Non-sensitizing Zr–O–N coatings for jewelry made of non-precious alloys

Abstract

Recent decades jewelry manufacturers put into practice using of non-precious alloys in order to decrease the production costs. Nevertheless, the large number of customers has allergic (sensitizing) body reaction on jewelries. Applying of non-sensitizing coating is able to decrease negative influence of jewelry material on human body. One of the biologically inert materials toward to human body tissues is zirconium. In the present work we examined the zirconium-based coatings applied by magnetron sputtering. Eleven coating regimes of AISI 430 steel substrates by zirconium oxynitride were investigated. Coatings corrosion test in Hank’s solution, microhardness measurements, color performance in CIE 1976 L*a*b* and RGB color spaces were carried out. The coating width was 0.4–1.2 μm. It was established that coatings have microhardness 2.5–3.0 GPa and can simulate jewelries colors. Using energy dispersive X-ray spectroscopy, it was evaluated that coatings consist of Zr, N and O. We select the sputtering regimes which provides metallic type coatings with the high optical reflectivity in the energy range near the infrared part of spectrum (<1.7 eV) and has golden color with a high lightness. It was experimentally proved that coatings are not corroding in Hank’s solution. The allergy patch test of jewelry with zirconium oxynitride coating demonstrate a good result on respondents with sensitizing reaction to non-precious alloys jewelry. The obtained results allow us to recommend the application of a zirconium-based coating magnetron sputtering in manufacturing of the non-precious alloys jewelry.