Current state of the functional chromium industry
For decades hexavalent chromium has been ruling the market for functional coatings manufactured with electroplating. It creates a strong and shiny protective surface and enhances the mechanical properties of the surface significantly compared to base material. The process is cost-effective and quite simple to operate. Unfortunately, the plating process and the HCr6 raw materials are carcinogenic and cause serious health and safety risks to the operators. This issue is common knowledge and has been considered worldwide by subjecting the use of chromic acid, the main ingredient in the hexavalent chromium process, under license. In the EU plating companies need to apply for permission to use chromic acid for every few years.
Because of the hazardous plating process, the search for alternatives has been active for many years. Different types of alternative processes have been widely tested, including e.g. electroless nickel, electrolytic nickel, trivalent chromium and so on. To this date a true alternative without drawbacks in terms of mechanical performance or costs has not been found. Processes such as thermal spraying, PVD (physical vapor deposition) can produce high-quality deposits but are considered a lot more expensive than electroplating methods.
Cr3 has been widely tested as the plating process is similar to Cr6-process, but in terms of mechanical properties such as wear resistance the deposit has not been able to compete/replace Cr6. However, after years of testing there are a few alternative functional trivalent processes available, e.g. Savroc TripleHard® and Atotech BluCr® (Verbrügge Nickel-Chrome 3 Thousand mixes electroless nickel, Cr3 and Cr6). Savroc and Atotech processes are REACH-compliant and can replace traditional HCr6 in a wide range of applications. The plating process is very much like HCr6 in terms of equipment, plating speed and plating infrastructure.
There is not much information or public references about BluCr®. It works fine in some applications like molds and hydraulic rods, where the wear is not so severe. Currently, it cannot completely replace HCr6. TripleHard® and the patented plating process combining chemical additive and heat treatment enhances the properties of the deposit above HCr6. With tough structure and hardness above 1700HV0.1, it has been widely tested in different applications. TripleHard® has passed many vigorous tests and has been industrially proven. Together with the other alternatives it is possible to replace the hazardous and carcinogenic hexavalent process even in very short term. Current plating lines are relatively easy to be changed to trivalent process.