铝合金氟铝酸盐转化膜硅酸钠封闭后的耐蚀性能

Anticorrosion Ability of Fluoroaluminate Conversion Coating on Aluminum Alloy after Sealing with Sodium Silicate Solution

为了提高5052铝合金表面氟铝酸盐转化膜的耐蚀性能,以硅酸钠溶液对其进行封闭并优选了其工艺条件,采用JSM-LV型扫描电镜、INCA型EDS能谱分析、中性盐雾试验和电化学极化曲线测量研究了其形貌、组构和耐蚀性能。结果表明:铝合金氟铝酸钠盐转化膜经硅酸钠溶液封闭处理后,膜表面成分由封闭处理前的50.75%F,16.89%Na,32.19%Al,0.17%Si变为42.21%F,12.17%Na,37.88%Al,1.47%Si,6.27%O。试片耐中性盐雾腐蚀时间从封闭前的48 h提高到封闭后的360 h;腐蚀电位正移,耐蚀性提高。

Fluoroaluminate conversion coating on Al 5052 alloy surface was sealed with the sodium silicate solution.The post-sealing condition was optimized;and the morphology,structure and anticorrosion ability of resultant sealed fluoroaluminate conversion coating were analyzed with a scanning electron microscope,an energy dispersive spectrometer,a neutral salt-spray test rig,and an electrochemical test rig.Results indicated that,after being sealed with the solution of sodium silicate,the composition of the fluoroaluminate conversion coating changed from 50.75%F(mass fraction;the same hereafter),16.89%Na,32.19%Al,and 0.17%Si to 42.21%F,12.17%Na,37.88%Al,1.47%Si,and 6.27%O.In the meantime,the neutral salt spray time rose from 48 h to 360 h,and the corrosion potential was shifted positively,corresponding to greatly improved anticorrosion ability of the conversion coating.