Abstract
The simultaneous chromizing — aluminizing of low-alloy steels has achieved Kanthal-like surface compositions of 16–21Cr and 5–8 wt.% Al by the use of cementation packs with a Cr-Al masteralloy and an NH4Cl activator salt. An initial preferential deposition of Al into the alloy induces the phase transformation from austenite to ferrite at the 1150°C process temperature. The low solubility of carbon in ferrite results in the rejection of solute C into the austenitic core, thereby preventing the formation of an external Cr-carbide layer, which would otherwise block aluminizing and chromizing. The deposition and rapid diffusion of Cr and Al into the external bcc ferrite layer follows. Parabolic, cyclic-oxidation kinetics for alumina growth on the coated steels in air were observed over a wide range of relatively low temperatures (637–923°C).
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
W. T. Bakker and R. A. Perkins, Proc. 3rd Berkely Conf. on Corrosion/Erosion/Wear of Materials at Elevated Temperatures, Jan. (1990).
C. S. Giggins and F. S. Pettit,Met. Trans. (1970).
C. Wagner,Corros. Sci. 5, 751–764 (1965).
B. Nciri and L. Vandenbulke,J. Less-Common Met. 95, 191 (1983).
P. N. Walsh, inChemical Vapor Deposition, G. G. Wadefield and J. B. Blocker, eds. (The Electrochemical Society, Pennington, NJ, 1973), p. 147.
R. A. Rapp, D. Wang, and T. Weisert, inHigh Temperature Coatings, M. Khobaib and R. C. Krutenat, eds. (TMS, Warrendale, PA, 1987), pp. 131–141.
D. M. Miller, S. D. Scarberry, and R. A. Rapp,Oxid. Met. 29, 239 (1988).
P. A. Choquet, E. R. Naylor, and R. A. Rapp,Mater. Sci. Eng. A121, 413 (1989).
S. C. Kung and R. A. Rapp,Oxid. Met. 32, 89 (1989).
D. M. Miller, PhD dissertation, The Ohio State University (1990), pp. 75–77.
Binary Alloy Phase Diagrams, Vol. 1, T. B. Massalski (ASM, Metals Park, OH, 1986), p. 104.
R. Bianco and R. A. Rapp,J. Electrochem. Soc. 140, 1181 (1993).
H. Flynn, A. E. Morris and D. Carter, Proc. 25th CIM Conf. for Metallurgists, TMS-CIM, Toronto, Ontario (1986).
Chemical Thermodynamics of Materials, C. H. P. Lupis (Elsevier Sci. Pub. Co., NY, 1983), p. 524.
S. K. Gupta, S. R. Adolph, L. C. Tandon, and L. L. Seigle,Met. Trans. 13A, 495 (1982).
S. C. Kung, Babcock & Wilcox Co., private communication.
P. Tomaszewicz and G. R. Wallwork,Oxid. Met. 20, 75–109 (1983).
F. S. Pettit,Met. Trans. AIME 239 (1967).
T. Amano, S. Yajima, and Y. Saito,Trans. Jpn. Inst. Met. 20, 431–441 (1979).
G. C. Rybicki and J. L. Smialek,Oxid Met. 31, 275–304 (1989).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Geib, F.D., Rapp, R.A. Simultaneous chromizing — Aluminizing coating of low-alloy steels by a halide-activated, pack-cementation process. Oxid Met 40, 213–228 (1993). https://doi.org/10.1007/BF00664491
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00664491