Technical Library » Plating Topics » Why is there a rust disclaimer on my quote for commercial nickel or tin plating on a ferrous component?

Why is there a rust disclaimer on my quote for commercial nickel or tin plating on a ferrous component?

Commercial deposits are very thin and are generally regarded as the most competitive thickness option for a given electro deposit.  Typically commercial deposits are the thinnest functional deposit thickness for a given deposit which are greater than a flash deposit but are still not of enough thickness to impart significant corrosion protection for environments other than mild service environments.  Common commercial thicknesses are typically in the range of 0.0001 to 0.0003 inches per side for non-precious metal deposits such as tin, nickel or copper.

Ferrous products (e.g. steel, ductile iron, cast iron) components plated with commercial thickness deposits that are cathodic to the iron substrate will have very minimal corrosion protection.  Examples of cathodic coatings on steel include electrolytic nickel, electroless nickel, silver, gold, tin and copper.  Reference, the Corrosion section of the Plating Topics within the APT Technical Library for additional information on cathodic verses anodic coatings and deposit thicknesses required to prevent corrosion and rusting.  Since these coatings are cathodic to the surface, a thin commercial deposit will be insufficient to seal the steel from the atmosphere.  This can result in visible rust or corrosion that occurs with even moderate exposure or service applications.

The environment in which commercially plated parts are stored can have a significant impact on if visible rust will occur on the surface.  For example commercial deposits on ferrous products which are plated and inventoried in dry environments – such as a Midwest warehouse in January – will have very different results when plated and inventoried in the same warehouse during hot, humid summer months.  Since Advanced Plating Technologies can not control the use or application of commercial deposits, a disclaimer is typically added to the quote warning of the corrosion limitations of the commercial deposit.

The technical sales group welcomes discussions regarding the corrosion requirements or service application of a component.  Deposit recommendations beyond standard commercial thicknesses can be provided based upon the specific engineering function.  Proprietary corrosion inhibitors or rust preventatives can also be offered in lieu of increased deposit thickness.  Finally, custom packaging methods can be suggested utilizing volatile corrosion inhibitor (VCI) paper or bags as well as sealed nitrogen bag packaging methods to greatly extend the storage life of commercially plated components.