In a variety of industries, from the automotive and aerospace sectors to tiny biomedical devices and implants inside the human body, coating procedures offer protection to a particular portion or section of a structure exposed to severe and corrosive environments. Special surface treatments are needed to attain the right characteristics on metal surfaces, especially steel surfaces. The most common surface treatment methods are surface coatings, although there are other methods as well. Numerous properties, including enhanced surface hardness, resistance to wear and corrosion, modifications in wettability, hydrophobicity, hydrophilicity, and others, can be offered by coatings. Various surface coating methods are employed depending on the intended usage. The impact of coating processing techniques on surface protection is a crucial topic in materials science and engineering since the performance, durability, and applicability of the coating are all greatly affected by the processing method selection.

Chromium (Cr) exists in multiple oxidation states, with Cr(III) and Cr(VI) being the most environmentally and industrially relevant due to their distinct toxicity profiles and chemical behaviour. This study presents a comprehensive method that combines chemical simulation modelling, emission spectroscopy for quantification, and the controlled laboratory production of Cr species. Key findings include that acid digestion effectively extracted the Cr(III) and total Cr species, while thermodynamic modelling forecasted their stability and speciation under various environmental conditions. Thematic analysis indicates that the current quantification of Cr species is still in early development and remains centralized. Mineralogical and surface investigations showed that samples 1 and 2 have a BET surface area below 1 m²/g, whereas samples 3 and 4 exceed this. All samples are crystalline, with approximately 54.3 weight percent Cr₂O₃, 7.3 weight percent SiO₂, 17.75 weight percent of MgO, and 8.3 weight percent Al₂O₃, suggesting Al and Fe²⁺ replacement of Cr in the spinel structure. Computational fluid dynamics (CFD) modelling revealed that longer residence times are necessary for higher Cr metallization under H₂-CH₄-reducing conditions, and accurately predicted carbon deposition on pellets. These results demonstrate that CFD can optimize the H₂:CH₄ ratio to minimize carbon deposition and enhance gas transport to reaction sites.