【摘要】：在微機(jī)械領(lǐng)域,尺度效應(yīng)的存在使得材料表／界面特性成為決定微器件功能的關(guān)鍵因素。在微／納米尺度上,相互接觸或存在微間隙的表面間黏著效應(yīng)顯著,從而導(dǎo)致微觀表面受到嚴(yán)重黏著磨損而失效。對(duì)材料表面進(jìn)行加工和改性使其具有超疏水性能是改善固體表面力學(xué)性能和摩擦學(xué)性能的有效方式,在微／納機(jī)電系統(tǒng)領(lǐng)域有重要的學(xué)術(shù)和工程價(jià)值。 本文建立親水表面微觀粗糙結(jié)構(gòu)模型,基于Gibbs自由能法則,并考慮接觸角滯后能的前提下,利用該模型從能量角度揭示了表面形貌對(duì)固體表面潤濕性能的影響規(guī)律,歸納得到了液滴在親水性粗糙表面穩(wěn)定處于Cassie狀態(tài)時(shí),微觀粗糙結(jié)構(gòu)形貌特征、幾何參數(shù)、分布特性的設(shè)計(jì)準(zhǔn)則。 通過建立微／納米尺度上平面-平面,球面-平面以及球面-球面間彎月面模型,基于Young-Laplace方程和Reynolds潤滑理論,分析得到固體表面接觸分離過程中彎月面力和黏著力的計(jì)算公式。在此基礎(chǔ)上,計(jì)算得到接觸表面分離過程中的彎月面形狀變化規(guī)律,并分別討論了固體表面分離距離、液滴初始彎月面高度、固體表面潤濕性能、分離時(shí)間、斷裂高度等因素對(duì)彎月面力和黏著力的影響。研究結(jié)果為微／納米表面抗黏著機(jī)理提供了理論依據(jù)。 采用電感耦合等離子體刻蝕法,在單晶硅基底上加工微米級(jí)方柱陣列粗糙結(jié)構(gòu)并修飾十八烷基三氯硅烷(octadecyltrichlorosilane, OTS)自組裝分子膜,成功獲得了性能穩(wěn)定的超疏水表面。通過接觸角與接觸角滯后的測(cè)量,進(jìn)一步分析表面微觀粗糙結(jié)構(gòu)特征參數(shù)以及自組裝分子膜特性對(duì)表面潤濕性能的影響規(guī)律。討論了液滴在親水性方柱陣列表面發(fā)生潤濕狀態(tài)轉(zhuǎn)變的原因,得到了與理論預(yù)測(cè)一致性較好的實(shí)驗(yàn)結(jié)果。 基于表／界面科學(xué)理論和摩擦學(xué)原理,分析超疏水表面減摩、抗磨、抗黏著機(jī)理,綜合探討微觀和宏觀摩擦學(xué)性能,總結(jié)和歸納出微觀粗糙結(jié)構(gòu)和OTS自組裝分子膜對(duì)減小摩擦并延長自組裝分子膜壽命的協(xié)同效應(yīng),得到了OTS自組裝分子膜在干摩擦條件下具有良好的減摩、抗磨性能的結(jié)論。
[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.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TH117

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