Dacromet treatment dip coating drying and spraying technology

Dip coating and drying are applicable to standard parts and other small workpieces. Workpieces generally need to be soaked for 10 to 20 seconds to fully form a purification membrane between hexavalent chromium and steel substrate; When centrifuging and drying, it is necessary to turn forward and reverse twice, ten to twenty seconds each time. For special parts, fixtures should be used. For parts that are difficult to throw, manual assistance should be used, such as stirring them in the centrifugal basket with a rod, and the speed should be fast. In short, it is necessary to ensure that there is no liquid accumulation, liquid hanging, bubbles, missing coating, etc. on the parts. Through multiple positive and negative liquid throwing and multiple adjustment of drying speed, the process parameters after * are determined according to the actual coating effect. 1.2 Dalian spraying and brushing are generally used for large parts, and for parts that are difficult to dip and dry by centrifugation

The coating sprayed in Dalian is uniform, thick, with poor adhesion but good finish, strong corrosion resistance but low efficiency. Attention should be paid to * * during construction, and the viscosity of slurry should be appropriately reduced during spraying. Dacromet liquid is divided into mother liquid and base liquid (some suppliers divide Dacromet liquid into three kinds: main agent, bridging agent, tackifier, and three solvents * * are used together.) The base solution is composed of extremely fine flake aluminum powder and zinc powder, and the mother solution is composed of acid and chromium salts. When in use, the two are mixed to form a bath liquid. The tank liquid must be continuously circulated or stirred to prevent the base material from settling. Because it is not easy to keep for a long time, it should be prepared and used now. During preparation, the temperature of the bath solution should not be too high (less than 20 ℃) to prevent the reaction of the solution itself. The coating thickness is determined by the process parameters such as immersion and drying time, drying speed, etc. Generally immerse Dacromet solution for 0.5 ~ 2.0 minutes. When different parts are dried, the rotating speed is different, generally 200-300 rpm. The number of times to dip Dacromet solution depends on the requirements of different parts. The coating of Dacromet solution is thickened by three to four microns once, and generally two to three times.