Gold, silver, tin, copper, and aluminium are likely to come up when you ask the ordinary individual to name a few metals. The words “molybdenum” or “tantalum” are likely to shock you. Refractory metals are a type of material that includes the latter two. Despite the fact that they aren’t well-known, refractory metals play an important part in the manufacturing processes of enterprises across a wide range of industries, and they frequently benefit from plating.

Refractory Metals 

Refractory metals are a type of material with exceptionally high melting temperatures, extreme hardness and density, and great wear, corrosion, and deformation resistance. Niobium, tungsten, and rhenium are among the “Big Five” refractory metals, along with molybdenum and tantalum. However, because of the peculiar qualities of these metals, some sources expand the definition of refractory metals to include titanium, iridium, ruthenium, and zirconium.

Advantages of Refractory Metals

Refractory metals are extremely useful in a wide range of applications and industries due to their unique properties. The following are some of their primary advantages:

  • A melting point: extremely high

Tungsten, molybdenum, and tantalum are refractory metals with high melting points, making them useful in the glass industry.

  • High intensity

They are extremely strong, even at extremely high temperatures. Rocket cones constructed of tungsten, for example, have twice the tensile strength of iron at normal temperatures.

  • Abrasion and wear resistance that is unparalleled

Valve seats, seals, nozzles, and other locations prone to excessive wear can benefit from refractory metals, particularly alloys.

  • Corrosion resistance is outstanding

In chemical factories, the pipe is usually built of refractory metals, which have a higher corrosion resistance than stainless steel.

  • Resistance to thermal shock

Metals such as tungsten can withstand the tension caused by rapid expansion due to heat. Tungsten has a high melting point and can tolerate multiple on/off cycles without losing its integrity.

  • Conduction of heat and electricity

Refractory metals like tungsten and molybdenum can be used as heat sinks in addition to their various electronic and electrical uses.

  • Extremely tough

Tungsten carbide is utilised to make the majority of cutting tools these days. In addition to producing metals and steel, refractory metals are used in mining and drilling gas and oil wells.

  • High specific gravity and density

The high density of most refractory metals makes them ideal for golf club heads and aircraft gyroscopes.

  • Refractory metals offer a wide range of applications, including acting as excellent radiation shields and chemical catalysts.

 Characteristics 

Heat resistance is one of the most distinguishing characteristics of refractory metals. The melting point of all metals in this category is more than 3,632°F (2,000 °C). These metals are ideal for drilling and cutting tools because they are robust at high temperatures and have a natural hardness. These metals are also extremely resistant to things like a thermal shock. This means that when they are repeatedly cooled and heated, they will not break, expand, or stress.

Moving forward, all five metals in this category have large densities, as well as excellent thermal and electrical properties. They are also resistant to creep, therefore when exposed to particularly harsh settings or conditions, they deform slowly. This is due to the ability of certain metals to form a protective layer, making them corrosion-resistant despite the fact that they can oxidise at high temperatures.

Challenges

Electroplating is a common finishing technique for promoting corrosion and wear resistance, increasing electrical conductivity, and improving the appearance of a product. It is the process of applying a metal coating onto the surface of another metal via electrodeposition. Electroplating conventional metals is a simple technique that many metal finishing firms can handle without difficulty.

Plating refractory metals, on the other hand, is more difficult. The most significant issue offered by refractory metals is their high reactivity, which makes them incompatible with most “non-exotic” base materials, such as tin, zinc, gold, silver, aluminium, and others. These frequently result in concerns such as poor adhesion or, in some situations, a change in the underlying metal’s composition. As a result, plating refractory metals is not a viable alternative in many metal finishing applications.

Key Electroplating Considerations for Refractory Metal Plating

If you’re familiar with basic metal electroplating processes, you’ll know that the process begins with the substrate being immersed in an aqueous solution known as the plating bath. Electroplating onto a refractory metal, on the other hand, necessitates the use of a non-aqueous solution. When working with refractory metals as substrates, fused-salt electrolysis is an example of a non-aqueous plating process that works effectively.

Plating on refractory metal alloys like molybdenum-tantalum, molybdenum-tungsten, and titanium-zirconium-molybdenum is also more likely to produce the required result than plating on unusual materials in their pure form.

For over a decade, Smart Microns has dominated the electroplating industry with specialisations in silver and gold plating for use in electrical and electronics. For the past 22 years, Smart Microns has been devoting its resources to researching and designing microns. Smart Creations, headquartered in Chennai, India, and being one of the first South Indian companies to launch the concepts of electroplating and Electrophoretic lacquer (ED lacquers), has Smart Microns as its child firm. The Micron electroplating services provided by Smart Microns utilise over 7 metals, including those that are available in various textured finishes.