本研究主要探討以包覆擴散製程對AISI 304及316不銹鋼施以矽化處理進行表面矽化改質，在其表面製作含矽不銹鋼擴散披覆層，探討此擴散披覆層對於高溫塵化之影響，並探討不同溫度下之材料塵化行為。將未施以表面研磨或經過表面研磨之矽化不銹鋼分別置入管形爐中，通入比例為100/1的CO-CO2混合氣體，在600℃或700℃之溫度下，進行500小時長時間暴露試驗。

試驗結果發現，304及316不銹鋼經包覆擴散表面改質處理後，試片存在六方晶系之SiO2、Cr2O3及尖晶石結構之(Mn,Cr,Fe)3O4等氧化物，顯示矽化的過程中，伴隨著不銹鋼表面的氧化反應。經包覆擴散矽化處理後，表面矽化304不銹鋼表面經研磨後生成矽含量約為1.3～1.6wt%的含矽不銹鋼披覆層，而表面矽化316不銹鋼則生成矽含量約為1.1～1.3 wt%的含矽不銹鋼披覆層。

在700℃/500小時的暴露試驗中，未施以表面研磨之矽化304不銹鋼表面可觀察到大量的碳沈積，由截面觀察得知在其下的金屬層表面有蝕孔生成；而表面施以＃1000砂紙研磨之矽化304不銹鋼其碳沈積現象較輕微並未觀察到蝕孔的生成，但觀察到塵化初期萌芽階段的反應特徵。而矽化316不銹鋼在600℃/500小時的暴露試驗中，表面未經研磨之矽化316不銹鋼試片表面觀察到的碳沈積量較700℃試驗所得結果為多；表面施以＃1000砂紙研磨之矽化316不銹鋼碳沈積現象較輕微，經截面觀察僅少數的蝕孔生成。此蝕孔的生成是發生塵化反應的結果，因此，不論在500小時700℃或600℃的暴露試驗中，表面經研磨之矽化試片均較未研磨試片具有更佳的塵化抵抗性。

The high temperature metal dusting behaviors of siliconized AISI 304 and 316 stainless steels in mixed CO/CO2 atmosphere at 600℃ or 700℃ were investigated. Siliconization was achieved by performing pack cementation treatment. The surface condition of siliconized AISI 304 and 316 stainless steels were ground and unground. The ratio of the mixed CO/CO2 atmosphere for exposing test was 100/1 and the experimental time was 500 hours in the tube furnace.

After pack cementation treatment siliconized AISI 304 and 316 stainless steels formed rich silicon layer. The surface production were SiO2 and Cr2O3 oxide of hexagonal structure and (Mn,Cr,Fe)3O4 oxide of spinal structure. The silicon content of siliconized 304 stainless steels after grinding off the surface was 1.3~1.6wt% and siliconized 316 was 1.1~1.3 wt%.

The experimental results showed that a thick carbon deposit was found on the specimen surface of each of the as-pack treated siliconized stainless steels after exposing in high temperature and high carbon activity gas atmosphere. The carbon deposition of siliconized 304 stainless steels was less than siliconized 316 stainless steels. Under the deposit, pits resulting from metal dusting reaction were found on the metal surface. By grinding off the surface compound formed during pack cementation, less carbon was deposited on the surface of the siliconized stainless steels. A few pits were found on ground siliconized 316 stainless steels and unfound on ground siliconized 304 stainless steels. No pits were found on the metal surface of such specimens. As a result, the ground siliconized stainless steels had better resistant of metal dusting than as-silionized stainless steels, even in 700℃ or 600℃exposing test for 500 hours.

1.W. B. Hoyt, R. H. Caughey, “High Temperature Metal Deterioration in Atmospheres Containing Carbon-Monoxide and Hydrogen”, Corrosion Vol.15,pp.627t~630t 1959.

2.P. A. Lefrancois, W. B. Hoyt, “Chemical thermodynamics of high temperature reactions in metal dusting corrosion”, Corrosion Vol.19,pp.360t~368t 1963.

3.R.F. Hochman, “Basic Studies of Metal Deterioration in Carbonaceous Atmospheres at Elevated Temperatures”, Proc. 4th Int. Congress Metal Corrosion, ed. N. E. Hamner (Houston, Texas: NACE, 1972), pp.258-263 1972.

4.R.F. Hochman, “Catastrophic Deterioration of High-Temperature Alloys in Carbonaceous Atmospheres”, in Proc. Symp. High -Temperature Alloys with Emphasis on Environmental Effects, eds. Z. A. Foroulis, F. S. Pettit (Pennington, NJ: The electrochemical Society, 1977) pp.715~732 1977.

