Publisher : The Korean Institute of Surface Engineering
DOI : 10.5695/JKISE.2016.49.2.211
Title & Authors
Formation of Multi-Component Boride Coatings Containing V and/or Cr and Evaluation of Their Properties Lee, Euiyeol; Yoon, Sanghyun; Kim, Jongha;
Boride coating applied on steam turbine parts of power plants has provided good particle erosion resistance under temperature of , but it isn`t able to protect the parts effectively any more in ultra super critical (USC) steam turbine which is being operated up to temperature of . To ensure stable durability for USC steam turbine parts, an alternative coating replacing boride coating should be developed. In this study, multi-component boride coatings containing elements such as chromium (Cr) and vanadium (V) were formed on base metal (B50A365B) using thermochemical treatment method called by pack cementation. The thermochemical treatments involve consecutive diffusion of boron(B) and Cr or/and V using pack powders containing diffusion element sources, activators and diluents. The top layer of Cr-boride coating is primarily consisted of and , while that of V-boride coating is mostly consisted of and . The (Cr,V)-boride coating is consisted of , and mostly. The top surfaces of 3 multi-component boride coatings show hardness of , which is much higher than that of boride, about . In 5 wt.% NaCl solution immersion tests, the multi-component boride coatings show much better corrosion resistance than boride coating.
Ultra super critical steam turbine;Boride coating;Multi-component boride coating;
W. Tabakoff, M. Metwally, A. Hamed, "High Temperature Coatings for Protection Against Turbine Deterioration", Trans. of the ASME, 117, (1995) 146-148.
R. Chatterjee-Fischer, "Thermochemical Treatment in Powdered Media", Proceedings of the Eight Internatinal Conference on Chemical vapor Deposition by Electrochemical Society, (1981) 508-515.
K. C. Goretta and A. C. Thompson, "Erosion of Heat-Treated AISI 4140 Steel", Mater. Sci. Eng. A, 161, (1993) L7-L10.
A. V. Levy, "The Erosion-Corrosion Behavior of Protective Coatings", Surf. Coatings Tech., 36, (1988) 387-406.
M. Jiang and K. C. Goretta, "Solutions for Solid Particle Erosion", Electric Power Research Institute Report, (1990) 30-37.
S. Usmani and S. Sampath, "Erosion Studies on Duplex and Graded Ceramic Overlay Coatings", JOM., 48, (1996) 51-56.
B. Venkataraman and G. Sundarajan, "The High Speeding Wear Behavior of Boronized Medium Carbon Steel", Surf. Coating Tech., 73, (1995) 177-178.
K. Natesan and Y. Y. Liu, "Erosion-Corrosion of Materials at Elevated Temperature", Mater. Sci. Eng. A, A121 (1989) 571-580.
E. Y. Lee, J. H. Kim, S. I. Jeong, S. H. Lee, G. W. Eum, "Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating", Corr. Sci & Tech., 14, (2015) 25-32.