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研究生：	賴文健 Lai, Wen-Chien
論文名稱：	樹脂披覆YBCO高溫超導體擄獲磁場能力之研究 The Trapped Field of Bulk HTSC YBCO With Resin Impregnation
指導教授：	陳引幹 Chen, Ingann
學位類別：	碩士 Master
系所名稱：	工學院 - 材料科學及工程學系 Department of Materials Science and Engineering
論文出版年：	2005
畢業學年度：	93
語文別：	中文
論文頁數：	100
中文關鍵詞：	超導體、擄獲磁場、碳纖維、環氧樹脂、電磁應力
外文關鍵詞：	trapped field, superconductor, YBCO, carbon fabric, resin
相關次數：	點閱：45 下載：2
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　　YBCO超導體塊材在TSMT製程以及充氧退火的過程中，因熱應力與熱膨脹係數差異，內部會存在一定數量的裂縫與孔洞。在強磁場之下超導體本身將承受極大的電磁應力，此力將足以摧毀整個超導塊材，因此本實驗的目的在於提升超導體的機械強度，增加在高磁場環境下使用。

　　使用自行成長的單晶粒塊材，磨成直徑17mm厚4mm的試片，利用具流動性的環氧樹脂滲入塊材的開放性裂縫中，並在超導塊材外部包覆一層碳纖維布，來增加超導塊材的機械性質。實驗中比較了不同黏滯係數的環氧樹脂滲入裂縫的能力，各種環氧樹脂都有相當良好的填縫能力，為了便於長時間的披覆工作，選擇流動性較佳的環氧樹脂Stycast1495FT 與工作時間至少四個小時的催化劑Catalyst 11進行披覆。

　　擄獲磁場的試驗是利用中央研究院物理研究所PPMS(physical property measure system ) 產生的磁場來進行，系統最大可以產生9 tesla的磁場。首先在3T、不同溫度下(35K~77K)量測單一試片的表面擄獲磁場，經過樹脂披覆的試片比未處理試片在不同溫度下增加7.1%~40.8%的擄獲磁場。比較實驗前後的磁浮力，有樹脂披覆的試片平均減少4.3%，未披覆樹脂試片平均減少了7.4%。顯示經過披覆處理塊材能夠減少微裂縫的生成。使塊材擄獲磁場能夠提升。

　　進行兩塊材之間量測擄獲磁場的實驗，來避免試片表面磁通量分散的情形。在15K，9T磁場下，未處理試片最多能擄獲2.34T的磁場，之後受電磁力作用破裂。經過補強處理的試片，則可擄獲7.1T而不破損。主要是樹脂滲入裂縫能夠阻止裂縫受電磁力作用進一步地擴張，外圍包覆碳纖維布，抵抗磁場作用在塊材的環形張力。即使試片在實驗中沒有發生破裂，但比較其前後磁浮力，仍有所下降(9.7%~36.6%)，顯示出高磁場仍對塊材產生損害。

　There were micro-cracks and voids existed in the single grained YBCO superconductors as growth and annealing process due to its difference in thermal expansion coefficients and thermal stresses. In practice, the interaction between the current inside the superconductors and the external magnetic field results in strong Lorentz force. If this electromagnetic stress is larger than the fracture toughness of the superconductor, macro-cracks or fractures will be observed. The purpose of this experiment is to enhance the mechanical properties of YBCO-superconductors and to endure stress at high external magnetic field.

　The single grained YBCO bulk superconductors were prepared and grinded to 17 mm in diameter, 4 mm in thickness. The improvement of the mechanical properties of YBCO superconductors is fulfilled by encapsulated with the commercial resins and carbon fabrics. In this experiment, the permeability of epoxy in different viscosities was compared. Then Catalyst 11 was chosen for its long working time( 4 hours minimum). Stycast 1495FT was chosen for its low viscosity.

　For trapped-field measurements, we used PPMS model 9000 (maximum field 9 tesla) at Institute of Physics, Academia Sinica as a magnetic source. We measured the trapped-field of single YBCO disc at 3 T. The trapp-field of YBCO discs with resin impregnation was 7.1%~40.8% larger than that without resin impregnation, from 35K~77K. The magnetic levitation force of YBCO discs with resin impregnation decreased 4.3% in average after experiment. The magnetic levitation force of YBCO discs without resin impregnation decreased 7.4% in average after experiment. We believe that resin impregnation reduced the formation of macro-crack of YBCO bulk superconductor, and the trapped-field of YBCO bulk superconductor was increased.

