. With the development of nanotechnology and biomimetic technology, hydrophobic surfaces are widely used in the field of surface frosting/ice protection. The hydrophobic surface can greatly inhibit the penetration and adhesion of liquid on the surface to achieve the effect of anti-icing, which is mainly affected by the surface micro-nano structure and low surface energy. At the same time, the durability of hydrophobic coatings in low-temperature and high-humidity environments is crucial. The construction of an integrated lubricating and hydrophobic coating on the substrate surface imparts excellent wetting and tribological properties to the substrate surface at the same time. The hydrophobic surface on 304 stainless steel was constructed by laser texture treatment combined with fluorine-doped diamond-like carbon (F-DLC) coating deposited by plasma enhanced chemical vapor deposition technology. The effects of micro-texture treatment and F-DLC coating on the wettability and tribological performances of the 304 stainless steel surface were investigated carefully. The results showed that fluorine doping could reduce the surface energy of diamond-like carbon (DLC) coating, resulting in the increase of the static water contact angle from 57° to 104° for the 304 stainless steel surface, which successfully realized the transition from hydrophilic surface to hydrophobic surface. The pattern of laser texture and the small particles formed by laser ablation during the process of laser texture contributed to the formation of a structure similar to cauliflower clusters after the deposition of the coating, which could further improve the hydrophobic performance of the surface. And thus, the static water contact angle could be raised to 144° resultantly. In this paper, two different types of texture patterns were selected, namely circular dot matrix pattern and grid pattern, and the arrangement spacing of the texture pattern and the laser texture process had an effect on the surface wettability. By depositing F-DLC coatings on the texture surface with different spacing and different texture processes, two texture patterns with the highest static water contact angles were selected in their respective types, namely 0.1 mm (spacing) ×0.1 mm (diameter) laser lattice and grid laser lattice with line spacing of 0.2 mm, and the static water contact angles reached 132° and 144°. The tribological properties of the F-doping DLC coatings could be tailored by designing different micro-weaving patterns. The F-DLC textured coating treated with 0.1 mm (spacing) ×0.1 mm (diameter) laser lattice had the best tribological properties with a stable friction coefficient of only 0.2. This was because the pits formed by the circular pass texture in this pattern could be used to store the abrasive debris generated during the friction process, reducing the friction coefficient of the coating as a result. However, even though the groove formed by the grid pattern texture with 0.2 mm spacing could also store the wear debris, the deposition of F-DLC surface textured by the 0.2 mm spacing pattern possessed a rough surface which is not so flat. And thus, the convex structure would affect the friction process, resulting in stress concentration, and the friction coefficient was slightly higher than that of the lattice pattern texture as a consequence. Therefore, the hydrophobic and tribological properties of the 304 stainless steel surface could be significantly improved by optimizing the laser lattice structure for micro-texture treatment combined with fluorine-doped DLC coating.

     

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