Burnt electroplated coating of electric heating tube

Burnt electroplated coating of electric heating tube

1.5 Coating blistering and peeling

(1) The problem lies in the pre-treatment before plating. As long as oil removal and acid washing are strengthened, and the workpiece is carefully inspected before entering the plating tank, it can be removed.

(2) Excessive addition of brightener; The drying temperature of the workpiece after galvanizing and passivation is too high, resulting in powdery detachment of the coating.

1.6 Coating burning

(1) Low conductive salt content, low deposition rate, and poor brightness; When the current is slightly high, the coating in the high current density area burns. Conductive salts can be added appropriately to eliminate faults.

(2) The cathode current density is out of control. Due to the inability of silicon rectifier power supply to maintain constant voltage and current, it mostly occurs during sudden changes in AC power supply. This is an inevitable temporary phenomenon that will soon restore normal current. Another situation is due to improper operation and excessive current, which can be eliminated by appropriately reducing the current.

(3) The workpiece is charged out of the groove, and the area where it collides with the zinc plate is burnt and blackened, and the location is uncertain. As long as the power is turned off and the workpiece comes out of the slot again, this fault will not occur.

1.7 Solution cloudy or slightly brown or brick red

Sometimes the zinc iron alloy plating solution is turbid or slightly brown, and in severe cases, it is inevitable to turn brick red. This is due to the oxidation of Fe2+into Fe3+in the solution, ultimately leading to rough coating.

When the plating solution is turbid, one possibility is that the concentration of conductive salts is high. After adding an appropriate amount of water and stirring evenly, the turbid solution immediately returns to clarity; Another method is to add water and still remain turbid. This is the colloidal state during the oxidation of Fe2+to Fe3+, causing the solution to become turbid and turn slightly brownish red. Dissolve 0.5gL of reducing agent in water and add it to the solution. After Fe3+is reduced to Fe2+, the solution returns to clarity..

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