Anti-corrosion Coating Systems for Rail Bolts and Their Long-Term Service Life
What are the main forms of corrosion faced by rail bolts?
The main forms are atmospheric corrosion, electrochemical corrosion, and crevice corrosion. In humid environments, water and oxygen cause rust; coastal salt spray and acid/alkali gases in chemical industrial zones accelerate corrosion; crevice corrosion easily occurs in the gaps between the bolt and nut, and the pressure plate, causing surface rust, reduced cross-section, decreased strength, and ultimately, breakage.
Why is ordinary paint insufficient for the corrosion protection requirements of rail bolts?
Rail bolts are prone to fretting wear under vibration and impact. Ordinary paint has poor adhesion and low wear resistance, easily peeling and flaking off under vibration, leaving it unprotected. At the same time, ordinary paint has poor weather resistance; long-term exposure to sun and rain easily leads to aging and powdering, failing to provide long-term effective corrosion protection.
Why is Dacromet coating suitable for rail bolt corrosion protection?
Dacromet coating is thin, has strong adhesion, and extremely high corrosion resistance, with salt spray tests lasting hundreds or even thousands of hours. The coating has no risk of hydrogen embrittlement, making it ideal for high-strength bolts. Its high temperature resistance, vibration resistance, and wear resistance allow for long-term protection of bolts in harsh environments, making it the mainstream corrosion protection technology for rail bolts.
How to choose a bolt corrosion protection system for different environments?
Ordinary inland environments: Dacromet or zinc-based coating. Coastal salt spray areas: Heavy-duty corrosion-resistant Dacromet + sealing coating. Chemically polluted areas: Fluorocarbon sealing or highly corrosion-resistant composite coating. Cold and freeze-thaw regions: Select freeze-thaw resistant and crack-resistant coatings to ensure long-term stability.
What are the benefits of a good corrosion protection coating for the track system?
It can significantly extend the bolt replacement cycle, reducing track maintenance costs. It prevents fastener failure and rail instability caused by bolt corrosion and breakage, improving operational safety. It reduces maintenance workload and improves track operation efficiency, which is especially significant for maintenance-difficult sections such as mountainous and coastal areas.