Black Coating

The common methods of blackening treatment are the traditional alkaline heating blackening and the late appearance of normal temperature blackening two kinds. But the darkening process at room temperature is not good for low carbon steel. The alkaline blackening is subdivided, and there is a difference between once blackening and twice blackening. The main ingredients of black liquor are sodium hydroxide and sodium nitrite. The temperature required for blackening is larger, probably between 135-155℃ can get a good surface, but the time required is a little long.

The advantages of black coating, such as blackening safety does not use electricity, with alkaline high temperature blackening needs 100% electricity. Save time, only need 1-2 hours. Low blackening cost, simple equipment, easy to operate; The blackening time is strictly controlled. Strong process adaptability: it solves the problem that nodular cast iron can not blacken.


Post time: Sep-13-2022