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1534 |
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Effect of the chemical composition and the post heat treatment on the corrosion resistance of cermet coatings deposited by HVOF
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Linda Gil / Universidad Nacional Experimental Politecnica(UNEXPO), Venezuela Maria Prato/ Universidad Central de Venezuela(UCV), Venezuela Mariana Staia/ Universidad Central de Venezuela (UCV), Venezuela Sugehis Liscano/ Universidad Nacional Experimental Politecnica (UNEXPO), Venezuela Raymundo Noriega/ Universidad Nacional Experimental Politecnica (UNEXPO), Venezuela |
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This study was conducted with the aim of determining the response on the corrosion performance of two thermal spray coatings based on the system NiCrBSi - (WC-12%Co). The coatings were deposited by high velocity oxyyfuel (HVOF) thermal spray process on an AISI 1020 steel substrate. Two different powder mixtures were produced mechanically prior to the spraying process: one with 50%wt (NiCrBSi) + 50 %wt (WC-12%Co) and the second one with 70 %wt (WC-12%Co) + 30%wt NiCrBSi. The coated samples were heat treated by using an oxyacetylene flame during 300 seconds on the samples surface. The coatings corrosion resistance was evaluated by conducting both potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in aerated 3,5 % sodium chloride solution. Scanning electron microscopy (SEM), X-Ray Diffraction (XRD) and Auger electron spectroscopy techniques were employed for the coatings microstructural characterization before and after the corrosion test in order to identify the possible mechanisms of corrosion. The investigations showed that both the amount of the WC-Co in the initial powder and the heat treatment affects significantly the corrosion coating performance. |