镀铝板用耐高温型无铬钝化结合机理及性能

传统的有机类无铬钝化产品在400 ℃的高温条件下黄变较重,在保持优异的耐高温前提下,同时具有优异的耐蚀性和加工性能,设计了镀铝板使用的无机类加少量有机类的无铬钝化产品。利用电化学工作站、X射线光电子能谱、X射线荧光谱、红外光谱等方法,对该无铬钝化药剂在热镀铝板表面的成膜机理进行了研究,并结合成膜动力学分析,完成了皮膜与铝硅镀层的界面结合机理分析。对膜重、固化温度对镀铝板工艺性能影响进行研究,得出综合性能优异的膜重控制范围为0.8～1.2 g/m2,对应的PMT温度大于80 ℃。所生产的无铬钝化热镀铝板产品耐高温、耐腐蚀和冲压性能优异,400 ℃烘烤2 h后表面色差ΔE＜3,72 h中性盐雾试验未出现锈蚀。

Bonding mechanism and technological properties of high temperature resistant chromium-free passivation coating for aluminized sheet

The traditional organic chromium-free passivation product has a serious yellowing change at 400 ℃. On the premise of maintaining excellent high-temperature resistance, it also has excellent corrosion resistance and processing performance. A chromium-free passivation product using inorganic and a small amount of organic was designed for aluminum plating. The methods of electrochemical workstation, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy and infrared spectroscopy were used. The film forming mechanism of the chromium-free passivation on the surface of the hot-dipped aluminum sheet was studied, and the interfacial bonding mechanism between the skin film and the aluminum-silicon coating was analyzed by combining the film forming kinetics analysis. The effects of film weight and curing temperature on the technological properties of the aluminized sheet were studied. It was concluded that the control range of film weight with excellent comprehensive properties was 0.8-1.2 g/m2, and the corresponding PMT temperature was above 80 ℃. The chromium-free passivated hot-dip aluminized sheet had excellent high-temperature resistance, corrosion resistance and stamping performance. The surface chromatic aberration ΔE was less 3 after baking at 400 ℃ for 2 h and the neutral salt spray test for 72 h did not show rust.