Al-Mg合金に対するカソード防食条件

抄録

Shiphulls made of Al-Mg alloy have a tendency to have pitting corrosion in anchorage. Cathodic protection systems using galvanic anodes have been applied to prevent such pitting corrosion. To clarify problematic points on application of cathodic protection, such as optimum protection potential, over-protection potential ranges and the most suitable galvanic anode, some experiments were conducted for bare and welded metal of Al-Mg alloy (JIS A-5083) in artificial sea water. Following results were obtained. A galvanic anode of Al-Zn-Mg-In-Si alloy was the most suitable from the view point of cost performance and protection efficiency. Optimum protection potentials were in the range of -950 ∼ -1000 mV refer to a saturated calomel electrode for the welded metal and -1000 mV for the base metal. Repassivation potential of the base metal measured in deaerated artificial sea water of pH 10 at 25℃ showed good coincidence with the optimum protection potential.