English  |  正體中文  |  简体中文  |  Items with full text/Total items : 886/886 (100%)
Visitors : 7697807      Online Users : 112
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version
    Please use this identifier to cite or link to this item: http://ccur.lib.ccu.edu.tw/handle/A095B0000Q/101


    Title: 以即時穿透式電子顯微鏡技術量測類鑽碳吸附力的研究;Research on measurement Diamond-Like-Carbon by In-situ Transmission Electron Microscopy
    Authors: 陳博倫;CHEN, PO-LUN
    Contributors: 機械工程系研究所
    Keywords: 哈梅克常數;分子動力學模擬;吸附力;類鑽碳;凡德瓦爾力;Hamaker constant;molecular dynamics simulation;adhesion;diamond-like carbon;Van der Waals force
    Date: 2017
    Issue Date: 2019-05-23 12:52:31 (UTC+8)
    Publisher: 機械工程系研究所
    Abstract: 類鑽碳鍍層是一種同時具有低摩擦力和低磨耗之保護材料的重要鍍層,廣泛的應用於如硬碟和刀具以及引擎元件等領域。吸附力的量測是探討磨潤現象的主要基礎,以往量測吸附力最重要儀器為原子力顯微鏡(AFM),但是原子力顯微鏡在大氣環境下樣品容易吸附汙染物,而且不能精確控制接觸點和時間。因此本研究應用穿透式電子顯微鏡來進行即時奈米定位量測,測量類鑽碳的吸附力。 本研究在穿透式電子顯微鏡(TEM)中進行即時量測,測量鑽石探針與原子力顯微鏡探針上鍍類鑽碳薄膜在接觸和脫離時的瞬間吸附力,即兩探針接近時的拉進力(Pull-in force)與脫離時的拉脫力(Pull-off force)。透過奈米壓痕儀控制壓電管移動鑽石探針與原子力顯微鏡探針接觸,但奈米壓痕儀中的力量感測器精度不夠不足以測量吸附力,因此應用精密定位及即時量測來測量鍍有類鑽碳之懸臂梁探針在接觸和脫離時瞬間彎曲的角度,此角度與臂梁探針的彈簧常數乘積即為拉進力與拉脫力。實驗中探討推進距離與停滯時間對吸附力的影響,結果顯示各種實驗情況下的拉進力值皆非常相近不受粗糙度影響。由實驗結果推導出拉進力的哈梅克常數(Hamaker constant),與理論上鑽石對鑽石的哈梅克常數十分接近,由此可以推論拉進力主要為凡得瓦爾力(van der Waals’ force)。在脫離時的拉脫力在不同推進距離與停滯時間的值顯示較為分散,由量測數據推論是受到類鑽碳表面粗糙度影響,粗糙度越大拉脫力越小。 本研究接著使用分子動力學模擬(Molecular Dynamics Simulation)進一步驗證實驗結果,模擬中探討論了類鑽碳表面粗糙度對拉進力與拉脫力的影響。模擬?果顯示拉進力值在不同表面粗糙度條件下變化不大,與實驗時拉進力保持不變的趨勢一致。而且分?從模擬和實驗結果計算的哈梅克常數與理論上鑽石對鑽石的哈梅克常數接近,證明了拉進力為凡得瓦爾力。然而模擬?果顯示拉脫力的值與粗糙度有關,且與實驗?果一致,隨著粗糙度的增加先?小後不變。此外從分子模擬?果確定了粗糙度對拉脫力的影響機制:粗糙度主要通過影響接觸面形成的原子鍵?數影響拉脫力。在粗糙度較小時,接觸面形成的鍵?數較多,接觸面分離時破壞的鍵?數較多,拉脫力則越大;當粗糙度增加時,接觸面形成的鍵?數逐漸?小最後保持穩定,拉脫力則隨之減小最後趨於穩定。
    Diamond-like carbon (DLC) coating is an important coating that has both low friction and low wear which can protect material, widely used in such as hard disks and knives and engine parts. The measurement of the adhesion force is the main basis for exploring the tribology phenomenon, the most important instrument for measuring the adhesion force was atomic force microscopy (AFM) but, atomic force microscopy in the atmosphere of the sample is easy to adsorb contaminants and can not precisely control the contact point and time. Therefore, in this study, the use of in-situ the transmission electron microscope (TEM), to carry out real time Nano-positioning measurement, measurement of diamond-like carbon adhesion force. In this study, real-time measurement was performed in TEM, measurement of DLC-coats AFM tip to diamond indenter of pull-in and pull-out instantaneous adhesion force, that two tips closed call pull-in force and two tips separated call pull-off force. Through the nanaindenter to control the piezo tube that enables the precise motion of the diamond indenter to contact with the atonic force microscope tip, but the force sensor in the nanoindenter is not accurate enough to measure the adhesion force. Thereore application of precision positioning and real-time measurement can be measured with a diamond-like carbon cantilever probe in contact and separate when the moment of bending, this angle multiply with the cantilever probe spring constant is pull-in force and pull-off force. At experiment discussed push distance and holding time effect to adhesion force, the result show pull-in force values are consistent and did not affect with roughness at any experiment situation. The experiment results in derivation the Hamaker constant from pull-in force, which is very similar to that measured for the Hamaker constant for Diamond on Diamond in theoretical, the value for DLC on Diamond is expected to be similar and therefore we conclude that the pull-in force observed is the result of van der Waals interactions. The pull-off force at different push distance and holding time are highly scattered, the pull-off force effect of DLC surface roughness, the increase of roughness decreases pull-off force. This study then uses molecular dynamics simulations to further validate the experiment results, DLC surface roughness discussed effecting of the pull-in force and pull-off force in the simulation. The simulation result show that the pull-in force remains unchanged at different roughness conditions, which is consistent with the tendency of the pull-in force in the experiment. Moreover, respectively the Hamaker constant calculated from the simulations and the experiment results are closed to the theoretical Hamaker constant of diamond, proving the pull-in force is Van derWaals force. However, the simulation results show the pull-off force is related to the roughness, and is consistent with experimental results. The roughness decreases first and then decreases. In addition, the effect of roughness of the pull-off force is determined form the molecular simulation results. Roughness mainly affects the pull-off force by affecting the number of bonds formed on the contact surface, roughness mainly affects the pull-off force by affecting the number of bonds forms on the contact surface. When the roughness is low the number of bonds formed on the contact surface becomed large, the number of the bonds broken when the contact surface separated is large, and the pull-off force will be larger; As the roughness increases, the number of bonds formed on the contact surface gradually decreases, eventually stabilizing, pulling force decreases, and eventually stabilizes.
    Appears in Collections:[機械工程學系] 學位論文

    Files in This Item:

    File Description SizeFormat
    index.html0KbHTML68View/Open


    All items in CCUR are protected by copyright, with all rights reserved.


    版權聲明 © 國立中正大學圖書館網頁內容著作權屬國立中正大學圖書館

    隱私權及資訊安全政策

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback