摘 要
一般的轉動機械中的軸承常因軸電壓和軸電流的作用導致電弧效應而發生電蝕，使電機機造成損壞。由於在實際運轉中無法即時以微觀來觀察電蝕發生機制，所以尚不能充分抑制電蝕損傷。因此，本研究使用次微米級精度的靜態電蝕試驗機，實驗探討在交流供應電壓與電流、油膜厚度和添加劑的實驗參數下探討常用軸承材料的潤滑之表面電蝕發生的門檻條件，並且使用掃瞄式電子顯微鏡(SEM)和能量釋放光譜儀(EDS)觀察電蝕表面的機制。
從純油潤滑的鋼配對之實驗結果建立由門檻電壓和油膜厚度的關係所構成之電蝕型態圖可分為電蝕區、過渡區及非電蝕區，在電蝕區中，於一定的電流作用下，界面電壓和界面功率及界面阻抗均隨著油膜厚度增大而微增；但於一定的油膜厚度作用下，界面電壓、界面功率隨著電流增大而增大，而界面阻抗卻隨著電流增大而變小。又，電蝕面積與界面功率有三次曲線的關係。
從純油潤滑的巴氏合金與鋼配對之實驗結果建立由門檻電壓與油膜厚度以及材料熔點的關係所構成的電蝕型態圖區分為電蝕區和非電蝕區。巴氏合金表面的電蝕型態受界面功率和油膜厚度的影響很顯著，亦即在較小油膜厚度下，電蝕表面呈現多孔狀凹坑，尤其是在高供應電流下，在凹坑的周圍形成凸起。在凸起的表面殘留試驗前的拋光痕跡，並且在巴氏合金和鋼兩試片材料之間，由於熔融的錫接觸到鋼球而發生大量的相互轉移層。但在較大油膜厚度下巴氏合金和鋼兩試片材料僅發生少量的相互轉移層。又，軸承表面的電蝕面積主要發生在電弧放電的初期，並隨著電弧放電時間的增加而少許增加，於最後達到飽和值。
從含有導電性二硫化鉬(MoS2)添加劑的潤滑油下，巴氏合金與鋼配對中的實驗結果得知，由門檻電壓和油膜厚度及顆粒濃度所組成之含電蝕和非電蝕等兩個區域的電蝕型態圖，電蝕區域隨著MoS2濃度及供應電流之增加而擴大。又，電蝕面積與界面功率的比值(Ap/P)在油膜厚度6mm以下時隨著油膜厚度和MoS2濃度的增加而增加，在油膜厚度6mm增至10mm以上時，則隨著油膜厚度和MoS2濃度的增加而急速增為近10倍。這是由於熔融凸起直接連結兩試片，使界面功率主要消耗於凸起和界面材料的加熱。從上述結果，提出在添加導電性MoS2粉末之潤滑油條件下電蝕表面凸起的成長模式。

Abstract
The electrical pitting often occurs at the bearing of the ro-tating machinery due to the actions of the shaft voltage and the shaft current resulting in the arcing effect on the lubricated surface and causing the bearing failure. Since the mechanism of the electrical pitting cannot be microscopically observed in process, it is difficult to prevent the bearing damage. Hence, this study uses a static electrical pitting tester with sub -micrometer accuracy to experimentally investigate the effects of supply voltage, supply current, oil film thickness, and ad-ditive on the threshold condition of electrical pitting under the conventional bearing material pairs. Moreover, according to the SEM micrograph and EDS analysis, the mechanism of the pitted surfaces is investigated.
According to the experimental results and the surface ob-servations of steel/steel pair using a paraffin base oil, three electrical pitting regimes are found under the influences of shaft voltage and oil film thickness, namely, pitting, transition, and no-pitting regimes. In the electrical pitting regime, the interface voltage, interface impedance, and interface power increases slightly with increasing oil film thickness at a certain supply current. However, the interface voltage and interface power increases with increasing supply current, and the inter-face impedance decreases with increasing supply current at a certain film thickness. Furthermore, the pitting area versus the interface power relationship is a cubic function.
According to the experimental results and the surface ob-servations of babbitt alloy/steel pair using a paraffin base oil, two electrical pitting regimes are found under the influences of shaft voltage, oil film thickness, and melting point of material, namely, pitting and no-pitting regimes. The mechanism of electrical pitting on the babbitt alloy surface is significantly influenced by the interface power and the oil film thickness. At the smaller oil film thickness, the eroded surface of babbitt alloy exhibits a concave crater with a few micro-porosity in the vicinity of center region with a plateau on its surrounding, especially at high supply current. The polished track can be observed at the plateau. A large amount of tin element trans-fers to the steel ball surface because the molten tin contacts the ball. At the higher oil film thickness, only a little amount of metal element transfers to each other. The major pitting area of the babbitt alloy is caused at the initial stage of the arc dis-charge. With increasing arc discharge time, the pitting area increases slightly, and finally reaches a saturated value.
According to the experimental results and the surface ob-servations of babbitt alloy/steel pair using an additive of MoS2 in a paraffin base oil, two electrical pitting regimes are found under the influences of shaft voltage, oil film thickness, and particle concentration of additive, namely, pitting and no-pitting regimes. The area of pitting regime increases with increasing additive concentration and supply current. Fur-thermore, the ratio of pitting area to the interface power in-creases with increasing additive concentration and supply current at the oil film thickness smaller than 6 mm. However, this ratio increases rapidly to about 10 times with increasing additive concentration and supply current as the oil film thickness increases from 6 mm to 10 mm. This results from the molten plateau that directly connects two specimens, and the interface power is mainly consumed at the heating of the pla-teau and the interfacial materials. According to the above re-sults, the growth model of the plateau on the pitting surface is proposed at the lubricated condition using an additive of MoS2 in paraffin base oil.

