In the production process of electric heating tubes, blackening treatment is sometimes used. Heat treatment is a process of heat treatment of metal objects such as stainless steel. After treatment, there will be an oxide film on the surface to achieve the purpose of corrosion and rust prevention. After the heating treatment, the wear resistance of the heating tube surface and the hardness of the surface will be improved, and it will not affect the parts inside the heating tube.
Under normal working conditions, the simple and convenient method for the blackening of the surface of the electric heating tube is as follows:
1. Clean the surface of the metal pipe first to keep it clean;
2. The second is degreasing treatment on the surface. In this process, the metal tube can be completely placed in the degreasing liquid. The pH value of the degreasing liquid is about 13, and the time is not less than half an hour. Rinse with water after degreasing.
3. Next, pickling can be carried out. The pH of the pickling solution is about 3, and the treatment time should not be longer than 10 minutes. After pickling, rinse with water;
4. Blackening treatment: The concentration of the pool solution is between pH 2-4, and the treatment time is 10 minutes up and down. After the blackening, it is extremely cleaned;
5. Drying and oiling;
According to the above five points, it is still a very effective method to blacken the electric heating tube.