Views: 0 Author: Site Editor Publish Time: 2023-07-10 Origin: Site
chrome bottle is a process for galvanizing a thin layer of chromium on metal. Chrome plating has two main functions, for decoration or as a protective layer.
What is the physical principle of chrome bottle production?
What is the raw material of the chrome bottle?
What chemical reaction does the chromium bottle participate in?
chrome bottle chrome plating requires a higher cathode current density, usually over 20.A.dm2, which is more than 10x higher than the general coating. Due to the large amount of gas released by the cathode and anode, the resistance of the plating solution is large, the tank pressure is increased, and the electroplating current supply must be high. Chromed anodes do not use metallic chromium, but insoluble anodes. Usually lead, lead antimony alloys and lead-tin alloys are used. Chromium consumed by deposition or for other reasons in the bath must be supplemented by the addition of chromic anhydride. There is a certain dependence between the operating temperature of the chromium cylinder and the cathode current density. By changing the relationship between the two, chrome plating with different properties can be achieved.
In addition to sulfate, fluoride, fluorosilicate, fluoroborate and mixtures of these anions are often used as catalysts for chromium plating. If the catalyst content is too low, no coating is obtained or little, mainly brown oxide, is obtained. If the catalyst is present in excess, this leads to poor coverage, reduced current yield and can lead to a partial or complete lack of coating. The most common catalyst is sulfuric acid. The sulphuric acid content depends on the ratio of chromic anhydride to sulfuric acid, which is generally regulated to 80 to 100:1, with the optimal value being 100:1.
The Cr6+ ion in the chromium plating solution of the chromium bottle is reduced at the cathode to produce Cr3+, and at the same time is re-oxidized at the anode, and the concentration of trivalent chromium quickly reaches equilibrium. The equilibrium concentration depends on the surface ratio of cathode and anode. Cr3+ ions are the main components of the colloid film formed by the cathode. Only if the coating solution contains a certain amount of Cr3+, the chromium deposition can proceed normally. Therefore, the newly applied bath must ensure by appropriate measures that it contains a certain content of Cr3+.
① Use a large area cathode for electrolytic treatment.
② Add a reducing agent to reduce Cr6+ to Cr3+. Alcohol, oxalic acid, candy sugar, etc. use. Among them, alcohol (98%) is used more often, and the dosage is 0.5 ml/l. When adding alcohol, it should be added under stirring because of the exothermic reaction, otherwise the chromic acid will splash out. After the addition of alcohol, it can be used after a small electrolysis.
③ Add some old bath solution.
Shanghai Gensyu Packaging Company Limited has been focusing on the development and production of chrome plated bottles for several years. And it is committed to providing perfect service to every customer from all over the world.