The alkaline blackening liquid used has low efficiency and high energy consumption, especially when dealing with cast iron, it is easy to appear khaki, and the appearance is often not satisfied with the customer, and it is blackened at room temperature.Coupling castings due to the particularity of the manufacturing process, the surface of the castings is easy to rust, and it is difficult to handle after rusting, if it does not attract attention.
Not only the anti-corrosion ability of the workpiece is poor, but also the decoration is not good. For this reason, many companies put forward higher corrosion resistance requirements for the castings, and according to the different working conditions of the castings, the castings (cast iron, cast steel) are required to be Blackening at room temperature, phosphating treatment and other special anti-rust treatments.