The anodized film of industrial aluminum fittings has many holes, and its surface is highly adsorbed, and the hand touch has a sticky feeling. In order to improve the anti-pollution and anti-corrosion function of the oxide film, sealing is an indispensable process. The sealing of industrial aluminum anodized film mainly includes heat sealing holes and cold sealing holes. Nowadays, cold sealing holes are basically used in China. Following the increase in film thickness and the quality of the sealing. The cost of cold sealer per ton of aluminum profile increases from 0.8 to 1.2 kg to 1.5 to 2.0 kg. Nickel fluoride is the main component of the current cold sealer, so the quality of the nickel fluoride determines the quality of the cold sealer. The impurities such as iron, zinc and copper in nickel fluoride are not obvious in the new tank solution, but the sealing quality is difficult to ensure after a period of production.
The pH of the cold-sealed hole was once considered to be 5.5 to 6.5, and should actually be determined according to the formulation characteristics of the cold sealing agent. The pH of the new tank is usually between 5.3 and 7.0. However, for the old tank which is used to adjust the fluoride ion with ammonium fluoride or ammonium hydrogen fluoride, the pH should be controlled at 6.5 to 7.1* because of the influence of ammonium ions. At this moment, the sealing speed is fast, the fluorine consumption is small, and the “whitehead” scene is not presented. The ammonium ion in the sealing groove is less likely to be powdered than the sodium ion, but the sealing speed is slower. In order to ensure the quality of the sealing, the technical operation points are as follows:
(1) The anodizing temperature is usually less than 23 ° C, the temperature is too high, the cold sealing agent is expensive, and the surface is "green".
(2) Anodizing should be washed in time in the future, and staying in the oxidation tank will affect the future sealing. Washing is not easy to cause sputum contamination, increasing the fluorine consumption of the sealing groove.
(3) Industrial aluminum and aluminum wire falling off in the sealing groove should be taken out in time, otherwise the pH rise and the consumption of fluorine will be accelerated.
(4) The sealing hole with fluorine fluoride adjusted by fluoride, after passing 20t of industrial aluminum per cubic meter, should be inverted to clear the bottom.
(5) The sealing hole with fluorine fluoride adjusted by hydrofluoric acid should be produced in 5 to 10 minutes in the future, and it should be in the form of 10% dilute solution.
(6) In order to improve the quality of sealing and accelerate the drying speed, after cold sealing, it is recommended to wash the water for 55~5°C for 10~15min, also known as cold sealing.