本研究首先探討片狀石墨鑄鐵(FC200)與球狀石墨鑄鐵(FCD400)在靜止空氣中之高溫氧化行為，觀察與分析氧化層的結構與成分，研究不同石墨形態對鑄鐵材料抗高溫氧化性之影響。隨後，經由兩種表面改質方法；熱浸鍍鋁與鍍鎳熱浸鍍鋁，分別施加鋁塗層與鎳鋁塗層於片狀石墨鑄鐵與球狀墨鑄鐵表面，分析鋁塗層與鎳鋁塗層對鑄鐵的高溫氧化保護性與抗熱疲勞性之差異，以及探討石墨形態對塗層之高溫性質的影響。
高溫氧化動力學顯示石墨型態對於鑄鐵材料抗高溫氧化性有明顯的影響，片狀石墨鑄鐵之抗高溫氧化性低於球狀石墨鑄鐵。觀察片狀石墨鑄鐵高溫氧化層的連續成長行為顯示，由於氧氣持續由氧化後之片狀石墨滲入，促使鐵氧化物沿片狀石墨晶界向材料內部快速生長，發生材料內部氧化，因此片狀石墨鑄鐵氧化速率常數高出球狀石墨鑄鐵氧化速率常數5倍。
兩類鑄鐵再藉由沉浸於700 °C之純鋁熔湯中120秒，施加鋁化塗層於兩種鑄鐵材料。鑄鐵材料經由熱浸鍍鋁後，鋁化塗層經組成相分析顯示，從表面至基材側皆依序為鋁、鐵鋁介金屬(FeAl3、Fe2Al5)與石墨所組成。在鑄鐵沉浸於鋁熔湯發生元素交互擴散過程，由於鑄鐵中的鐵元素向外擴散的速率大於鋁熔湯中的鋁向鑄鐵材料內擴散的速率，所以片狀石墨/球狀墨鑄鐵材料經熱浸鍍鋁後，片狀石墨與球狀石墨將散佈於鋁化塗層，因而造成鋁化塗層經高溫氧化後可能發生塗層失效，其中又以鋁塗層內的片狀石墨氧化所造成的鋁塗層孔洞、失效與剝落最為嚴重，對鋁塗層耐高溫氧化性能具有明顯的負面影響。
為了避免鑄鐵熱浸鍍鋁後石墨散佈於鋁化塗層，造成塗層經高溫氧化後產生裂縫與孔洞，本研究提出兩階段披覆塗層方法：鑄鐵材料先經電鍍鎳披覆一純鎳層在鑄鐵材料表面，再進行熱浸鍍鋁處理。實驗結果顯示鑄鐵表面經由預鍍鎳再熱浸鍍鋁所得到之鋁鎳塗層不會有石墨存在，鋁鎳塗層是由鋁、鎳鋁介金屬與鎳所組成。氧化動力學與顯微結構觀察結果顯示，經由預鍍鎳-熱浸鍍鋁方式所塗覆在鑄鐵材料表面的鎳鋁塗層有更好的抗高溫氧化與抗熱疲勞性。

Flake and spheroidal graphite cast iron with similar composition were subjected to high temperature oxidation in static air to investigate graphite morphology and distribution effects on the oxidation behavior. Flake graphite and spheroidal graphite cast iron were coated with aluminide coating and Ni-Al coating. In order to realize high temperature oxidation and thermal fatigue resistance of aluminide coating/Ni-Al coating, isothermal and thermal cycling oxidation tests of two types of cast iron with aluminide coating/Ni-Al coating have been conducted.
High temperature oxidation kinetics reveal graphite morphology influence oxidation resistance of cast iron at high temperature. The flake graphite cast iron exhibited the worse high-temperature oxidation resistance compared with spheroidal graphite cast iron. Since graphite flakes provide suitable sites for the iron oxide growth and are almost interconnected, the iron oxide grows faster and penetrates along the graphite flakes boundaries resulting in the subsurface oxidation. Due to the severe subsurface oxidation flake graphite cast iron parabolic rate constants is 5 times higher than that of the spheroidal graphite cast iron.
