硅基超疏水微界面材料润湿特性和摩擦学性能研究
发布时间：2019-03-22 18:12
【摘要】：在微机械领域,尺度效应的存在使得材料表／界面特性成为决定微器件功能的关键因素。在微／纳米尺度上,相互接触或存在微间隙的表面间黏着效应显著,从而导致微观表面受到严重黏着磨损而失效。对材料表面进行加工和改性使其具有超疏水性能是改善固体表面力学性能和摩擦学性能的有效方式,在微／纳机电系统领域有重要的学术和工程价值。 本文建立亲水表面微观粗糙结构模型,基于Gibbs自由能法则,并考虑接触角滞后能的前提下,利用该模型从能量角度揭示了表面形貌对固体表面润湿性能的影响规律,归纳得到了液滴在亲水性粗糙表面稳定处于Cassie状态时,微观粗糙结构形貌特征、几何参数、分布特性的设计准则。 通过建立微／纳米尺度上平面-平面,球面-平面以及球面-球面间弯月面模型,基于Young-Laplace方程和Reynolds润滑理论,分析得到固体表面接触分离过程中弯月面力和黏着力的计算公式。在此基础上,计算得到接触表面分离过程中的弯月面形状变化规律,并分别讨论了固体表面分离距离、液滴初始弯月面高度、固体表面润湿性能、分离时间、断裂高度等因素对弯月面力和黏着力的影响。研究结果为微／纳米表面抗黏着机理提供了理论依据。 采用电感耦合等离子体刻蚀法,在单晶硅基底上加工微米级方柱阵列粗糙结构并修饰十八烷基三氯硅烷(octadecyltrichlorosilane, OTS)自组装分子膜,成功获得了性能稳定的超疏水表面。通过接触角与接触角滞后的测量,进一步分析表面微观粗糙结构特征参数以及自组装分子膜特性对表面润湿性能的影响规律。讨论了液滴在亲水性方柱阵列表面发生润湿状态转变的原因,得到了与理论预测一致性较好的实验结果。 基于表／界面科学理论和摩擦学原理,分析超疏水表面减摩、抗磨、抗黏着机理,综合探讨微观和宏观摩擦学性能,总结和归纳出微观粗糙结构和OTS自组装分子膜对减小摩擦并延长自组装分子膜寿命的协同效应,得到了OTS自组装分子膜在干摩擦条件下具有良好的减摩、抗磨性能的结论。
[Abstract]:In the field of micro-machineries, the existence of scale effect makes the material surface / interface characteristics become the key factor to determine the function of micro-devices. On the micro / nano scale, the adhesion effect between the surfaces in contact with each other or with micro gap is remarkable, which leads to the failure of the micro surface due to serious adhesion wear. It is an effective way to improve the mechanical and tribological properties of solid surface by processing and modifying the surface of materials with superhydrophobic properties. It is of great academic and engineering value in the field of micro / nano electromechanical systems. Based on the Gibbs free energy rule and taking into account the contact angle hysteresis energy, the influence of surface morphology on the wettability of solid surface is revealed from the energy point of view by using the model, which is based on the law of free energy of the hydrophilic surface and the hysteresis energy of contact angle. The design criteria for the morphology, geometric parameters and distribution characteristics of the micro-rough structure of the droplets on the hydrophilic rough surface stable in the Cassie state are obtained. Based on Young-Laplace equation and Reynolds lubrication theory, the models of plane-plane, spherical-plane and spherical-spherical meniscus on micro / nano-scale are established. The calculation formulas of meniscus force and adhesion in the process of solid surface contact separation are obtained. On the basis of this, the shape of the meniscus in the separation process of contact surface is calculated, and the separation distance of solid surface, the height of initial meniscus of liquid drop, the wettability of solid surface and the separation time are discussed respectively. The influence of fracture height on meniscus force and adhesion. The results provide a theoretical basis for the anti-adhesion mechanism of micro / nano surface. By means of inductively coupled plasma etching (ICP), the coarse structure of micron square column array and the modification of octadecyltrichlorosilane (octadecyltrichlorosilane, OTS) self-assembled molecular film on monocrystalline silicon substrates were fabricated. The superhydrophobic surface with stable performance was successfully obtained. By measuring the contact angle and the contact angle lag, the influence of the characteristic parameters of the surface microstructure and the self-assembled molecular film on the wettability of the surface is further analyzed. The reasons for the wettability transition of the droplets on the surface of the hydrophilic square column array are discussed, and the experimental results are in good agreement with the theoretical prediction. Based on the theory of surface / interface science and tribology, the mechanism of anti-friction, anti-wear and adhesion of super-hydrophobic surface is analyzed, and the micro-and macro-tribological properties are discussed comprehensively. The synergetic effects of microstructure and OTS self-assembled molecular film on reducing friction and prolonging the lifetime of self-assembled molecular film are summarized and summarized. It is concluded that OTS self-assembled molecular film has good anti-friction and anti-wear properties under dry friction condition.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH117
本文编号：2445806
[Abstract]:In the field of micro-machineries, the existence of scale effect makes the material surface / interface characteristics become the key factor to determine the function of micro-devices. On the micro / nano scale, the adhesion effect between the surfaces in contact with each other or with micro gap is remarkable, which leads to the failure of the micro surface due to serious adhesion wear. It is an effective way to improve the mechanical and tribological properties of solid surface by processing and modifying the surface of materials with superhydrophobic properties. It is of great academic and engineering value in the field of micro / nano electromechanical systems. Based on the Gibbs free energy rule and taking into account the contact angle hysteresis energy, the influence of surface morphology on the wettability of solid surface is revealed from the energy point of view by using the model, which is based on the law of free energy of the hydrophilic surface and the hysteresis energy of contact angle. The design criteria for the morphology, geometric parameters and distribution characteristics of the micro-rough structure of the droplets on the hydrophilic rough surface stable in the Cassie state are obtained. Based on Young-Laplace equation and Reynolds lubrication theory, the models of plane-plane, spherical-plane and spherical-spherical meniscus on micro / nano-scale are established. The calculation formulas of meniscus force and adhesion in the process of solid surface contact separation are obtained. On the basis of this, the shape of the meniscus in the separation process of contact surface is calculated, and the separation distance of solid surface, the height of initial meniscus of liquid drop, the wettability of solid surface and the separation time are discussed respectively. The influence of fracture height on meniscus force and adhesion. The results provide a theoretical basis for the anti-adhesion mechanism of micro / nano surface. By means of inductively coupled plasma etching (ICP), the coarse structure of micron square column array and the modification of octadecyltrichlorosilane (octadecyltrichlorosilane, OTS) self-assembled molecular film on monocrystalline silicon substrates were fabricated. The superhydrophobic surface with stable performance was successfully obtained. By measuring the contact angle and the contact angle lag, the influence of the characteristic parameters of the surface microstructure and the self-assembled molecular film on the wettability of the surface is further analyzed. The reasons for the wettability transition of the droplets on the surface of the hydrophilic square column array are discussed, and the experimental results are in good agreement with the theoretical prediction. Based on the theory of surface / interface science and tribology, the mechanism of anti-friction, anti-wear and adhesion of super-hydrophobic surface is analyzed, and the micro-and macro-tribological properties are discussed comprehensively. The synergetic effects of microstructure and OTS self-assembled molecular film on reducing friction and prolonging the lifetime of self-assembled molecular film are summarized and summarized. It is concluded that OTS self-assembled molecular film has good anti-friction and anti-wear properties under dry friction condition.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH117
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