hot dip About the process description!
(5) hot dipThe temperature of the zinc solution, the dip time and the speed of the workpiece from the zinc solution should be controlled. Generally, the extraction speed is 1.5m /min, the temperature is too low, the zinc liquid is poor in fluidity, the coating is thick and uneven, it is easy to generate flow suspension, and the appearance quality is poor.High temperature, good liquid zinc liquid, liquid zinc is easy out of the workpiece, reduce sagging and wrinkled skin, strong adhesion, and thin coating, good appearance, high production efficiency, but the temperature is too high, artifacts and zinc pot iron loss serious, produced a large number of zinc.Slag, which affects the quality of zinc-impregnated layer, is easy to cause color difference, making the surface color unsightly and zinc consumption high.The thickness of the zinc layer depends on the temperature of the zinc solution, the time of zinc immersion, the steel material and the zinc liquid composition.General manufacturers in order to prevent high temperature deformation of workpiece and reduce the losses caused by zinc slag, is 450 ~ 470 ℃, and 0.5 ~ 1.5 min, some factories to master and cast iron with high temperature, but to avoid the iron losses peak, temperature range. However, it is recommended to add the alloy with the function of removing iron and reducing eutectic temperature to the zinc solution and plating it.Zinc temperature drops to 435-445 ℃.
(6) to sort outAfter plating, the finishing of the workpiece is mainly to remove the residual zinc and zinc tumor on the surface.
(7) passivationThe purpose is to improve the anti-atmospheric corrosion performance of workpiece surface, reduce or prolong the occurrence time of white rust, and keep the coating with good appearance. All were passivated with chromate, such as Na2Cr207 80~100q/L, and sulfuric acid 3~4ml/L. However, this passivator seriously affected the environment, and it was best to use chrome-free passivation.