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7316 |
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Wednesday, May 04, 2022, Hall G1 2:40 PM HVOF / HVAF Spraying I |
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Influence of primary carbide size on coating characteristics of high velocity sprayed WC-Co-Cr powders |
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Guido Reisel* / Oerlikon Metco WOKA GmbH, Germany Jonathan Gutleber / Oerlikon Metco (US) Inc., U.S.A. Ville Eronen/ Oerlikon Metco Europe GmbH, Finland |
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Thermal sprayed coatings of tungsten carbide (WC) in a cobalt or nickel base matrix are often used in applications which require wear and corrosion protection. Feedstock powders produced by agglomeration and sintering exhibit a spherical shape with a certain inherent intra-particle porosity. The cobalt matrix is often alloyed by chromium to increase hardness, corrosion and wear resistance, which is necessary in many applications in paper industry. High velocity oxy-fuel (HVOF) spray guns have evolved through several generations since the early 1980s with both gas fuel (GF) and liquid fuel (LF) variants as industrialized processes. The development of high velocity air fuel (HVAF) spray guns, which use air instead of oxygen for combustion, was begun in the 1990s based on a patent from Browning. HVAF gun designs were improved and optimized in subsequent years, where by circa 2010, guns suitable for industrial production processes were available on the market. The aim of the presented work is to systematically evaluate the influence of the primary carbide size in WC-Co-Cr powders sprayed with several high velocity spraying methods (HVOF-GF, HVOF-LF and HVAF) on the microstructure as well as the mechanical, tribological and corrosion properties of the applied coatings. |