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在粉末渗剂和45钢试样上施加4 A电流的直流电场,于800℃进行直流电场增强渗硼。以X射线衍射、光学显微观察和显微硬度测试等手段,分析位于电场不同位置试样渗硼层的相结构、显微组织、厚度与及显微硬度分布。结果表明:电场渗硼的渗层组织形态基本与常规渗硼的一致,以锯齿状楔入基体,但其相结构、显微硬度分布、厚度等与试样位置有关;朝正极面的渗层一般由Fe B和Fe2B两相组成,渗层较厚且较硬;朝负极面的渗层主要由Fe2B组成,随渗硼时间延长Fe B先增加,后减少至消失;渗硼时间等于及超过2 h,渗层下出现明显的过渡区;渗层厚度与保温时间关系曲线呈抛物线特征。从直流电场对渗剂化学反应、含硼活性基团在气氛中的扩散及硼在试样内扩散的影响等方面进行了分析。
A DC electric field of 4 A was applied to the powder seepage and 45 steel samples, and DC electric field enhanced boronizing was performed at 800 ° C. The phase structure, microstructure, thickness and microhardness distribution of the boronizing layer at different electric field locations were analyzed by X-ray diffraction, optical microscopy and microhardness test. The results show that the morphology of the infiltrated layer in electric field is basically the same as that of conventional boronizing. The wedged in wedged matrix, but the phase structure, the distribution of microhardness and the thickness are related to the position of the sample. Generally composed of Fe B and Fe2B two phases, the diffusion layer thicker and harder; toward the negative surface of the infiltration layer is mainly composed of Fe2B, with boronizing time prolonged Fe B first increased, then reduced to disappear; boronizing time equal to and beyond 2 h, there is a clear transition zone under the infiltrating layer. The relationship between the thickness of the infiltrating layer and the holding time is parabolic. The effects of DC electric field on the chemical reaction of penetration agent, the diffusion of boron-containing active groups in the atmosphere and the influence of boron diffusion in the sample were analyzed.