Flake and spheroidal graphite cast iron were aluminized with hot-dipping in Al for 120 s. As-coated aluminide layer consists of the outer Al topcoat, inner Fe-Al intermetallic layer (FeAl3, Fe2Al5) and dispersed graphite. Since Fe diffusion rate is faster than that of Al during hot-dipping in Al melt, aluminide layer gradually grows inward, that is, graphite would gradually be trapped in aluminide layer during hot-dipping in Al melt. Graphite would directly interact with oxygen causing graphite oxidation leaving cracks or pores in the aluminide layer which results in oxygen penetration through aluminide coating to the cast iron substrate. The structure of flake graphite in the aluminide layer and the substrate is extended and connected, producing continuous pass, allowing oxygen penetration through the aluminide coating to cast iron substrate, initiating oxygen attack. Consequently, aluminide coating on flake graphite cast iron exhibits less oxidation resistance and adhesion to the substrate.
In order to avoid graphite trapped in aluminide coating and overcome trapped graphite oxidized leaving cracks or pores in the coating, we conducted two-step coating method; plating Ni layer on cast iron surface and then aluminizing nickel-plated cast iron with hot-dip Al. As-coated Ni-Al layer is free of graphite, which consists of the outer Al topcoat, inner Ni-Al intermetallic layer (NiAl3, Ni2Al3) and Ni layer. The results of high temperature oxidation tests and microstructure examinations reveal that Ni-Al coating exhibits significantly better high temperature oxidation resistance than that of aluminide coating.

