passzivációt

Passzivációt, commonly translated as passivation, is a metallurgical process that significantly reduces the electrochemical reactivity of a metal's surface. This is achieved by forming a thin, protective film, often an oxide layer, that acts as a barrier against corrosion. While metals like iron naturally form rust, which is a porous and non-protective oxide, passivated surfaces develop a dense, stable, and inert film.

The most well-known example of passivation involves stainless steels. When stainless steel is exposed to oxygen, a passive chromium oxide layer spontaneously forms on its surface. This layer is extremely thin, typically only a few nanometers thick, yet it provides excellent resistance to oxidation and attack by many corrosive agents. The effectiveness of passivation is directly related to the chromium content of the alloy; higher chromium content generally leads to a more robust and reliable passive layer.

Passivation can occur naturally, as with stainless steels, or it can be induced through specific treatments. For instance, stainless steel parts are often subjected to chemical passivation processes, typically using nitric acid or citric acid solutions. These treatments remove any free iron from the surface and enhance the formation of a uniform and stable chromium oxide film. Other metals, such as aluminum and titanium, also exhibit passive behavior, forming protective oxide layers under certain conditions. Passivation is crucial for many applications, including medical implants, food processing equipment, and architectural components, where corrosion resistance is paramount.