【摘要】：石墨烯擁有獨(dú)特的二維晶體結(jié)構(gòu),同時兼具力、電、光、熱等諸多優(yōu)異的物理特性,因此在納米復(fù)合材料、柔性電子器件、微納機(jī)電系統(tǒng)等領(lǐng)域展現(xiàn)出廣闊的應(yīng)用前景。傳統(tǒng)理論指出,材料、器件的宏觀功能表現(xiàn)很大程度上依賴其界面的結(jié)合力和穩(wěn)定性。而當(dāng)材料尺寸降至納米尺度后,原本微弱的非經(jīng)典力作用(如范德華力、靜電力等)變得更加不可忽略,甚至在變形行為中占據(jù)主導(dǎo)地位,使得界面力學(xué)問題更加顯著。另一方面,石墨烯由于具有原子級的厚度以及超高的比表面積,相比于傳統(tǒng)材料將引入更多界面相面積,對界面作用力也更加敏感,因此石墨烯也是研究納米尺度界面摩擦和粘附特性的一個理想選擇。本文發(fā)展了一個多尺度的實驗檢測平臺,即宏觀上實施可控的變形加載,細(xì)觀上觀測顯微形貌的演化,微觀上測量材料局部的應(yīng)變響應(yīng),進(jìn)而針對石墨烯與不同材料基底的界面力學(xué)性能和行為展開了相關(guān)研究,具體研究內(nèi)容如下:1、研究了單層石墨烯/聚甲基丙烯酸甲酯材料體系在軸向拉伸變形過程中的微觀界面力學(xué)行為。利用拉曼光譜記錄石墨烯在不同應(yīng)變下的力學(xué)響應(yīng),結(jié)合非線性剪滯模型分析彈性變形和剪切滑移兩個階段的應(yīng)力傳遞,獲取界面剪切強(qiáng)度、界面剛度等關(guān)鍵力學(xué)參數(shù)。在此基礎(chǔ)上,探討了多次循環(huán)加載條件下界面穩(wěn)定性,并利用原子力顯微鏡表征變形過程中表面形貌的演化,分析界面性能改變的微觀機(jī)制。進(jìn)一步,通過化學(xué)修飾的方法改變石墨烯與基體的鍵合作用類型,修正非線性剪滯模型指導(dǎo)界面力學(xué)性能的微觀調(diào)控,最終尋求界面的優(yōu)化設(shè)計。2、研究了聚甲基丙烯酸甲酯/石墨烯/聚甲基丙烯酸甲酯“三明治”結(jié)構(gòu)體系在雙向壓縮變形過程中的微觀界面力學(xué)行為。利用拉曼光譜探測石墨烯在不同應(yīng)變下的力學(xué)響應(yīng),揭示其微觀變形演化的三個階段,即彈性壓縮變形階段,歐拉屈曲變形階段以及界面局部脫粘階段。在彈性壓縮變形階段,結(jié)合宏觀力學(xué)載荷和微觀局部應(yīng)變,推算石墨烯的表觀壓縮模量。在歐拉屈曲變形階段,分析尺寸和層數(shù)對臨界屈曲應(yīng)變的影響,并探究其在多次循環(huán)加載條件下的界面穩(wěn)定性。對于界面局部脫粘階段,利用拉曼光譜表征界面的失效模式,建立力學(xué)模型描述其微觀力學(xué)行為,提取臨界脫粘應(yīng)變等力學(xué)參數(shù)。3、研究了鼓泡變形過程中單層石墨烯與硅基底的界面力學(xué)性能。發(fā)展了基于微孔鼓泡-探針技術(shù)-拉曼光譜聯(lián)用的力學(xué)檢測平臺,其中利用原子力顯微鏡表征孔內(nèi)石墨烯的離面位移,采用拉曼光譜監(jiān)測孔外界面剪切作用區(qū)域的可控擴(kuò)展。在Hencky解的基礎(chǔ)上,考慮孔外界面的剪切變形,修正了邊界條件,建立力學(xué)模型解析石墨烯與硅基底之間的界面剪切應(yīng)力。同時,通過調(diào)控壓力載荷使界面產(chǎn)生脫粘,結(jié)合理想氣體狀態(tài)方程和能量分析,推算其界面粘附能。利用原子力顯微鏡觀測鼓泡脫粘后的形貌演化,揭示界面剪切滑移變形與邊界條件對脫粘行為以及鼓泡形貌的影響。4、研究了多層石墨烯層間界面力學(xué)性能的測量與調(diào)控�；谏鲜隽W(xué)檢測平臺,我們對雙層石墨烯實施可控加載,并監(jiān)測孔外石墨烯層間剪切作用區(qū)域的擴(kuò)展。結(jié)合修正的Hencky理論,首次實現(xiàn)雙層石墨烯層間剪切應(yīng)力的精確測量。利用超低波數(shù)拉曼光譜探測多層石墨烯的剪切振動模,結(jié)合線性鏈模型擬合獲得層間剪切力常數(shù),并推算層間剪切模量。進(jìn)一步通過對石墨烯硼摻雜處理實現(xiàn)石墨烯層間距及層間耦合作用的有效調(diào)控,探究其對雙層石墨烯在納米壓痕試驗中力學(xué)行為的影響。
[Abstract]:Graphene has a unique two-dimensional crystal structure, and has many excellent physical properties such as force, electricity, light, heat and the like, and therefore, the graphene has a wide application prospect in the fields of nano-composite materials, flexible electronic devices and micro-nano-electromechanical systems. The traditional theory indicates that the macroscopic function of the material and the device depends largely on the binding force and the stability of its interface. When the size of the material drops to the nanometer scale, the original weak non-classical force (such as van der Waals force, electrostatic force, etc.) becomes more and more important, even in the deformation behavior, so that the interfacial mechanics problem becomes more remarkable. On the other hand, because of the thickness of atomic layer and superhigh specific surface area, graphene is more sensitive to interface force than traditional materials, so graphene is an ideal choice for studying the friction and adhesion characteristics of nano-scale interface. In this paper, a multi-scale experimental detection platform is developed, which is to implement controllable deformation loading on a macroscopic scale, observe the evolution of micro-topography on the micro-scale, and measure the local strain response of the material on the micro-scale. The mechanical properties and behavior of the interface between graphene and different materials are studied in this paper. The specific research contents are as follows: 1. The micro-interface mechanical behavior of single-layer graphene/ polymethyl methacrylate material system in axial tensile deformation is studied. The mechanical response of graphene under different strains is recorded by Raman spectroscopy, and the critical mechanical parameters such as interface shear strength, interface stiffness and the like are obtained by combining the nonlinear shear lag model to analyze the