稀土铈对热浸镀铝层组织和性能的影响

Effect of Rare Earth Element Cerium on Properties and Microstructure of Hot Dip Aluminum Coating on Q235 Steel

研究了稀土铈对热浸镀铝层组织结构、耐蚀和耐热性能的影响。结果表明：稀土铈质量分数低于0．3%时,热浸镀铝层的耐蚀性能和高温抗氧化性能都得到提高,超过此含量镀层的性能下降。稀土铈使得过渡层由锯齿形结构转变为平滑结构,使镀层中FeAl_3析出相在表层中呈网状分布,随其含量增加过渡层厚度减小。稀土含量超过0．3%时,稀土化合物在表层中呈条块状第二相析出并偏聚,并且随着稀土铈含量增加,表面层中稀土化合物呈块状,且偏聚程度加大。

The effect of rare earth element Ce on the microstructure of hot dip aluminum（HDA） coating on Q235 steel have been studied by means of SEM and XRD. The anticorrosive property and oxidation resistance of the coating was also studied by immersion test in 3. 5% sodium chloride solution and at 900℃ for 300 h respectively. If the content of Ce in the hot dip aluminum bath was lowere than 0. 3%, with increasing the content of Ce in the bath, the anticorrosive property and oxidation resistance of HDA coating were improved obviously. If the content of Ce in the bath was higher than 0. 3%, the properties of the HDA coating became poor. By adding Ce into the HDA bath, the saw-toothed shape of transition layer of HAD coating became smooth, FeAl3 phase distributed in the surface layer in netted shape, but the thickness of the transition layer varied little with increasing the content of Ce in the bath. If the content of Ce was more than 0. 3% in the bath, the Ce compound separated out in strip-like shape in the surface layer and got together in the boundary of FeAl3 phase, and with increasing the Ce content in the bath, the shape of Ce compound became blocky and the degree of segregation was more serious.