The High-Temperature Wear and Oxidation Behavior of CrC-Based HVOF Coatings
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The High-Temperature Wear and Oxidation Behavior of CrC-Based HVOF Coatings ˇ esa´nek2 • Eva Smazalova´2 • Frantisˇek Luka´cˇ3 Sˇa´rka Houdkova´1 • Zdeneˇk C
Submitted: 6 June 2017 / in revised form: 18 August 2017 ASM International 2017
Abstract Three commercially available chromium carbide-based powders with different kinds of matrix (Cr3C225%NiCr; Cr3C2-25%CoNiCrAlY and Cr3C2-50%NiCrMoNb) were deposited by an HVOF JP-5000 spraying gun, evaluated and compared. The influence of heat treatment on the microstructure and properties, as well as the oxidation resistance in a hot steam environment (p = 24 MPa; T = 609 C), was evaluated by SEM and XRD with respect to their potential application in the steam power industry. The sliding wear resistance measured at room and elevated (T = 600 C) temperatures according to ASTM G-133. For all three kinds of chromium carbide-based coatings, the precipitation of secondary carbides from the supersaturated matrix was observed during the heat treatment. For Cr3C2-25%NiCr coating annealed in hot steam environment as well as for Cr3C2-25%CoNiCrAlY coating in both environments, the inner carbide oxidation was recorded. The sliding wear resistance was found equal at room temperature, regardless of the matrix composition and content, while at elevated temperatures, the higher wear was measured, varying in dependence on the matrix
This article is an invited paper selected from presentations at the 2017 International Thermal Spray Conference, held June 7-9, 2017, in Du¨sseldorf, Germany, that has been expanded from the original presentation. & Sˇa´rka Houdkova´ [email protected] 1
Research and Testing Institute in Plzenˇ, s.r.o., Tylova 46, 316 00 Plzenˇ, Czech Republic
2
University of West Bohemia, Univerzitnı´ 8, 306 14 Plzenˇ, Czech Republic
3
Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague, Czech Republic
composition and content. The chromium carbide-based coating with modified matrix composition Cr3C250%NiCrMoNb is suitable to replace the Cr3C2-25%NiCr coating in a hot steam environment to eliminate the risk of failure caused by inner carbide oxidation. Keywords ceramic matrix composite high-temperature oxidation high-temperature wear HP/HVOF power plant
Introduction The power generation industry is one of the more challenging from the materials point of view. The most stressed components are exposed to a combination of high temperature, aggressive environment and mechanical load. Only materials with superior properties, such as highly alloyed steels or super alloys, can be used for such applications. The material costs can be reduced by the application of surface protective layers that can also increase the functional properties of coated components. The thermal spray technology, namely high-velocity oxy-fuel (HVOF) spraying, is a suitable technology for applying hard, wearresistant and oxidation-resistant coatings onto the surface of less noble steels. Among HVOF-sprayed wear-resistant coatings, applicable in high-temper
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