本研究目的在探討還原環境對於玻璃陶瓷和金屬連接板接合件的接合強度及破壞模式的影響，所使用的玻璃陶瓷為核能研究所開發一款代號為GC-9的材質，金屬連接板則是使用代號為Crofer 22 H的商用肥粒鐵系不銹鋼。藉由製作兩款三明治試片，分別量測接合件在室溫與800 oC還原環境下的剪力及張力強度，同時評估還原環境時效處理對接合件強度的影響，並比較在還原環境與氧化環境下接合件所受之影響。
結果顯示，經一千小時還原環境時效處理的剪力試片，在常溫下接合強度比未經時效處理之試片增加24%，而在高溫下則下降19%；張力試片的接合強度亦有相同之趨勢，與未時效相比較，時效處理後接合強度在常溫下增加與高溫下減少的幅度分別為47%與51%。時效處理後常溫接合強度增加的主因可能為：(1) 時效熱處理的過程中，改變GC-9玻璃陶瓷基材中缺陷的大小、形貌；(2) 時效熱處理時有應力鬆弛的現象；(3) 時效熱處理後，GC-9玻璃陶瓷結晶化程度提高。而在時效處理後，高溫下接合強度降低的主因為時效熱處理時，在GC-9玻璃陶瓷基材中的玻璃相與結晶相之間形成微孔洞所導致。
由微結構及破斷面分析結果發現，接合件試片有四種破壞模式：(1) 破裂發生在玻璃陶瓷基材的內部；(2) 脫層現象發生於玻璃陶瓷基材與鉻酸鋇層的界面；(3) 脫層現象發生於金屬連接板與氧化鉻層的界面；(4) 破裂發生於玻璃陶瓷/鉻酸鋇/氧化鉻的混和層內。將微結構及破斷面分析結果與接合強度做比對，發現當破裂只發生於玻璃陶瓷基材的內部時通常伴隨的較高的接合強度，而破裂發生於界面或混和層時會有較低的接合強度。
在還原環境與氧化環境下，未時效試片的接合強度與破壞模式並未有明顯差異，而在一千小時長時效處理後，還原環境與氧化環境皆會降低試片之接合強度，下降的幅度皆為19%。

The objective of this study is to investigate the effect of reducing environment on the mechanical properties of a joint between a glass-ceramic sealant and an interconnect steel. A technique is developed for measuring the joint strength between glass-ceramic and metallic interconnect under tensile or shear loading in reducing environment at room temperature and 800 oC. The applied materials are a GC-9 glass-ceramic developed at the Institute of Nuclear Energy Research (INER) and a commercial Crofer 22 H ferritic stainless steel. Comparison of oxidizing and reducing environment effects on mechanical properties of a joint are also presented for variously, thermally aged conditions.
Both tensile and shear joint strengths are increased at room temperature and decreased at 800 oC after a reducing aging treatment. A reducing aging treatment at 800 oC for 1000 h enhances the joint strength of shear loading at room temperature by 24% and degrades it at 800 oC by 19%. A reducing aging treatment at 800 oC for 1000 h increases the joint strength of tensile loading at room temperature by 47% and deterioriates it at 800 oC by 51%. Promotion of joint strength at room temperature may be related to changes in the flaw size and morphology, relaxation of residual stresses, and a greater extent of crystallization during aging treatment. Degradation of joint strength at 800 oC is probably due to formation of micro-voids between crystalline and glassy phases after aging treatment.
Through fractography anaysis, fracture mode of the joint is correlated with the measured fracture strength. Four types of fracture modes are identified for the joint specimens. Firstly, fracture occurs within the glass-ceramic layer. Secondly, delamination takes place at the interface between the GC-9 glass-ceramic sealant and a chromate layer. Thirdly, delamination occurs at the interface between the metal substrate and a Cr2O3 layer. Fourthly, fracture involves cracking in the interfacial mixed layer of glass-ceramic/chromate/chromia. A greater joint strength is accompanied by cracking within the glass-ceramic layer, while a lower joint strength corresponds to fracture involving interfacial delamination or cracking in the interfacial mixed layer of glass-ceramic/chromate/chromia.
