• 作者： Wu, Nae-Lih; Lee, Sern-Nan
• 中文摘要： 在本文中首創利用滲透方式製備含連續超導氧化物架構之YBa/sub 2/Cu/sub 3/O/sub 7/(簡稱YBCO)與樹脂結合的複合塊材,並探討樹脂浸透對YBCO塊材機械強度與耐熱衝擊性的影響。純YBCO塊材的彎曲強度很低,並隨溫度下降(由室溫至78K)而降低,而其常態電阻亦因架構龜裂形成短路而急遽升高。由複合材料的結構觀察發現利用滲透法樹脂很容易便充滿了 YBCO塊材內的間隙部分,並與YBCO晶體強力結合。塊材的超導溫度不因樹脂浸透而改變。此外,其具有較純YBCO塊材更高(2-3倍)之彎曲強度及耐熱衝擊性,其機械性質的改善機構可歸因於(1)對裂縫擴展的阻力增加,(2)與結構缺陷相關之應力集中效應的降低,(3)因YBCO與樹脂不同熱膨脹係數與引起之擠壓應力效應。最後,在文中亦發現複合塊材較YBCO塊材具有更佳之耐腐蝕性。
• 英文摘要： Bulk YBa/sub 2/Cu/sub 3/O/sub 7//epoxy composite containing the continuous oxide matrix were prepared by an infiltration method. Investigations were made to determine the effectiveness of epoxy impregnation as a means for improving the mechanical strength of YBa/sub 2/Cu/sub 3/O/sub 7/ (the YBCO oxide) and its stability during cryogenic thermal cycling. For a pure polycrystalline YBCO bulk, its flexural strength, determined by a three-point loading test, was low and decreased rapidly with the decrease in temperature, while its normal-state resistivities escalated after repeated cooling- and-warming cycles between room and liquid nitrogen temperatures due to formation of cracks by thermal stress. Epoxy was found to readily fill up the voids (structural flaws) within a sintered YBCO bulk and to form strong bonding with the oxide grains. The superconducting critical temperature (T/sub c/) of the oxide was not changed by the epoxy impregnation process. Moreover, the epoxy- impregnated composite exhibited a much greater flexural strength and a better stability during thermal cycling than the pure YBCO. Possible strengthening mechanisms, including (i) additional resistance to crack nucleation and propagation owing to the occupancy of epoxy in the pore regions, (ii) reduction of stress-concentrating effects associated with the structural flaws of the oxide matrix, and (iii) compressive residue stress due to different thermal contraction behaviors between the oxide and epoxy, were discussed. Finally, the composite also showed a better chemical stability against moisture corrosion than that of the pure YBCO.
• 中文關鍵字： 樹脂複合材料; 氧化物; 超導體; 高分子; 製備; 描述; 複合材料; 耐蝕性
• 英文關鍵字： Epoxy Composite; Oxide; Superconductor; Polymer; Preparation; Characterization; Composite Material; Corrosion Resistance