La含量对渗铝层/基体界面孔洞生长的影响

采用热浸镀铝的方法在20碳钢上分别制备了不同La含量的热浸镀铝涂层,通过高温氧化试验以及测量孔洞平均直径和形核数量随氧化时间的变化,研究了La含量对渗铝层/基体界面孔洞生长的影响规律.结果表明,渗铝层/基体界面孔洞的生长可划分为快速生长和稳定生长两阶段.在快速生长阶段,当La含量小于0.5wt%时,随La含量的增加,渗铝层/基体界面孔洞的生长速度逐渐减小;当La含量大于0.5wt%时,随La含量的增加,界面孔洞的生长速度逐渐增大.在稳定生长阶段,渗铝层/基体界面孔洞的生长速度随La含量的变化规律与热浸镀铝后合金层厚度随La含量的变化规律相吻合.分析了La含量对渗铝层/基体界面孔洞生长的影响机理.

Effect of La content on growth of voids along interface between aluminized coating and steel substrate

The aluminized coating with different La content on low carbon steel 20 was prepared by hot dip aluminizing method. The effect of La content on the formation and growth of voids along the interface between the aluminized coating and steel substrate of aluminized steel were investigated by means of cyclic oxidation test and measuring variations of average size and number of the voids with oxidation time. The results show that the growth of the voids can be divided into two stages of fast growth and stable growth. At the stage of fast growth, the growth speed of the voids decreases gradually with the increasing of La content at 0 ～ 0.5wt% , but the growth speed of the voids increases when the content is more than 0.5wt% . At the stage of stable growth, the variation regulation of the growth speed of the voids with La content are in accord with the variation regulation of the thickness of the alloy layer after hot dip aluminizing with La content. The influence mechanism of La content on the growth of the voids is also analyzed.