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混合自组装膜共吸附法的制备及其微摩擦学性能研究

发布时间:2018-05-31 19:06

  本文选题:混合自组装膜 + 分子模拟 ; 参考:《中国矿业大学》2015年硕士论文


【摘要】:随着自组装膜(SAMs)技术在MEMS器件润滑方面研究的不断深入,有机硅烷类SAMs特别是由两种及两种以上硅烷分子制备的混合SAMs以其特有的减摩性能得到了研究人员的广泛关注。本文对3-氨基丙基三乙氧基(APS)和十二烷基三甲氧基(WD-10)两种硅烷分子混合自组装膜的制备工艺及其微摩擦学性能进行了研究。为了获得混合自组装膜制备过程中最佳的组装工艺,利用Materials Studio(MS)软件,分别建立Si(1 0 0)基底、APS和WD-10的分子模型,并基于硅烷分子在基底表面的覆盖率,建立了包含SAMs层和硅片基底层的分子体系模型。同时,对创建的分子体系模型进行分子动力学模拟,探究了不同组装温度和分子浓度比等制备工艺对混合自组装膜性能的影响,为混合自组装膜的制备实验提供理论依据。基于MS软件模拟结果,在利用共吸附法自组装技术制备APS和WD-10混合分子膜的过程中,充分考虑组装温度、分子浓度比以及组装时间、溶液的PH值等制备环境对其性能的影响,制定了正交试验表制备出相应的混合自组装膜。利用X射线光电子能谱仪(XPS)与原子力显微镜(AFM)分别对制备好的混合自组装膜和原始硅片表面的化学组成元素与表面形貌进行表征分析,通过结果对比,获得混合自组装膜制备过程中的最好组装条件,确定最佳的制备工艺。通过对混合自组装膜共吸附法的制备过程进行热力学计算,得出硅烷分子能够自发的吸附在硅片基底表面;利用微分变化和Maxwell关系式,推导出混合分子膜表面能的计算公式,发现薄膜表面能的降低有助于硅烷分子在基底组装反应的自发进行。同时,对共吸附法制备过程中环境因素影响硅烷分子在基底表面的组装机理进行了研究。最后,利用摩擦磨损试验机(UMT)对三种不同浓度比混合分子膜进行宏观摩擦实验,探究了SAMs技术的减摩润滑情况。同时,利用MEMS微摩擦试验机对混合分子膜的微观摩擦学性能进行了测试,分析了微摩擦过程中的摩擦机理,并对不同浓度比混合分子膜与原始硅片的摩擦系数与相对滑动速度之间的关系进行了测量,探讨了不同载荷对混合自组装膜摩擦系数的影响。
[Abstract]:With the development of self-assembled monolayer (SAMs) technology in the lubrication of MEMS devices, the hybrid SAMs prepared by two or more kinds of silane molecules has been paid more and more attention by researchers because of its unique antifriction properties. In this paper, the preparation and tribological properties of two kinds of silane molecular mixed self-assembly films, 3-aminopropyl triethoxy (APS) and dodecyl trimethoxy (WD-10), have been studied. In order to obtain the best assembly process during the preparation of hybrid self-assembled films, the molecular models of Si(1 _ (00) substrates and WD-10 were established by using Materials Studio MS software, respectively, and based on the coverage of silane molecules on the substrate surface. A molecular system model including SAMs layer and silicon substrate was established. At the same time, the molecular dynamics simulation of the molecular system model was carried out, and the effects of different preparation processes such as assembly temperature and molecular concentration ratio on the properties of the hybrid self-assembled films were investigated, which provided the theoretical basis for the preparation of the hybrid self-assembled films. Based on the simulation results of MS software, in the process of preparing APS and WD-10 mixed molecular membranes by co-adsorption self-assembly technology, the effects of assembly temperature, molecular concentration ratio and assembly time, PH value of solution on the properties of the films were considered. The orthogonal test table was established to prepare the corresponding mixed self-assembly films. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize and analyze the chemical composition and surface morphology of the mixed self-assembled films and the original silicon wafers, respectively. The best assembly conditions were obtained and the optimal preparation process was determined. Based on the thermodynamic calculation of the preparation process of the mixed self-assembled membrane, it is concluded that the silane molecules can spontaneously adsorb on the surface of the silicon substrate, and the formula for calculating the surface energy of the mixed molecular membrane is derived by using the differential variation and the Maxwell relation. It is found that the decrease of the surface energy of the films is helpful to the spontaneous assembly of silane molecules on the substrate. At the same time, the effect of environmental factors on the assembly mechanism of silane on the substrate surface was studied. Finally, three kinds of mixed molecular films with different concentration were tested by using friction and wear tester, and the antifriction lubrication of SAMs technology was investigated. At the same time, the micro-tribological properties of the mixed molecular films were tested by MEMS micro-friction tester, and the friction mechanism in the process of micro-friction was analyzed. The relationship between friction coefficient and relative sliding velocity of mixed molecular film and original silicon wafer with different concentration ratio was measured and the influence of different loads on friction coefficient of hybrid self-assembled film was discussed.
【学位授予单位】:中国矿业大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:TB383.2

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