Types of metal plating process
The metal plating process is of two different types: Electroplating and electroless plating. While electroplating requires electrical current, electroless plating involves dipping the component in a liquid solution to bring about the desired reaction. Both the processes have their own pros and cons. The choice of plating method is determined by the application type of the component, and costs.
Electroplating method
This process uses electrical current to achieve uniform metal plating. The current reduces dissolved metal cations that are nothing but positively charged ions. Electrodes are the key components of the electroplating process. The material to be plated is also a cathode which is negatively charged whereas the metal which is to be coated on the object is the positively charged anode. Both these components are immersed into an electrolyte solution comprised of metal salts and other ions to facilitate the proper circulation of electrical current. The current then leads metal cations to form a thin coating onto the object to be plated. This process is called electrodeposition.
In electroplating, an external power source must supply electrical current to the anode to oxidise and dissolve metal atoms into the electrolyte solution. These dissolved ions then go on to plate the object. The ions present in the electrolyte are replenished throughout the process by the anode which is made up of the metal used for plating the object. At the end of the process, the chemical properties of the component. are altered. Its resistance to corrosion improves, dulling is prevented, increasing the component’s durability, and it gains added tensile strength. A part that could not perform under pressure might be able to do so after plating.
Electroplating is the best method to achieve a uniform thickness of the coating. Despite a high consumption of power, it is an economical method due to the high volume of components to be plated. Other benefits of this process include uniform surface abrasion and building thickness of the metal substrate. Electroplating enhances the surface of components, making them ideal for plaining.
Electroless method
The electroless method uses an auto-catalytic chemical reaction and not an electrical current to plate components. This process involves dipping the component in a liquid to induce multiple reactions at once. Electroless plating does not need two electrodes and an external power source. It uses one electrode and relies purely on chemical methods. This also makes electroless plating less costly.
Electroless plating uses a reducing agent for plating. Nickel tends to be the most commonly used metal in this process. However, other metals such as copper, silver and gold can also be plated onto components using electroless plating. Since this method does not need electrolyte baths and external application of current, it allows more flexibility in the shape and size of objects to be plated and can deliver varying levels of finishing brightness in the coating. On the downside, however, electroless plating tends to be much slower and cannot deliver the desired thickness of the coating that electroplating can.
It is still a very effective method to alter the physical and chemical properties of components with effective coating and improve their durability.
