热镀5%铝-锌钢板在青岛不同海水区带的腐蚀行为

开展了热镀5%铝-锌钢板在青岛不同海水区带的实海腐蚀测试,并利用电化学测试、失重腐蚀测试和扫描电镜首次研究了镀层的海水腐蚀行为.结果表明,由于腐蚀电流密度小,腐蚀产物具有保护性,镀层在全浸区表现出较好的耐蚀性能;镀层在潮差区出现不同程度的生物污损,而比较充分的充气条件又促进了镀层的氧化,其腐蚀速度比全浸区明显降低;镀层在飞溅区未出现生物污损,耐蚀性能最好,可能与良好的充气条件和腐蚀产物层的阻挡作用有关.镀层在飞溅区和潮差区的耐蚀性比全浸区分别提高197%和183%;但在全浸区和潮差区,镀层有局部腐蚀倾向.

Corrosion Behavior of Hot-Dip 5% Al-Zn Alloy Coated Sheet Steel Exposed to Different Seawater Zones in Qingdao

Commercial hot dip 5 %Al-Zn alloy coated sheet steel was investigated for its corrosion behavior in three different seawater zones at Qingdao site with electrochemical measurement, weight loss test and SEM. The results indicated that in immersion zone 5 % Al-Zn alloy coating resists well to the seawater corrosion because of its low current density and highly protective products from corrosion. In tidal zone the biofouling was found somewhat on coupons with oxidized surface resulting from quite good aeration, and the corrosion rate of the coating exposed in this zone is obviously lower than that in immersion zone. As to splash zone, 5%Al-Zn alloy coating shows the best corrosion resistance without biofouling found, which may be attributed to the advantageous aeration in combination with the corrosion resistant effect of the products from corrosion itself. A conclusion is therefore drawn that the corrosion resistance of 5 % Al-Zn alloy coating increases by 197% and 183% in splash and tidal zones, respectively in comparison with that in immersion zone, and this coating tends to suffer from local corrosion in immersion and tidal zones.