For years, palladium has been regarded as the ideal intermediate or final layer among the platinum metals. Due to the continuous rise in the price of the precious metal, which has increased fivefold in the past year, the call for alternatives is becoming ever louder, especially in the decorative industry. Precious metal specialist Umicore Metal Deposition Solutions has now expanded its Ruthuna product family.
Ruthuna can be used directly as a final layer and impresses with light coatings with an L* value (L*a*b* color space) of 74 to very dark coatings with an L* value of 63
In addition to its cost-effectiveness, which is reflected in a significant price advantage (as of December 2022), Ruthuna scores equally well in terms of sustainability, quality, user-friendliness and, in the technical segment, for selected applications in the area of functionality. Previous compromises in these areas no longer have to be accepted. Replacing the electrolytes, which can also be deposited on non-ferrous metals due to their pH neutrality, is almost effortless.
The costs for energy, buildings, raw materials, etc. are rising - in order to continue to produce economically and sell at a competitive price, savings are necessary. The palladium price, which is currently just over 50 euros per gram, makes Ruthuna interesting. From an economic perspective alone, ruthenium stands out directly among the platinum metals. At less than 20 euros per gram, ruthenium is currently significantly cheaper. The price of the precious metal was only slightly higher in the peak periods of recent years. This offers the opportunity to calculate ahead.
Ruthenium - the most abrasion-resistant platinum metal
Nevertheless, and especially nowadays, price is no longer the only decisive factor. Customers, suppliers and therefore also producers are also concerned with quality and sustainability - now the basis for customer loyalty and winning new customers in a highly competitive market. Ruthenium is also a good choice in these respects. Pure ruthenium, for example, is by far the most abrasion-resistant platinum metal. Despite constant friction, nothing stands in the way of a long service life for brooches, rings, bracelets, buckles and other decorative accessories. An abrasion of 0.05 μm in the Bosch-Weinmann test attests to Ruthuna's clear quality advantage over palladium. In our in-house test laboratory, pure palladium with 6.8 μm achieves 136 times higher abrasion in the same test procedure.
Ruthenium is also ahead in terms of a constant supply of raw materials. At 90 tons per year, Russia is the world's largest producer of palladium. Unfortunately, Russia has not proven to be a reliable partner for raw materials due to the events in the conflict with Ukraine. In contrast, 87% of ruthenium comes from South Africa and only 4% from Russia (as of 2021). Ruthuna is also interesting because Umicore has announced that it will take back ruthenium from used electrolytes at daily updated prices. The company is thus closing the circle in terms of sustainability.
Ruthuna can be used directly as a final layer and is virtually abrasion-resistant for life under normal use. Light coatings with an L* value (L*a*b* color space) of 74 to very dark coatings with an L* value of 63 are possible as standard. However, ruthenium is not always desired as a final layer or the brightness is not bright or radiant enough. Here, ruthenium has a natural limitation in terms of color compared to palladium (L* value: 84) or rhodium (L* value: 90). Nevertheless, the obvious advantages of Ruthuna can largely be exploited when used as a solid intermediate layer. Although a final layer may rub through quickly in places, the color-matched intermediate layer means that rub-through is not visible to the naked eye.
Some technical applications also benefit
A change from the previous precious metal can also be considered for various technical applications such as reed switches, inkjet printer foils, catalytic converter surfaces or electrolysis electrodes. In addition to the economic and sustainable aspects, functional properties such as reduced sparking in current-conducting applications also speak in favor of Ruthuna. However, the coating process still limits its broad applicability in all technical areas.
"Our partnership with our customers was also the impetus for this development. Due to price developments, many decorative producers wanted a cost-effective intermediate layer that could replace a large proportion of palladium without hesitation. This is exactly what is now possible with our new Ruthuna processes and, as far as I know, unique," says Martin Stegmaier (Head of Decorative Applications), explaining the development. Only accessories with final gold layers still require palladium in the form of a wafer-thin barrier layer - without this, corrosion of the gold cannot yet be avoided. However, Stegmaier is optimistic that the product family can be quickly optimized to eliminate this flaw in the near future. Switching to Ruthuna as an intermediate layer for gold surfaces is nevertheless advantageous in all respects.
