With an acid solution to remove scale and rust on the steel surface was a method called pickling. A method for cleaning a metal surface. It is usually carried out in conjunction with the pre-membrane (pre-passivating treatment).

Usually the workpiece is immersed in an aqueous solution of sulfuric acid to remove oxides and other metal surface of the film. Pre-treatment process or intermediate plating, enamel, rolling and other processes.

Pickling products grade

Principle
Oxide, iron oxide rust (Fe3O4, Fe2O3, FeO, etc.) with an acid solution of a chemical reaction to form a salt dissolved in the acid solution is removed.

Quick wash process editor
Stage pickling process used to remove thick stainless steel surface oxide skin, high temperature, long pickling time, resulting in high processing costs; and room temperature, the descaling process to remove oxide thin good effect, the effect is not thick oxide ideal, especially black slag welding substantially not removed. In view of this situation, the author summarizes the basis of pre-treated stainless steel on the successful experience, integrated two-stage acid treatment technology, successful research fast pickling stainless steel at room temperature. At room temperature, the process can quickly remove thick stainless steel surface oxide skin, especially for welding black and inclusion removal is good, clean and bright surface after pickling, non-volatile light fading, yellowing.

Process
→ hanging pieces of stainless steel chemical degreasing (conventional alkaline degreasing chemical degreasing agent or surfactant) → hot water washing → water washing → acid → water washing → Step Step pickling → → water washing into the next processes (such as: chemical coloring recycling → → water wash → hardening → water washing → closed treatment → water washing → drying → finished)

Scale formation
Scale is one or more compounds of the mixture into the scale comprises calcium and magnesium carbonates, sulfates, silicates and iron oxides. Common carbonate due to low solubility of calcium and magnesium carbonate, calcium and magnesium in the water mostly as the presence of bicarbonate, bicarbonate and carbonate, carbon dioxide was in the balance as follows:
Ca (HCO3) 2 === CaCO3 + CO2 ↑ + H2O
Mg (HCO3) 2 === MgCO3 + CO2 ↑ + H2O

In cleaning cleaning project, since the acid reacts with the scale of carbon dioxide and hydrogen, intolerable and sulfate scale, etc. With a large number silica scale carbonate scale is dissolved and becomes loose residue pieces fall off or erosion by the pneumatic obliterated, while the insoluble calcium and magnesium salts off automatically flush.