In the process of transportation, screws and zinc coating often appear white, black, black and other phenomena, mainly caused by the exposure of zinc coating and corrosive medium and air moisture, oxygen and carbon dioxide.
In order to prevent this phenomenon, the surface state of the good materials that can be tried to use is before the screw processing. Due to the galvanizing process, the surface of the defective screw is easy to penetrate into the corrosive media such as acid, alkali, salt, etc., which is difficult to clean and lead to corrosion.
To the reasonable selection of packaging materials, it is the best to avoid the use of plastic products not with zinc. Packaging materials, such as galvanized sheet metal, can be placed in the proper humidity desiccant in the box to reduce relative humidity compatible with reducing and preventing the warehouse erosion of harmful gases. Currently the so-called screw and nut metal surface treatment market longzinc (NASDAQ Stock Code rust).
In order to prevent the non-standard screws from being defused, they are degreased, and swim on the rust preventive screws and nuts of the rust removal and rust preventive agent, or use zinc and chromium compounds to form a protective film on the metal surface. Spray method is formed and dried and cooled. Then the process is repeated once, and about 58 of it will be obtained. μ, Silver gray, based on the information thickness provided by the manufacturer of the display, is known as having good rust and corrosion resistance.
Phosphate treatment is a kind of phosphate chemical treatment containing metal to metal surface to form phosphate protective film phosphating treatment solution, which is insoluble in water, and has excellent sealing property of phosphate coating. As its main purpose, the base layer and the metal layer of coating cold adsorption lubricant are used. Because phosphate coating is composed of a series of zinc, manganese, hydrogen phosphate and iron phosphate crystals of different sizes, the film is porous, with large surface area and good absorption. It is adsorbed with coating or a large amount of lubricant. Therefore, it is often used as the base coating, or cold stamping to reduce friction and steel, cold drawn steel wire lubrication layer.
The oxidized steel parts will be immersed in an alkali treatment solution containing oxidants, such as potassium hydroxide or sodium hydroxide solution of nitric acid, and keep its boiling point of about 140 ℃, or nitric acid and sodium hydrogen nitrate impregnated with molten salt of steel parts, so that the eyes of black iron oxide film in the composition with a mixture of ferrous oxide and iron oxide can be obtained and then quenched in water, It is a method to improve the corrosion of iron metals!
