Electropolishing is an electrochemical dissolution process without mechanical force, and a dense and firm oxide film is formed on the surface after polishing, no process deterioration layer, no residual stress, and no limitation of materials.
Electropolishing Features:
1) Low current, large gap.
2) Simple and quick.
3) The oxide film plays a role of anti-corrosion protection.
4) No work hardening and residual stress.
The main factors affecting electrolytic polishing:
1. Electrolyte composition
According to the different polishing materials, the electrolyte composition and density used are different, and the polishing parameters are also different.
2. Current density
The current density has a significant effect on the leveling rate of the metal surface and the amount of metal dissolution. If the processing time is the same, the surface leveling and the metal dissolution rate are faster when the current density is large, and the relative flatness ratio (roughness ratio before and after polishing) of the unevenness is irrelevant to the current density at the same electric quantity.
3. Temperature and agitation
The temperature of the electrolyte has a great influence on the solution viscosity and the performance and composition of the anode film. Generally, the higher the temperature, the faster the leveling speed. When the temperature was raised from 30°C to 70°C, the dissolution rate of the metal increased by almost 1.5 times. If the current density is 0.5 A/cm2, the electropolishing time is 10 min, and the optimum temperature is 100° C. However, in order not to boil the solution, it is generally about 70° C.
The electrolyte should be stirred as far as possible during electropolishing, which can not only promote the flow of the electrolyte, but also ensure the diffusion of ions in the polishing area and the replenishment of the new electrolyte, and reduce the difference in the temperature of the electrolysis, thus ensuring the most suitable polishing conditions.