5.H.J. Grabke, R. Krajak, E.M. Müller -Lorenz, S. Strauss, “Metal dusting of nickel-base alloys”, Materials and Corrosion, Vol.47, pp.495~504 1996.

6.Holland M. L., de Bruyn, H. J., “Metal dusting failure in methane reforming plant”, The International Journal of Pressure Vessels and Piping, Vol.66, Issue.1~3, pp.125~133 1996.

7.K.L. Baumert, J.J. Hoffman, “Materials experience in methanol reforming units”, Materials Performance Vol.37. No.5, pp.60~64 1998.

8.H.J. Grabke, “Metal dusting of low-and high-alloy steels”, Corrosion, Vol.51, No.9, pp.711~720 1995.

9.F. Dettenwanger, D. Grotmann, H. Friedrich, E. Berghf-Hasselbächer, M. Schorr, M. Schütze, “Damage of a heat-treatment retort by metal dusting attack”, Materials and Corrosion, Vol.50, pp.289~293 1999.

10.T. Shibasaki, K. Takemura, T. Mohri, H. Hashimoto, “Experience with Metal dusting in H2/CO/CO2/H2O atmosphere”, Ammonia Technical manual (Ammonia plant safety and related facilities), Vol.36, pp.165~179 1996.

11.H.J. Grabke, R. Krajak, J.C. Nava Paz, “On the mechanism of catastrophic carburization: ‘Metal Dusting’”, Corrosion Science, Vol.35, No.5~8, pp.1141~1150 1993.

12.H.J. Grabke, E.M. Müller Lorenz, “Protection of high alloy steels against metal dusting by oxide scales”, Materials and Corrosion, Vol.49, pp.317~320 1998.

13.D. Monceau, E.M. Muller-Lorenz, H.J. Grabke, “Metal dusting of stainless steels”, Materials Science Forum, Vol.251~254, pp.665~670 1997.

14.S. Strauss, H.J. Grabke, “Role of alloying elements in steels on metal dusting”, Materials and Corrosion, Vol.49 pp.321~327 1998.

15.D. C. Agarwal, Ulrich Brill, “Performance of Alloy 602CA (USN N06025) in High Temperature Environment up to 1200 ℃ (=2200℉)”, CORROSION 2000, Paper No.00521, March 26~31,2000 Orlando, Florida, USA 2000.

16.S. Strauss, H. J. Grabke, “Role of alloying elements in steels on metal dusting”, Materials and Corrosion, Vol.49 pp.321~327 1998.

17.D. J. Young, “High Temperature Corrosion in reducing Gas”, The 10th Asia Pacific Corrosion Control Conference, Paper No.K1, pp.27~31 Oct.1997 Bali, Indonesia, 1997.

18.N. V. Bangaru and R. C. Krutenat, “Diffusion coating of steel: Formation mechanism and microstructure of aluminized heat-resistance steels”, J. Vac. Sci. Technology, Vol. B2(4), pp.806~815, Oct.~ Dec. 1984

19.D. M. Miller, S. C. Kung, S. D. Scarberry and R. A. Rapp, “Simultaneous Chromizing-Aluminizing Coating of Austenitic Stainless Steel”, Oxidation of Metals, Vol. 29, Nos. 3/4, pp.239~254, 1988

20.F. D. Geib and R. A. Rapp, “Simultaneous Chromizing-Aluminizing Coating of Low Alloy Steel by a Halide-Activated, Pack Cementation Process”,
Oxidation of Metals, Vol. 40, Nos. 3/4, pp.213~228, 1993

21.K. Y. Kim, H. G. Jung, B. G. Seong and S. Y. Hwang, “Improvement of Cyclic High-Temperature Corrosion Resistance of Pack-Aluminized Heat-Resistance Stainless Steels”, Oxidation of Metals, Vol. 41, Nos. 1/2, pp.11~35, 1994

22.P. A. Choquet, E. R. Naylor and R. A. Rapp, “Simultaneous Chromizing-Aluminizing Coating of Iron-base Alloys”, Materials Science and Engineering, Vol. A121, pp.413~418, 1989

23.W. D. Coasta, B. Gleeson and D. J. Young, “Codeposited Chromium-Aluminide Coating”, J. Electrochem. Soc., Vol. 141, No. 10,pp.2690~2698, Oct., 1994

24.R. Mevrel, C. Duret and R. Pichoir, “Pack Cementation Processes”, Materials Science and Technology, Vol. 2, p.201, 1986

25.J.C. Nava Paz, H.J. Grabke, “Metal dusting”, Oxidation of Metals,Vol.39, No.5/6, pp.437~456 1993.

26.H.J. Grabke, R. Krajak, E.M. Müller Lorenz, “Metal Dusting of High Temperature Alloys”, Werkstoffe und Korrosion, Vol.44, pp.89~97 1993.

