Hard anodising, like that used by Poeton refers to the application of a high-pressure, ultra-sonorous, ultra-high temperature coating to steel or other metal to increase both its hardness and wear resistance properties. This hardening is done using a chemical compound, often oxalic acid, which reacts with the surface area of the metal to form the final hard layer. Hard anodizing is often combined with heat treatment to achieve better corrosion resistance properties. Hard anodized metals are typically used for applications requiring wear resistance, where damage from abrasion, abrasions, and impact is common. The coating may also be used to increase the mechanical strength of the metal, thus increasing its ability to withstand high stress loads. Additionally, hard anodized metals have high resistance to corrosion attack by organic substances, making them suitable for use in a wide range of environments.
Some typical examples of properties gained from hard anodising include corrosion resistance, hardness (comfortable wearing), thickness, mechanical strength, and mechanical properties including fatigue life. As compared to other forms of metal corrosion resistance, however, the wear resistance of anodized coating is considerably less. Hard anodized metals that have undergone this process are not considered to be rust-resistant. However, many coatings have been developed to improve upon this property of the anodized coating, such as the use of atomic heat-beds, which combines the property of wear resistance with a slightly higher concentration of cryogenic chemicals that inhibit corrosion. Other methods include electrochemical treatment (ET), which combines electrochemical oxidizers and sacrificial anode coatings for a longer-lasting and more effective protection.
Another application of this hard anodising process is to the aerospace industry, particularly in the areas of sealing ductile elements and seals. Sealing ductile elements in an aircraft structure has two objectives: sealed cold air and sealing hot air. Because hot air must be kept within the confines of a sealed ductile flow, the use of a penetrating anodic coating for sealing cold air inlet or outlet pipes results in superior sealing efficiency than sealing with a standard uncoated pipe.