High-Temperature Oxidation of a High Silicon SiMo Spheroidal Cast Iron in Air with In Situ Change in H₂O Content

Abstract:

Exhaust manifolds for diesel engines are made of high-Si ferritic nodular cast irons. It is experimentally well established that their oxidation kinetics are highly sensitive to the presence of water vapor, though the mechanism for such an effect is still controversial. In the present work, isothermal oxidation tests were performed on a SiMo nodular cast iron at 700°C and 800°C in dry and humid air for 25 and 50 hours. Other samples were oxidized for 50 h with in-situ change in H₂O content after 25 h, switching from dry air to humid air or the other way round. Samples were then analyzed using XRD, SEM-EDS and Raman spectroscopy. Thermogravimetric records clearly showed the effect of temperature and environment on oxidation and decarburization. The kinetics of these phenomena depends on silica formation at the metal-oxide interface. At both temperatures, water vapor was seen to promote internal oxidation of Si instead of its external oxidation. This leads to higher oxidation kinetics at 700°C and higher decarburization kinetics at 800°C.

• Periodical: Materials Science Forum (Volume 925)
• Pages: 353-360
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.925.353
• Online since: June 2018
• Authors: André Ebel*, Serge Yapi Brou, Benoît Malard, Jacques Lacaze, Daniel Monceau, Loïc Vaissière
• Keywords: Cast Iron, High Temperature Oxidation, SiMo, Water Vapor

References

[1] W. Fairhurst, K. Rohrig, High-silicon nodular irons, Foundry Trade Journal. 146 (1979) 657–681.

[2] R. Yamauchi, S. Ishizuka, N. Suzuki, Development of Vanadium-added Heat Resistant Cast Iron for Exhaust Manifold, SAE Technical Paper, (2010).

DOI: 10.4271/2010-32-0073

[3] M. Ekström, Oxidation and corrosion fatigue aspects of cast exhaust manifolds, Doctoral thesis, KTH Royal Institute of Technology, (2015).

[4] K. Papis, S. Tunzini, W. Menk, Cast iron alloys for exhaust applications, 10th International Symposium on the Science and Processing of Cast Iron, Mar Del Plata, Argentina. (2014).

[5] P. Bastid, P. Pilvin, C. Grente, E. Andrieu, Microstructural Evolution of Spheroidal Graphite Cast Iron at High Temperature: Consequences on Mechanical Behaviour, Adv. Mat. Res. 4–5 (1997) 139–146.

DOI: 10.4028/www.scientific.net/amr.4-5.139

[6] Y. Yamaguchi, S. Kiguchi, H. Sumimoto, D.K. Nakamura, Effect of graphite morphology on decarburized cast iron, Int. J. Cast. Metal Res. 16 (2003) 137–142.

DOI: 10.1080/13640461.2003.11819572

[7] L.L. Liu, Q.Q. Guo, Y. Niu, Transition Between Different Oxidation Modes of Binary Fe–Si Alloys at 600–800 °C in Pure O2, Oxid Met. 79 (2013) 201–224.

DOI: 10.1007/s11085-012-9318-2

[8] M. Ekström, P. Szakalos, S. Jonsson, Influence of Cr and Ni on High-Temperature Corrosion Behavior of Ferritic Ductile Cast Iron in Air and Exhaust Gases, Oxid Met. 80 (2013) 455–466.

DOI: 10.1007/s11085-013-9389-8

[9] F. Tholence, M. Norell, High-Temperature Corrosion of Cast Irons and Cast Steels in Dry Air, Materials Science Forum. 369–372 (2001) 197–204.

DOI: 10.4028/www.scientific.net/msf.369-372.197

[10] I. Svedung, N.-G. Vannerberg, The influence of silicon on the oxidation properties of iron, Corros. Sci. 14 (1974) 391–399.

DOI: 10.1016/s0010-938x(74)80032-6

[11] A. Atkinson, A theoretical analysis of the oxidation of Fe–Si alloys, Corros. Sci. 22 (1982) 87–102.

[12] J.B. Heywood, Internal combustion engine fundamentals, Mcgraw-hill New York, (1988).

[13] F. Tholence, M. Norell, High Temperature Corrosion of Cast Alloys in Exhaust Environments I-Ductile Cast Irons, Oxid Met. 69 (2008) 13–36.

DOI: 10.1007/s11085-007-9081-y

[14] M. Fukumoto, S. Maeda, S. Hayashi, T. Narita, Effect of Water Vapor on the Oxidation Behavior of Fe–1.5Si in Air at 1073 and 1273 K, Oxid Met. 55 (2001) 401–422.

[15] S. Parent-Simonin, C. Moreaux, J.C. Margerie, Influence of the Annealing Atmosphere on the Structure of Malleable Cast Irons, Rev. Metall. 74 (1977) 537–543.

DOI: 10.1051/metal/197774100537

[16] M. Ekström, S. Jonsson, High-Temperature Corrosion Fatigue of a Ferritic Ductile Cast Iron in Inert and Corrosive Environments at 700oC, 10th International Symposium on the Science and Processing of Cast Iron, Mar Del Plata, Argentina. (2014).

[17] X. Wu, G. Quan, R. MacNeil, Z. Zhang, X. Liu, C. Sloss, Thermomechanical Fatigue of Ductile Cast Iron and Its Life Prediction, Metall. Mater. Trans. A. 46 (2015) 2530–2543.

DOI: 10.1007/s11661-015-2873-9

[18] V. Norman, P. Skoglund, D. Leidermark, J. Moverare, Damage Mechanisms in Silicon-Molybdenum Cast Irons subjected to Thermo-Mechanical Fatigue, Int. J. Fatigue. 99 (2017) 258–265.

DOI: 10.1016/j.ijfatigue.2017.01.014

[19] B.E. Deal, A.S. Grove, General relationship for the thermal oxidation of silicon, J. Appl. Phys. 36 (1965) 3770–3778.

[20] A. Atkinson, J.W. Gardner, The diffusion of Fe3+ in amorphous SiO2 and the protective properties of SiO2 layers, Corros. Sci. 21 (1981) 49–58.

DOI: 10.1016/0010-938x(81)90063-9

[21] C. Wagner, Reaktionstypen bei der Oxydation von Legierungen, Zeitschrift Für Elektrochemie, Berichte Der Bunsengesellschaft Für Physikalische Chemie. 63 (1959) 772–782.

DOI: 10.1002/bbpc.19590630713