1. C. Labrecque and M. Gagne, Canadian Metallurgical Quarterly 37 (1998) 343.
2. P. Curcio, B. Kerezsi, P. Brown, Eng. Fail. Anal. 11 (2004) 925.
3. C. Labrecque and M. Gagne, Can. Metall. Quart 37 (1998) 343.
4. G.S. Cho, K.H. Choe, K.W. Lee, A. Ikenaga, Mater. Sci. Technol. 23 (2007) 97.
5. A.R. Ghaderi, M. Nili Ahmadabadi, H.M. Ghasemi, Wear 225 (2003) 410.
6. M. Hatate, T. Shoita, N. Takahashi, K. Shimizu, Wear 251 (2001) 885.
7. Y. Zhang, Y. Chen, R. He, B. Shen, Wear 166 (1993) 179.
8. N. Birks and G. H. Meier, "Introduction to high temperature oxidation of metals," Edwar Arnold Ltd, p. 73, 1983.
9. Park, "Development of a heat resistant cast iron alloy for engine exhaust manifolds," SAE 2005.
10. R. Sivakumar and E. Janardhana Rao, Oxid. Met. 17 (1982) 391.
11. G. A. Capuano, A. Dang, U. Bernabai, and F. Felli, Oxid. Met. 39 (1993) 263.
12. T. Zhang and L. Dy, Mater. Sci. Eng. A277 (2000) 18.
13. C. J. Wang and C. C. Li, Surf. Coat. Technol. 177-178 (2003) 37.
14. C. C. Tsaur, J. C. Rock, and Y. Y. Chang, Mater. Chem. Phys. 91 (2005)
15. T. C. Simpson, Corrosion 49 (1993) 550.
16. G. W. Goward, Surf. Coat. Technol. 108-109 (1998) 73.
17. A. L. Purvis and B. M. Warnes, Surf. Coat. Technol. 146-147 (2001) 1.
18. M. B. Lin, C. J. Wang, Alex A. Volinsky, Oxid. Met. 76 (2011) 161.
19. M. B. Lin and C. J. Wang, Surf. Coat. Technol. 205 (2010) 1220.
20. M. B. Lin and C. J. Wang, Advanced Materials Research 79-82 (2001) 2151.
21. M. B. Lin and C. J. Wang, Surf. Coat. Technol. 205 (2010) 1220.
22. N. Birks and G. H. Meier, "Introduction to high temperature oxidation of metals", Edwar Arnold Ltd, p.17, 1983.
23. O. Kub and E. LL. Evans, "Metallurgical Thermochemistry", Pergamion, New York, p. 225 (1958).
24. D. R. Stull and H. Prophet, "JANAF Thermochemical Table", Edward Arnold, London, NSRDSNBS37, p. 31 (1983).
25. A. S. Khanna, "Introduction to High Temperature Oxidation and Corrosion ", ASM International, USA, pp.26 (2002).
26. A. S. Khanna, "Introduction to High Temperature Oxidation and Corrosion", ASM International, USA, pp.38 (2002).
27. U. R. Evans, "The Corrosion and Oxidation of Metals", Edward Arnold, London, p.39 (1960).
28. M. G. Fontana, "Corrosion Engineering", McGraw-Hill Book Company, New York, p.505 (1986).
29. J. M. West, "Basic Corrosion and Oxidation", Prentice Hall, New York, pp. 171-173 (1986).
30. O. Kubaschewaki and B. E. Hopkins, "Oxidation of Metals and Alloys", Academic Press, New York, pp.113 (1962).
31. N. Birks and G. H. Meier, "Introduction to high temperature oxidation of metals", Edwar Arnold Ltd, pp.73 (1983).
32. F. Gesmundo and F. Viani, Corrosion Sci. 18 (1978) 231.
33. A. Rahmel, Chem. Metall. Iron Steel 146 (1973) 395.
34. N. Birks and G. H. Meier, "Introduction to high temperature oxidation of metals", Edwar Arnold Ltd, pp.54 (1983).
35. Chester T. Sims, Norman S. Stoloff, William C. Hagel. , "Superalloys II", Wiley, New York, p.295 (1987).
36. 40th Census of World Casting Production-2005, Modern Casting, p.28 (2006).
37. J. R. Dryden, G. R. Purdy, Acta metall. 37 (1989) 1999.
38. William F. Smith, "Structure and Properties of Engineering Alloys", McGraw-Hill, New York, p.335 (1993).
39. Yun Long Yang, Zhan Yi Cao, Yang Qi, Yong Bing Liu, Advanced Materials Research 97-101 (2010) 530.
40. J. Robertson and M.I. Manning, Mater. Sci. Tech. 5 (1989) 741.
41. A. R. Kiani Rashid and D. V. Edmonds, Surf. Interface Anal. 36 (2004) 1011.
42. Yoon-Jun Kim, Ho Jang, and Yong-Jun Oh, Metall. Mater. Trans. A 40 (2009) 2087.
43. F. Tholence and M. Norell, Oxid. Met. 69 (2008) 13.
44. C. H. Koo and T. H. Yu, Surf. Coat. Technol. 126 (2000) 171.
45. F. J. Perez, M. P. Hierro, C. Carpintero, F. Pedraza, and C. Gomez, Surf. Coat. Technol. 140 (2001) 93.
46. H. J. Kim and M. E. Walter, Mater. Sci. Eng. A360 (2003) 7.
47. F. H. Stott, Rep. Prog. Phys. 50 (1987) 861.
48. G. W. Goward, Mater. Sci. Technol. 2 (1986) 194.
49. S. T. Bluni and A. R. Marder, Corrosion 52 (1996) 213.
50. S. R. J. Saunders and J. R. Nicholls, Mater. Sci. Technol. 5 (1989) 780.
51. F. Barbier, D. Manuelli, and K. Bouche, Script. Mater. 36 (1997) 425.
52. F. M. Robert, "Metals handbook", American Society for Metals, 9th Edn.,Vol.5 (1983) 333-347.
53. A. Bahadur and O. N. Mohanty, Mater. Trans. JIM. 32 (1991) 1053
54. D.M. Dovey and A. Waluskit, "Continuous Dip Aluminising of Steel" ,Metallurgia, pp. 211-217 (1963).
55. S. Kobyashi and T. Yakou, Mater. Sci. Eng. A338 (2002) 44.
56. T. B. Massalski and H. Okamoto, Binary Alloy Phase Diagrams, Vol. 1. ASM International, 1990, pp.148
57. P. N. Bindumadhavan, S. Makesh, N. Gowrishankar, H. K. Wah, O. Prabhakar, Surf. Coat. Technol. 127 (2000) 252.
58. K. Bouche, F. Barbier, and A. Coulet, Mater. Sci. Eng. A249 (1998) 167.
59. D. Wang and Z. Shi, Appl. Surf. Sci. 227 (2004) 255.
60. K. Stein-Fechner, J. Konys, and O. Wedemeyer, J. Nucl. Mater. 249 (1997) 33.
61. D. R. G. Achar, J. Ruge, and S. Sundaresan, "Joining Aluminum and Steel, Especially by Means of Welding", Aluminum Monography, Aluminum-Verlag, Dusseldorf, 1980.
62. S. C. Deevi and V. K. Sikka, Intermetallics 4 (1996) 357.
63. N. A. EI-Mahallawy, M. A. Taha, M. A. Shady, A. R. EI-Sissi, A. N. Attia, and W. Reif, Mater. Sci. Technol. 13 (1997) 832.
