本研究係使用Thermo-calc熱力學模擬軟體設計六款以抗鹼性溶液腐蝕與抗高溫腐蝕為目標的含鉻鎳基合金並以真空電弧熔煉製作成試片。新合金可歸納為兩大類：高鉻含量合與低鉻含量合金。透過四種不同的腐蝕實驗，包括：極化實驗、氫氧化鈉浸沒實驗、鹽類浸沒實驗以及鹽類披覆實驗，新合金於不同環境中的抗腐蝕性質得以被評估，且實驗結果已完成與Monel-400與Ni-205進行比較。
實驗結果證實，鉻的添加有助於提升合金抗腐蝕性。在氫氧化鈉溶液中，鉻原子會誘發合金的二次鈍化，並且延緩過鈍化的發生。相較於高鉻合金，低鉻合金能夠避免在氫氧化鈉溶液中與鈉產生可溶性的化合物，展現良好的表面穩定性。另外，在高溫形成的保護性氧化鉻層則能夠阻止合金進一步被氧化。鉻含量超過10 wt.%的合金能在高溫腐蝕的環境下形成連續之氧化鉻，有效達到抗腐蝕效果。綜合各項腐蝕實驗結果顯示，在不同環境中，合金D2(Ni-20Cr)皆能夠展現卓越的抗腐蝕性質。

Six Cr-containing Ni-base alloys have been developed for the purpose to resist the attack of concentrated NaOH and molten salts. The content of the alloys was designed with the assistance of Thermo-Calc simulation software, and practically fabricated by vacuum arc melting (VAM). The newly designed alloys can be categorized as high Cr content alloys (alloy A, B and C) and low Cr content alloys (alloy D1, D2 and E). These newly designed alloys have been comprehensively evaluated with respect to their corrosion resistance under different conditions. Corrosion experiments were conducted, including polarization test, NaOH immersion test, salt immersion test and salt coated test. Experimental results have been compared to those of Monel-400 and Ni-205.
Research results illustrate the Cr addition does enhance the corrosion resistance of these alloys. The Cr atoms are able to induce a secondary passivation state and retard the beginning of the transpassivation in NaOH solutions. Furthermore, low Cr content alloys performed better in NaOH immersion test because the ability to avoid the formation of soluble compounds. In hot corrosion tests, the formation of protective Cr2O3 layer at elevated temperature can hinder further oxidation. Therefore, alloys with Cr more than 10wt.% can form continuous Cr2O3 layers effectively and result in better surface stability. To sum up, alloy D2 (Ni-10Cr) presented an outstanding corrosion resistance throughout all the corrosion tests.

Abstract...................I
摘要.......................II
致謝.......................III
Table of Contents..........V
List of Figures............VII
List of Tables.............XII
1. Introduction............................1
2. Literature Review.......................3
2.1. Nickel and nickel base alloys........3
2.1.1. Nickel.............................3
2.1.2. Monel-400..........................4
2.1.3. Ni-Cr alloys.......................5
2.2. Basic corrosion mechanism............7
2.3. Linear sweeping voltammetry..........9
2.4. Corrosion of Ni and Ni-base alloys in alkaline solution....11
2.5. Hot Corrosion Mechanism..............14
3. Material and Experiments................18
3.1. Experimental procedure...............18
3.2. Alloy design.........................19
3.3. Specimen preparation.................24
3.4. Corrosion experiments................24
3.4.1. Polarization test..................24
3.4.2. NaOH immersion test................26
3.4.3. Salt immersion test................27
3.4.4. Salt coated test...................28
3.5. Analyzing methods....................29
3.4.5. Optical microscopy.................29
3.4.6. X-ray diffraction..................29
3.4.7. Scanning electron microscopy.......29
4. Results and Discussion..................30
4.1. Polarization test....................30
4.2. NaOH immersion test..................35
4.2.1. NaOH immersion at 350℃ for 168 h....35
4.2.2. NaOH immersion at 400℃ for 168 h....40
4.2.3. NaOH immersion at 400℃ for 336 h....49
4.3. Hot corrosion test...................51
4.3.1. Salt immersion test................51
4.3.2. Salt coated test...................63
5. Conclusion..............................72
6. Future work.............................74
7. Reference...............................75

[1] Juan José Galán José A. Orosa, and Mar Toledano, A Real Case Study On The State Of Corrosion Of The Spanish Boats Journal of Marine Science and Technology, 2013. 21: p. 391-399.
