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Hard Anodizing

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Hard anodizing, also known as hard coat (or hardcoat) anodizing, is Type III aluminum anodizing. Standard aluminum anodizing is Type II anodizing. Hard anodizing is very similar to standard anodizing. Both are controlled chemical processes used to increase corrosion resistance and surface hardness, allow dyeing, and/or improve lubrication or adhesion of aluminum and aluminum alloy materials. Hardcoat anodizing can be thought of simply as a “heavy duty” form of standard anodizing. In hard coat anodizing, an anodic film forms on the part by converting its surface into aluminum oxide. Aluminum naturally self-passivates when exposed to oxygen, creating an oxide layer approximately 2 to 3 millimeters thick. Alumiunum alloys form oxide layers from 5 to 15 millimeters thick through self-passivation. Hard anodizing aluminum an