Fluorine and sulfur co-doped amorphous carbon films to achieve ultra-low friction under high vacuum
Fluorine and sulfur co-doped amorphous carbon films to achieve ultra-low friction under high vacuum
复制标题
DOI：
10.1016/j.carbon.2015.09.084
复制
发表时间：
2016
期刊：
影响因子：
10.9
通讯作者：
F. Wang;Liping Wang;Q. Xue
中科院分区：
文献类型：
--
作者：
F. Wang;Liping Wang;Q. Xue
采用C2 H2和SF6混合等离子体制备了氟硫共掺杂非晶碳（a-C：S：F）薄膜，并对薄膜中S和F的成键状态进行了研究。a-C：S：F薄膜比氢化薄膜具有更有序的碳结构。在高真空条件下测试了薄膜与GCr 15轴承钢球的摩擦性能。当a-C：S：F含量为2.0at.%时，薄膜的稳态摩擦系数为0.01 ~ 0.02 H，取决于膜中S和F的浓度。球表面上的石墨状转移层提供了由-CF 2-和-CF 3基团封端的低粘附性滑动表面。F-终止的转移层与S-和F-终止的碳结构之间的静电排斥相互作用可能是超低摩擦行为的原因。有趣的是，sp2-C簇含有噻吩-S（-C-S-C-）结构的薄膜可能有助于低摩擦时，对高氟化表面滑动。这些结果表明，通过硫、氟共掺杂可以实现a-C薄膜在真空中的润滑性能，这对开发a-C薄膜作为真空润滑剂具有重要意义。
Fluorine and sulfur co-doped amorphous carbon (a-C:S:F) films were synthesized from C2H2and SF6plasma mixture, and the bonding states of S and F in films were scrutinized. The a-C:S:F films exhibited a more ordered carbon structure than hydrogenated films. The friction behavior of films was tested against GCr15 bearing steel balls under high vacuum (HV) conditions. Ultra-low steady-state friction coefficient (0.01–0.02) was achieved for a-C:S:F films containing about 2.0 at.% H, depending on the concentrations of S and F in films. Graphite-like transfer layer on the ball surface provided a low-adhesive sliding surface terminated by –CF2- and –CF3groups. The electrostatic repulsive interaction between the F-terminated transfer layer and the S- and F-terminated carbon structure was probably responsible for the ultra-low friction behavior. Intriguingly, the sp2-C clusters containing ‘thiophene-S’ (–C–S–C–) structure in films might contribute to the low friction when sliding against an highly fluorinated surface. These results demonstrate that the lubricating properties of a-C films in vacuum can be achieved through the S and F co-doping, which is of great significance for developing a-C films as vacuum lubricants.