Influence of Cr3C2-NiCr Coating Thickness on Corrosion Behavior of Carbon Steel in Alkali Chloride Atmospheres
Safitry Ramandhany (a,b*), Djoko Triyono (a*), Eni Sugiarti (b*), Hubby Izzuddin (b), Agus Sukarto Wismogroho (b), Ahmad Afandi (b), Jayadi (b), Wahyu Bambang Widayatno (b), Nurul Latifah (b), Kurotun Aini (b)

a) Department of Physics, Faculty of Mathematics and Natural Science, Universitas Indonesia, Depok 16424, Indonesia
*safitry.ramandhany41[at]ui.ac.id, djoko.triyono[at]sci.ui.ac.id
b) Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), Serpong 15314, Indonesia
*enis006[at]brin.go.id

Abstract

The development of protective coatings against alkali-induced high-temperature corrosion is critical for extending the service life of components in aggressive environments such as boiler co-firing biomass. This study investigated the influence of Cr3C2-NiCr coating thickness on the corrosion performance of A516 carbon steel substrates exposed to alkali chloride vapor (NaCl + 55wt% KCl) at 600C for 100 hours. Coatings with approximate thicknesses of 150um and 20um were deposited via High Velocity Oxy Fuel (HVOF) spraying, using Cr3C2-NiCr as the coating material. Their degradation behaviors were evaluated through mass change measurements, corrosion rate analysis, and detailed microstructural characterization using field emission-scanning electron microscopy (FE-SEM) equipped with electron dispersive spectroscopy (EDS), X-Ray Diffraction (XRD), and surface hardness testing. The thicker coating exhibited a significantly lower corrosion rate (0.1495mm/y during the first 20 hours) than the thinner coating, which experienced rapid degradation and visible spallation after 40 hours. XRD analysis revealed that the surface of the thicker coating was dominated by Cr2O3 and NiCr2O4. In contrast, the thinner coating formed a more complex oxide mixture consisting of Cr2O3, Fe3O4, Fe2O3, and NiCr2O4, indicating a severe corrosion attack to the thinner coating and substrate. The underlying mechanisms of alkali salt vapor corrosion for both coating thicknesses are explained in this paper, offering understanding into microstructural of Cr3C2-NiCr coating on A516 carbon steel in corrosive high-temperature environments.

Keywords: alkali, Cr3C2-NiCr, corrosion, mechanisms, thickness

Topic: Material Physics