Aluminum honeycomb is widely used in construction, transportation and other fields due to its light weight, high strength and stable structure, but its corrosion resistance is significantly affected by the surface state. Through scientific and reasonable surface treatment technology, its corrosion resistance can be effectively improved and its service life can be extended. The following analysis is carried out from three dimensions: treatment principle, process type and practical application.
The essence of aluminum honeycomb corrosion is the electrochemical reaction between the metal matrix and water, oxygen, chloride ions and the like in the environment. The core of surface treatment is to build a physical barrier or chemical passivation layer to block the direct contact between the corrosive medium and the matrix. For example, anodizing treatment forms a dense aluminum oxide film on the aluminum surface through electrolysis, which can reach a thickness of microns, has low porosity and high hardness, and can significantly improve corrosion resistance. In addition, some coating technologies form a molecular-level protective layer through chemical bonding or physical adsorption to further enhance the anti-penetration ability.
Chemical conversion film is one of the basic processes for aluminum surface treatment, which generates insoluble compounds through the reaction of solutions such as chromate and zirconium-titanium salt with the matrix. Traditional chromate treatment is gradually being replaced due to environmental issues, while chromium-free conversion technology (such as zirconization treatment) has become mainstream due to its low toxicity and good corrosion resistance. This process forms a nano-scale crystal film on the aluminum surface, which can not only close the microscopic pores, but also form a synergistic protective effect with the subsequent coating. In practical applications, chemical conversion film is often used as a primer pretreatment to improve the adhesion and durability of the coating.
Organic coatings isolate corrosive media by covering, and their protective effect depends on the density, adhesion and weather resistance of the coating. Fluorocarbon coatings have excellent chemical resistance and self-cleaning properties due to high C-F bond energy and low surface energy in the molecular chain, and are often used in high-end building curtain walls. Polyester powder coatings are widely used in the field of interior decoration due to their cost advantages and environmental protection characteristics. To improve the level of protection, a multi-layer coating process can be used, such as a composite structure of primer + topcoat + varnish, to achieve complementary advantages through the superposition of different functional coatings.
Physical vapor deposition (PVD) technology deposits metal or ceramic films on the aluminum surface by bombarding the target with high-energy particles. For example, titanium nitride (TiN) coating has high hardness, low friction coefficient and chemical inertness, which can effectively resist acid and alkali corrosion. The film thickness formed by this process is usually at the nanometer level, which does not affect the dimensional accuracy of the substrate and is suitable for scenes that are sensitive to weight and thickness, such as precision instrument housings. In addition, the glossiness and color adjustability of PVD coating can also give aluminum honeycomb decorative functions.
Electrophoretic coating uses the electric field to deposit charged paint particles on the surface of the workpiece to form a uniform and dense paint film. This process is particularly suitable for aluminum honeycombs with complex shapes, which can ensure the coverage integrity of pore edges and deep cavity parts. The environmental protection and low VOC emissions of water-based electrophoretic paint are in line with the trend of green manufacturing, while cathodic electrophoretic coating can further improve the adhesion and corrosion resistance of the paint film through the pretreatment of the anodized film. The composite use of electrophoretic coating and subsequent powder coating can achieve the dual effect of "basic protection + functional enhancement".
Micro-arc oxidation (MAO) technology uses high-voltage discharge to grow a ceramic oxide layer in situ on the aluminum surface. The thickness can reach hundreds of microns and the hardness is close to that of sapphire. The oxide layer formed by this process has a three-dimensional mesh structure, low porosity and metallurgical bonding with the substrate, which can resist strong acid, alkali and salt spray corrosion. The high insulation and wear resistance of the micro-arc oxidation layer make it suitable for extreme environments such as marine engineering and rail transportation. However, this process has high equipment requirements and high energy consumption, and the application scenarios need to be comprehensively evaluated based on cost-effectiveness.
The corrosion resistance of aluminum honeycomb needs to be customized in combination with the use environment. In coastal areas with high humidity and high salt fog, it is recommended to use a composite protection system of micro-arc oxidation + fluorocarbon coating; for indoor dry environments, a lower-cost chemical conversion film + polyester coating can be selected. In addition, regular maintenance is equally important, such as cleaning surface contaminants and checking coating integrity to avoid local corrosion spread. Through the coordinated optimization of materials, processes and environment, aluminum honeycomb can maintain stable corrosion resistance throughout its life cycle.
The selection of surface treatment technology needs to balance protection performance, processing costs and environmental protection requirements. With the continuous iteration of new materials and new processes, the corrosion resistance of aluminum honeycomb will be further improved, providing reliable solutions for more stringent application scenarios.
