High-performance composite coating protection technology for fishplates
- What are the components of the fishplate composite coating?
The composite coating is usually composed of primer, intermediate paint and topcoat. The primer is zinc-rich primer with a zinc content of not less than 90%, which uses the sacrificial anode principle to protect the substrate; the intermediate paint is epoxy micaceous iron intermediate paint to increase the coating thickness and shielding properties; the topcoat is polyurethane topcoat, which has good wear resistance, weather resistance and UV resistance. The total coating thickness is controlled at 200-250μm, and each layer has good adhesion and compatibility.
- What is the role of nanomaterials in fishplate coatings?
Adding nano titanium dioxide to the coating can improve the weather resistance and self-cleaning ability of the coating. The photocatalytic effect of nano titanium dioxide can decompose surface pollutants and reduce the amount of stains attached to the coating surface by 70%. Nano zinc oxide has excellent anti-corrosion properties, can fill the pores of the coating, improve the density of the coating, and increase the salt spray resistance time of the coating from 1000 hours to 1500 hours. In addition, the wear resistance of the nano-carbon fiber reinforced coating reduces the wear of the coating when it rubs against the rails and bolts by 30%.
- What are the key points of the construction process of the composite coating?
Before construction, the surface of the fish plate needs to be sandblasted to meet the Sa2.5 cleanliness standard, and the roughness is controlled at 40-70μm to enhance the adhesion of the coating. During the coating process, the drying time and temperature of each coating are strictly controlled. After the primer is dried, it needs to be polished to ensure that the intermediate paint and the primer are fully combined. High-pressure airless spraying technology is used for construction to ensure uniform coating thickness and avoid defects such as sagging and missing coating. After each coating is applied, film thickness detection and adhesion test are required, and the next process can be carried out only after passing the test.
- What is the protective effect of the composite coating in different environments?
In coastal areas, the composite coating can effectively resist salt spray erosion. After 3 years of exposure test, there is no obvious corrosion on the fish plate substrate, while the corrosion area of the uncoated fish plate exceeds 50%. In industrial pollution areas, the nanomaterials in the coating can neutralize acidic gases, prevent chemical corrosion, and extend the service life of the fishplate by 2-3 times. In high-cold areas, the coating maintains good flexibility, does not crack or peel at low temperatures of -40℃, and continues to provide protection for the fishplate.
- How to evaluate the failure life of the fishplate composite coating?
The evaluation is conducted by combining accelerated aging tests (such as salt spray tests and UV aging tests) with on-site monitoring. The salt spray test simulates the marine environment. When the coating has large-scale bubbling and peeling, and the substrate corrosion depth exceeds 0.5mm, the coating is considered to be failed. On-site monitoring regularly checks the appearance of the coating, measures the coating thickness and substrate corrosion, and combines environmental data with the coating performance attenuation model to predict the actual service life of the coating. A railway department uses this method to control the error of the fishplate coating replacement cycle within ±6 months.