Copper is one of the most versatile metals that we use in electroplating, with many applications across multiple industries. One of the most interesting ways it is used is for the hardening of steel components. Now, we know what you’re thinking: How can copper, this soft, malleable metal, possibly be used to harden steel?
That’s precisely what’s so interesting about it. In this article, we are going to discuss the hardening process, the role we play in it, and how it can benefit your products.
Copper plating as a primer
There are two ways to harden steel using copper plating. The most common is to use copper as a primer layer on which to plate other metals, such as nickel. Thanks to copper’s excellent adhesive properties, this sandwich layer of copper provides a perfect surface for nickel plating.
The other use of copper in hardening steel components is in a process known as case hardening. In this technique, steel components are submerged in molten cyanide salt baths as part of the treatment process. This enriches the surface of the substrate with nitrogen and carbon, improving wear resistance and hardening the topmost layer of steel. While this is not a treatment we provide at Karas Plating, sometimes the whole component does not require hardening, only select parts. This is where copper plating comes into play.
Copper plating for selective hardening
A common application for selective hardening is for large gears, often used in the petrochemical and defence industries, among others. These components need the teeth to be hardened for optimal performance and efficiency, but not the rest of the gear wheel. For orders like this, we receive the substrate prior to it being machined into a workable gear wheel. We apply a layer of copper plating to protect the substrate from the hardening process and return it to our client. They will then machine the metal into the required shape, stripping the copper from the gear teeth as they do so. This leaves raw steel that can be hardened in a cyanide salt bath, while the rest of the component is unaffected.
Finishing hardened components
Once the hardening process has been applied, the copper plating is no longer needed, but our clients tend not to have the materials or expertise to effectively remove it without damaging the substrate beneath. We can strip the remaining copper from the steel using an acid solution. We work quickly, but carefully to make sure the acid does not etch the underlying steel. Once the copper is stripped, we rinse the components before returning them to our client.