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This study aims to investigate the electrochemical corrosion performance of high velocity oxygen fuel (HVOF) sprayed WC–12Co coating in 3.5 Wt.% NaCl solution, which provided a guiding significance on the corrosion resistance of H13 hot work mould steel.

A WC–12Co coating was fabricated on H13 hot work mould steel using a HVOF, and the electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution was measured using open circuit potential (OCP), potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) tests.

The OCP and PPC of WC–12Co coating positively shift than those of substrate, its corrosion tendency and corrosion rate decrease to enhance its corrosion resistance. The curvature radius of capacitance curve on the WC–12Co coating is larger than that on the substrate, and the impedance and polarization resistance of WC–12Co coating increase faster than those of substrate, which reduces the corrosion process.

The electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution is first measured using OCP, PPC and EIS tests, which improve the electrochemical corrosion resistance of H13 hot work mould steel.

This paper aims to study the corrosion protection of 410 stainless steel (410SS) cracked by fatigue tests. The purpose of this study is to show that using polymeric coatings, it is possible to reduce the corrosion rate in metallic structures in operation.

Poly(3-hexylthiophene) (P3HT)/poly(methyl-methacrylate) (PMMA) composite was used as a coating to protect the cracked 410SS in the corrosive environment 0.5 M NaCl at 25°C and 80°C. Physicochemical characterization was carried out by adhesion tests, thermogravimetric analysis, nuclear magnetic resonance and size exclusion chromatography. Surface morphology was studied before and after the electrochemical tests by scanning electron microscopy. Uncoated and coated cracked 410SS were characterized by DC electrochemical techniques: linear polarization resistance and potentiodynamic polarization curves.

P3HT/PMMA coating reduced corrosion rate and crack propagation of 410SS in the corrosive medium NaCl 0.5M. The P3HT/PMMA coating increased the polarization resistance by one order of magnitude and decreased the corrosion current density by one order of magnitude, relative to the values obtained with uncoated cracked 410SS. The coating helped to have a less damaged surface and less crack propagation on the cracked 410SS. The feasibility of increasing the useful life of cracked metal structures in a saline environment was demonstrated through polymeric composite coatings.

In the literature, no works were detected that report the use of organic coatings to protect cracked metals against corrosion. This is the first reported work on the corrosion protection of 410SS in a saline medium using coatings based on P3HT/PMMA.

The purpose of this study is to investigate the effect of Y₂O₃ mass fraction on the electrochemical corrosion performance of CrNi coating, which provided a foundation for the performance optimization of CrNi coatings.

CrNi coatings with the different Y₂O₃ mass fractions were fabricated on AISI H13 steel by laser cladding, and the effect of Y₂O₃ mass fraction on the electrochemical performance of CrNi coating in 3.5% NaCl solution was investigated using an electrochemical workstation.

The electrochemical corrosion performance of CrNi coating enhances with the increase of Y₂O₃ mass fraction, and the CrNi–15%Y₂O₃ coating has the largest polarization resistance and the lowest corrosion current density, which displays the best electrochemical performance among the CrNi–5%Y₂O₃, –10%Y₂O₃ and –15%Y₂O₃ coatings. The protective films are formed with the increase of Y₂O₃ mass fraction, which inhibits the occurrence of electrochemical corrosion.

The Y₂O₃ was first added to the CrNi coating to improve its electrochemical corrosion performance, and the influence of Y₂O₃ on the corrosion resistance of the CrNi coating was discussed by the corrosion model.