The joint strength and fracture mode are comparable between the given reducing and oxidizing environments for non-aged specimens. Thermal aging treatments in both given environments have detrimental effects on the joint strength at 800 °C. Compared to the shear strength of the non-aged specimens, 19% of reduction in strength is both observed for the specimens exposed to the given reducing and oxidizing environments.

REFERENCES
1. A. Choundhury, H. Chandra, and A. Arora, “Application of Solid Oxide Fuel Cell Technology for Power Generation-A Review,” Renewable and Sustainable Energy Reviews, Vol. 20, pp. 430-442, 2013.
2. K. Kendall, N. Q. Minh, and S. C. Singhal, “Cell and Stack Designs,” Chapter 8 in High Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications, edited by S. C. Singhal and K. Kendall, Elsevier, Kidlington, UK, 2003.
3. W. Z. Zhu and S. C. Deevi, “A Review on the Status of Anode Materials for Solid Oxide Fuel Cells,” Materials Science and Engineering, Vol. A362, pp. 228-239, 2003.
4. P. Batfalsky, V. A. C. Haanappel, J. Malzbender, N. H. Menzler, V. Shemet, I. C. Vinke, and R. W. Steinbrech, “Chemical Interaction Between Glass-Ceramic Sealants and Interconnect Steels in SOFC Stacks,” Journal of Power Sources, Vol. 155, pp. 128-137, 2006.
5. Y. Zhao and J. Malzbender, “Elevated Temperature Effects on the Mechanical Properties of Solid Oxide Fuel Cell Sealing Materials,” Journal of Power Sources, Vol. 239, pp. 500-504, 2013.
6. A. Nakajo, J. Kuebler, A. Faes, U. F. Vogt, Hans J. Schindler, L.-K. Chiang, S. Modena, J. van Herle, and T. Hocker, “Compilation of Mechanical Properties for the Structural Analysis of Solid Oxide Fuel Cell Stacks. Constitutive Materials of Anode-Supported Cells,” Ceramics International, Vol. 38, pp. 3907-3927, 2012.
7. J. W. Fergus, “Sealants for Solid Oxide Fuel Cells,” Journal of Power Sources, Vol. 147, pp. 46-57, 2005.
8. K. S. Weil, J. S. Hardy, and B. J. Koeppel, “New Sealing Concept for Planar Solid Oxide Fuel Cells,” Journal of Materials Engineering and Performance, Vol 15, pp. 427-432, 2006.
9. K. S. Weil and B. J. Koeppel, “Thermal Stress Analysis of the Planar SOFC Bonded Compliant Seal Design,” International Journal of Hydrogen Energy, Vol. 33, pp. 3976-3990, 2008.
10. Y. Zhao, J. Malzbender, and S. M. Gross, “The Effect of Room Temperature and High Temperature Exposure on the Elastic Modulus, Hardness and Fracture Toughness of Glass Ceramic Sealants for Solid Oxide Fuel Cells,” Journal of the European Ceramic Society, Vol 31, pp. 541-548, 2011.
11. V. A. C. Haanappel, V. Shemet, S. M. Gross, Th. Koppitz, N. H. Menzler, M. Zahid, and W. J. Quadakkers, “Behaviour of Various Glass-Ceramic Sealants with Ferritic Steels under Simulated SOFC Stack Conditions,” Journal of Power Sources, Vol. 150, pp. 86-100, 2005.
12. P. A. Lessing, “A Review of Sealing Technologies Applicable to Solid Oxide Electrolysis Cells,” Journal of Materials Science, Vol. 42, pp. 3465-3476, 2007.
13. K. S. Weil, “The State-of-the-Art in Sealing Technology for Solid Oxide Fuel Cells,” JOM, Vol. 58, pp. 37-44, 2006.
14. G. Kaur, O. P. Pandey, and K. Singh, “Interfacial Study Between High Temperature SiO2-B2O3-AO-La2O3 (A = Sr, Ba) Glass Seals and Crofer 22APU for Solid Oxide Fuel Cell Applications,” International Journal of Hydrogen Energy, Vol. 37, pp. 6862-6874, 2012.
15. S. R. Choi and N. P. Bansal, “Mechanical Properties of SOFC Seal Glass Composites,” Ceramic Engineering and Science Proceedings, Vol. 26, pp. 275-283, 2005.
