缓蚀剂在高压阳极箔电解扩孔中的作用机理

将高压阳极发孔铝箔在70℃、质量分数为3%的硝酸液中阳极电解扩孔,研究了添加大分子缓蚀剂聚苯乙烯磺酸(PSSA)后高压阳极箔的腐蚀机理。结果显示:添加PSSA后,腐蚀箔减薄量明显降低,质量损失率减小,并孔率降低,520 V化成的比容提高了约23%。隧道孔由孔口大、孔内小的"锥子"状转变为孔口小、孔内大的"垒球棒"状。铝箔表面的电位显著上升,而隧道孔内的电位基本保持不变,从而证明了,大分子缓蚀剂PSSA提高了铝箔表面和隧道孔口附近的电化学反应的阻力,电流主要分布到孔内,加速了孔内的扩孔过程。

Mechanism of inhibitor on electrochemical enlarging the diameter of tunnels on Al foil for high voltage anode

The effect of polymeric corrosion inhibitor polystyrene sulfonic acid (PSSA) on electrochemical enlarging the diameter of tunnels on Al foil in 3% (mass fraction) HNO3 at 70℃ was studied.It is proved that,after adding PSSA into nitric acid solution,the thickness reduction,mass loss rate and tunnel-mergers of Al foil are all improved significantly and the capacitance formed at 520 V is increased by 23%.SEM images indicate that the morphologies of tunnel pits are transformed from the shape like as a cone to a baseball bat after adding PSSA.Furthermore,the anodic polarized curves demonstrate that the potential at the surface of Al-foil is increased,but the potential inside the surface of tunnel pits is changed slightly,which means that PSSA enhances the electrochemical reaction resistance on the surface of Al foil and at the mouth of tunnels,so that electric current distributes mainly inside the tunnel pits,and accelerates enlarging where diameter.