By the influence of electric current in an electrolyte, the surface of metals can be selectively removed. Through this process, the material is polished and high-gloss and resistant surfaces are formed.
The most frequently electropolished material is stainless steel. The method offers many advantages:
- Improvement of the appearance – high gloss
- Removal of thermally and mechanically generated tensions within the metal surface.
- Deburring; The electropolishing process removes sharp edges
- No residues of polishing agents in the metal surface
- Significantly thicker passive layer on stainless steel. Electroplated stainless steel is much more corrosion resistant.
- The much smoother surface results in better flow characteristics in pipelines or in reactors.
Electropolished surfaces can be cleaned and disinfected more effectively. Germs cannot attached onto polished surfaces easily.
- Uniform polishing of parts with complex geometry
- Polishing of small parts faster and more economical than mechanical methods
Electropolishing of Stainless Steel
For the electropolishing of stainless steels, Foster Chemicals offers products from the AnoFos 100 series. In addition to fresh solutions, ready-mixed blends with already incorporated metal salts are also offered. The products consist of inorganic acids with additives that improve luster, leveling and efficiency. The polishing time and the anodic current density are decisive for the metal removal.
1. Time Depending on the desired degree of polishing or layer thickness:
– Protective polishing: time 6 min, removal approx. 6-8 μm
– standard polishing: time 6 min, removal approx. 12-15 μm
– extra polishing quality: time 30 min, 30 μm.
2. Anodic current density
– Standard stainless steel qualities (Cr-Ni steel): 10-20 A / dm2
– Chrome steel grades (Cr steel): 15-30 A / dm2
Electropolishing of Aluminum
Electropolishing aluminum is a metal-removing anodic process in an electrolyte based on phosphoric acid and sulfuric acid. Electropolishing greatly reduces the microroughness of the aluminum surfaces, resulting in a high gloss even at low mass losses. A good gloss is possible on aluminum alloys with the silicon content below 1%.
Product: AnoFos 300 The standard procedure of Foster Chemicals for the electropolishing of aluminum and aluminum alloys offers the following advantages: – high gloss in a short time – suitable for many commercially available materials.
Temperature: 64-67 ° C (50-80 ° C)
Time: 2-10 min
Current density: 5-15 A / dm2
For a good polishing result, many parameters of the electrolyte must be monitored and – if necessary – corrected. We offer our customers analytical methods for all important bath parameters and advise them on bath maintanance. When using fresh electrolytes, we analyze the acid ratio and the iron content of the old baths.