What makes arc anodizing more durable than traditional anodizing?

Superior Durability of Arc Anodizing: A Matter of Structure and Composition

The exceptional durability of Arc Anodizing compared to traditional anodizing (Type II) stems from fundamental differences in the coating's structure, composition, and the method of its formation. While both processes create a ceramic oxide layer, Arc Anodizing produces a coating that is fundamentally tougher, harder, and more integrated with the substrate.

Coating Structure: From Porous to Dense Ceramic

Traditional anodizing creates a relatively thin, amorphous oxide layer with a highly ordered, porous structure. While this provides good corrosion resistance after sealing, the underlying structure can be prone to cracking under mechanical stress and the pores can be pathways for corrosion if the seal is compromised.

In contrast, Arc Anodizing utilizes high-voltage plasma discharges to create a much thicker, denser coating. This process fuses the oxide, transforming it from an amorphous state into a crystalline structure rich in hard, wear-resistant alpha-alumina phase—the same material used in cutting tools and abrasives. The result is a monolithic, pore-free ceramic layer that is inherently more resistant to abrasion, erosion, and impact.

Enhanced Mechanical Properties and Bonding

The plasma-driven growth mechanism results in superior mechanical properties:

• Extreme Surface Hardness: Traditional anodizing typically achieves 300-500 HV. Arc Anodizing routinely produces coatings with a microhardness of 400-600 HK or higher, making it significantly more resistant to scratching and wear.

• Superior Adhesion: The coating is not merely deposited on the surface; it is grown metallurgically from the substrate through the plasma electrolysis process. This creates a robust, integral bond that is highly resistant to delamination, spalling, or peeling under stress or thermal cycling.

Integrated Corrosion and Wear Protection

The combination of extreme hardness and a dense, non-porous structure provides a synergistic protective effect. In traditional anodizing, wear can quickly break through the thin coating and expose the soft substrate. The thick, hard layer from Arc Anodizing acts as a massive barrier, capable of withstanding both prolonged abrasive wear and corrosive attack simultaneously. This is why it can achieve 500 to 1000+ hours in salt spray testing (ASTM B117), far exceeding the capabilities of standard anodizing. This integrated protection is a key reason it's specified for components in demanding sectors like power tools and automotive applications.