1.What are the effects of ultraviolet radiation on galvanized coils?
Reason: The higher the altitude, the thinner the atmosphere, and the weaker the filtering effect on solar ultraviolet rays. Ultraviolet radiation intensity increases significantly with altitude.
Impact on galvanized coils:
If the galvanized coil surface has a powder-coated or painted coating (most shared lockers have powder-coated shells), strong ultraviolet radiation will accelerate the aging of these organic polymer coatings, leading to chalking, loss of gloss, and micro-cracks.
Once the coating is damaged, the underlying galvanized layer is directly exposed to the environment, losing its first line of protection.
2.What impact does the diurnal temperature range have on galvanized coils?
Reason: High-altitude areas experience strong sunlight and high temperatures during the day; at night, rapid heat dissipation causes a sharp drop in temperature. This significant diurnal temperature range makes it easy for the surface temperature of objects to fall below the dew point of the air.
Impact on galvanized coils:
It leads to frequent condensation, meaning a film of water forms on the metal surface at night and in the early morning.
This water film is a necessary condition for electrochemical corrosion. In low-altitude areas, the metal surface may only be wet when it rains, while in high-altitude areas, condensation can form almost every night, effectively extending the time the metal is in a humid environment.
3.What effects do special corrosive substances have on galvanized coils?
Reasons: Some high-altitude areas may have unique environmental conditions.
Coastal high-altitude areas: Such as the Qinghai-Tibet Plateau, although at high altitudes, some areas may be affected by salt lake dust or salt winds, resulting in air containing chloride ions. Chloride ions are a major cause of damage to galvanized coatings and pitting corrosion.
Industrial or geothermal areas: If there is industrial activity or geothermal activity in high-altitude areas, the air may contain acidic gases such as sulfur dioxide (SO₂). These gases dissolve in water films to form acids, accelerating the corrosion of zinc and the steel substrate.
4.What are the rust prevention mechanisms of galvanized coils and the challenges they face at high altitudes?
The rust prevention of galvanized coils relies mainly on two aspects:
Barrier protection: The dense galvanized layer physically isolates the steel substrate from air and moisture.
Sacrificial anode protection: Zinc is chemically more reactive than iron. When the coating is damaged, it corrodes preferentially over iron, thus protecting the steel substrate.
At high altitudes, increased condensation frequency and UV weakening of the coating both challenge the "barrier protection." Once the barrier effect weakens, the "sacrificial anode" effect of zinc accelerates, meaning the galvanized layer is consumed at a higher rate than in lower altitude areas.
5.What are the countermeasures?
Choose a thicker zinc plating layer: When purchasing, specify higher zinc plating standards (such as Z60, Z90, or even Z120) to provide a thicker zinc layer as a "consumable".
Ensure a high-quality powder coating:
Choose powders with strong resistance to ultraviolet (UV) aging (such as high-quality polyester resin systems).
Increase the coating thickness to provide a stronger physical barrier.
Pre-treatment must be done well (such as phosphating) to ensure coating adhesion and prevent peeling after UV aging.
Avoid water accumulation and structural traps in the design: The structural design of storage cabinets should avoid dead corners that easily accumulate moisture and dust, ensuring good drainage and ventilation to reduce the time condensation remains.
Regular maintenance: In high-altitude areas, a more frequent inspection and maintenance system is needed to promptly detect and treat localized damage to the coating (such as scratches), perform touch-up painting, and prevent the damaged areas from becoming the starting point of corrosion.