What is chrome plating?
Chrome plating refers to a common surface treatment process in which chromium is deposited as a coating on other metals. There are mainly two types of hot galvanizing and cold galvanizing. Cold galvanizing is also called electric galvanizing. The main purpose is to increase the corrosion resistance and decorative effect of the material.
Process principle
The principle of chromium plating process is based on electrochemical reaction. In the process of chromium plating, the plating bath containing metal chromium anode and plating solution is used as the cathode, and the electrolytic reaction will occur after the power is turned on.
This process can be divided into three main steps: anodic dissolution, metal deposition, and sediment molding. Anodic dissolution refers to the gradual dissolution of the metal chromium anode into a cation under the action of an electric current.
Metal deposition refers to the transfer of cations through the electrolyte to the cathode surface, reducing into chromium metal, thereby depositing metal on the surface of the part to be plated. Sediment forming refers to the gradual formation of a uniform and bright chromium layer after metal chromium is deposited on the surface of the parts to be plated.
Process steps
- Cleaning: Before chrome plating, the plated object needs to be thoroughly cleaned to remove impurities and oil on the surface. Commonly used cleaning methods include pickling, alkali washing and electrolytic washing to ensure the cleanliness of the surface of the plated object.
- Pickling: Pickling is required before chrome plating. Pickling can remove the oxide film and rust on the surface of the plated material to ensure that the subsequent chromium plating process can proceed smoothly. Generally using dilute nitric acid or dilute acid soaking method for pickling treatment.
- Electroplating: Electroplating is the core step of the chromium plating process. The plated object is used as the cathode, the chromate solution is used as the anode, the chromium ion is reduced to chromium on the surface of the plated object by the action of external current, and the surface is attached to form a chromium layer. This step requires controlling the size of the voltage and current, as well as the temperature and concentration of the bath to ensure uniform, dense chromium.
- Cleaning: After chromium plating, the coating needs to be cleaned to remove residual chemicals. Generally, two methods of washing and pickling are used for cleaning to ensure the quality of the coating.
- Polishing: After cleaning, the coating can also be polished to further improve its appearance and gloss. Polishing can make the coating smoother and reduce surface defects and inhomogeneity.
- Inspection: Finally, it is necessary to test the product after chrome plating to ensure that its quality meets the requirements. Common inspection methods include appearance inspection, thickness measurement and corrosion resistance test.
Process advantages
- Improving the appearance quality of the product: the chrome plating process can form a uniform and bright chrome layer on the surface of the product, making the appearance of the product more beautiful. The high reflectivity of the chrome layer can also increase the brightness of the product and enhance its value.
- Improving the corrosion resistance of the product: the chromium layer has good corrosion resistance, which can effectively protect the metal surface of the parts to be plated from oxidation, corrosion and other damage. This makes the chrome plating process widely used in automobiles, motorcycles and other products to extend their service life.
- Increasing the hardness and wear resistance of the product: chromium metal is a material with high hardness, and a layer of chromium with high hardness and good resistance can be formed on the surface of the parts to be plated through the chromium plating process to improve the service life of the product.
