La对热浸镀铝合金层生长动力学的影响

Effect of Rare Earth Elements on Kinetics of Hot Dip Aluminizing

研究了工业纯铁分别热浸镀纯铝和稀土铝后合金层厚度随浸镀时间的变化.结果表明,稀土镧渗入了合金层,并对镀铝有明显的催渗作用,使镀铝速度提高约20%～30%.对740℃经不同时间的热浸镀铝试样测定合金层厚度(y).将y及所对应时间(t)代入经验公式lny=(1/n)lnK+(1/n)lnt,经一元线性回归处理后,y与t之间满足y2=Kt抛物线关系.稀土渗入合金层,会增大晶体缺陷密度,有利于铝原子的扩散.稀土的添加可降低铝原子的扩散激活能,起到催渗的作用.此外,测定了合金层的镧含量分布.

Effects of hot dip time on the alloy layer depth of hot-dip aluminizing were investigated. The results show that lanthanum element permeates into alloy layer and has an obvious catalytic effect on hot dip aluminizing on 0 pure iron surface. The hot dip aluminizing rate can increase by about 20%-30%. The case depth （y） of the samples which has undergone different periods of the hot-dip aluminizing time at 740℃ was measured . These depth values （y） and its corresponded time （t） were substituted into the experience formula：lny= （1/n）lnk＋（1/n）lnt,and were processed by mono-linear regression, It is found that y and t have the relationship of y^2 =Kt Permeating of rare earths into alloy layer increases the crystal fault density,and, together with its excellent chemical activation, makes aluminum atoms diffuse easily. These functions of rare earth can decrease the diffusion activation energy of the aluminum atoms, and therefore has catalytic effect on permeation.