　We also stacked two YBCO discs, in which the magnetic flux was less dispersed than single disc. We measured the trapped-field at 15K, and the applied field was 9T. The maximum trapped-field between two discs without resin impregnation was 2.34T before the discs fractured by the huge electromagnetic stress. On the other hand, the two YBCO discs with resin impregnation trapped 7.1T without fracture. Resin permeated into the crack of YBCO bulk superconductor, and the resin prevented the further expansion of crack under electromagnetic force. The carbon fabrics surrounded the YBCO discs could resist the annular tension produced by the Lorentz force. For the YBCO discs which did not fracture after experiment, the magnetic levitation force decreased from 9.7% to 36.6%. It revealed that high magnetic still caused partial damage to the YBCO discs with resin impregnation.

摘要                                    I
Abstract                               II
目錄                                   IV
圖目錄                               VIII
表目錄                                XIV
第一章  緒論                            1
1-1  前言                               1
1-2  研究目的                           2
第二章  理論基礎與文獻回顧              4
2-1  YBCO超導體的機械性值               4
2-1-1機械性質與微結構的關係             4
2-1-2超導體在晶體成長過程中承受的應力   4
2-1-3 超導體表面裂縫及孔洞分佈型態                             5
2-1-3-1  a-b平面裂縫生成原因                                   5
2-1-3-2  c軸裂縫生成原因                                       6
2-1-3-3  表面孔洞分佈型態                                      7
2-2 磁場對超導體的產生的應力與破壞                             7
2-2-1外加磁場對超導體產生的電磁應力                            7
2-2-2電磁應力對超導體產生的破壞                               10
2-3  環氧樹脂及碳纖維的基本性質                               11
2-3-1  環氧樹脂的基本性質                                     11
2-3-2  環氧樹脂與硬化劑的反應機構                             11
2-3-3  碳纖維的歷史                                           12
2-3-4  碳纖維的編織                                           12
2-3-5  碳纖維的優點及應用                                     13
2-4  包覆環氧樹脂與碳纖維對機械性質的改善                     13
2-4-1  超導塊材被覆樹脂方式                                   13
2-4-2  被覆樹脂與碳纖維對於塊材機械性質的影響                 14
2-4-2-1  彎曲強度                                             14
2-4-2-2  拉伸強度                                             14
2-4-3  被覆樹脂與碳纖維布對於塊材在熱循環應力的改善           15
2-4-3-1  施加反覆磁場對超導體造成的破壞                       16
2-4-3-2  Hihg Tc magnet                                       16
第三章 實驗步驟                                               38
3-1 實驗材料                                                  38
3-2 實驗步驟                                                  38
3-2-1 單晶粒塊材的成長                                        38
3-2-2 塊材的前處理                                            39
3-2-3 環氧樹脂的披覆                                          39
3-2-3-1 環氧樹脂的調製                                        39
3-2-3-2 碳纖維布的包覆                                        40
3-2-3-3 樹脂披覆試片的步驟                                    40
3-3不同流動性環氧樹脂滲入塊材裂縫的觀察                       41
3-4 擄獲磁場實驗                                              41
3-4-1 實驗儀器                                                41
3-4-2 試片座與霍爾元件的裝配                                  42
3-4-3 擄獲實驗的流程                                          42
3-5儀器設備                                                   43
第四章 實驗結果與討論                                         57
4-1實驗樣品前處理                                             57
4-1-1 YBCO單晶粒成長情形                                      57
4-1-2實驗樣品選擇                                             57
4-1-3 YBCO塊材的樹脂披覆                                      57
4-1-3-1塊材的前處理                                           57
4-1-3-1環氧樹脂的披覆                                         58
4-1-4-2包覆碳纖維布的方式                                     58
4-1-4-1包覆碳纖維的優點                                       58
4-1-4-2包覆碳纖維的方法                                       59
4-2不同樹脂與塊材介面的觀察                                   60
4-2-1 樹脂流動性與工作時間的比較                              60
4-2-2 介面觀察                                                60
4-3 擄獲磁場實驗儀器                                          68
4-3-1 PPMS（physical property measure system）                68
4-3-2霍爾元件的校正                                           68
4-3-3 試片的裝置                                              70
4-4 單一塊材擄獲磁場實驗                                      74
4-5  sandwich structure 方式量測磁通密度                      82
4-5-1未經披覆的試片                                           82
4-5-2經過樹脂碳纖維披覆的試片                                 87
4-5-3樣品包覆兩層碳纖維布之擄獲磁場實驗                       92
第五章 結論                                                   96
                                    

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校內：2008-08-03公開
校外：2008-08-03公開

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