Passivation is a process that prevents corrosion on the surface of metals by forming a thin, protective oxide layer. This passive film acts as a barrier between the metal and the surrounding environment, preventing the metal from reacting with corrosive agents such as water, oxygen, and other chemicals. The passive layer is typically only a few nanometers thick but is highly effective in reducing the rate of corrosion.Examples of metals that can undergo passivation include:1. Stainless steel: Stainless steel is an alloy of iron, chromium, and other elements. The chromium content in stainless steel allows it to form a passive chromium oxide layer on its surface, which protects the underlying metal from corrosion. The presence of at least 10.5% chromium in the alloy is necessary for passivation to occur.2. Aluminum: Aluminum naturally forms a passive aluminum oxide layer on its surface when exposed to air. This layer is highly resistant to corrosion and protects the underlying aluminum from further oxidation.3. Titanium: Titanium can form a passive titanium dioxide layer on its surface, which is highly resistant to corrosion. This layer protects the underlying titanium from reacting with the environment.The mechanism involved in the passivation process can be explained as follows:1. Formation of the passive layer: When the metal is exposed to air or an oxidizing environment, the metal atoms on the surface react with oxygen to form a thin oxide layer. This layer is typically only a few nanometers thick but is highly effective in reducing the rate of corrosion.2. Stability of the passive layer: The passive layer is stable and adheres tightly to the metal surface, preventing further contact between the metal and the corrosive environment. This stability is due to the strong chemical bonds between the metal and the oxygen atoms in the oxide layer.3. Self-healing property: If the passive layer is damaged or removed, the exposed metal will react with the environment to form a new passive layer. This self-healing property ensures that the metal remains protected from corrosion even if the passive layer is damaged.In summary, passivation prevents corrosion on the surface of metals by forming a thin, protective oxide layer that acts as a barrier between the metal and the surrounding environment. Metals such as stainless steel, aluminum, and titanium can undergo passivation, and the mechanism involved in the process includes the formation, stability, and self-healing properties of the passive layer.