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7420 |
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Thursday, May 05, 2022, Hall G1 3:40 PM Ceramic Coatings |
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Microstructural characterization and oscillating sliding wear investigations of the aqueous suspension sprayed HVOF WC-12Co coatings |
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Filofteia-Laura Toma* / Fraunhofer IWS, Germany Anja Meyer / Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Germany Oliver Kunze/ Fraunhofer Institute for Material and Beam Technology (IWS), Germany Irina Shakhverdova/ Fraunhofer Institute for Material and Beam Technology (IWS), Germany Fabian Härtwig/ Fraunhofer Institute for Material and Beam Technology (IWS), Germany Annegret Potthoff/ Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Germany Markus Mayer/ Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Germany Johannes Pötschke/ Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Germany Stefan Makowski/ Fraunhofer Institute for Material and Beam Technology (IWS), Germany |
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Thermally sprayed WC-based hardmetal coatings are characterized by high wear, abrasion and corrosion resistance and find large applications in mechanical engineering, valves and apparatus construction, or offshore applications. WC-Co coatings are mainly produced by high-velocity oxy-fuel spraying (HVOF) from conventional spray feedstock powders. In our previous work, the potential of the suspension-HVOF spraying (S-HVOF) to produce dense-structured WC-12Co coatings has been shown. Significant work was devoted to the development of appropriate aqueous hardmetal suspensions starting from commercially available fine WC and Co raw powders feedstock. This contribution proposes a step forward in the development of the S-HVOF WC-12Co coatings and the evaluation of their microstructural and tribological properties. Suspension spraying trials were carried out using from one side the gas-fueled HVOF TopGun and from other side the liquid-fueled HVOF K2 systems. For comparison purposes, HVOF K2 was employed to spray WC-12Co coatings starting from commercial available spray powder, too. Microstructural evaluations included SEM microscopy, X-Ray diffraction, fracture toughness and microhardness measurements. Oscillating sliding wear tests on the sprayed coatings were conducted against Al2O3 ceramic and WC-6Co balls. Significant changes in the chemical and phase compositions were observed in the S-HVOF coatings. The sliding wear was preferential abrasive and the presence of tribofilm was observed for almost all tested specimens. The different sliding wear performances of the S-HVOF vs. HVOF coatings will be discussed in terms of the microstructural coating properties and the ball-coating test couples. |