Metal Matrix Composite Coatings Manufactured by Thermal Spraying: Influence of the Powder Preparation on the Coating Pro
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JTTEE5 23:190–196 DOI: 10.1007/s11666-013-9999-3 1059-9630/$19.00 ASM International
Metal Matrix Composite Coatings Manufactured by Thermal Spraying: Influence of the Powder Preparation on the Coating Properties D. Aussavy, S. Costil, O. El Kedim, G. Montavon, and A. -F. Bonnot (Submitted May 13, 2013; in revised form September 4, 2013)
The purpose of this study is to manufacture metal matrix composite coatings by thermal spraying. In order to improve coatings mechanical properties, it is necessary to increase homogeneity. To meet this objective, the chosen approach was to optimize the powder morphology by mechanical alloying. Indeed, the mechanical alloying method (ball milling) was implemented to synthesize NiCr-Cr3C2 and NiCrBSiWC composite powders by using cold spraying and high-velocity oxygen fuel process, respectively. After optimizing the process parameters on powder grain size, the composite coatings were compared with standard coatings manufactured from mixed powders. SEM observations, hardness measurements, and XRD analyses were the first technologies implemented to characterize the metal matrix composite coatings. Different characteristics were then observed. When mechanical alloying process is employed to synthesize composite powders strengthened by particle dispersion, the powders tend to fracture into small segments, especially when high content of hard particles is added. Powder microstructures were then refined, which induced thinner coating morphologies and reduced porosity rate. Once an improved microstructure is obtained, manufacturing of coating using milled powders was found suitable in comparison with coatings manufactured only with mixed powders.
Keywords
cold spray, HVOF, metal matrix composite, mechanical alloying, mechanical properties, nickel alloys
1. Introduction Nowadays, NiCr and NiCrBSi thermal-sprayed coatings are widely used in a variety of industrial applications to protect materials from high-temperature wear or corrosion (like gas turbine or steam turbine) (Ref 1-3). However, breakthroughs in those technologies involve higher critical environmental conditions, which decrease materials lifetimes, e.g., high temperatures, high-speed gas, hot gas, oxidation, or corrosion environment. For these reasons, innovative materials are needed to improve This article is an invited paper selected from presentations at the 2013 International Thermal Spray Conference, held May 13-15, 2013, in Busan, South Korea, and has been expanded from the original presentation. D. Aussavy, S. Costil, and G. Montavon, IRTES-LERMPS, Universite´ de Technologie de Belfort—Montbe´liard (UTBM), 90010 Belfort Cedex, France; O. El Kedim, Institut FEMTO ST- MN2S, UMR 6174 CNRS, UTBM, Site de Se´venans, 90010 Belfort Cedex, France; and A.-F. Bonnot, AREVA NP, 10 rue J. Re´camier, 69006 Lyon, France. Contact e-mail: sophie. [email protected].
190—Volume 23(1-2) January 2014
coating properties. In this way, composite materials can offer tremendous advantages since they combine different materials to obtain new
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