Sulphuric acid anodising is a popular surface treatment that transforms aluminium and its alloys into something more durable and corrosion-resistant. Instead of just painting or coating the metal, this process actually changes the surface itself, creating a layer of aluminium oxide that is hard and protective. It’s used everywhere -from aircraft parts and car components to electronics – because it improves both performance and appearance.
How the Process Works
Essentially, sulphuric acid anodising, such as www.poeton.co.uk/surface-treatments/anodising/sulphuric-acid-anodising, is an electrochemical process. The aluminium part is submerged in a sulfuric acid bath and connected to an electrical circuit. When current flows, the aluminium then surface reacts with the acid to form a thick, porous layer of aluminium oxide. This layer is naturally hard and sticks tightly to the underlying metal, which makes it far more durable than traditional coatings. The porous nature of the oxide also allows for dyes or sealants to be applied later, so manufacturers can change the colour.
The thickness of the anodised layer in sulfuric acid anodising can be precisely controlled by adjusting the voltage, current, and time in the bath
Benefits
One of the biggest advantages of this process is how the part becomes corrosion resistant. The anodised layer acts as a shield, protecting aluminium from moisture, chemicals, and wear from the environment. It also increases surface hardness, improving scratch and abrasion resistance, which is why anodised aluminium is popular in aerospace and car components. On top of that, the process is versatile aesthetically – dyes can then be absorbed into the porous surface to produce vivid, long-lasting colours.
