On-site testing makes easy work: Fischer Instrumentation (GB) Ltd describes the principles behind ensuring the sealing quality of anodised coatings

摘要

Aluminium is often used for architectural building facades for its clean lines and smart contemporary looks. It is also lightweight and fairly easy to work and being durable, it requires little to no maintenance over the long term, when effectively protected by an anodised coating. However, to ensure the reliability of the corrosion protection, the sealing of the coating must be verified. Pure aluminium is actually highly susceptible to corrosion. However, in contrast to iron, it naturally forms a corrosion-inhibiting layer on its surface when it comes into contact with oxygen, which preserves it very well under normal environmental conditions. When this protective oxide layer is scratched away, it is quickly replenished upon renewed exposure to oxygen. However, for many applications, especially out-of-doors, this natural protection does not suffice because even the smallest entrapment of heavy metals can prevent the formation of a seamless oxide layer, allowing corrosion to get in and cause damage.