What Does Electrolytic Cleaning Mean?
Electrolytic cleaning is a method of removing soil, scale or corrosion products from a metal surface by subjecting it as an electrode to an electric current in an electrolytic bath. It is a form of electroplating that can be applied to all electric conductive materials.
The electrolytic method is cheap and effective, causing minimal alteration to the metal surface.
This precision cleaning method is usually applied as last cleaning step before electroplating and after a pre-cleaning with solvents or alkaline baths.
Corrosionpedia Explains Electrolytic Cleaning
In electrolytic cleaning, a DC current is applied between an insoluble electrode and the workpiece to be cleaned. There are two general methods of electrolytic cleaning:
- Anodic electrocleaning - The workpiece is made the anode in the system. This is performed in a basic solution to facilitate the oxidation reaction 4(OH)- = 2H2O + O2(g) + 4e-. Oxygen gas bubbles are generated directly at the workpiece, beneath the contaminant, which helps lift and remove the rust, deposits and light oils.
- Cathodic electrocleaning - The workpiece is made the cathode and a reduction reaction occurs at the surface. In this case, the pH of the system needs to be acidic to provide sufficient hydrogen ions to sustain the reaction 4H+ + 4e- = 2H2(g). In the same manner, it lifts deposits like rust or oxide from the metal surface.
In the case of cathodic electrocleaning, the system is said to be more efficient because twice as much hydrogen is produced as oxygen is in the related anodic reaction. Electrocleaning of ferrous metals is generally done in an alkaline environment in the anodic mode. Cathodic electrocleaning is often used for nonferrous materials only.
In some cases, a technique called periodic reverse cleaning, which is thought to be the most effective at oxide (rust) removal, is used.
The electrolytic process is more aggressive than ultrasonic cleaning, with a risk of acid solutions dissolving the iron surface content of the wire.