Research On Smokeless Flux In Process Of Hot-Dip Galvanizing

Hot-dip galvanizing technology has a long history. It can realize double protection of physics and electrochemistry for matrix materials and have a dense and durable coating which combines with the matrix materials well, so it has got the general use. However, the smoke problem while hot-dip galvanizing has not been solved effectively, which not only influences regular working for operators, but also results in serious pollution to the circumjacent environment. In recent years, with the environmental requirement enhancing unceasingly, smoking problem has got more people’s attention.This thesis sets down research on the reason of smoke production, attempting to use chloride、fluoride and surfactant instead of ammonium chloride which is the ingredient of traditional flux, we hope that it can reach the purpose of cleaner production through this method. In this work, we select eight kinds of fluxes and each flux has six different concentrations. After selecting the best formula, we also analyze the coating performance through methods of visual study、metallographic microscope、laser scanning confocal microscope(LSCM)、electrochemical workstation and salt spray test etc. The main results include:In the condition of temperature450℃, galvanizing time1.5minutes, fluxing time3minutes, the flux which consists of zinc chloride and little surfactants can get a zinc coating, but it also produces some smoke and have serious miss out. For this reason, the flux effect is not ideal; other fulxes get the uniform coating surface. That is to say, these methods expect zinc chloride and little surfactants realize cleaner production. Especially with the formula of200g/L ZnCl2+80g/L CeC13+90g/LKF·2H2O+80g/LNaCl can get the best performance and have no smoke production which improves the surface quality and corrosion resistance; KF is unfavourable to corrosion resistance; after adding SnCl2, the thickness of ξ phase and surface roughness increase, but the corrosion resistance reduce, so the appesrance quality is poor; NaCl improves the brightness of zinc coating; after adding10%CeCl3, ξ phase becomes more compact and uniform, and also corrosion resistance improves. Therefore, it has been shown that the mechanism of action of hot-dip aluminuming is similer to hot-dip galvanizing.