中温锌-钙-锰系黑磷化液的制备及膜层性能

Preparation of Medium Temperature Zn-Ca-Mn System Black Phosphating Fluid and Performance of Resultant Phosphating Coating

已有的高温锰系一步法黑色磷化能耗高,沉渣多,溶液不稳定;中温两步法黑色磷化膜疏松、附着不牢。两者都不适应大生产需要。制备了一种含Zn2+,Mn2+,Ca2+3种离子的中温黑色磷化液,采用环境扫描电镜(ESEM)观察磷化膜表面微观形貌,用X射线能谱仪(EDS)分析磷化膜成分,通过硫酸铜点滴试验评价了磷化膜的耐蚀性能,并考察了ρ(PO43-)/ρ(NO3-)、TA/FA、磷化温度和磷化时间对膜层耐蚀性的影响。结果表明,在磷化温度65～75℃,磷化时间30～35min,TA/FA为9～13,ρ(PO43-)/ρ(NO3-)为2.5条件下,所得磷化膜结晶均匀、致密,呈深黑色,耐蚀性良好。

In view of high energy consumption and poor fluid stability of high-temperature Mn-system one-step black phosphating as well as incompact structure and poor adhesion to substrate of black phosphating coating obtained by medium-temperature two-step route,medium temperature black phosphating solution containing Zn2+, Mn2+ and Ca2+ was prepared. The morphology of resultant black phosphating coating was observed using an environmental scanning electron microscope (ESEM), and its composition was analyzed using an X-ray energy dispersive spectrometer. The corrosion resistance of the black phosphating coating was evaluated using dropping tests of copper sulfate. Moreover, the effects of mass concentration ratio of PO43- to N3O-, ratio of total acidity to free acidity (TA/FA), phosphating temperature and phosphating time on the corrosion resistance of the phosphating coating were investigated. Results indicate that uniform and compact black phosphating coating with good corrosion resistance can be prepared at a temperature of 65～75 ℃, phosphating time of 30~35 min, TA/FA of 9~13 and ρ(PO43-)/ρ(NO3-) of 2.5.