Anti-corrosion Treatment and Durability Improvement for Fastening Systems
- What are the common anti-corrosion treatment methods for fastening systems?
Hot-dip galvanizing is a common method. This involves immersing fastening system components in molten zinc, forming a zinc layer on their surface that effectively isolates them from oxygen and moisture, providing protection for 15-20 years. Electrogalvanizing, which deposits a zinc layer on the component surface through electrolysis, is relatively inexpensive, but its protection is less effective than hot-dip galvanizing, with a typical protection period of 5-10 years. Another common method is anti-corrosion paint, which can be applied with options such as epoxy zinc-rich paint and polyurethane paint. The appropriate paint type is selected based on the environment, offering flexibility in application and providing protection for 8-15 years.
- How should I choose an anti-corrosion treatment method for fastening systems in different environments?
In normal atmospheric conditions, electrogalvanizing or conventional anti-corrosion paint are sufficient. In humid and rainy areas, hot-dip galvanizing is more suitable, as it provides a thicker zinc layer and greater corrosion resistance. In coastal areas, due to the high salt content and corrosive nature of the air, a combined anti-corrosion method of hot-dip galvanizing followed by a high-performance anti-corrosion paint is required to enhance protection. In areas with severe industrial pollution, where the air contains acidic or alkaline pollutants, acid- and alkali-resistant anti-corrosion paint should be used, combined with galvanizing, to improve the corrosion resistance of the fastening system.
- What impact does anti-corrosion treatment have on the mechanical properties of fastening systems?
The high temperatures encountered during the hot-dip galvanizing process may cause a decrease in the mechanical properties of some fastening system components (such as high-strength bolts), such as reduced strength and toughness. However, this impact can be minimized by properly controlling the galvanizing process parameters and subsequent heat treatment. Electrogalvanizing has a lesser impact on mechanical properties. While applying anti-corrosion paint generally does not alter the mechanical properties of components, the paint layer thickness must be carefully controlled. Excessive thickness may affect the fit of components, indirectly impacting connection performance.
- How can the durability of a fastening system after anti-corrosion treatment be evaluated? Salt spray testing can be performed by placing anti-corrosion treated components in a simulated salt spray environment and observing the time it takes for corrosion to appear. Generally, no noticeable corrosion is required within 500-1000 hours. Outdoor exposure testing can also be performed, where components are installed in their actual operating environment and regularly inspected for corrosion. Durability can be assessed based on the severity of the corrosion. Electrochemical testing can also be performed to measure the corrosion potential and corrosion current of components in corrosive media, assessing corrosion rates and predicting service life.
- What maintenance measures are required for fastening systems after anti-corrosion treatment?
Regularly inspect the anti-corrosion coating for damage or peeling, and repair any damage promptly. For hot-dip galvanized components, if localized damage to the zinc coating is found, zinc-rich paint can be used for repair. Regularly clean the fastening system to remove surface dust, dirt, and corrosive media to reduce corrosion. In harsh environments, the inspection interval can be shortened to ensure the effectiveness of the anti-corrosion treatment and the reliability of the fastening system.