[2] E. Aragon, Woillez, J., Perice, C., Tabaries, F., and Sitz, M., Corrosion resistant material selection for the manufacturing of marine diesel exhaust scrubbers. Materials & Design, 2009. 30: p. 1548-1555.
[3] H. Ezuber, El-Houd, A., and El-Shawesh, F., A study of the corrosion behavior of a aluminum alloys in seawater. Materials & Design, 2008. 29: p. 801-805.
[4] C. P. and Melchers Gardiner, R. E., Corrosion of mild steel by coal and iron ore. Corrosion Science, 2002. 44: p. 2665-2673.
[5] A. Al-Hahem, Abdullah, A., and Riad, W., Cavitation corrosion of nodular cast iron (NCI) in seawater: Microstructural effects. Materials Characterization, 2001. 47: p. 383-388.
[6] Weimin Zhao, Timing Zhang, Yonglin Wang, Jianhua Qiao, and Zerui Wang, Corrosion Failure Mechanism of Associated Gas Transmission Pipeline. Materials, 2018. 11(10).
[7] Mehdi Javidi and Shima Bekhrad, Failure analysis of a wet gas pipeline due to localised CO2 corrosion. Engineering Failure Analysis, 2018. 89: p. 46-56.
[8] Hamed Mansoori, Reza Mirzaee, Feridun Esmaeilzadeh, Arash Vojood, and Alireza Soltan Dowrani, Pitting corrosion failure analysis of a wet gas pipeline. Engineering Failure Analysis, 2017. 82: p. 16-25.
[9] S. Srikanth B. K. Panigrahi, J. Singh, Corrosion Failure in the Sugar Industry: A Case Study. Journal of Failure Analysis and Prevention, 2007. 7(3): p. 187-191.
[10] Robert Heidersbach, Metallurgy and Corrosion Control in Oil and Gas Production. 2010: John Wiley & Sons, Inc.
[11] Neil G Thompson, Mark Yunovich, and Daniel Dunmire, Cost of corrosion and corrosion maintenance strategies. Corrosion Reviews, 2007. 25(3-4): p. 247-262.
[12] Gerhardus H Koch, Michiel PH Brongers, Neil G Thompson, Y Paul Virmani, and Joe H Payer, Corrosion cost and preventive strategies in the United States. 2002.
[13] M.G.S. Ferreira M.F. Montemor, N.E. Hakiki , M. Da Cunha Belo, Chemical Composition and Electronic Structure of the Oxide Films Formed on 316L Stainless Steel and Nickel Based Alloys in High Temperature Aqueous Environments. Corrosion Science, 2000. 42: p. 1635-1650.
[14] Sudhangshu Bose, Chapter 4 - OXIDATION, in High Temperature Coatings, S. Bose, Editor. 2007, Butterworth-Heinemann: Burlington. p. 29-52.
[15] Environmental degradation: the role of coatings, in The Superalloys: Fundamentals and Applications, R.C. Reed, Editor. 2006, Cambridge University Press: Cambridge. p. 283-350.
[16] https://www.thebalance.com/metal-profile-nickel-2340147.
[17] https://en.wikipedia.org/wiki/Nickel.
[18] https://www.nickelinstitute.org/about-nickel/.
[19] http://megamex.com/monel-400-nickel-alloy.htm.
[20] https://www.hpalloy.com/Alloys/descriptions/MONEL400.aspx.
[21] Sudhangshu Bose, High Temperature Coatings. 1st ed. ed. 2007: Butterworth-Heinemann.
