摘要
对比研究了单渗硼和氮硼复合渗对渗层的组织结构及硬度的影响,测定了两种渗层生长的动力学曲线,预先渗氮后,由于氮原子优先占据了表层晶界、缺陷等形核的有利位置,使随后渗硼时硼化物的形核机率减少,氮原子的存在还阻碍了硼原子扩散,故在相同保温时间内,复合渗比单一渗渗层较薄,但两种渗层形成的动力学曲线形状相似,都存在两个阶段。第一阶段渗层厚度(x)与保温时间(t)的关系符合抛物线规律:x=k t^(1/2)。第二阶段此关系偏离抛物线而近似呈直线上升:x=A+B^t。结合 TEM 观察,对动力学过程进行了分析。
This paper deals with the difference of the microstructure,morp-
hlogy and microhardness between boronizing and complex nitroboronizing
of iron.Besides,formation mechanism of compound layers of boronizing and
complex nitroboronizing have also been discussed.The results show that
the depth of nitroboronizing layer is thinner than that of boronizing only.
The kinetics curves of both boronizing and complex nitroboronizing may
be divided into two stages.At the first stagey,the layer thickens according
to a parabolic law when the process time prolongs.At the second stage,the
relationship deviates from parabolic law,and growth approaches to a straight
line.With TEM observation,the theoretical analysis of kinetic curves is
conducted.
关键词
渗硼
氮硼复合渗
组织结构
硬度
boronizing
complex nitroboronizing
density of nucleation
