Are Ni–SiC nanoparticle electroplated coatings a safer alternative to hard chromium? A comprehensive aging, toxicity, and in silico study to assess safety by design†

Abstract

Considering the increasing interest in utilising nanoparticles (NPs) for advanced, safe, and sustainable coatings, this paper addresses the toxicological concerns associated with nickel–silicon carbide (Ni–SiC) electroplated nanocomposite coatings as an alternative to conventional chromium electrodeposition. We present Ni–SiC nanocomposite coatings as potential substitutes and conduct a comprehensive investigation into the impact of impregnated SiC particles on coating properties. Specifically, we examined the aging of Ni-Watts type and Ni Watts–SiC nanocomposite coatings in various environmental and biological media. Our release and transformation data indicate an enhanced release and transformation of Ni in the simulated media (e.g., up to 200 μg mL⁻¹ in cell culture media) and the formation of NiO and Ni(OH)₂ species as confirmed by XPS analysis. Transmission electron microscopy data reveal the release of SiC NPs in the respective simulated aging medium. The Ni ion release from Ni-Watts type and Ni–SiC nanocomposite coatings was also investigated in silico to support safe-by-design (SbD) approaches in the development of nanoalloys for electroplating. An in vitro cytotoxicity assay according to ISO shows a significant reduction in cell viability for Ni–SiC nanocomposite coated samples (up to 80% after 72 hours) compared to standalone Ni-Watts type electroplated coatings (up to 20% after 72 hours). Our findings suggest that the co-deposition of Ni with SiC NPs enhances Ni release, which is a major factor in causing toxicity. These results could be pivotal in the adoption of safe and sustainable by design principles within the electroplating industry. This paper contributes to the fields of nanotoxicology and surface coatings, providing a foundation for designing and optimising environmentally friendly, high-performance coatings with broad industrial applications.