passiivaatio

Passiivaatio is a process that reduces the reactivity of a material, typically a metal, by forming a protective film on its surface. This film, often an oxide or nitride layer, acts as a barrier, preventing further chemical reactions such as corrosion. The term "passivity" refers to this state of reduced reactivity.

The mechanism of passivation often involves exposure to an oxidizing environment. For example, stainless steel spontaneously passivates in air due to the formation of a thin, invisible layer of chromium oxide on its surface. This chromium oxide layer is highly stable and self-healing, meaning it can reform if damaged. Other metals like aluminum and titanium also form passive oxide layers.

Passivation is a crucial surface treatment in many industries. In the medical device industry, it is used to improve the biocompatibility and corrosion resistance of implants and surgical instruments. In the chemical industry, passivated equipment is used to handle corrosive substances safely. The process can be achieved through various methods, including chemical treatments with specific acids or oxidizing agents, or electrochemical processes. The effectiveness of passivation depends on factors such as the material composition, the nature of the corrosive environment, and the quality of the passivation treatment.