27.H.J. Grabke, C.B. Bracho-Troconis, E.M. Müller Lorenz, “Metal Dusting of low alloy steels”, Werkstoffe und Korrosion, Vol.45, pp.215~221 1994.

28.S. Forseth, P. Kofstad, “Metal Dusting phenomenon during carburization of Fe-Ni-Cr-alloys at 850~1000℃”, Materials and Corrosion, Vol.46, pp.201~206 1995

29.H.J. Grabke, E.M. Müller-Lorenz, J. Klower, D.C. Agarwal, “Metal dusting of Nickel-based Alloys”, Materials Performance, Vol.37. No.7, pp.58~63
1998.

30.B.A. Baker, G.D. Smith, “Metal dusting of Nickel-containing alloys”,CORROSION 1998, Paper No.445, March 22~27,1998 San Diego, California, USA
1998.

31.Brian A. Baker, Gaylord D. Smith, “Metal Dusting Behavior of High Temperature Alloys”, CORROSION 1999, Paper No.54, April 25~30 1999, San
Antonio, Texas, USA 1999

32.Mark Maier, James F. Norton, “Studies concerned with the metal dusting of Fe-Cr–Ni Materials”, CORROSION 1999, Paper No.75, April 25~30 1999, San Antonio, Texas, USA 1999

33.Eckhard Pippel, Jorg Woltersodorf, Hans Jurgen Grabke, Silke Strauss,“Microprocesses of metal dusting on iron”, Steel Research Vol.66, No.5, pp217~221 1995.

34.S. K. Bose, H.J. Grabke, “Diffusion Coefficient of Carbon in Fe-Ni Austenite in the Temperature Range 950~1100℃”, Zeitschrift fur Metallkunde Vol.69, pp.8~15 1978.

35.R. Schneider, E. Pippel, J. Woltersdorf, S. Strauss, H.J. Grabke,“Microprocesses of metal dusting on nickel and Ni-base alloys”, Steel
Research Vol.68, No.4, pp326~332 1997.

36.E. Pippel, J. Woltersdorf, R. Schneider, “Micromechanisms of metal dusting on Fe-base and Ni-base alloys”, Materials and Corrosion, Vol.49,
pp.309~316 1998.

37.Brian A. Baker, Gaylord D. Smith, “Metal Dusting Behavior of High Temperature Alloys”, CORROSION 1999, Paper No.54, April 25~30 1999, San
Antonio, Texas, USA 1999.

38.S. Strauss, H.J. Grabke, “Role of alloying elements in steels on metal dusting”, Materials and Corrosion, Vol.49 pp.321~327 1998.

39.D. J. Young, “High Temperature Corrosion in reducing Gas”, The 10th Asia Pacific Corrosion Control Conference, Paper No.K1, 27~31 Oct.1997
Bali, Indonesia, 1997.

40.H.J. Grabke, E.M. Müller-Lorenz, “Occurrence and Prevention of Metal dusting”, CORROSION 2001, Paper No.01373, March 11~16,2001 Houston,Texas, USA 2001.

41.Mark Maier, James F. Norton, “Studies concerned with the metal dusting of Fe-Cr–Ni Materials”, CORROSION 1999, Paper No.75, April 25~30 1999, San Antonio, Texas, USA 1999.

42.D. J. Young, “High Temperature Corrosion in reducing Gas”, The 10th Asia Pacific Corrosion Control Conference, Paper No.K1, 27~31 Oct.1997 Bali, Indonesia, 1997.

43.H.J. Grabke, E.M. Müller Lorenz, “Protection of high alloy steels against metal dusting by oxide scales”, Materials and Corrosion, Vol.49, pp.317~320 1998.

44.D. Monceau, E.M. Muller-Lorenz, H.J. Grabke, “Metal dusting of stainless steels”, Materials Science Forum, Vol.251~254, pp.665~670 1997.

45.H.J. Grabke, R. Krajak, J.C. Nava Paz, “On the mechanism of catastrophic carburization Metal Dusting”, Corrosion Science, Vol.35, No.5~8,
pp.1141~1150 1993.

46.E.M. Müller-Lorenz, S. Strauss, H.J. Grabke, “Effects of Surface state, Microstructure and alloying additions on metal dusting Resistance of High Alloys steel”, EURROCORR 98, Paper No.24, 28th Sept.~1st Oct. Jaarbeurs Congress Center Utrecht, The Netherlands 1998.

47.Wen-Ta Tsai, Hung-Wen Hsu, “Method for the CO-deposition of Silicon and Nitrogen on Stainless Steel Surface”, United States Patent No.: US 6,428,849 B1.Aug.6, 2002