64. L. N. Larikov, V. M. Falchenko, D. F. Polishebuk, V. R. Ryabov, and A. V. Lonovskays, "Protective Coatings on Metals", vol. III, Consultant Bureau, New York, 1971, p. 56.
65. 張榮珍，表面處理，文京圖書，1988。
66. 柯賢文，表面與薄膜處理技術，全華科技圖書，2005。
67. G.W. Goward, Surf. Coat. Technol. 108–109 (1998) 73
68. A. Squillace, R. Bonetti, N.J. Archer and J.A. Yeatman, Surf. Coat. Technol. 120–121 (1999) 118
69. Z.D. Xiang, J.S. Burnell-Gray and P.K. Datta, J. Mater. Sci. 36 (2001) 5673.
70. P. Nash, M.F. Singleton, J.L. Murray, in: P. Nash (Ed.), Phase Diagrams of Binary Nickel Alloys, Materials Park, OH, 1991, pp. 3.
71. S. C. Deevi and V. K. Sikka, Intermetallics 4 (1996) 357.
72. R. Sivakumar and B. L. McMordie, Surf. Coat. Technol. 37 (1989) 160.
73. A. G. Evans, G. B. Crumley, and R. E. Demaray, Oxid. Met. 20 (1983) 193.
74. J. H. Sun, E. Chang, C. H. Chao and M. J. Cheng, Oxid. Met. 40 (1993) 465.
75. Y. Wang, Z.-K. Liu, L.-Q. Chen, Acta metall., 52 (2004) 2665.
76. Touloukian YS, Kirby RK, Taylor RE, Desai PD. Thermophysical properties of matter thermal expansion, Plenum Press , New York,1975.
77. Ho CY, Properties of selected ferrous alloying elements, Hemisphere Publishing Corporation, 1989.
78. P. Kofstad, Nonstoichiometry, Diffusion and Electrical Conductivity in Binary Metal Oxides, Wiley-Interscience, New York, 1972.
79. A.S. Khanna, High Temperature Oxidation and Corrosion, ASM International, Nevada, 2002, pp. 1-11.
80. D. D. Double and A. Hellawell, Acta Metall. 22 (1974) 481.
81. H.R. Shaverdi, M. R. Ghomashchi, S. Shabestari, J. Hejazi, J. Mater. Process. Technol. 124 (2002) 345.
82. G. Neumann, in: H. Mehrer (Ed.), Diffusion in Solid Metals and Alloys, Numerical Data and Functional Relationships in Science and Technology, vol. 26, Springer, 1990,
83. A.D. Le Claire, "Diffusion in Solid Metals and Alloys, Numerical Data and Functional Relationship in Science and Technology", vol. 26, Springer, 1990, p. 129.
84. G. Eggeler, W. Auer, H. Kaesche, Z. Metallkde 77 (1986) 239.
85. H. Bakker, "Diffusion in Solid Metals and Alloys", Numerical Data and Functional Relationship in Science and Technology, vol. 26, Springer, 1990, p. 220.
86. B.A. Pint, J. Leibowitz, J.H. De Van, Oxid. Met. 51 (1999) 181.
87. N. Birks and G.H. Meier, "Introduction to High Temperature Oxidation of Metals", Edward Arnold, London, 1983, p.73.
88. J. Wang, H.J. Engell, Steel Res. 63 (1992) 320.
89. G. Róg, G. Borchardt, M. Wellen, W. Löser, J. Chem.Thermodynamics 35 (2003) 261.
90. R. C. Voigt and S. D. Holmgren, AFS Trans., 98 (1990) 213.
91. K.S. Kumar, S.K. Mannan, R.K. Viswanadham, Acta metall., 40 (1992) 1201.
92. Ricardo A. Martinez, Eng. Fract. Mech. 77 (2010) 2749.
93. Charles F. Walton, "Gray and Ductile Iron Castings Handbook", The Gray and Ductile Iron Founders Society Inc., Cleveland, 1971, pp. 256.
94. S. G. Denner and R. D. Jones, Met. Technol. 4 (1977) 167.
95. G. A. Lopez, S. Sommadossi, P. Zieba, W. Gust, and E. J. Mittemeijer, Mater. Chem. Phys. 78 (2003) 459.