Effect Of Hot-dip Galvanized Without Surfactant Ammonium Fluxing Process

As the enhance of awareness and stringent of national requirements of environmental protection, cleaner production were received attention gradually in hot-dip galvanizing industry. The traditional technology of hot-dip galvanizing has advantages with lower cost, good stability and plating quality, but the ammonium chloride in the flux were caused pollution to water and air quality of surrounding environment. In view of the insufficiency of traditional technology, through study the ammonium-free flux and technology, expect to alternatives to traditional flux by ammonium-free flux, change the state of environmental protection of hot-dip galvanizing industry fundamentally.The article mainly is analyze the role of surfactant to flux, salt membrane and the formation of coating in ammonium-free fluxing process. According to the previous experimental phenomenon, theorizes that surfactant can improves the wettability of flux solution, and plays a positive role in plating and coating formation process. And prove the inference from several aspects, including characterize the activity of single and compound surfactant, measure and analyze the properties of flux solution and salt membrane, then combined with the evaluate results of coating quality and performance, to discuss the role of surfactant in plating and coating formation process systematically, and provide technical parameters for the application of surfactant.Through the analysis of the experiments, the following conclusions:The surfactant can plays a positive role in plating assistant and coating formation process. First of all, the surface tension of flux, contact angle between flux and workpiece are reduce significantly after adding surfactants to flux, so the wettability of the flux can be improved, then the flux can wetting workpiece effectively. Second, the surfactant can improves the uniformity of salt membrane, its structure became smaller and much compact, then played an effective protection for substrate. In addition, the apparent quality and can corrosion resistance of coating were improved effectively.Relative to the single type surfactant, FC09-Ⅱ which compound with different surfactant has much prominent and stable activity, can improves the wettability of the flux effectively, because of the synergistic effect between the different components. And the adding concentration of surfactant should be controlled between1×10-3～1×10-2g/ml.Associated with the evaluation result of coating quality, we found that the characteristic index of flux and salt membrane should be control effectively to make sure good quality of the coating. The surface tension of the flux ought to lower than24mN/m, contact angle between flux and workpiece should be less than47°, and the ideal amount of salt membrane which adhered on the surface of workpiece is about3.8g/m2.At the same time, the experimental results shows that the amount of salt membrane and thickness of coating were decreased by adding the surfactant to flux, so it is available to reduce the consumption of zinc and flux by adding proper amounts of surfactant to flux in industrial production process, it is helpful to the production process and the surrounding ecological environment.