几种苛刻海洋大气环境下的海工材料腐蚀机制

Corrosion Mechanism of Materials in Three Typical Harsh Marine Atmospheric Environments

以南极低温高辐照冰雪凝-融环境、南海高温高湿高盐雾环境以及滨海氯-霾耦合环境3种典型环境为研究对象,开展了典型海工材料的腐蚀行为研究。结果表明,南极低温环境下冰层、雪层覆盖下电化学腐蚀过程依然可以发生,冰雪凝-融过程导致液膜长周期存在促进了腐蚀的进行且加速局部腐蚀。南海高温高湿高盐雾环境下有色金属材料表面存在化学氧化和电化学腐蚀协同作用机制,不同铝合金的局部腐蚀萌生扩展驱动力不同(即扩散与电荷转移、氢致沿晶裂纹、腐蚀产物楔入效应),表面润湿时间和Cl^(-)协同作用导致腐蚀动力学偏离幂函数规律。滨海氯-霾耦合环境下NH_(4)^(+)加速腐蚀的关键控制因素为缓冲效应导致的持续供H^(+),Cl^(-)、NH_(4)^(+)、NO_(3)^(-)协同作用下镁合金发生“类自催化点蚀”。

In this work,the corrosion behavior of marine engineering materials in three typical harsh marine atmospheric environments is investigated i.e.,the so called"Antarctic low-temperature and high-ir-radiation ice-snow freezing-melting environment","high-temperature,high-humidity and high-salt fog at-mospheric environment of South China Sea",and"coastal chlorine-haze coupling environment".The re-sults show that in Antarctic environment,the electrochemical corrosion process can occur even beneath the cover of snow and ice at extremely low temperature.The freezing-melting process of ice and snow leads to the existence of surface electrolyte film for a long period,which promotes the corrosion reactions and accelerates the localized corrosion.In the environment of the South China Sea,there is a synergistic effect of chemical oxidation and electrochemical corrosion on the surface of non-ferrous materials in high humidity and high Cl^(-)atmospheric environment at high temperature.Different aluminum alloys have differ-ent corrosion initiation and propagation driving forces(i.e.,diffusion and charge transfer,hydrogen-in-duced intergranular cracking,and wedging effect of corrosion products).The synergistic effect of time of wetness(TOW)and Cl^(-)content lead to the deviation of corrosion dynamics from the power function.In the coastal chlorine-haze coupling environment,the key controlling factor of NH_(4)^(+)in acceleration of corro-sion in the chlorine-haze environment is the continuous supply of H^(+)caused by the buffering effect of NH_(4)^(+).Meanwhile,“quasi auto-catalytic pitting”corrosion occurs because of the synergistic effect of Cl^(-),NO_(3)^(-),and NH 4^(+).