總 目 錄

總目錄 i
圖目錄 v
表目錄 x
符號說明 xi
論文摘要(中文) xii
論文摘要(英文) xiv
第一章 緒論 1
1-1 研究動機 1
1-2 軸電壓與軸電流之來源 3
1-3 放電現象之發生與種類 9
1-4 文獻回顧 11
1-4-1 軸電壓、軸電流形成之原因 11
1-4-2 軸電流對軸承電蝕損傷之影響 12
1-4-3 電蝕機制之探討 15
1-4-4 二硫化鉬電蝕潤滑特性之探討 16
1-4-5 電流變流體機制與放電加工機制之探討 17
1-5 論文之研究方向與架構 20
第二章 交流電場下之潤滑表面電蝕機制與形成準則 22
2-1 前言 22
2-2 實驗設備及實驗程序 24
2-2-1 次微米級精度靜態電蝕試驗機 24
2-2-2 實驗訊號量測設備 27
2-2-3 資料收集分析系統 27
2-2-4 實驗時間控制之計時回路 27
2-2-5 次微米級精度的油膜厚度控制系統 29
2-2-6 試片之幾何形狀與尺寸 31
2-2-7 試片處理方法 32
2-2-8 潤滑油性質 32
2-2-9 實驗條件 32
2-2-10 實驗步驟 33
2-3 結果與討論 38
2-3-1 界面電壓與界面阻抗 41
2-3-2 界面功率 47
2-3-3 電蝕孔形成機制 52
2-3-4 電蝕凹坑和電蝕面積 54
2-3-5 門檻電壓 62
2-4 結　論 67
第三章 交流電場下巴氏合金與鋼配對之潤滑表面電蝕機制 68
3-1　前言 68
3-2 實驗條件與方法 70
3-2-1 試片之幾何形狀與尺寸 70
3-2-2 試片處理方法 71
3-2-3 潤滑油性質 71
3-2-4 實驗條件 71
3-3 結果與討論 72
3-3-1 潤滑表面之電氣行為 72
3-3-2 電蝕孔形成機制 82
3-3-3 門檻電壓 95
3-3-4 電弧放電過程之界面狀態 98
3-4 結　論 102
第四章 添加劑對巴氏合金與鋼配對之潤滑表面電蝕機制之影響 103
4-1 前言 103
4-2 實驗條件與方法 105
4-2-1 試片之尺寸及處理方法 105
4-2-2 潤滑油性質 105
4-2-3 二硫化鉬顆粒之處理 105
4-2-4 二硫化鉬之特性 106
4-2-5 實驗條件與方法 108
4-2-6 數位訊號處理 110
4-3 結果與討論 112
4-3-1 界面電壓和電阻的變化 112
4-3-2 電蝕形成的門檻條件 117
4-3-3 電蝕表面的觀察 123
4-3-4 凸起的形成機制 128
4-3-5 電蝕的形成機制 135
4-4 結論 138
第五章　總論與展望 139
5-1 總論 139
5-2 展望 142
參考文獻 143
著作目錄 151
作者簡介 153

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