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http://dx.doi.org/10.14773/cst.2013.12.1.007

HVOF spray coating of WC-metal powder for the improvement of friction, wear and corrosion resistance of magnetic bearing shaft material of turbo blower  

Joo, Y.K. (Materials Engineering Department, Changwon National University)
Yoon, J.H. (Materials Engineering Department, Changwon National University)
Cho, T.Y. (Institute of Industrial Technology, Changwon National University)
Chun, H.G. (School of Materials Science and Engineering, University of Ulsan)
Publication Information
Corrosion Science and Technology / v.12, no.1, 2013 , pp. 7-11 More about this Journal
Abstract
High velocity oxy-fuel (HVOF) spray coating of WC-metal powder (powder) was carried out to improve the resistances of friction, wear and corrosion of magnetic bearing shaft material Inconel718 (In718) of turbo blower. A micron sized WC-metal powder (86.5% WC, 9.5% Co 4% Cr) was coated onto In718 surface using HVOF thermal spraying. During the spraying, the binder metals and alloy such as Co, Cr and Co-Cr alloy were molten and a small portion of WC particles were partially decomposed to $W_2C$ and free carbon at above its decomposition temperature of $1250^{\circ}C$. The free carbon and excessively sprayed oxygen formed carbon oxide gases, resulting a porous coating of porosity of $2.2{\pm}0.3%$. The surface hardness of substrate increased approximately three times from 400 Hv of In718 to $1260{\pm}30Hv$ of the coating The friction coefficients of the coating were approximately $0.33{\pm}0.03$ at $25^{\circ}C$ and $0.26{\pm}0.03$ at $450^{\circ}C$. These values were smaller than those of In718 substrate at both temperatures due to the lubrication from the free carbon and the cobalt oxide debris. The corrosion resistance of the coating was higher than that of In718 both in salt water of 3.5% NaCl and acid of 1 M HCl solutions, on the contrary, it was lower in base solution of 1 M NaOH. According to this study, the HVOF WC-metal powder coating is recommended for the durability improvement of magnetic bearing shaft of turbo blower.
Keywords
Coating; friction; wear; corrosion;
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1 T. Y. Cho, J. H. Yoon, K. S. Kim, K. O. Song, Y. K. Joo, W. Fang, S. H. Zhang, S. J. Youn, H. G. Chun, S. Y. Hwang, Surf. Coating Tech., 202, 5556 (2008).   DOI   ScienceOn
2 T. Y. Cho, J. H. Yoon, K. S. Kim, S. J. Youn, N. K. Baek, B. C. Park and H. G. Chun, Transactions, Korea Society, Machine Tool Engineers, 15-6, 32 (2006).
3 S. Y. Park, C. G. Park, J. Kor. Inst. Met & Mater, 42, 582 (2004).
4 T. Y. Cho, J. H. Yoon, S. K. Hur, H. G. Chun, Shi-hong Zhang, Mater. Sci. Forum, 686, 654 (2011).
5 T. Y. Cho, J. H. Yoon, K. S. Kim, W. Fang, Y. K. Joo, K. O. Song, S. J. Youn, S. Y. Hwang and H. G. Chun, J. Kor. Inst., Surf. Eng., 40-4, 170 (2007).   DOI   ScienceOn
6 Shi Hong Zhang, Jae Hong Yoon, Ming Xi Li, Tong Yul Cho, Yun Kon Joo, Jae Young Cho, Mater. Chem. & Phys., 119, 458 (2010).   DOI   ScienceOn
7 T. Y. Cho, J. H. Yoon, K. S. Kim, K. O. Song, Y. K. Joo, W. Fang, S. H. Zhang, S. J. Youn, H. G. Chun, S. Y. Hwang, Adv. Mater. Res. 26-28, 1325 (2007).
8 Jae-Bong Lee, Mater. Chem. & Phys., 99, 2224 (2006).
9 S. J. Kim, J. C. Park, M. S. Han and S. K. Jang, Corros. Sci. Tech., 9, 331 (2012).
10 H. Y. Lee, Corrosion of Metals, Yeungyung Moonwhasa, (2004).
11 J. R. Davis, Handbook of Thermal Spray Technology, ASM International, USA (2004).
12 T. Y. Cho, Y. K. Joo, J. H. Yoon, H. G. Chun and S. H. Zhang, Adv. Mat. Res. 561, 1052 (2012).