The corrosion resistance of LED tri-proof lights in salt spray environments primarily relies on the protective design of their surface treatment processes for metal components. Chloride ions in salt spray environments have strong penetrating power, accelerating metal oxidation reactions and leading to rust, perforation, and even structural failure in components such as the lamp housing and bracket. Therefore, the core objective of surface treatment processes is to block the contact between chloride ions and the metal substrate through physical barriers or chemical modification, while simultaneously improving the material's stability in humid and hot environments.
Anodizing is a common protective method for aluminum alloy components. This process forms a dense alumina film on the metal surface through electrolysis. Its low porosity and high hardness effectively block salt spray corrosion. The thickness and density of the oxide film directly affect the protective effect and are usually optimized by adjusting the electrolyte composition and current density. Some high-end products further enhance corrosion resistance by sealing the oxide film using boiling water or nickel salt solutions to fill the micropores. Metal surfaces treated with this process can form a stable passivation layer in salt spray environments, making it less prone to chain corrosion reactions even if localized damage occurs.
Electroplating technology provides another layer of protection for metal components. Zinc plating is widely used due to its sacrificial anodic protection properties; when the plating is damaged, zinc preferentially corrodes and forms oxide products that fill the gaps, slowing down the corrosion process of the base metal. For applications requiring higher corrosion resistance, nickel or chromium plating can be used; their dense crystalline structure can resist salt spray penetration for extended periods. Modern electroplating processes have also developed composite plating technologies, such as zinc-nickel alloy plating. By adjusting the alloy ratio, both corrosion resistance and mechanical strength can be achieved, making it suitable for harsh environments such as coastal areas or chemical plants.
Spraying processes achieve protection by forming an organic coating on the metal surface. Epoxy resins, polyester powders, and other materials, after electrostatic spraying, can form a uniform insulating layer on the component surface, blocking the electrochemical contact between salt spray and the metal. Nanopowdering technology further enhances coating performance; by adding nanoparticles to the resin, the density, hardness, and adhesion of the coating can be significantly enhanced. Some products also employ a double-coating system, with a rust-preventive primer as the base layer and a weather-resistant topcoat as the top layer. This prevents salt spray penetration and resists UV aging, extending the lifespan of the lamps in outdoor environments.
Chemical conversion coating provides a low-cost protection solution for metal components. Phosphating treatment generates an insoluble phosphate film on the metal surface through a chemical reaction. This porous but highly absorbent film is often used as a pretreatment layer for subsequent coatings. Chromate conversion coatings were once widely used due to their excellent corrosion resistance, but due to environmental restrictions, they are gradually being replaced by chromium-free conversion technologies. Newer processes such as silane treatment form chemically bonded siloxane films on the metal surface, meeting environmental requirements while providing protection comparable to chromate, making them suitable for cost-sensitive LED tri-proof light products.
Sealing design is an important complement to surface treatment processes. Even with protective treatments on metal components, salt spray can still penetrate the lamp's interior through structural gaps. Therefore, LED tri-proof lights typically employ silicone rubber sealing rings, waterproof connectors, and other accessories, combined with an overall potting process, to ensure that the luminaire's IP protection rating reaches IP65 or higher. Some products also use conductive foam in critical areas, achieving both electromagnetic shielding and preventing salt spray penetration through seams, forming a multi-layered protection system.
The coordinated design of material selection and surface treatment is key to improving corrosion resistance. For example, using stainless steel eliminates the need for electroplating, allowing for a corrosion-resistant surface directly through polishing; while aluminum alloy components require a combination of anodizing and spraying processes to balance lightweighting and protection requirements. Modern LED tri-proof lights also utilize modular design to isolate metal components from electronic components, ensuring that even if localized corrosion occurs on the outer casing, the core function of the luminaire remains unaffected, thereby improving overall reliability.
