Electropolishing is commonly used for decorative finishing of steel, stainless steel, aluminum, copper and other parts or coatings of copper, nickel, etc., surface finishing of some tools, or for making highly reflective surfaces and for making metallographic test pieces. Wait.
In many cases, electropolishing can be used to replace heavy mechanical polishing, especially for parts that are more complex in shape and difficult to machine by mechanical means. However, electropolishing does not remove or mask surface defects such as deep scratches and deep pitting, nor can it remove non-metallic inclusions in the metal. In a multiphase alloy, when one phase is not easily dissolved by the anode, the quality of the electropolishing will be affected.
Chemical polishing is the chemical etching of metal parts under specific conditions. During this etching process, the metal surface is etched and leveled by the solution, resulting in a relatively bright surface.
Chemical polishing can be used for surface finishing of instruments, aluminum mirrors, and decorative processing of other parts or coatings.
Compared with electropolishing, the advantages of chemical polishing are: no need for external power supply, can handle more complex shapes, high production efficiency, but the surface quality of chemical polishing is generally slightly lower than electrolytic polishing, and solution adjustment and regeneration are also compared. Difficulties, harmful gases such as nitrogen oxides are often precipitated during the polishing process.
The electropolishing liquids currently used in production mainly include:
a polishing solution consisting of sulfuric acid, phosphoric acid and chromic anhydride;
a polishing solution consisting of sulfuric acid and citric acid;
A mixed polishing solution consisting of sulfuric acid, phosphoric acid, hydrofluoric acid, and glycerin or the like.
Electropolishing of aluminum and aluminum alloys is widely used in production. If the polished parts are subjected to a short-time oxidation treatment, not only can a flat and bright appearance be obtained, but also a complete oxide film can be formed, corrosion resistance can be improved, and the surface gloss can be maintained for a long period of time.
Chemical polishing is the process of etching and leveling a part in a specific solution. The chemical polishing equipment is simple and can handle parts with more complex shapes. Disadvantages The quality of chemical polishing is not as good as electrolytic polishing. The adjustment and regeneration of the solution is also difficult and limited in application. In particular, during the chemical polishing operation, nitric acid emits a large amount of yellow-brown harmful gas, which is very serious to the environment.