The chemical oxidation conversion film on the metal surface refers to a processing technology that uses chemical oxidation treatment agents to cause a chemical oxidation reaction between the metal surface and the solution interface, thereby generating a stable oxide film. The chemical passivation conversion film is the product of the oxidation reaction between anions and the metal in the medium, enabling it to achieve self-oxidation conversion. The chemical oxidation process is complex and is to a certain extent the result of the combined effects of chemistry, electrochemistry, and physical chemistry. 

The interface reaction with the metal chemical oxidation medium generates secondary products, which become the main components of the metal film. The main component of the obtained film is the product generated by the secondary reaction. The chemical oxidation conversion film is a film formed by the chemical oxidation reaction at the interface between the metal surface and the solution. Its characteristics are good adhesion to the metal material, thin film layer, fine structure, and resistance to various strong corrosive media. 
The chemical conversion coating mainly enhances the thermal power and stability of the metal in the environmental medium by reducing the metal's own chemical reactivity. It also relies on the isolation of the conversion products on the metal surface from the environmental medium. The formed chemical oxidation conversion coating can significantly improve the corrosion resistance of the metal. For other types of conversion coatings (passivation coatings), the protection effect of steel in strong acidic media is not as good as that of the oxidation conversion coating. The oxidation treatment of the 316L stainless steel surface mainly comes from the anodic protection of oxidants and alloy elements, and is a method to achieve metal passivation and slow down corrosion. It can convert the activated corrosion potential to the passivation zone, enter the hydrogen evolution state, causing Pd to accumulate on the surface, and thereby forming the passivation of the base metal. 
The mechanism of the oxide film is that oxygen atoms in the molecular layer adsorb on the metal surface, forming a stable compound film layer on the metal surface. It mainly isolates the anode double-layer potential through the single layer of oxygen atoms in the oxide, forming a protective barrier, resulting in a decrease in the double-layer conductivity of the anode region. 
The chemical oxide film is a passive reaction resulting from the oxidation of a chemical medium, leading to the formation of some intermediate products. The oxide passivation film has the advantages of being complete, dense, having strong thermal stability, strong thermal expansion coefficient, diffusion coefficient and elastic modulus. This passivation oxide film is not prone to cracking and peeling during the thermal expansion process. The oxide passivation film is an anode protection method that keeps the metal potential in a stable region.