界面接触特性对两种自组装分子膜摩擦特性的影响

Effects of Interfacial Contact Characteristics on the Friction Properties of Ooctadecyltrichorosilane and 3-Aminopropyltrimethoxysilane Self-Assembled Monolayers

利用多功能微摩擦磨损试验机,在不同滑动速度和载荷条件下,采用不同摩擦副分析了界面接触特性对自组装分子膜摩擦特性的影响,同时采用Lennard-Jone势对铜和镍与三氯十八硅烷(OTS)和3-氨基丙基-三甲氧基硅烷(APS)自组装分子膜之间的相互作用进行了比较.结果表明,镍同OTS和APS对摩的摩擦系数均大于铜同2种自组装分子膜对摩的摩擦系数,这是因为镍与自组装分子膜间具有较强的相互作用所致.铜和镍与OTS对摩的摩擦系数随滑动速度的增加而增大,随载荷增加而减小;铜与APS对摩的摩擦系数随滑动速度的增加而减小,载荷对摩擦系数的影响则很小;而镍与APS对摩的摩擦系数随滑动速度增加而增大,随载荷增加而减小.可以用分子弛豫来解释2种自组装分子膜的摩擦特性差异.

The effects of interfacial contact characteristics on the friction properties of octadecyltrichorosilane (OTS) and 3-aminopropyltrimethoxysilane (APS) self-assembled monolayers (SAMs) were investigated on a universal micro-tribometer by sliding the SAMs against vacuum-deposited Cu or Ni coating at various sliding velocities and normal loads. At the same time, Lennard-Jone potential was used to compare the interaction between the Cu or Ni coating and the SAMs of OTS and APS. The results indicated that the friction coefficients of the Ni coating sliding against both the OTS and APS SAMs were larger than those of the Cu coating sliding the two SAMs under the same test conditions. This was attributed to the stronger interaction between the Ni coating and the two SAMs. The friction coefficients of the Cu and Ni coatings sliding against the OTS SAM increased with increasing sliding velocity and decreased with increasing load. Moreover, the Cu coating sliding against the APS SAM recorded a decreased friction coefficient with increasing sliding velocity, while the Ni coating sliding against the APS SAM had an increased friction coefficient with increasing sliding velocity but a reduced one with increasing load. The differences in the friction behaviors of the OTS and APS SAMs against the Cu and Ni coatings were related to the different relaxation behaviors of the SAMs and the different interactions among the SAMs and the metallic coatings as the counterparts.