Archive for June 19, 2013

Electroplating and Electroless Nickel Plating – Advantages and Disadvantages

There are two methods of depositing a thin layer of nickel onto the surface of a metallic object. One is electroplating, the other electroless plating. So what is the difference and why would you use one over the other?

In this post we’ll look at the differences between these two types of nickel plating, from the chemistry behind the processes, to the ideal uses for each.

Electroplating

The process of electroplating occurs when a rod of the plating method is used as an anode. The anode is immersed in a bath of electrolyte which contains the salt of the metal to be plated. For nickel plating, the salt used is Nickel Chloride.

With electroplating, two or three plating processes may be used, sometimes with a layer of a different metal underneath to improve adhesion.

Disadvantages of electroplating

Electroplating may result in hydrogen embrittlement, where the hydrogen gas leaks out at the surface of the cathode and diffuses into the surface of the component to be plated, making it brittle.

This embrittlement can be reduced by post plate heat treatment at a low temperature, which reverses the process of hydrogen diffusion into the surface layers of the component.

 

 

 

Electroless nickel plating

The other method of plating with nickel is electroless nickel plating. This type of plating doesn’t need an electric current because it happens using a chemical reaction.

The electroless nickel solution consists of nickel ions, reducing agents and other chemicals. The most commonly used reducing agent is sodium hypophosphite.

Advantages of electroless nickel plating

Electroless nickel plating has many fantastic properties which makes the process superior to other types of metal plating.

  • The process extends the life of any component that it coats.
  • The metal layer deposited by the electroless nickel plating process has an even thickness over all surfaces of the component.
  • This effect cannot be achieved with electrodeposited coatings.
  • Electroless nickel plating also provides excellent wear and corrosion resistance, as well as hardness and lubricity.

Another advantage of the process of electroless nickel plating is that the parts to be plated do not need to conduct electricity. This means that electroless nickel plating can be applied to ceramics, composites and polymers.

This method of plating is great for producing prototypes of metallic parts by plating a polymer casting or part to give some idea of the finished piece.

Disadvantages?

It is still possible for electroless nickel plated parts to suffer from hydrogen embrittlement, so for parts that are prone to corrosion through use, post heat treatment may be needed to improve the adhesion of the nickel and reduce the internal stresses within the nickel that has been deposited. When heat treating electroless nickel, it is also important to ensure that the heat treatment doesn’t temper-soften the existing material.

If you are looking for a quality company specialising in the process of electroless nickel plating, look no further than NiTEC. Talk to a member of our friendly team on 0845 224 3571 or email info@nitec-enp.co.uk for more information.

Electroless Nickel Plating and Its Use in Aerospace Applications

Electroless nickel has many fantastic qualities which make it perfect for use in the aerospace industry. Below are some of the components used in the aerospace industry that electroless nickel is commonly use to plate.

Turbine blades and compressor blades

Turbine blades and compressor blades are parts of aircraft engines frequently exposed to highly corrosive environments. Electroless nickel is extremely corrosion resistant, making it favourable for this type of use.

Engineers working in the aerospace industry often use aluminium because of its light weight and density. An electroless nickel coating compliments the properties of aluminium by adding solderability, corrosion protection, wear resistance and hardness.

Piston Heads

The combination of electroless nickel and aluminium is often used to make piston heads. Electroless nickel is an effective coating because it prevents wear, and therefore increases the life of the piston. Aluminium is effective because it is so lightweight, meaning that the piston is able to work better.

Aircraft shafts

Electroless nickel is often used to plate the main shafts of air craft engines because it provides an excellent bearing surface. Typically, during air craft maintenance, rebuilding the shaft may be necessary. But with electroless nickel, the surface can be stripped off and re-plated to the thickness needed instead of buying new components, therefore saving money. This technique is also used when reconditioning rear compressor hub sleeves and bearing liners.

For more information about the use of electroless nickel plating in aerospace applications, please contact the specialist team at NiTEC on 0845 224 3571, email: info@nitec-enp.co.uk or visit the NiTEC website.

Engineering Applications of Electroless Nickel Plating

Over the years the staff at NiTEC have developed a wide range of metal finishing and metal plating techniques. We are able to process many materials such as ferrous substrates, plate stainless steel, plate copper and its alloys, and even plate aluminium alloys.

There are endless applications for electroless nickel, and they can be found in a huge number of industries.

Electroless nickel plating is a very common choice for many engineering applications because it has lots of great qualities, for example:

  • Wear resistance
  • Hardness
  • Corrosion resistance
  • Uniform coating
  • The ability to plate non-conductive surfaces

 

 

 

Electroless nickel plating can be used for a number of industrial applications, including, but not limited to the following:

  • Sea water pumps
  • Aircraft control systems
  • Photographic equipment
  • Oil field drilling equipment
  • Aircraft engine mounts
  • Undercarriage fixtures
  • Hydraulic pistons
  • Valves and pump shafts
  • Printing rollers
  • Machine slideways
  • Excavating equipment
  • Hydraulic cylinders
  • Fine instrument pivots
  • Memory discs
  • Spray nozzles
  • Worm wheels
  • Valve blocks

If you would like to find out more about electroless nickel can be used as a corrosion resistant, hard wearing coating for your engineering application, contact the specialist team at NiTEC on 0845 224 3571, or email: info@nitec-enp.co.uk

Phosphorous Variations in Electroless Nickel Coatings

As experts in electroless nickel plating, NiTEC provide the full spectrum of nickel and phosphorous alloys.

Electroless nickel can be alloyed with between 4 and 14% phosphorous. There are three main types of electroless nickel, which are outlined below.

Low phosphorous electroless nickel coatings

Low phosphorous electroless nickel is alloyed with approximately 4% phosphorous. Electroless nickel coatings of this type are typically very hard, have good corrosion protection in alkaline environments and lowest impact on fatigue. Low phosphorous electroless nickel is best for higher temperatures.

Medium phosphorous electroless nickel coatings

Medium phosphorous electroless nickel is alloyed with between 5 to 9% phosphorous. This is the most common type of electroless nickel plating and is typically very bright. Medium phosphorous electroless nickel plating offers moderate corrosion and wear protection.

High phosphorous electroless nickel coatings

High phosphorous electroless nickel is alloyed with 10 to 14% phosphorous. This type of electroless nickel coating has a glass-like structure with the highest level of corrosion protection. It is also non-magnetic.

If you would like advice from the experts on which type of electroless nickel coating will best suit your product and it’s use, contact NiTEC on 0845 224 3571, email info@nitec-enp.co.uk or visit our website to contact a specific member of staff.