[22] N. S & Sims Stoloff, Chester T. (Chester Thomas), 1923- & Hagel, William C (1987), ed. Superalloys II. 1987, Wiley: New York.
[23] T.-K.; Yeh Tsao, A.-C.; Kuo, C.-M.; Murakami, H., High Temperature Oxidation and Corrosion Properties of High Entropy Superalloys. Entropy, 2016. 18.
[24] Shin-Puu Jeng, Paul H. Holloway, and Chris D. Batich, Surface passivation of Ni/Cr alloy at room temperature. Surface Science, 1990. 227(3): p. 278-290.
[25] Song Qian, R. C. Newman, R. A. Cottis, and K. Sieradzki, Computer simulation of alloy passivation and activation. Corrosion Science, 1990. 31: p. 621-626.
[26] P. Marcus and J. M. Grimal, The anodic dissolution and passivation of NiCrFe alloys studied by ESCA. Corrosion Science, 1992. 33(5): p. 805-814.
[27] K. Fukumoto M. Yasuda, Y. Ogata, and F. Hine, Corrosion Behavior of Ni and Ni-Based Alloys in Concentrated NaOH Solutions at High Temperatures. Journal of The Electrochemical Society, 1988.
[28] Brian Norton Anthony J. Farrell, David M. Kennedy, Corrosive effects of salt hydrate phase change materials used with aluminium and copper. Journal of Materials Processing Technology, 2006. 175.
[29] Denny Jones, Principle and Prevention of Corrosion. 1996, New Jersy: Prentice-Hall.
[30] Handbook of Chemistry and Physics. 71st ed. ed. 1991: CRC Press.
[31] Mariano Iannuzzi. Electromotive force (EMF) series. 2014.
[32] H. H. Uhlig R. W. Revie, Corrosion and corrosion control: an introduction to corrosion science and engineering. 2008, Kindle Edition.
[33] P. R. Roberge, Corrosion Engineering: Principles and Practice. 2008, McGraw-Hill Professional.
[34] Chih Chun Hung, Cholride Pitting Corrosion Resistance in Ge-containing in SS430, SS304 and SS316, in Materials Science and Engineering. 2017, National Tsing Hua University.
[35] Liping Wang, Junyan Zhang, Yan Gao, Qunji Xue, Litian Hu, and Tao Xu, Grain size effect in corrosion behavior of electrodeposited nanocrystalline Ni coatings in alkaline solution. Scripta Materialia, 2006. 55(7): p. 657-660.
[36] M Abdallah, IA Zaafarany, S Abd El Wanees, and R Assi, Corrosion behavior of nickel electrode in NaOH solution and its inhibition by some natural Oils. Int. J. Electrochem. Sci, 2014. 9(3): p. 1071-1086.
[37] JW Graydon and DW Kirk, Corrosion of nickel and stainless steels in concentrated lithium hydroxide solutions. Corrosion, 1990. 46(12): p. 1021-1028.
[38] M. Vuković, Voltammetry and anodic stability of a hydrous oxide film on a nickel electrode in alkaline solution. Journal of Applied Electrochemistry, 1994. 24(9): p. 878-882.
[39] https://en.wikipedia.org/wiki/Pourbaix_diagram.
[40] Naoto Takeno, Atlas of Eh-pH diagrams. Geological survey of Japan open file report, 2005. 419.
[41] F. S. Pettit J. A. Goebel, G. W. Goward Mechanisms for the hot corrosion of nickel-base alloys Metallurgical Transactions, 1973. Volume 4.
[42] G. H. Meier N. Birks, F. S. Pettit, Superalloys, Supercomposites and Superceramics. 1989: Academic Press.
[43] R. A. Rapp and K. S. Goto, Hot corrosion of metals by molten salts. Electrochemical Society, 1981.
[44] J. A. Goebel and F. S. Pettit, Na2SO4-induced accelerated oxidation (hot corrosion) of nickel. Metallurgical Transactions, 1970. 1(7): p. 1943-1954.
