Surface Treatment Technologies for Aluminum Die-Cast Products

Aluminum die-cast products require surface treatments to enhance their corrosion resistance, aesthetic appeal, and functional performance, as the casting process can leave porous surfaces or oxide layers. One common technology is anodizing, which involves electrolytic oxidation to form a thick, porous aluminum oxide layer (5 to 25 μm) on the surface. This layer can be dyed in various colors and sealed to improve corrosion resistance, making it suitable for decorative parts in consumer electronics or automotive trim. Hard anodizing, producing a thicker layer (25 to 100 μm), increases wear resistance, ideal for mechanical components like gears or valve bodies.

Another widely used technique is powder coating, where a dry powder (typically polyester or epoxy) is electrostatically applied and cured at high temperatures (150 to 200°C) to form a durable, uniform film. Powder coating offers excellent corrosion resistance, impact strength, and color retention, making it suitable for outdoor applications such as garden furniture or automotive parts.

Electroplating is also employed, with processes like nickel plating, chrome plating, or zinc plating. Nickel plating provides a smooth, wear-resistant surface with good adhesion, while chrome plating adds a bright, reflective finish and enhances hardness. Zinc plating, often with a chromate conversion coating, offers cost-effective corrosion protection for undercarriage components or hardware.

Other treatments include chemical conversion coatings (e.g., chromate or phosphate), which form a thin protective layer to improve paint adhesion and corrosion resistance, and electrophoretic deposition (EPD), where a paint film is deposited via electrophoresis for uniform coverage on complex geometries. Each technology balances factors like cost, performance, and environmental impact, allowing manufacturers to select the optimal treatment based on the product’s intended use.

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