Railways fastening systems requirements for surface treatment

Galvanizing:
Galvanizing is a common anti-corrosion treatment method, which is suitable for railway fastener systems.
The galvanized layer can effectively prevent fasteners from rusting and extend their service life.
Galvanizing treatment should meet the relevant national or industry standards to ensure that the quality and thickness of the coating meet the requirements.
Passivation treatment:
Passivation treatment is to form a dense oxide film on the surface of the fastener to improve corrosion resistance.
The selection and treatment conditions of passivation fluid should be determined according to the fastener material and application environment.
Phosphating treatment:
Phosphating treatment is to form a phosphating film on the surface of the fastener to enhance the adhesion and corrosion resistance of the coating.
The quality of phosphating film is affected by the composition of phosphating solution, treatment temperature and time.
Dacromet treatment:
Dacromet treatment (zinc-chromium coating) has excellent corrosion resistance, permeability and adhesion.
However, Dacromet coating has low hardness and poor wear resistance, and may not be applicable in fasteners that are disassembled many times.
Other coating treatments:
Depending on the specific needs, the railway fastener system may also use spray, paint and other coating treatment methods.
The coating should be uniform, bright and firm, without defects such as peeling, peeling, nodule, hollow drum and color difference.