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Difference between Electroplating and Electroless Plating
In metal processing industry, plating is a process of depositing a thin layer of one metal onto the surface of another metal. Plating is done to improve appearance of the metal surface and protect from corrosion. Electroplating and Electroless Plating are commonly used techniques for plating of metals.
The main difference between electroplating and electroless plating is in their working principle. Electroplating utilizes an externally supplied electric current to deposit a layer of metal onto the surface of another metal, while electroless plating utilizes chemical reactions to deposit a metal coating on the surface.
In this article, we will explore all the important differences between electroplating and electroless plating.
What is Electroplating?
An electrochemical process in which a thin layer of one metal is deposited onto the surface of another metal to enhance its appearance or corrosion resistance is referred to as electroplating.
In electroplating, an electrochemical cell is formed, consisting of two electrodes namely, anode and cathode immersed in an electrolytic solution. The cathode is the metal or article on which the coating has to be done while the anode is made of the metal which has to be coated onto the surface of the cathode. These two electrodes are connected to an external DC power supply.
When an electric current flows through the circuit of the electrochemical cell. This electric current oxidizes the metal atoms and dissolves them into the electrolytic solution. These dissolved atoms of metal are then reduced at the cathode and deposited on it to form a thin layer. The thickness of the layer deposited can be controlled by varying the current, plating time, and concentration of the electrolyte.
Electroplating is widely used in manufacturing of decorative items, jewelries, corrosion resistant objects, etc.
What is Electroless Plating?
A process of coating one metal onto the surface of another metal through chemical reactions rather than electric current is referred to as electroless plating.
In electroless plating, the metal surface that has to be coated is thoroughly cleaned and is immersed in an activation solution to provide adhesion of the metal coating. Now, the electroless plating bath is prepared which consists of a chemical solution having metal ions of the metal that has to be deposited on the substrate. The cleaned and activated substrate is now immersed into the electroless plating solution, where the chemical reaction for plating is initiated by the reducing agent present in the solution. This plating reaction allows a thin metal coating to be deposited onto the surface of another metal.
Electroless plating is very commonly used in applications that involve complex geometric shapes, even thickness distribution of coating layer, and coating of non-conductive material surfaces.
Difference between Electroplating and Electroless Plating
The important differences between electroplating and electroless plating are listed in the following table −
Parameter |
Electroplating |
Electroless Plating |
|---|---|---|
Definition |
A metal plating process which involves the use of electric current to drive the chemical reaction for plating is referred to as electroplating. |
A metal plating process in which chemical reactions are involved to deposit a layer of metal onto the surface of another metal is referred to as electroless plating. |
Need of external power source |
Electroplating requires an external power source to drive the plating reaction. |
There is no need of external power source in the electroless plating to drive the plating reaction. |
Anode |
In electroplating, a separate anode is used that is made up metal which has to be coated on the surface of another metal. |
In electroless plating, there is no anode, instead the catalytic surface of the substrate plays the same role. |
Cathode |
In electroplating, the substrate on the which the coating layer is to be deposited forms the cathode. |
Electroless plating has no cathode, instead the activated surface of the substrate serves the same function. |
Deposition rate control |
In electroplating, the deposition rate is primarily controlled by changing electric current and plating time. |
In electroless plate, the deposition rate is controlled by changing the concentration of plating solution. |
Type of substrate material |
Electroplating is limited to used for conductive materials only. |
Electroless plating can be used for plating of both conductive and non-conductive materials. |
Uniformity in thickness |
Electroplating can provide a coating of uneven thickness in the case of complex geometry of the substrate. |
Electroless plating provides comparatively uniform thickness of deposition on the complex-shaped surfaces. |
Process steps |
Electroplating process steps are substrate preparation, set up electrochemical cell, formation of coating, and finishing. |
The steps involved in the electroless plating are substrate preparation, substrate activation, plating solution preparation, formation of coating, and finishing. |
Throwing power |
Electroplating requires low throwing power. |
Electroless plating requires high throwing power. |
Nature of process |
Electroplating is a non-catalytic plating process. |
Electroless plating is a catalytic plating process. |
Suitability for hollow parts |
Electroplating is not suitable for plating of hollow parts. |
Electroless plating is suitable for plating of hollow parts. |
Impact on environment |
Electroplating involves the use of toxic chemicals that have significant impact the environment. Hence, it requires proper waste management. |
Electroless plating also contain harmful chemicals but they are relatively less toxic and hence have less impact on the environment. |
Operational cost |
Electroplating has high operation cost due to electric power consumption. |
Electroless plating has comparatively lower operating cost. |
Coating characteristics |
Electroplating provides a coating having high hardness, good adhesion and corrosion resistance. |
Electroless plating provides a coating with uniform thickness and good corrosion resistance. |
Nature of deposit |
In electroplating, a pure metal is deposited onto surface of the substrate. |
In electroless plating, the depositing metal contains reducing and oxidizing agents. |
Levellers |
In electroplating, the levellers are required. |
In electroless plating, there is no need of levellers. |
Applications |
Electroplating is mainly used to manufacture decorative items, improve corrosion and wear resistance of metals. |
Electroless plating is mainly used for coating of complex-shaped objects. |
Conclusion
The main purpose of both electroplating and electroless plating is the same, i.e. to deposit a layer of one metal onto the surface of another metal. The most significant difference between electroplating and electroless plating is their technology, i.e. electroplating relies on electric current for the plating process, whereas the electroless plating depends on a chemical reaction.
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