{"id":9113,"date":"2019-11-07T13:57:13","date_gmt":"2019-11-07T12:57:13","guid":{"rendered":"https:\/\/kluthe.com\/magazin\/?p=9113"},"modified":"2025-02-07T14:37:11","modified_gmt":"2025-02-07T13:37:11","slug":"pickling-and-passivation","status":"publish","type":"post","link":"https:\/\/kluthe.com\/magazin\/en\/pickling-and-passivation\/","title":{"rendered":"Pickling and Passivation"},"content":{"rendered":"

\u00ab What does it mean? \u00bb<\/h2>\n

Pickling and passivation are chemical or electrochemical surface treatment processes that deliberately modify the properties of the material’s surface layers. These methods are commonly used in the pretreatment of metal workpieces to create corrosion prevention<\/a> and prepare surfaces for subsequent coating processes.<\/p>\n

Purpose of Pretreatment with Pickling and Passivation<\/h2>\n

Metals react with oxygen in the air at their surfaces, leading to visible signs of corrosion. Examples include rust on iron-based materials and patina on copper. These oxide layers, particularly in the presence of moisture, can impede functionality. High temperatures involved in processes such as heat treatment, rolling, welding, and laser cutting exacerbate corrosion, often leading to oxidation or discoloration in heat-affected zones.<\/p>\n

Left untreated, such components degrade over time. Surface treatment prevents or delays this by applying coatings that separate the material from its environment. Effective coatings rely on the removal of natural oxide layers through pickling and the creation of defined material structures on the surface via passivation<\/a>.<\/p>\n

\"Car
\u00a9 wlad074 – stock.adobe.com<\/figcaption><\/figure>\n

The Pickling Process<\/h2>\n

Loose layers of corrosion can be removed mechanically, but the remaining oxides require chemical removal through a pickling process<\/a>. This process typically utilizes acids or acid mixtures. Since acids cannot dissolve oils or greases, thorough degreasing is necessary before processing. Neutral or alkaline pickling agents are also \u00a0employed, with alkaline solutions capable of combining degreasing and pickling in a single step. Neutral pickling agents consist of salts that chemically react with the metal to form water-soluble compounds.<\/p>\n

\"Industrial<\/a><\/p>\n

Chemical Pickling<\/h2>\n

Pickling agents penetrate the oxide layer and dissolve the underlying base material, detaching the oxide layer from the metal. The exposure time for the pickling agent must be precisely calibrated for the material and the product. Temperature also influences the reaction. The goal is to minimize material loss while effectively removing the oxide layer. Once the process is complete, the surface is thoroughly rinsed with water, leaving behind a clean, metallic surface.<\/p>\n

Electrolytic Pickling<\/h2>\n

Electrolytic pickling enhances the process by using direct current to dissolve surface material. Voltage adjustments allow for precise control, enabling extremely accurate results.<\/p>\n

\"Galvanizing
\u00a9 bogdanvija – stock.adobe.com<\/figcaption><\/figure>\n

Practical Execution of Pickling<\/h2>\n

The method of applying the pickling agent to the metal surface determines the pickling process, which may include:<\/p>\n