扩散型热浸镀铝-镧钢的抗腐蚀机理研究

Mechanism of corrosion resistance for hot-dip La-aluminized steel

对扩散型热浸镀铝-镧钢的抗H2S腐蚀性能及机理进行了研究。通过SEM、TEM、XRD等对热浸镀铝-镧扩散层的组织结构进行观察和分析。结果表明,稀土镧可提高热浸镀铝钢的抗腐蚀性能。热浸镀铝-镧钢的扩散层中存在非晶态相,且稀土镧的添加可使扩散层中的非晶含量增加。在靠近扩散层的最外层表面有一约30μm厚的过渡层,该层为非晶态占优的非晶合金与纳米晶粒的混合区,且随着深度增加,非晶逐渐减少。分析认为,扩散层中存在大量的非晶态合金是稀土镧提高扩散型热浸镀铝钢抗腐蚀性能的主要原因。

The H2S corrosion resistance and its mechanism of the hot-dip La-aluminized steel after diffusion treatment were investigated. The microstructure of diffusion layer in the La-aluminized steel was observed and analyzed by means of TEM, SEM and XRD. The results show that the rare earths La can enhance the corrosion resistance of the aluminized steel. There is amorphous phase in diffusion layer of the hot-dip La-aluminizing and the content of the amorphous phase increases due to the addition of rare earths La. Near the outer surface of the diffusion layer there forms a transition zone with high content of amorphous phase and 30~m in thickness. The transition zone is a hybrid area of amorphous alloy and nano-crystal. The content of the amorphous phase gradu- ally decreases with increasing the distance from the surface. The main reason that La improves the corrosion re-sistance of the aluminized steel is that there is a large amount of amorphous phase in diffusion layer after hot-dip La-aluminizing.