Blackening is also called bluing. When the workpiece is heated to an appropriate temperature at room temperature or in a solution of air, water vapor or chemical drugs, a blue or black oxide film is formed on the surface of the workpiece. The main component of this oxide film is tetroxide Three irons.
Blackening treatment is just a surface treatment, it will not have any effect on the internal structure, and has no effect on the hardness and strength of the product. It is not a heat treatment, and it is fundamentally different from quenching.
It is a surface treatment process that can improve its corrosion resistance and appearance.
Process:
First put the chain in the water with sodium bicarbonate dissolved in it to decontaminate (it will not cause any damage to the chain), then put the water in the black boiling pool, add a certain proportion of sodium nitrite, sodium hydroxide and other chemical materials, and heat it , Heat to 130-150℃, then put the polished chain into the black boiling pool, boil it in water for 30 minutes and then exit the pool. After exiting the pool, use a high-pressure water gun to rinse off the sediment on the surface of the chain. Check that there is no problem. package.
Blackened chains need to be inspected by technicians, mainly to check the chain's blackness, brightness, and adhesion.
