How is Plating Onto Refractory Metals Different From “Traditional” Electroplating?
If you ask the average person to name a few metals, they are likely to list materials such as gold, silver, tin, copper and aluminum. You’d probably be shocked to hear the words “molybdenum” or “tantalum.” The latter two are examples of a category of materials known as refractory metals. Although they may not be “household names,” refractory metals play a critical role in the manufacturing processes of companies in a wide variety of industries, and they often benefit from plating.
What Are Refractory Metals?
Refractory metals represent a specific class of materials that exhibit extraordinarily high melting points, extreme hardness and density and exceptional resistance to wear, corrosion and deformation. In addition to molybdenum and tantalum, the refractory metals “Big Five” includes niobium, tungsten and rhenium. However, some sources broaden the refractory metals scope to include materials such as titanium, iridium, ruthenium and zirconium due to the unique properties these metals offer.
Challenges When Electroplating Onto Refractory Metals
Electroplating, which is the process of applying a metal coating onto the surface of another metal via electrodeposition, is a common finishing technique used for purposes such as promoting corrosion and wear resistance, increasing electrical conductivity and improving the appearance of a product. Electroplating onto traditional metals is a straightforward process that many metal finishing companies can perform with ease.
However, plating onto refractory metals is not so simple to accomplish. The biggest challenge posed by refractory metals is their high reactivity — they are not compatible with most “non-exotic” materials used as a base, including tin, zinc, gold, silver, aluminum and others. These often result in issues such as poor adhesion, or in some cases, the changing of the composition of the underlying metal. Because of this, plating onto refractory metals is not a practical option for many metal finishing applications.
Key Electroplating Considerations for Plating Onto Refractory Metal
If you are familiar with basic metal electroplating techniques, then you know the process involves immersing the substrate in an aqueous solution referred to as the plating bath. In contrast, electroplating onto a refractory metal requires the use of a non-aqueous solution. Fused-salt electrolysis is one example of a non-aqueous plating method that works well when working with refractory metals as substrates.
Also, plating onto refractory metal alloys such as molybdenum-tantalum, molybdenum-tungsten and titanium-zirconium-molybdenum is more likely to achieve the desired outcome than plating on exotic materials in their pure form.
SPC Can Handle Your Refractory Metal Electroplating Project
SPC is one of the few metal finishing companies that knows how to overcome the obstacles impeding a successful refractory plating process. Our more than 90 years of metal finishing expertise enables us to develop a customized technique to plate onto refractory metal for your manufacturing project. Contact us for more information and to receive a no-obligation quote today.