Blackening/black coating
The surface of steel do black coating, which is also called blue coating.
The principle is to rapidly oxidize the surface of steel products to form a dense oxide film protective layer.
The commonly used methods for blackening treatment are the traditional alkaline heating blackening and the late normal temperature blackening.
room temperature blackening treatment process is mainly completed by the following process steps:
1) Cleaning;
2) Degreasing: The workpiece must be completely immersed in the degreasing solution; the concentration of the degreasing solution is 12-14, the processing time is 10-30min, shaking up and down several times every 3-5 minutes, and the chemical solution concentration is lower than ph12 Degreasing powder;
3) Washing with water;
4) Pickling: the concentration of the pickling solution has a pH value of 2-4, and the treatment time is 5-10min;
5) Washing with water; 12min;
6) Blackening: the concentration of the pool solution is pH 2.5-3.5, and the treatment time is 10-12min
7) Wash with water;
8) Dry;
9) Apply oil.
The advantages of blackening treatment:
1. The blackening is safe without electricity, and 100% electricity is required for alkaline high-temperature blackening.
2. Improve work efficiency: 1-2 minutes in total.
3. The blackening cost is low, the equipment is simple, and the operation is convenient; the blackening time is strictly controlled.
4. Strong process adaptability: solve the problem that nodular cast iron can’t blacken. Blackening is for wear and rust prevention.