What is pickling?
Pickling is the process of treating metal surfaces to remove impurities from them. Inorganic pollutants, rust, scale, stains, etc. are examples of impurities. The metals we use for this process include precious metals such as copper and silver, aluminum alloys, iron and its alloys, and precious metals such as gold.
Pickle liquid is the chemical we use in this operation. Acids are usually present; strong acids such as sulfuric acid and HCl are common. There is still some substance in it. Wetting agents, corrosion inhibitors, etc. are some examples. This pickling procedure is often used to clean steel surfaces during the steelmaking process. This process is necessary to remove contaminants from the metal surface that may interfere with future metal processing, such as plating and painting. Descaling is a critical stage in this process. On metal surfaces, multiple thermal processing activities can leave a discolored oxide layer (scale). We can remove this layer of limescale by soaking it in a bucket of pickle liquid.
What is passivation?
The process of “passivating” a material from corrosion is called passivation. In other words, it protects metal surfaces from corrosion. Passivated metal is less susceptible to environmental influences. Using this method, a shielding material is formed as an outer layer. It can be used as a microcoat. We can apply this covering using a chemical reaction or a spontaneous reaction (we can keep the metal in the air to oxidize). Furthermore, only certain circumstances can cause metal passivation. Maintaining the appearance of metal is very beneficial.
The difference between pickling and passivation:
- Pickling is a method of cleaning metal surfaces to remove impurities. Pickle wine can be used for this. The result is that it protects metal surfaces from contaminants. “Passivating” Materials Corrosion is accomplished through the process of passivation, which means adding an oxide coating to the surface of the metal.
- While pickling is best for metals that already have oxides, heat tint, and weld discoloration, passivation promotes the formation of an oxide layer that provides corrosion resistance to the stainless steel surface. Additionally, the metal must first be clean and free of grease for pickling to be effective.
- The chemical solution used in pickling is more abrasive than the chemical solution used to passivate stainless steel with acid. It uses a mixture of nitric and hydrofluoric acids for pickling. Nitric acid or citric acid are the acids used in passivation.
- The pickling process causes more changes to the metal surface. Pickling removes surface rust and discoloration left by metal welding. Passivation usually does not penetrate below the surface of the metal. The properties of the metal do not change either.
- During the pickling process, a thin metallic coating is removed from the surface. Acid-based passivation does not remove any metal from the surface.
- Pickling removes weld scale, heat tint and surface iron contamination. The result of chemical micro-etching after pickling is a dull, matte, uniform gray surface on the metal. In contrast, passivation only removes free iron contaminants from the stainless steel surface.
Advantages of pickling passivation:
- Remove any residual contaminants from the metal produced
- Prevents contaminants from penetrating metal and eventually causing rust and damage
- Make sure the metal surface is flawless and smooth.
- Increase the durability of metal
Metals are often very susceptible to reactions when exposed to ordinary air. We can use two methods to protect metal surfaces: pickling and passivation. Pickling and passivation are different processes as passivation protects the metal surface from corrosion while pickling is used to remove contaminants from the metal surface.
Tianjin Anton Metal Manufacture Co., Ltd. is a company specializing in the production of various nickel-based alloys, Hastelloy alloys and high-temperature alloy materials. The company was established in 1989 with a registered capital of 10.0 million, specializing in the production and sales of alloy materials. Anton Metal’s products are widely used in aerospace, chemical industry, electric power, automobile, nuclear energy and other fields, and can also provide customized alloy material solutions according to customer needs. If you need to know the price consultation of alloy materials or provide customized alloy material solutions, please feel free to contact the sales staff.
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Post time: Jan-09-2024
