SO_4^<2->イオンを含んだ溶液中でのアルミニウム合金の孔食成長挙動 Pitting corrosion growth characteristics of aluminum alloys in the solution containing SO_4^<2-> ion
To investigate the pitting corrosion growth rate of aluminum alloys in the solution containing SO<sub>4</sub><sup>2-</sup> ion, the immersion corrosion test and electrochemical measurements were carried out on aluminum and Al–0.4%Cu alloy clad with the liner containing Zn. In the solution containing SO<sub>4</sub><sup>2-</sup> ion the pitting corrosion could grow deeply even in the alloy having gradient of Zn concentration. While Cl<sup>-</sup> and SO<sub>4</sub><sup>2-</sup> ions concentrated into the pit, SO<sub>4</sub><sup>2-</sup> ion had little effect on electrochemical characteristics in acidified higher chloride solution. The pitting potential of aluminum became much less noble with as a little addition of Zn as 0.2%, but that of Al–Cu alloy scarcely varied in acidified higher chloride solution. As the SO<sub>4</sub><sup>2-</sup> ion had the controlling effect of pitting corrosion density, which introduced higher chloride ion concentration in a pit. Therefore, for the control of pitting corrosion growth rate the potential slope had to be sharper in the solution containing SO<sub>4</sub><sup>2-</sup> ion. Enough Zn content at surface was required to obtain better pitting corrosion resistance, especially in Al–Cu alloy.
軽金属 48(6), 288-293, 1998-06-30
The Japan Institute of Light Metals