Microbiologically Induced Corrosion Resistance and Erosion–corrosion Resistance Behavior of a Ni–CrN/NiCr layer Grown via Arc-Added Glow Discharge Plasma

Arc-added glow discharge plasma plating is a thermochemical technique used to enhance the corrosion and wear resistance of steel and other metals. In this study, a NiCr layer was grown in situ on the surface of Q235 carbon steel using arc-added glow discharge plasma plating, followed by plasma nitriding of the NiCr layer. Therefore, a gradient layer was obtained, consisting of a NiCr layer at the bottom and a nickel-containing CrN layer on the top ( marked as Ni-CrN/NiCr). Ni, which acts as an element to improve the toughness of CrN, originates from the previously prepared NiCr layer and is uniformly distributed within the CrN layer. Using X-ray diffraction, scanning electron microscopy, surface property testing techniques, microbiologically influenced corrosion testing methods, and erosion-corrosion testing methods, the resistance of this gradient CrN composite layer to microbial corrosion, chemical corrosion, and erosion corrosion in microorganism-containing and sand-laden seawater was investigated. The Ni-CrN/NiCr layer exhibited a water contact angle of up to 126.4°, indicating good hydrophobicity, and a hardness (HV 0.5 ) of up to 1628.5. After 11 days of corrosion in a 3.5 wt.% NaCl solution containing microorganisms, the corrosion potential shifted positively by 0.4170V relative to the substrate, and the corrosion rate decreased from 0.35 mm/a for carbon steel to 0.18 mm/a for Ni-CrN/NiCr layer, with a relative reduction of 48.57%. Under erosion-corrosion conditions, the potential shifted positively by 0.4430 V, and the i corr decreased by approximately 84.81%. The Ni-CrN/NiCr layer prepared in this study exhibited excellent corrosion resistance in seawater environments containing both flowing sand and microorganisms.