16. C.-K. Liu, T.-Y. Yung, and K.-F. Lin, “Effect of La Addition on the Thermal and Crystalline Properties of SiO2-B2O3-Al2O3-BaO Glasses,” Proceedings of the Annual Conference of the Chinese Ceramic Society (CD-ROM), 2007. (in Chinese)
17. C.-K. Liu, T.-Y. Yung, S.-H. Wu, and K.-F. Lin, “Study on a SiO2-B2O3-Al2O3-BaO Glass System for SOFC Applications,” Proceedings of the MRS_Taiwan Annual Meeting (CD-ROM), 2007. (in Chinese)
18. C.-K. Liu, T.-Y. Yung, and K.-F. Lin, “Isothermal Crystallization Properties of SiO2-B2O3-Al2O3-BaO Glass,” Proceedings of the Annual Conference of the Chinese Ceramic Society (CD-ROM), 2008. (in Chinese)
19. H.-T. Chang, “High-Temperature Mechanical Properties of a Glass Sealant for Solid Oxide Fuel Cell,” Ph.D. Thesis, National Central University, 2010.
20. J.-H. Yeh, “Analysis of High-Temperature Mechanical Durability for the Joint of Glass Ceramic Sealant and Metallic Interconnect for Solid Oxide Fuel Cell,” M.S. Thesis, National Central University, 2011.
21. C.-K. Lin, T.-T. Chen, Y.-P. Chyou, and L.-K. Chiang, “Thermal Stress Analysis of a Planar SOFC Stack,” Journal of Power Sources, Vol. 164, pp. 238-251, 2007.
22. A.-S. Chen, “Thermal Stress Analysis of a Planar SOFC Stack with Mica Sealants,” M.S. Thesis, National Central University, 2007.
23. C.-K. Lin, L.-H. Huang, L.-K. Chiang, and Y.-P. Chyou, “Thermal Stress Analysis of a Planar Solid Oxide Fuel Cell Stacks: Effects of Sealing Design,” Journal of Power Sources, Vol. 192, pp. 515-524, 2009.
24. Y.-S. Chou, J. W. Stevenson, and P. Singh, “Effect of Pre-Oxidation and Environmental Aging on the Seal Strength of a Novel High-Temperature Solid Oxide Fuel Cell (SOFC) Sealing Glass with Metallic Interconnect,” Journal of Power Sources, Vol. 184, pp. 238-244, 2008.
25. V. A. Haanappel, V. Shemet, I. C. Vinke and W. J. Quadakkers, “A Novel Method to Evaluate the Suitability of Glass Sealant-Alloy Combinations under SOFC Stack Conditions,” Journal of Power Sources, Vol. 141, pp. 102-107, 2005.
26. J. Malzbender, J. Mönch, R. W. Steinbrech, T. Koppitz, S. M. Gross and J. Remmel, “Symmetric Shear Test of Glass-Ceramic Sealants at SOFC Operation Temperature,” Journal of Materials Science, Vol. 42, pp. 6297-6301, 2007.
27. K. S. Weil, J. E. Deibler, J. S. Hardy, D. S. Kim, G.-G. Xia, L. A. Chick, and C. A. Coyle, “Rupture Testing as a Tool for Developing Planar Solid Oxide Fuel Cell Seals,” Journal of Materials Engineering and Performance, Vol. 13, pp. 316-326, 2004.
28. F. Smeacetto, M. Salvo, M. Ferraris, V. Casalegno, P. Asinari, and A. Chrysanthou, “Characterization and Performance of Glass-Ceramic Sealant to Join Metallic Interconnects to YSZ and Anode-Supported-Electrolyte in Planar SOFCs,” Journal of the European Ceramic Society, Vol. 28, pp. 2521-2527, 2008.
29. E. V. Stephens, J. S. Vetrano, B. J. Koeppel, Y. Chou, X. Sun, and M. A. Khaleel, “Experimental Characterization of Glass-Ceramic Seal Properties and their Constitutive Implementation in Solid Oxide Fuel Cell Stack Models,” Journal of Power Sources, Vol. 193, pp. 625-631, 2009.
30. J.-Y. Chen, “Analysis of Mechanical Properties for the Joint of Metallic Interconnect and Glass Ceramic in Solid Oxide Fuel Cell,” M.S. Thesis, National Central University, 2010.
