Kromihappoanodointi

Kromihappoanodointi, also known as chromic acid anodizing, is an electrochemical process used to create a protective oxide layer on aluminum and its alloys. This method utilizes a solution of chromic acid, typically around 3-10% concentration, as the electrolyte. When a direct current is applied, with the aluminum part acting as the anode, a thin, hard, and porous layer of aluminum oxide is formed on the surface.

The resulting oxide layer offers several benefits. It provides excellent corrosion resistance, making it suitable for components exposed to harsh environments. Additionally, the porous nature of the layer allows for subsequent treatments like sealing or dyeing, which can further enhance its protective properties or provide decorative finishes. The coating's thickness is generally in the range of a few micrometers, and it is known for its good adhesion to the base metal.

Compared to sulfuric acid anodizing, chromic acid anodizing produces a softer, less abrasive coating that is less prone to cracking. However, the process is slower and generally results in a thinner coating. Due to the environmental concerns associated with chromic acid, its use has been subject to stricter regulations in many regions, leading to a decline in its widespread application in favor of alternative anodizing methods or treatments. Despite these challenges, it remains a valuable technique for specific applications where its unique properties are advantageous.