陰極防食用鉛合金陽極の研究 (第3報)

銀の最適添加量の決定

抄録

As clearly stated in the previous notes, the adding of silver has proven to be the most important factor in improving the anti-corrosive quality of lead. However, this involves two problems: 1) silver is relatively costly, 2) how should we determine the quantity to be added to the lead?
This time, I conducted the experiment only from the corrosion point of view, aside from this economical problem. And, I was able to obtain some favorable results on the determination of adding amount of silver.
The corrosion test was performed in artificial sea-water at constant current density. The results obtained were as follows:
1) The most suitable addition of silver to obtain the best anti-corrosive quality is from 3.0% to 4.5% in range.
2) When its addition is 1% or less, anodic corrosion advances so that it no more keeps an anti-corrosive property.
3) The addition more than 4.5% will not improve its anti-corrosive quality when performed in 3.0%-4.5% solution.
4) The temperature of solution does not affect the adding amount of silver, i. e., 3.0%-4.5%.
5) The stirring, also, does not change the adding amount of silver, to get the best possible results.