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7612 |
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Wednesday, September 21, 2022, TZ 6 12:30 PM Moderne Beschichtungstechnik |
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Thermische Spritzen mit Suspensionen - Neuartige, wirtschaftliche Hartmetall-basierte Schichten |
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Filofteia-Laura Toma* / Fraunhofer IWS, Germany Anja Meyer / Fraunhofer Institute IKTS, Germany Oliver Kunze/ Fraunhofer Institute IWS, Germany Annegret Potthoff/ Fraunhofer Institute IKTS, Germany Irina Shakhverdova/ Fraunhofer Institute IWS, Germany Markus Mayer/ Fraunhofer Institute IKTS, Germany Johannes Pötschke/ Fraunhofer Institute IKTS, Germany Björn Matthey/ Fraunhofer Institute IKTS, Germany |
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Thermally sprayed HVOF hardmetal coatings are characterized by outstanding wear resistance, excel-lent abrasion, and corrosion protection under heavy loads. However, the good wear resistance of these coatings requires high finishing costs for grinding and polishing which are estimated to be up to 3-4 times higher than the spray coating process itself. Thus, a great interest to deposit hardmetal coatings with near-net-shape exists. For more than one decade, modified thermal spraying using suspensions as feedstock materials have continuously gained interest. The feeding of a fine dispersed particles containing suspensions has led to new possibilities for coating architectures that can be tailored for coating thicknesses ranging from few µm up to hundreds of µm. Moreover, lower surface roughnesses result reduce the effort for inten-sive post-processing. Suspension sprayed coatings starting from oxide ceramic materials have been studied mostly, whereas only few limited research was done with hardmetals. In the framework of an AiF/DVS-funded national project (IGF-Nr. 20.675 BR), development of easy-to-handle aqueous WC-12%Co suspensions, from which high-quality carbide coatings can be economically produced, was done. The developed suspensions were fed from an industrial-suitable suspension feeder system and sprayed using gas-fueled HVOF TopGun system. For comparison purpose liquid-fueled HVOF K2 was employed to deposit WC-12Co coatings starting from commercially available agglomerated and sintered spray powders, too. With suspension spraying, dense-structured coatings with homogeneous distribution of fine carbides in the coating matrix and smoother surface roughness were obtained. The sliding wear resistance, as well as the corrosion performance of the S-HVOF coatings were comparable to those of conventionally sprayed coatings. Different demonstrator-parts were coated with thin and thick suspension sprayed WC-Co coatings to validate the potential of suspension spraying technology for deposition of cost-effective water-based tungsten carbide suspensions. |