Microstructure and Oxidation Behavior of Cr39Ni7C Cermet Coatings Deposited by Diamond Jet Spray Process
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JTTEE5 17:942–947 DOI: 10.1007/s11666-008-9260-7 1059-9630/$19.00 Ó ASM International
Microstructure and Oxidation Behavior of Cr39Ni7C Cermet Coatings Deposited by Diamond Jet Spray Process F.-X. Ye, S.-H. Wu, and A. Ohmori (Submitted May 15, 2008; in revised form September 14, 2008) For the promising erosion and oxidation resistance of carbide cermet coating, Cr39Ni7C cermet coatings were deposited by Diamond Jet spray process using a commercial Sulzer Metco 5241 powder in this study. The microstructure, phase compositions, and high-temperature oxidation behavior of the deposited coatings were investigated. The speed and temperature of in-flight particles were measured by DPV2000. The results revealed that the speed of in-flight particles decreased from 229 to 150 m/s with the increasing of the spraying distance from 100 to 300 mm, whereas the average temperature of in-flight particles increased from 1926 to 2245 K. The decarburization of Cr3C2 increased with the increasing of the fuel gas flow from 58 SLPM to 77 SLPM for higher heat enthalpy of the flame. Due to the formation of Cr2O3 on/in the coatings at high temperature, the sprayed coatings had good oxidation resistance at 1073 K in an air atmosphere. The oxidation behavior was found to be governed by the parabolic rate law. For the lower porosity of the coating deposited under the spraying distance of 150 mm, its oxidation resistance was better than that of the coating sprayed at the spraying distance of 200 mm. A slight reduction of sprayed Cr39Ni7C cermet coating in micro hardness occurred after high temperature at 723 K and 1073 K high-temperature oxidation.
Keywords
cermet coatings, HVOF microstructures, influence of properties
1. Introduction Thermal spraying is an expanding area within the technology of surface engineering. It is a process that involves the deposition of molten or semi-molten droplets of powder on to a substrate to form a coating (Ref 1). Tungsten carbide and chromium carbide-based coatings are frequently used in various industrial fields such as the power generation industry and aerospace industry to improve the resistance to sliding, abrasive and erosive wear, and high-temperature oxidation (Ref 2-12). Although the This article is an invited paper selected from presentations at the 2008 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Thermal Spray Crossing Borders, Proceedings of the 2008 International Thermal Spray Conference, Maastricht, The Netherlands, June 2-4, 2008, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2008. F.-X. Ye, School of Materials Science and Engineering, Tianjin University, Weijin Road No.92, Tianjin 300072, PeopleÕs Republic of China; S.-H. Wu, Suzhou Nuclear Power Research Institute, Suzhou, PeopleÕs Republic of China; and A. Ohmori, TOCALO Co. Ltd., Minamifutami, Futami-Cho, Akashi, Japan. Contact e-mail: [email protected].
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