passiváló

Passiváló is a term used in materials science and electrochemistry to describe the process by which a material forms a protective, often thin, layer on its surface. This layer, known as a passive film, significantly reduces the material's reactivity with its environment, particularly against corrosion. The most common example is the formation of a passive film on metals like stainless steel, aluminum, and chromium. This film typically consists of oxides or hydroxides of the metal itself.

The formation of a passive film is a spontaneous process that occurs under specific electrochemical conditions, usually in the presence of an oxidizing agent, such as oxygen in the air or dissolved in a liquid. The passive layer acts as a barrier, preventing further electrochemical reactions that would lead to the dissolution of the underlying metal. This phenomenon is crucial for the durability and widespread use of many metallic materials in various applications, from construction to medical implants.

The effectiveness and stability of the passive film depend on factors such as the material's composition, the surrounding environment (pH, temperature, presence of specific ions like chlorides), and the applied electrochemical potential. In some cases, the passive film can be damaged or break down, leading to localized corrosion. Understanding and controlling the passivation process is essential for preventing corrosion and ensuring the longevity of metallic structures and components.