SibFU Scientists Created Hypoallergenic Alloys for Jewelry
Scientists from the School of Non-Ferrous Metals and Materials Science of Siberian Federal University have developed new alloys based on gold 585 containing palladium and silver and modified with rhodium and ruthenium. They also created an alloy based on silver 925 modified with silicon.
One of the features of these alloys is the complete absence of nickel in their composition. It’s a metal that causes a persistent allergic reaction in some people. Compared to the already known, jewelry made from new alloys has a higher level of mechanical and operational properties. So it will become a hypoallergenic alternative to products made from widely used nickel-containing alloys.
Large-scale work has been carried out at SibFU to create a line of jewelry alloys based on precious metals.
“We proposed the compositions of alloys that increase the level of mechanical, operational and aesthetic properties of jewelry. Many variations of alloys were studied in laboratory conditions, both for jewelry production and for technical purposes. All alloys were studied at different stages of the technological chain of production to identify mechanical properties in cast and deformed states at various stages. We took into account the strength, ductility and uniformity of the composition, the grain size of the alloy — the finer it is, the higher the strength, the more uniform the properties and the more attractive the appearance of jewelry,” said Yulia Ditkovskaya, the co-author of the study and senior lecturer at the Department of Metal Forming, SibFU.
The team of study authors noted that one of the main results was an increase in the level of mechanical and operational properties of products from new alloys. As a result, a decrease in the number of defective products during the production of jewelry occurred. The research was carried out on one of the most labor-intensive items in the production — a jewelry chain, which requires numerous complex manufacturing features.
“It was important to develop nickel-free alloys. The European Union issued a directive a long time ago prohibiting the introduction of more than five hundredths of a percent of this metal into jewelry alloys. The reason is the appearance of various forms of allergic skin diseases in contact with nickel-containing products (jewelry, bijouterie and piercing). In one form or another, 15% of women and 5% of men worldwide suffer from this type of allergy,” Yulia Ditkovskaya continued.
In the Laboratory of Physical Chemistry of Metallurgical Processes and Materials, Krasnoyarsk researchers have developed software that allows you to design processes for the production of long deformed semi-finished products. The technological modes of rolling and drawing of new alloys are also calculated. After conducting a series of experiments, the scientists found that new alloys and their processing modes using the processes of sectional rolling and drawing make it possible to obtain jewelry wire with a diameter of up to 0.25 mm with a high level of mechanical and operational properties under industrial conditions. Such a wire is ideal for weaving a chain, for example, "Snake".
According to the developers, the production of jewelry from new alloys has a nice bonus — the cost of products can be significantly reduced, since rare and valuable metals — modifiers (for example, rhodium and ruthenium) are used in very small quantities, while the benefits from them in the composition of alloys are enormous. Unfortunately, the introduction of new alloys will require a significant improvement of existing equipment, which means that jewelry from “palladium” gold may not appear on the shelves of jewelry stores soon.
“We have already done a similar study on a modified red gold alloy. According to calculations, in the case of the production of jewelry chains of Snake weaving — this is a round-section chain that looks like snake skin — using the developed alloy compositions and production technologies, it is possible to reduce the annual cost by up to five million roubles and increase the company's revenue. We believe that the introduction of 14-carat white gold and 925-carat silver alloys that we offer into production will make it possible to produce products that are more cost-effective in terms of price and quality,” Yulia Ditkovskaya explained. “These alloys are aesthetically pleasing and do not pose a health risk.”
Works on the creation of alloys based on precious metals have been carried out for more than ten years, since 2009 under the guidance of Professor N. N. Dovzhenko, Cand.Sc. (Engineering), Professor S. B. Sidelnikova, Cand.Sc. (Engineering), and Associate Professor I. V. Uskova, Cand.Sc. (Engineering). The materials of this work were published in The International Journal of Advanced Manufacturing Technology, included in the bibliographic and abstract database "Scopus".