stress transfer at two stages of elastic deformation and shear slip. On this basis, the interfacial stability under multiple cyclic loading conditions is discussed, and the evolution of surface morphology during deformation process is characterized by atomic force microscopy, and the micro-mechanism of interface performance change is analyzed. Further, the type of bond cooperation between graphene and matrix is changed by chemical modification, the micro-regulation of mechanical properties of the interface is modified by modifying the nonlinear shear lag model, and the optimization design of the interface is finally sought. "Sandwich" The micro-interface mechanical behavior of the structural system in the two-way compression deformation process. The mechanical response of graphene under different strains is detected by Raman spectroscopy, and the three stages of micro-deformation evolution are revealed, namely, elastic compression deformation stage, Euler buckling deformation stage and interface local debonding stage. In the elastic compression deformation stage, the apparent compressive modulus of graphene is calculated by combining macroscopic mechanical load and micro local strain. In Euler buckling deformation stage, the influence of size and number of layers on critical buckling strain is analyzed, and the interfacial stability under multiple cyclic loading conditions is investigated. In this paper, the failure mode of the interface is characterized by Raman spectrum, the mechanical model is established to describe the micro-mechanical behavior of the interface, and the mechanical parameters such as critical desorption strain are extracted. The mechanical properties of the single layer graphene and the silicon substrate during the deformation of the drum are studied. A mechanical detection platform based on microcellular bubble-probe technology-Raman spectroscopy is developed, which uses atomic force microscope to characterize the off-plane displacement of graphene in pores, and uses Raman spectroscopy to monitor the controllable expansion of the external surface shear region. Based on the Hencky solution, the shear deformation of the external surface of the hole is considered, the boundary condition is modified, and the interfacial shear stress between the graphene and the silicon substrate is analyzed by establishing a mechanical model. At the same time, by regulating the pressure load, the interface is debonded, and the interfacial adhesion energy is calculated by combining the state equation of state and energy analysis. The effects of interfacial shear slip deformation and boundary conditions on debonding behavior and bubble morphology were investigated by atomic force microscopy, and the measurement and control of the interfacial mechanical properties of multi-layer graphene layers were studied. Based on the above-mentioned mechanical detection platform, we can load the double-layer graphene and monitor the expansion of the shearing action area between the outer graphene layers of the hole. Combined with modified Hencky theory, the accurate measurement of shear stress between two layers of graphene layers is realized for the first time. The shear vibration modes of the multilayer graphene are detected by using ultra-low wavenumber Raman spectroscopy, the shear constants of the layers are obtained by combining the linear chain model, and the inter-layer shear modulus is estimated. Further, the effective regulation of graphene layer spacing and inter-layer coupling effect was realized by boron doping treatment of graphene, and the influence of the graphene on the mechanical behavior of the double-layer graphene in the nano-indentation test was investigated.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：O613.71

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