The process
At the heart of NiKrom III’s success lies the process developed in cooperation with leading companies in the chemical industry. To mitigate the potentially lower performance of the CrVI-free chemistry, we have utilized our extensive experience and knowledge in duplex nickel-chrome coatings. With this approach, we have been able to transfer the unparalleled corrosion resistance performance of our NiKrom products to the CrVI-free NiKrom III products.
The process requires careful control because of the sensitivity of the Cr III bath’s chemical formulation to contaminants. Maintaining consistency and reliability depends on precise oversight. The outcome is a highly durable coating.
The first demonstrators from a manually operated pilot facility were produced in Ovako’s Redon facilities in 2017, this is the French plant where we produce our nickel-chrome products. Since then, we have carried out extensive development of the process and chemistry. Production has also ramped up to a fully functional pre-series line able to produce bars up to 3m in length in diameters between 20mm and 140mm.
Passing key tests
For NiKrom III to provide a viable alternative to the Cr VI coating it is essential that it can be used with existing hydraulic cylinder designs. Nikrom III has a similar surface structure, hardness and friction properties as standard chrome products, this makes it possible to use with existing sealing designs. Furthermore, NiKrom III can be applied on any Ovako Cromax steel base without additional heat treatment, so customers do not have to compromise on mechanical properties, fatigue life or ease of welding.
Superior performance in certain environments
One of the key aspects of hard chrome is its stability in aggressive environments. There are however rare cases where the chrome layer can be degraded due to chemical or electro-chemical attacks. NiKrom III has proven to have superior stability in such environments. One example of where these conditions can occur is coastal areas where cyclic wet-dry corrosion occurs. Other field experience includes a copper mine in Poland with a highly corrosive saline atmosphere. The findings here are promising: where conventional nickel-chrome cylinders showed significant corrosion within 1,000 hours, NiKrom III cylinders remained corrosion-free after 5,200 hours of operation – see Figure 1.
Figure 1 – Comparing performance of hexavalent chrome and NiKrom III in the salt-laden conditions of a copper mine
This fivefold improvement in performance can lead to notable cost reductions for industries that depend on heavy machinery. By decreasing the need for frequent replacements and maintenance, NiKrom III helps balance its initial higher costs with long-term operational benefits.
A sustainable vision
NiKrom III aligns with Ovako Cromax’s overarching sustainability goals. For example, attention is given to the carbon footprint in all steps in the production process from steelmaking via hot-rolling, transport, machining to plating. The final product has a carbon footprint 80% lower than the global average, and, on request, we can provide carbon footprint data on the article number level.
The road ahead
As industries using hydraulic equipment adapt to stricter sustainability regulations, Ovako can provide solutions in this challenge. NiKrom III is an additional piece in the puzzle that aligns with these evolving demands. The technology is ready to scale up to meet the needs of sectors like mining, marine, wind turbines, and coastal infrastructure, all of which benefit from its properties.
It is important to remember that NiKrom III isn’t just an alternative to Cr VI, it can also be a problem solver in niche applications. It shows how innovation and sustainability can work in tandem to deliver a significant return on investment.
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