Electroplating on Superalloys

Plating Onto Superalloys

Superalloys are high-performance metal alloys developed to provide several important characteristics, including heat resistance, surface stability and resistance to oxidation and corrosion. A superalloy can stand up to conditions other alloys wouldn't be able to handle. Due to their tightly packed crystalline structure, they can hold their shapes almost to their melting points. Because these alloys hold such extraordinary properties, they're commonly used as materials for parts in high-stress environments, like on aircraft and inside nuclear reactors.

Today, nickel-based superalloys are the most commonly used type. However, the nickel may also be mixed with small amounts of other elements such as copper, aluminum, titanium and more. Lesser-known varieties are cobalt- and iron-based superalloys, which present similar but distinct properties.

Superalloys generally find pragmatic use in jet engines, on spacecraft and inside nuclear reactors and thermal power plants. In the energy and aerospace industries, the aesthetic properties of the metal are secondary to its function, so plating onto superalloys in these sectors is generally a practical consideration. Specifically, nickel plating is sometimes used to assist with brazing. For jet engines and other vital parts of machinery, various coatings may be applied to promote initial oxidation or protect from heat and other threats.

Though plating onto superalloys may not be common, it's occasionally useful or necessary. It's possible to plate onto many different superalloys. Below, you can find overviews of a few examples:

1. Inconel: Inconel is the industry name for a group of nickel-based superalloys trademarked by Special Metals Corporation. Inconel alloys are primarily composed of nickel, though they also incorporate other elements, notably chromium, molybdenum, aluminum and titanium, depending on the specific alloy. Inconel can withstand extremely hot temperatures and resist corrosion, so it's often used in high-temperature or corrosive environments.
2. Monel: First developed in 1905, Monel is another type of nickel-based superalloy containing copper, aluminum, titanium and iron as well as other secondary components. Weaker versions of Monel alloys briefly enjoyed applications on kitchen countertops and appliances before being replaced by stainless steel. The Monel superalloy has high strength at increased temperatures, giving it a variety of aerospace applications.
3. Rene 41: Rene 41 is a nickel-based superalloy first discovered by General Electric. It's easily welded and forged and performs well in extremely high temperatures up to 1,800 degrees Fahrenheit. It's commonly used in jet engines and missile components.
4. Cobalt-based superalloys: Cobalt-based superalloys have higher melting points and are easier to weld compared to nickel-based alloys. At lower temperatures, cobalt superalloys are weaker than nickel superalloys, but they can withstand greater heat overall. For this reason, cobalt-based superalloys perform best in environments that are high temperature but low stress.
5. Iron-based superalloys: Like nickel- and cobalt-based versions, these superalloys are characterized by strength under high temperatures and resistance to wear and oxidation, giving them similar potential applications. Iron-based superalloys are generally less expensive than their cobalt and nickel counterparts.

Benefits of Plating Superalloy vs. Alloy

Plating onto superalloys like Monel or Inconel comes with a variety of benefits over plating on regular alloys. Superalloys are known for their heat resistance and strength, so choosing a superalloy can greatly enhance the performance of a part in extreme conditions. This enhancement may be especially important for those in the aerospace, automobile and electronics industries.

Any material that needs to stand up to intense heat or corrosive conditions could be crafted out of a superalloy metal. Superalloys could also potentially find industrial applications in production facilities that rely on constant use of fast-moving equipment.

Likewise, plating onto superalloys can provide advantages to leaving components in their natural state. In the aerospace industry, for example, electroplating and electroless plating both play important roles in improving strength and further reducing the risk of corrosion. Notably, zinc-nickel coatings are used to protect parts from air corrosion and prevent the development of white and red rust.

Though superalloys may not be the best materials for every project, they're worth considering for industrial products that need to be strong, durable and reliable. In order to assure peak performance, it's important to consult a metal finisher that knows the intricacies of alloys and superalloys within your industry.

At SPC, we have 90 years of finishing experience, but we're still constantly striving toward innovation. We work closely with a variety of thriving industries — including aerospace, electronics and automotive — to find the best finishing treatments for every individual client, regardless of the base materials they're using. Whether you're plating a superalloy or not, SPC can help you develop a finishing process that meets your specialized needs. Contact us to learn more about our options.

Additional Resources:

• Challenges of Plating Onto Ceramics
• Benefits of Ceramic Plating
• Plating on Exotic Refractory Metals
• Applications of Plating Glass Biotechnology