Blackening of metals at room temperature
Author: Robby
Metal room temperature blackening agent formula
The main ingredients of metal room temperature blackening agent include copper sulfate, selenite, phosphate, nitrate, etc. The concentration and proportion of these ingredients in the formula can be adjusted according to different needs.
For example, a common formula is 4-8 g/l of copper sulfate, 4-8 g/l of selenium dioxide, 7-15 g/l of phosphate, 2-4 g/l of nitrate, and 2-4 g/l of citrate, with a pH value between 2.0 and 2.5, and a treatment time of 3-5 minutes.
The use of metal room temperature blackening agent
Pre-treatment: including chemical degreasing and pickling. Chemical degreasing can use a mixture of sodium hydroxide, trisodium phosphate and washing powder, the temperature needs to reach more than 80 ℃, processing time of 1 to 10 minutes. Acid washing can use a mixture of hydrochloric acid and sulphuric acid, and the treatment time depends on the degree of corrosion.
Blackening treatment: the pre-treatment of the workpiece immersed in the blackening solution, the time should be adjusted according to the actual situation, usually a few minutes to several minutes. In order to obtain uniform blackening effect, you can shake the workpiece in the blackening process.
Post-treatment: Including washing, neutralisation and oil immersion sealing steps to ensure that the blackening film bonding and corrosion resistance.
Application areas of metal blackening agent
Metal blackening agents are widely used in the surface treatment of various metal products to improve their corrosion resistance and aesthetics. Common applications include tools, knives, machine parts, etc.