"Electroless" vs. "Electrolytic" Nickel Plating For Aircraft MRO

Nickel plating is a cornerstone solution for repair and refurbishment in aircraft MRO. The excellent corrosion protection, similar lubricity properties to chromium, and wear-resistant surface are valuable on restored aircraft components. A reliable cleaning followed by a durable nickel finish will lengthen the time until the parts must be maintained again.

However, you’ll need to choose between two techniques for getting the job done: electrolytic and electroless nickel plating (EN). Let’s compare.

What is “Electrolytic” Nickel Plating?

The electroplating process requires an electrolyte bath and an electrical current. The substrate material (your aerospace part) must also be conductive. After the part is carefully cleaned, it is submerged in the bath and wired up to an electrical current. As the electricity flows through the component and the bath, it draws nickel ions out of the solution and deposits a thin layer on the surface of the part. 

What is “Electroless” Nickel Plating?

The process for electroless nickel plating, or EN, is much more straightforward because it does not require conductive materials or any electricity. Electroless plating instead coats the aerospace component in nickel through a chemical reaction. After cleaning the part, it is submerged in a bath where a catalyst starts a chain reaction that deposits metal ions (which form a nickel-phosphorus alloy plating) onto the substrate.

What are the Advantages of Each Method?

Benefits of Electrolytic Plating

Benefits of Electroless Plating

  • Can be a faster process (depending on ion concentration and voltage)
  • Often the cheapest option
  • Creates a thicker coating, but less uniform
  • Soft and more ductile, bends without cracking
  • More consistent, reliable, and repeatable coating with even thickness
  • Effectively coats sharp edges, deep recesses, seams, threats, and complex geometries
  • Phosphorus in the deposit adds extra corrosion resistance and surface lubricity
  • No conductivity required in the part to be plated
  • Hard, crunches/flakes/cracks when bent

For some aircraft maintenance and repair needs, the lower price of electrolytic may become a deciding factor. However, any kind of nickel coating is also likely to cost more in the current economic environment. Much of the world’s nickel is produced in Russia, so the conflict in Europe has led to extreme volatility in the nickel market and material price increases across the board. This has de-emphasized one of the key selling points of nickel electroplating.

The electrolytic process can also lead to uneven distribution of the nickel coating. Excess deposits can form on the edges or corners of the substrate (where the electrical current is typically higher). With the electroless process, the plate is uniformly deposited, eliminating the need for post-plate machining on critical dimensions.

Which Technique Gives a Superior Finish for Aircraft MRO?

The truth is that each plating style has its uses and trade-offs, but one is not categorically better than the other.

Electrolytic plating is preferred for applications where its greater ductility and softness and thicker overall coating are an advantage, or when the plating needs to be done rapidly for potentially lower costs.

Electroless plating offers greater corrosion resistance and reliable, repeatable coating of a uniform thickness generally, with the tradeoff of a somewhat slower process and the potential for higher costs (largely due to time). Price differences do matter less in a volatile and unpredictable nickel market, however, in which the cost for either style of plating has gone up. You can learn more about the applications and specifications relevant to electrolytic and electroless nickel plating here

If you’re anticipating some upcoming repair and refurbishment work that could use nickel plating, request a quote! Metal Finishing Technologies is the largest finishing house in the northeast. Our facility responds to every RFQ within 24 hours and offers industry-leading turnaround times on plating and finishing for aircraft MRO. 

MFT is also a certificated FAA Repair Station that’s been relied upon by aircraft MRO companies since 1947 for component restoration, refurbishment, and repair. We’re prepared to support your aircraft MRO needs with diverse cleaning, stripping, and plating solutions. Get in touch!

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