Electroplating processing vs passivation processing, who is more rustproof?

When exploring the differences between stainless steel plating processing and stainless steel passivation processing, you first need to understand the nature of stainless steel. Stainless steel is a chromium-containing steel, and its corrosion resistance mainly comes from the chromium and oxygen reaction to generate a chromium-rich oxide film. This film is tightly attached to the steel surface, effectively blocking further oxidation, and therefore has a certain ability to prevent rust. However, in some harsh environments, in order to further improve its corrosion resistance, people usually electroplating or passivation processing of stainless steel.

Electroplating is a process of depositing a layer of other metals or alloys on the metal surface through the action of electric current. The plating process for stainless steel is mostly zinc, nickel, chromium and other materials. This layer of plating not only enhances the appearance of gloss and aesthetics, but also provides additional corrosion protection. Because the plated metal often has better corrosion resistance than the stainless steel itself, thus forming a sacrificial anode protection, so that the plating before the base material oxidation, and thus protect the stainless steel from erosion.

The passivation of stainless steel is different from the electroplating process, it is a chemical treatment method, the purpose is to make the stainless steel surface of the chromium-rich oxide film more stable and solid. In the passivation process, stainless steel will be immersed in pickling solution or passivation solution, through the chemical reaction to remove surface iron filings, contaminants and oxidized discoloration after welding, while thickening the original oxide film, making it more dense and stable. This layer of optimized oxide film can better isolate aggressive substances, such as acids, alkalis, salts, etc., significantly improve the corrosion resistance of stainless steel.

The main difference between the two is that electroplating adds a layer of external metal to the surface of the stainless steel to provide protection, while passivation improves and enhances the stainless steel's own protective film. In the long run, the protection provided by passivation is more durable, as it does not have the problem that the added material may fall off after wear or damage; while once the plating layer is damaged, the stainless steel underneath may be exposed to a corrosive environment.

The two treatments also differ in application scenarios. Plating processing is usually used for parts that require a high degree of decorativeness or are used in extreme corrosive environments, such as bathroom fittings, door and window fittings, and so on. Passivation processing is used for equipment or piping that needs to be kept hygienically clean for a long period of time and is often exposed to corrosive substances, such as food processing equipment, medical devices, etc.