Effects of PEG, PVP and SDS on the Properties of Chromium Coatings Prepared from Trivalent Chromium Chloride Baths Using Experimental Design and Multi-Response Optimisation

The effects of three organic additives polyethylene glycol (PEG), sodium dodecyl sulphate (SDS), and polyvinylpyrrolidone (PVP), on the electrodeposition of chromium from trivalent chromium chloride baths were investigated. The experiments were performed based on a two-level factorial design. The effects of electrolysis parameters: pH, temperature, and current density, as well as the concentrations of the three additives, on the thickness, roughness, and corrosion current density of the chromium deposited layers were analysed. Statistical results revealed that all response models are significant. It was found that the contributions of factors in thickness and interactions in roughness and the corrosion current density are more important. The main and interaction effect studies showed that pH and current density have significant effects on all of the responses, whereas the additive concentration only has an effect on the corrosion current density, especially in the presence of PVP and PEG. The interactions of pH with the current density and the temperature with current density have the most important effects on all responses. Optimisation and technical, economic, and environmental investigations revealed that PEG is the most suitable additive for usage in technical and decorative processes. PVP and SDS could substitute PEG for decorative and technical processes, respectively.