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5399 |
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Friday, June 09, 2017, Hall 26 12:20 PM Corrosion Protection |
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Comparative study of the corrosion and cavitation resistance of HVOF and HVAF FeCrMnNiSi and FeCrMnNiSiB coatings
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Luciana Leite Silveira* / Universidade Tecnológica Federal do Paraná, Brazil Anderson Geraldo Marenda Pukasiewicz/ Parana's Federal University of Technology , Brazil Alfredo José Zara/ State University of Ponta Grossa, Brazil Per Nylén/ University West, Sweden Stefan Björklund/ University West, Sweden |
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Cavitation and corrosion wear process on hydrodynamic components and systems reduces dramatically the operational efficiency, leading to economic losses and accidents in the workplace. The use of wear resistant coatings have been studied as a solution to the problem of corrosion and cavitation in the industrial environment. High performance alloys with good mechanical and corrosion properties can be used as coating to protect these components. Thermal spray processes are recognized as excellent technique to deposit coatings. The high velocity oxyfuel process (HVOF) is one of the most important thermal spray technique that can produces high density and bond strength coatings. High speed air-fuel process (HVAF) is currently an alternative process. HVAF process were shown to be superior regarding corrosion protection and production costs. HVAF can deposit coating with shorter dwell time and lower temperature than HVOF process, producing coating with lower oxide content. This paper studies the use of HVOF and HVAF process to deposit FeCrMnNiSi and FeCrMnNiSiB coatings resistant against corrosion and cavitation. Microstructure of the coatings were analyzed by XRD, microscopic means and mechanical testing. The cavitation and corrosion behavior of the coatings were also studied comparatively. HVAF coatings presented lower porosity and oxide levels, as well as higher hardness values, compared with the coatings deposited by HVOF process. Initial analysis showed that the HVAF process presented better cavitation resistance than HVOF coatings, with a mass loss rate of 2,68 mg/h against 4,46 mg/h for FeCrMnNiSi samples and 5,32 mg/h against 6,70 mg/h for FeCrMnNiSiB samples. The addition of boron was effective in increasing the coatings hardness, however, the alloys showed cavitation erosion rates higher than the alloys without boron addition. |