31. Z. Yang, K. D. Meinhardt, and J. W. Stevenson, “Chemical Compatibility of Barium–Calcium–Aluminosilicate Sealing Glasses with the Ferritic Stainless Steel Interconnect in SOFCs,” Journal of the Electrochemical Society, Vol. 150, pp. A1095-A1101, 2003.
32. N. H. Menzler, D. Sebold, M. Zahid, S. M. Gross, and T. Koppitz, “Interaction of Metallic SOFC Interconnect Materials with Glass–Ceramic Sealant in Various Atmospheres,” Journal of Power Sources, Vol. 152, pp. 156-167, 2005.
33. F. Smeacetto, M. Salvo, M. Ferraris, J. Cho, and A. R. Bocaccini, “Glass–Ceramic Seal to Join Crofer 22 APU Alloy to YSZ Ceramic in Planar SOFCs,” Journal of the European Ceramic Society, Vol. 28, pp. 61-68, 2008.
34. V. A. Haanappel, V. Shemet, I. C. Vinke, S. M. Gross, T. Koppitz, N. H. Menzler, M. Zahid, and W. J. Quadakkers, “Evaluation of the Suitability of Various Glass Sealant-Alloy Combinations under SOFC Stack Conditions,” Journal of Materials Science, Vol. 40, pp. 1583-1592, 2005.
35. Z. Yang, J. W. Stevenson, and K. D. Meinhardt, “Chemical Interactions of Barium–Calcium–Aluminosilicate-Based Sealing Glasses with Oxidation Resistant Alloys,” Solid State Ionics, Vol. 160, pp. 213-225, 2003.
36. Z. Yang, G. Xia, K. D. Meinhardt, K. S. Weil, and J. W. Stevenson, “Chemical Stability of Glass Seal Interfaces in Intermediate Temperature Solid Oxide Fuel Cells,” Journal of Materials Engineering and Performance, Vol. 13, pp. 327-334, 2003.
37. J.-W. Tian, “Analysis of Thermal Stress and Mechanical Properties for the Components of Solid Oxide Fuel Cell,” M.S. Thesis, National Central University, 2009.
38. K.-L. Lin, “Analysis of Creep Properties of Glass Ceramic Sealant and Its Joint with Metallic Interconnect for Solid Oxide Fuel Cells,” M.S. Thesis, National Central University, 2012.
39. Y.-T. Chiu, “Creep and Thermo-Mechanical Fatigue Properties of Ferritic Stainless Steels for Use in Solid Oxide Fuel Cell Interconnect,” Ph.D. Thesis, National Central University, 2012.
40. C.-K. Liu, T-.Y. Yung, K.-F. Lin, R.-Y. Lee, and T.-S. Lee, Glass-Ceramic Sealant for Planar Solid Oxide Fuel Cells, United States Patent No. 7,897,530 B2, 2011.
41. M. Tomozawa, H. Li, and K. M. Davis, “Water Diffusion, Oxygen Vacancy Annihilation and Structural Relaxation in Silica Glasses,” Journal of Non-Crystalline Solids, Vol. 179, pp. 162-169, 1994.
42. S. Fujita, A. Sakamoto, and M. Tomozawa, “Behavior of Water in Glass During Crystallization,” Journal of Non-Crystalline Solids, Vol. 320, pp. 56-63, 2003.
43. T. Jin, M. O. Naylor, J. E. Shelby, and S. T. Misture, “Galliosilicate Glasses for Viscous Sealants in Solid Oxide Fuel Cell Stacks: Part III, Behavior in Air and Humidified Hydrogen,” International Journal of Hydrogen Energy, Vol. 38, pp. 16308-16319, 2013.
44. W. Liu, X. Sun, and M. A. Khaleel, “Predicting Young’s Modulus of Glass/Ceramic Sealant for Solid Oxide Fuel Cell Considering the Combined Effects of Aging, Micro-Voids and Self-Healing,” Journal of Power Sources, Vol. 185, pp. 1193-1200, 2008.
45. P. Alnegren, “Oxidation Behavior of Selected FeCr Alloys in Environments Relevant For Solid Oxide Electrolysis Applications,” M.S. Thesis, Chalmers University, 2012.