What is chemical nickel plating (DurniCoat)?

On this page we will explain what chemical nickel plating entails and what the advantages of chemical nickel plating are. If you have any questions, our experienced employees will be pleased to help you.

Mifa Surface Treatment Processes

What is chemical nickel plating?

By means of a chemical process a well adhering amorphous nickel phosphor layer (NiP) is deposited on the metal workpiece / profile. The process takes place without an external power source and is therefore non-electrolytic.

The process liquid consists of a dissolved nickel salt, reducing agent, complexing agents and stabilisers. The nickel salt is the source of the required nickel, the reducing agent initiates the precipitation reaction and is the source of the phosphorus. Complexing agents ensure that the reaction products formed during nickel separation remain in solution. Stabilisers ensure a uniform precipitation rate and prevent spontaneous decomposition of the electrolyte. Once nickel is precipitated the process proceeds automatically, this is called an auto-catalytic process.

The working window of a chemical nickel liquid lies in a certain pH range and temperature, which depend on the type of chemical nickel liquid. The precipitation rates can be influenced by both parameters; precipitation rates are between 10 – 15 µm/hour.

Due to the continuous formation of the reaction products, the chemical nickel liquid only has a limited lifetime. The phosphor component influences the properties of the formed chemical nickel layer in terms of hardness, ductility and corrosion resistance, among other things.

Why chemical nickel plating?

In an electroless nickel process, the positive Ni ions are deposited on a negatively connected work piece (cathode) by means of an external current source. On corners and edges there is an increased layer build-up, in bores there is little or no build-up (without the use of complex auxiliary anodes). The chemical process results in a very uniform layer build-up, closely following the contours of a product. This allows for very precise tolerances of ± 10% of the layer thickness.

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What are the benefits of chemical nickel plating?

Advantages of nickel plating

  • Narrow size tolerances: Where the layer thickness with electroless nickel processes reach tolerances of ± 30-50% or higher, with chemical nickel this is ± 10%.
  • Chemical and corrosion resistance: The chemical nickel layers have a very good chemical and corrosion resistance, especially the layers with a high phosphor content.
  • Adhesion improvement: Through heat treatment an even better adhesion can be obtained.
  • Adjustable final hardness: The hardness of the formed chemical nickel layer can be increased by heat treatment. The layer hardnesses that can be achieved are 500 to 1,000 HV. Whereby the nickel layer changes from amorphous to crystalline. This treatment results in a very wear-resistant layer.
  • Ductility and solderability: Compared to electroless nickel, the layer is fairly ductile and is also solderable.
  • Low friction coefficient: The chemical nickel layer has a low friction coefficient.
  • Like all metals the chemical nickel layer is also current conducting.

Disadvantages of chemical nickel plating

Higher cost: in comparison to electrolytically deposited nickel layers, the process costs for chemical nickel plating are higher. These are caused by high chemical and waste costs as well as the slower deposition rate of this process.

What opportunities can we offer you with chemical nickel

  • The chemical nickel process, called DurniCoat (DNC), is an entirely unique development. The composition of the bath chemistry has been further developed and improved over time. This ensures a very consistent product quality that meets the latest technical requirements and applicable guidelines. Our extensive experience within Mifa Surface Treatment and Aalberts can be used to implement project-based customer wishes through adjustments to the chemistry.
  • Various heat treatments, to improve adhesion or hardness and wear resistance
  • Product size up to 3,600 mm length
  • Nickel strike also up to 3,600 mm, necessary for highly alloyed steels (and stainless steel)
  • Product mass max. 750 Kg.
  • Post treatment with polymers; see Nedox® under process group polymer layers.

Which processes do we offer

There are several nickel processes, depending on the customer requirements the right one can be chosen. We have chosen the DNC 520-9 chemical nickel process. This is a medium-phosphor variant with a base hardness of approximately 500 HV. This layer has a good corrosion resistance and is hardenable to approx. 1,000 HV, and can therefore be used as a substitute for hard chromium layers.

Other chemical nickel-plating processes are possible, including chemical nickel plating of other metals such as aluminium, copper/brass and titanium. We carry out these processes together with our sister companies.

Customised precision products

With our technical knowledge and extensive experience, we are happy to advise you on the best surface treatment or aluminium coating for any application. We provide mechanical, electrochemical and galvanic surface treatments, polymer coatings, priming and lacquering.

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