EFFECTS OF ALLOYING ELEMENTS AND SURFACE PROPERTIES ON THE CORROSION BEHAVIOR OF HVOF-DEPOSITED WC COATINGS

The main purpose of this study is to investigate the corrosion behavior of nickel-aluminum buffer and tungsten-carbide-based ceramic-metal composite coated materials on EN 1.4404 quality stainless steels in a sulfuric acid (H2SO4) environment for pet-rochemical industry applications. For this purpose, tungsten-carbide-based coatings were produced on nickel-aluminum -depos-ited 1.4404 stainless-steel substrates using the HVOF (High Velocity Oxy-Fuel) technique. In the characterization of coatings, X-ray diffraction (XRD) for phase analysis, optical microscope and scanning electron microscope (SEM) for surface morphol-ogy, image analyzer for coating thickness measurements, energy distribution spectroscopy (EDS) for elemental analysis, and roughness device for surface structures, were used. WC-, Co-, Ni-, and NiAl-based phases were observed in the coatings. Ac-cording to metallographic studies, all the coatings had a similar coating microstructure and made good contact with the sub-strate. Potentiodynamic polarization measurements and corrosion tests were carried out to determine the corrosion behavior of HVOF plasma-sprayed coatings using a potentiostat/galvanostat. The results showed that the WCCo-NiAl-coated stainless-steel substrate had a higher corrosion resistance to the H2SO4 environment than the NiAl and WCNi-NiAl samples.