What are the solutions for discoloration of copper strips

1. Solution for discoloration of copper strip

(1) Control the concentration of the acid solution during pickling. In the case where the surface oxide layer of the annealed copper strip is washed away, the acid concentration is too high to make any sense. On the contrary, the concentration is too high, and the residual acid adhering to the surface of the copper strip is not easily washed away, and the contamination of the washing water is accelerated, and the residual acid concentration in the washing water is too high, so that the copper strip after washing is more likely to be discolored. Therefore, when determining the concentration of the pickling solution, the principle should be followed: the concentration of the copper oxide on the surface of the copper strip can be removed as much as possible.

(2) Control the conductivity of pure water. Control the conductivity of pure water, that is, control the content of harmful substances such as chloride ions in pure water. Generally, it is safe to control the conductivity below 50μS/cm.

(3) Control the conductivity of the hot wash water and passivation agent. The increase in the conductivity of the hot wash water and passivation agent mainly comes from the running of the copper strip to bring in the residual acid. Therefore, in the case of ensuring the quality of water used for cleaning pure water, controlling the conductivity also controls the amount of residual acid. According to many experiments, it is safe to control the conductivity of the hot washing water and the passivating agent to be less than 200 μS/cm, respectively.

(4) Ensure that the copper strip is dry. Partially closed at the air-ring furnace take-up exit, and a humidifier and air conditioner are used in the partial enclosure to control the humidity and temperature during the coiling of the copper strip within a certain range.

(5) Passivation using a passivating agent. Most copper processing plants now use benzotriazole, BTA (molecular formula: C6H5N3) as a passivating agent. It has proven to be a convenient, economical and practical passivating agent. When the copper strip passes through the BTA solution, the oxide film on the surface complexes with BTA to form a dense complex, which acts to protect the copper matrix.

2. Copper belt shear indentation solution

To prevent the occurrence of cutting edge indentation, it is mainly necessary to select the reasonable outer diameter difference between the circular knife and the rubber peeling ring according to the thickness and hardness of the strip; the hardness of the rubber peeling ring satisfies the requirements for the use of the cut strip; When the width of the strip is small, the thickness of the round knife should be reasonably selected to increase the width of the rubber peeling ring.

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