Screws, zinc coatings during transportation often appear white, black, black and other phenomena, mainly due to galvanization and corrosion of corrosive media and atmospheric moisture, oxygen and carbon dioxide.
In order to prevent this phenomenon, you can try to use a good material before the screw is processed. Due to the galvanizing process, the surface of the defective screw is easily penetrated by corrosive media such as acid, alkali and salt, which is difficult to clean and cause corrosion.
To the reasonable choice of packaging materials, to avoid the use of plastic products that are not compatible with zinc, packaging materials such as galvanized iron sheet metal is the best, can be placed in a box with a suitable amount of desiccant to reduce relative humidity and reduce compatibility and reduce harmful gases Treasury erosion.
In order to prevent the anti-corrosion treatment of non-standard screws, it is already degreased, and the Nasdaq derusting and antirust agent water tank rustproof screw nut swims freely, or the zinc and chromium compounds are used to form a protective film on the metal surface, forming a spray method, Drying, cooling, and then repeating the process once, the obtained thickness of about 5 to 8 μ, silver gray, based on the information provided by the manufacturer of the display, is said to have good rust and corrosion resistance.
Phosphate treatment is a chemical treatment of phosphate containing metal to metal surface to form a phosphate protective film. Phosphating treatment solution is insoluble in water and has excellent adhesion of phosphate film as its main purpose. Bottom layer and coating Cold-adsorbed lubricant metal layer. Since the phosphate coating is composed of a series of different sizes of zinc, manganese, hydrogen phosphate and iron phosphate crystals, the film is porous, has a large specific surface area, has good absorption, an adsorbed coating or a large amount of lubricant Therefore, it is often used as a primer, or cold stamping to reduce friction and lubricating layer of steel, cold drawn wire.
The oxidized steel parts will be immersed in an alkali treatment solution containing an oxidant such as potassium hydroxide or sodium hydroxide solution of nitric acid, and keep its boiling point at about 140 ° C, or nitric acid and sodium hydrogen nitrate impregnate the molten salt of steel It is pleasing to remove the surface layer. The black iron oxide film in the composition having a mixture of ferrous oxide and iron oxide can be obtained after the eyes are quenched in water, which is a method to improve the corrosion of ferrous metals.