Refractory metals are a sub-group of metallic elements on the periodic table. These elements are grouped together due to their alike physical and chemical qualities. All refractory metals have melting points beyond 2000 °C and are chemically inert. On top of this, these metals are some of the strongest on the entire periodic table.
These qualities make refractory metals like Tungsten, a useful substrate in a variety of industries. However, unlike light and common metals such as aluminum, copper, and nickel, refractory metals present a more unique challenge during their plating processes.
The biggest difference between plating onto refractory metals versus plating onto common metals is that the aqueous solution (chemical bath) used in the typical electroplating process is ineffective when trying to adhere ions to the surface of a refractory substrate. Due to this, electroless nickel is the most common finish for refractory substrates, acting as a base layer for the application of other metals.