Ferrous materials or conductors of electricity such as metal can be treated in the manufacturing process through the techniques of electropolished. The electropolished It is a chemical process that allows to reduce the micro-roughness of a metal, this electrolytic process smoothes and streamlines the microscopic surface of the treated object. That is, the metal surface is microscopically free of features. This type of treatment does not affect the chemical, mechanical or thermal form of the metal, so it can be applied to objects considered fragile in some way, although it is adapted to large objects.
Corrosion resistance through electropolishing of stainless steel
This procedure has become very common in alloys such as stainless steels, being the electropolished stainless steel one of the best processes to increase corrosion resistance. One of the most benefited industries of this chemical process in metals is the industry pharmaceutical, biochemical and food, because the metallic materials to be used are easy to clean due to their smooth surface free from roughness.
How is the stainless steel electropolishing process carried out?
The chemical treatment of electropolished It is carried out by immersing the piece to be treated in an electrolytic bath of controlled temperature.
As we can see in the image, the piece (anode) has a positive charge, while the cathodes have a negative charge. The process of electropolished works the metal electrolytically, in what way? It does it ion by ion where the electrolyte acts as a conductor of the current, carrying out the separation of the ions of the piece towards the cathodes, freeing it from metal residues, to leave a microscopically clean surface, and in view with a better appearance. This process does not affect in any way the chemical or mechanical properties of the workpiece.
For a uniform finish, the following must be taken into account:
- The placement of the cathodes and their design
- The way in which the piece to be worked with is held
The amount of material removed from the part varies depending on the amount of current applied and the duration of the part immersed. The main chemical reactions that occur in the electrical anode, that is, in the piece, are the following:
Metal – Electrons to Metal Ions
The reaction that comes from the process indicates that the metal dissolves from the anode electrode, forming a soluble salt of the metal. An alloy such as stainless steel, made up of iron, chromium and nickel, undergoes this reaction simultaneously, producing a controlled smoothing of the surface. Various side reactions also occur, creating by-products that must be controlled in order to produce the highest quality product possible. electropolished.
What factors should be taken into account before carrying out the stainless steel electropolishing process?
One of the most important factors is the preparation of the metal, in order to eliminate surface oils, grease, oxides or any contaminant that may interfere with the uniform finish of the metal. electropolished stainless steel.
To carry out the preparation of the metal, it goes through a cleaning process that consists of the following:
- Alkaline Soaking: through which the remains of oil or grease, any dirt, traces, etc., that the piece may have are removed from the piece.
- Cold water rinse: after soaking the piece in alkaline, a cold water rinse process is carried out to remove the chemical residue from the previous operation and prevent any residue from appearing in the subsequent operation.
- Descaling: one of the things that can affect the finish of the electropolished in the piece are the features of oxidation in it, for this reason the decalcification allows to eliminate said oxidation, in the same way it neutralizes the alkaline film. The process of sanding and polishing the part can eliminate the need for descaling.
- Final cold water rinse: it is based on the same operation as the alkaline cleaning rinse, the difference is that acid solutions are mostly difficult to remove by washing alkaline residues.
Benefits of electropolishing stainless steel
The electropolished stainless steel provides a number of benefits to our treated piece, which are:
- A considerable improvement in the physical appearance of the piece, achieving a shiny and smooth enamel, with a uniform shine throughout the piece.
- Improved mechanical properties: as mentioned above, the process of electropolished it does not affect the chemical or mechanical properties of the piece, but it does provide improvements, in this case in the mechanical properties.
- Increase in production cycles, especially in the food area, since electropolishing considerably reduces obstructions, product accumulation, encrustation, etc.
- Relieves stress from the part surface.
- It gives the part excellent protection against corrosion.
- Improves sterilization and maintenance of hygienically clean surfaces for food, drug, beverage, and chemical processing equipment.
- It allows to discover defects in the treated metal surface that are undetectable by other means.
Without a doubt he electropolished stainless steel It is one of the most used techniques for process improvements in industries in order to always achieve the best results.