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采用LSB型渗硼剂分别在渗硼温度为1123、1173和1223 K,保温时间为2、4、6和8 h的工艺参数下对球墨铸铁表面进行固体渗硼处理。用扫描电子显微镜(SEM)对渗层横断面进行了显微组织观察,用X射线能谱仪分析了沿渗层表面到心部的元素分布。用X射线衍射仪(XRD)分析出渗硼层为Fe2B单相,用显微硬度计测试渗层的硬度分布,其显微硬度值在1170~1392HV0.025之间。渗层厚度随着渗硼时间和渗硼温度的增加而增加,其范围约为35~118μm。对实验数据进行分析和拟合,得出渗层动力学曲线和等厚度图,并且经回归分析计算出硼在球墨铸铁中的扩散激活能约为175 kJ/mol。
The surface of the ductile cast iron was treated by solid boriding with LSB type boronizing agent under the technological parameters of boronizing temperature of 1123, 1173 and 1223 K and holding time of 2, 4, 6 and 8 h respectively. The cross section of the layer was observed by scanning electron microscopy (SEM), and the elemental distribution along the surface of the layer was analyzed by X-ray energy dispersive spectrometer. The boronizing layer was Fe2B single phase by X-ray diffraction (XRD). The hardness distribution of the layer was tested with a microhardness tester. The microhardness value was between 1170 and 1392 HV0.025. The thickness of the layer increases with increasing boronizing time and boronizing temperature, which ranges from 35 to 118 μm. The experimental data were analyzed and fitted to obtain the kinetic curves of the infiltration layer and the isopach map, and the diffusion activation energy of boron in the ductile iron was calculated by regression analysis to be about 175 kJ / mol.