[45] J. A. Goebel and F. S. Pettit, The influence of sulfides on the oxidation behavior of nickel-base alloys. Metallurgical Transactions, 1970. 1(12): p. 3421-3429.
[46] Zhen Yang, Jin-tao Lu, Zheng Yang, Yan Li, Yong Yuan, and Yue-feng Gu, Oxidation behavior of a new wrought Ni-30Fe-20Cr based alloy at 750°C in pure steam and the effects of alloyed yttrium. Corrosion Science, 2017. 125: p. 106-113.
[47] F. A. Golightly, F. H. Stott, and G. C. Wood, The influence of yttrium additions on the oxide-scale adhesion to an iron-chromium-aluminum alloy. Oxidation of Metals, 1976. 10(3): p. 163-187.
[48] M. Bojinov, G. Fabricius, P. Kinnunen, T. Laitinen, K. Mäkelä, T. Saario, and G. Sundholm, The mechanism of transpassive dissolution of Ni–Cr alloys in sulphate solutions. Electrochimica Acta, 2000. 45(17): p. 2791-2802.
[49] M. Bojinov, I. Betova, R. Raicheff, G. Fabricius, T. Laitinen, and T. Saario, Mechanism of the Transpassive Dissolution and Secondary Passivation of Chromium in Sulphuric Acid Solutions. Materials Science Forum, 1998. 289-292: p. 1019-1028.
[50] N. Sato and K. Kudo, An ellipsometric study of anodic passivation of nickel in borate buffer solution. Electrochimica Acta, 1974. 19(8): p. 461-470.
[51] 宋光鈴, 曹楚南, and 林海潮, -不鏽鋼過鈍化二次鈍化的研究. 中國腐蝕與防護學報, 1994. 14(3): p. 208-216.
[52] V. P. Yurkinskii, E. G. Firsova, and L. P. Baturova, Corrosion resistance of a number of structural materials in a NaOH melt. Russian Journal of Applied Chemistry, 2010. 83(10): p. 1816-1821.
[53] V Venugopal, VS Iyer, V Sundaresh, Ziley Singh, R Prasad, and DD Sood, Standard molar Gibbs free energy of formation of NaCrO2 by emf measurements. The Journal of Chemical Thermodynamics, 1987. 19(1): p. 19-25.
[54] Ewa Ura-Binczyk, Nadzeya Homazava, Andrea Ulrich, Roland Hauert, Malgorzata Lewandowska, Krzysztof J Kurzydlowski, and Patrik Schmutz, Passivation of Al–Cr–Fe and Al–Cu–Fe–Cr complex metallic alloys in 1 M H2SO4 and 1 M NaOH solutions. Corrosion Science, 2011. 53(5): p. 1825-1837.
[55] Reidar Haugsrud, On the influence of non-protective CuO on high-temperature oxidation of Cu-rich Cu-Ni based alloys. Oxidation of Metals, 1999. 52(5-6): p. 427-445.
[56] M. P. Brady, I. G. Wright, and B. Gleeson, Alloy design strategies for promoting protective oxide-scale formation. JOM, 2000. 52(1): p. 16-21.
[57] NS Bornstein, MA DeCrescente, and HA Roth, The relationship between relative oxide ion content of Na 2 SO 4, the presence of liquid metal oxides and sulfidation attack. Metallurgical Transactions, 1973. 4(8): p. 1799-1810.
[58] H Cc Graham and HH Davis, Oxidation/vaporization kinetics of Cr2O3. Journal of the American Ceramic Society, 1971. 54(2): p. 89-93.
[59] Sofia Karlsson, Jesper Pettersson, L-G Johansson, and J-E Svensson, Alkali induced high temperature corrosion of stainless steel: the influence of NaCl, KCl and CaCl 2. Oxidation of metals, 2012. 78(1-2): p. 83-102.
[60] Z Szklarska-Smialowska, Effect of the ratio of Cl−/SO42− in solution on the pitting corrosion of Ni. Corrosion Science, 1971. 11(4): p. 209-221.