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    Please use this identifier to cite or link to this item: http://ir.lib.ksu.edu.tw/handle/987654321/3294

    Title: 摩擦磁化機制之量化研究與應用
    Quantitative study and application on the tribo-magnetization mechanisms
    Authors: 張育斌
    Keywords: 滑動速率
    TiN coating
    Sliding speed
    Normal load
    Surface magnetization
    Date: 2007-10-22
    Issue Date: 2009-08-14 00:07:18 (UTC+8)
    Abstract: 本文研究鐵自配於乾燥且嚴重磨耗條件下摩擦對表面磁化之影響。藉由比較滑動速率與垂直負荷對表面磁化的影響,本文因此可釐清摩擦磁化之物理矛盾問題。結果顯示:劇烈的摩擦現象為形成表面磁化的原因,並且,鐵自配摩擦時之動態最大飽和值僅約為18G。當摩擦試驗後表面磁化即迅速衰減至0~1G 之範圍。隨著滑動速率之增加,表面磁化會明顯呈現逐漸減小的趨勢。這是因為高摩擦速度而使得真接觸區域產生明顯溫昇及氧化物,而遮蔽了磁區,且磁區也會因熱震動而導致方向趨於凌亂,故能產生消磁現象。平均表面磁化與滑動速率呈現反比之關係。在較輕負荷下,表面磁化極不明顯。當垂直負荷超過30N 時,平均表面磁化會明顯隨垂直負荷之增加而線性正比例的增加,平均表面磁化並與wear loss 之變化趨勢相當吻合,這是因為產生嚴重磨耗及材料轉移時,此時因為氧化膜破裂而新鮮鐵裸露,且鐵材料之磁區受到摩擦活化及地球磁場之影響而扭向同一方向,故能產生表面磁化現象。本研究最後並提出能量及質量之不同觀點以釐清摩擦對表面磁化的影響。並且,一般而言,以往動態評估薄膜抗磨耗性能的參數皆為摩擦係數,然而,從過去的研究文獻中發現,摩擦係數的靈敏性常常並不夠高,因此,本論文提出使用表面磁化的變化作為評估薄膜抗磨耗性能的新方法。使用工具鋼(SKD11)為基材,分別鍍上物理氣相沉積(CVD)及化學氣相沉積(PVD)之TiN coatings 進行乾摩擦實驗,研究垂直負荷對不同TiN coatings 之摩擦及磨耗性能。從實驗中發現表面磁化之動態變化較傳統摩擦係數之情況易判斷出薄膜破裂之瞬間及耐久壽命,因此,綜合實驗結果可發現表面磁場之動態變化具有發展成為評價不同表面處理方式之磨潤性能的發展潛力。The effects of friction ontribo-magnetization mechanisms forself-mated iron pairs under dry friction wereexperimentally investigated in this study. Bycomparing the effects of sliding speeds andnormal loads on surface magnetization, thephysical contradiction in frictionalmagnetization can therefore be classified.Results showed that severe frictionphenomena are the pre-requisite conditionsfor tribo-magnetization to occur. Themaximum dynamic saturated value oftribo-magnetization for the self-mated ironpairs during the friction process was found tobe only about 18G but rapidly decreased tothe range of 0~1G after the test. It was alsofound that tribo-magnetization decreasedsignificantly with increasing sliding speed.This was due to a rise in surface temperatureand the presence of oxide materials at theactual contact areas from higher slidingspeeds. The magnetic domains were also randomly oriented due to thermal vibration,which explained surface demagnetizationwith increasing sliding speed. In general, theaverage tribo-magnetization was inverselyproportional to the sliding speed. Undersmall normal loads, tribo-magnetization wasinsignificant. For normal loads exceeding30N, the average tribo-magnetizationincreased linearly with increasing normalload. It was revealed that variations of theaverage tribo-magnetization coincided withwear losses under heavy normal loads. Thereasons were that as the oxide film broke,fresh ferromagnetism was exposed to severewear and material transfer. The orientation ofthe magnetic domains was caused by bothfrictional activation and the earth’s magneticfield. Tribo-magnetization was thussignificantly increased by friction and wearwith increasing normal load. Finally, thisstudy proposed two perspectives on energyand material to clarify the physicalcontradictions of the tribo-magnetization.Moreover, generally speaking, the majorparameter which has been used to monitorthe dynamic tribological properties of thefilms over the past decades is frictioncoefficient. However, it has shown low insensitivity for many cases. Therefore, it isnecessary to introduce more improvedphysical measurements other than the frictioncoefficient to monitor and control the filmtribological characteristics in sliding contacts.In view of this, the novel technology of usinginstead surface magnetization variations forevaluating the wear-resistant properties of thefilms is proposed. The experiment wasconducted by the pairs of SUS304 rubbingwith SKD11 substrate with different TiNfilms (PVD and CVD) on the surface atdifferent normal loads in dry friction process.The effects of normal loads on the frictionand wear properties for the die surfaces withdifferent TiN films were investigated. Theexperimental results show that the continuoussurface magnetization variations can be usedto determine the timing of film fracture andthe endurance life more accurately than thatby the friction coefficient variations as usual.Therefore, the novel method of using surfacemagnetization variations does show greatpotentialities for evaluating the tribological properties of the die surfaces with differentTiN films.
    Appears in Collections:[機械工程系所] 研究計畫

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