Microstructure and corrosion resistance of Fe/Mo composite amorphous coatings prepared by air plasma spraying

Abstract

Fe/Mo composite coatings were prepared by air plasma spraying (APS) using Fe-based and Mo-based amorphous and nanocrystalline mixed powders. Microstructural studies show that the composite coatings present a layered structure with low porosity due to adding the self-bonded Mo-based alloy. Corrosion behaviors of the composite coatings, the Fe-based coatings and the Mo-based coatings were investigated by electrochemical measurements and salt spray tests. Electrochemical results show that the composite coatings exhibit a lower polarization current density and higher corrosion potentials than the Fe-based coating when tested in 3.5wt% NaCl solutions, indicating superior corrosion resistance compared with the Fe-based coating. Also with the increase in addition of the Mo-based alloy, a raised corrosion resistance, inferred by an increase in corrosion potential and a decrease in polarization current density, can be found. The results of salt spray tests again show that the corrosion resistance is enhanced by adding the Mo-based alloy, which helps to reduce the porosity of the composite coatings and enhance the stability of the passive films.

Keywords

composite coatings / plasma spraying / amorphous / corrosion resistance / microstructure

References

[1] Zhou Z., Wang L., Wang F.C., Zhang H.F., Liu Y.B., Xu S.H. Formation and corrosion behavior of Fe-based amorphous metallic coatings by HVOF thermal spraying. Surf. Coat. Technol., 2009, 204, 563

[2] Singh A., Bakshi S.R., Agarwal A., Harimkar S.P. Microstructure and tribological behavior of spark plasma sintered iron-based amorphous coatings. Mater. Sci. Eng. A, 2010, 527, 5000

[3] Li M., Christofides P.D. Multi-scale modeling and analysis of an industrial HVOF thermal spray process. Chem. Eng. Sci., 2005, 60, 3649

[4] Wang Y.Y., Li C.J., Ohmori A. Influence of substrate roughness on the bonding mechanisms of high velocity oxy-fuel sprayed coatings. Thin Solid Films, 2005, 485, 141

[5] Inoue A., Shen B.L., Chang C.T. Super-high strength of over 4000 MPa for Fe-based bulk glassy alloys in [(Fe_1−x-Co_x)_0.75B_0.2Si_0.05]₉₆Nb₄ system. Acta Mater., 2004, 52, 4093

[6] Zhou Z., Wang L., He D.Y., Wang F.C., Liu Y.B. Microstructure and electrochemical behavior of Fe-based amorphous metallic coatings fabricated by atmospheric plasma spraying. J. Therm. Spray Technol., 2011, 20, 344

[7] Lu W.H., Wu Y.P., Zhang J.J., Hong S., Zhang J.F., Li G.Y. Microstructure and corrosion resistance of plasma sprayed Fe-based alloy coating as an alternative to hard chromium. J. Therm. Spray Technol., 2011, 20, 1063

[8] Ponnambalam V., Poon S.J., Shiflet G.J. Fe-Mn-Cr-Mo-(Y,Ln)-C-B (Ln=Lanthanides) bulk metallic glasses as formable amorphous steel alloys. J. Mater. Res., 2004, 19, 3046

[9] Kiminami C.S., Souza C.A.C., Bonavina L.F., de Andrade Lima L.R.P., Suriñach S., Baró M.D., Bolfarini C., Botta W.J. Partial crystallization and corrosion resistance of amorphous Fe-Cr-M-B (M=Mo, Nb) alloys. J. Non Cryst. Solids, 2010, 356, 2651

[10] Zhang P.L., Yan H., Yao C.W., Li Z.G., Yu Z.S., Xu P.Q. Synthesis of Fe-Ni-B-Si-Nb amorphous and crystalline composite coatings by laser cladding and remelting. Surf. Coat. Technol., 2011, 206, 1229

[11] Yoo Y.H., Lee S.H., Kim J.G., Kim J.S., Lee C. Effect of heat treatment on the corrosion resistance of Ni-based and Cu-based amorphous alloy coatings. J. Alloys Compd., 2008, 461, 304

[12] Guo R.Q., Zhang C., Chen Q., Yang Y., Li N., Liu L. Study of structure and corrosion resistance of Fe-based amorphous coatings prepared by HVAF and HVOF. Corros. Sci., 2011, 53, 2351

[13] Liu L., Qiu C.L., Chen Q., Zhang S.M. Corrosion behavior of Zr-based bulk metallic glass in different artificial body fluids. J. Alloys Compd., 2006, 425, 268

[14] Zhang W.X., Jiang Z.H., Li G.Y., Jiang Q., Lian J.S. Electroless Ni-Sn-P coating on AZ91D magnesium alloy and its corrosion resistance. Surf. Coat. Technol., 2008, 202, 2570

[15] Niranatlumpong P., Koiprasert H. The effect of Mo content in plasma-sprayed Mo-NiCrBSi coating on the tribological behavior. Surf. Coat.Technol., 2010, 205, 483

[16] Pang S., Zhang T., Asami K., Inoue A. Bulk glassy Ni(Co-)Nb-Ti-Zr alloys with high corrosion resistance and high strength. Mater. Sci. Eng. A, 2004, 375–377, 368.

[17] Kawakita J., Kuroda S., Fukushima T., Kodama T. Improvement of corrosion resistance of high-velocity oxyfuel-sprayed stainless steel coatings by addition of molybdenum. J. Therm. Spray Technol., 2005, 14, 224