离子渗复合处理与单一离子渗氮动力学对比研究

Comparative Study on Plasma Complex Treatment and Plasma Nitriding

为发挥离子渗氮和离子氮碳共渗两种技术各自的优势并克服其不足,研发了离子氮碳共渗与离子渗氮复合处理(以下简称离子渗复合处理),并与单一离子渗氮进行了对比。采用金相显微镜、X射线衍射仪和显微硬度计对离子渗层厚度、物相、截面硬度进行了测试,并对化合层形成动力学进行了对比分析。结果表明,45钢经离子渗复合处理后化合层明显厚于单一离子渗氮,化合物层形成效率显著提高,且表层硬度提高。经离子渗复合处理后化合层新增了Fe_(3)C相,且主要物相发生了由γ′相向ε相的转变。动力学分析表明,离子渗复合处理化合层形成扩散激活能比单一离子渗氮明显降低,从179.7 kJ·mol^(–1)降低到87.1 kJ·mol^(–1),同时得出了45钢在783~843 K温度范围内离子渗氮与离子渗复合处理化合层厚度与温度之间的关系式分别为d_(plasma nitriding)=exp(15.8–10810/T)与d_(complex treatment)=exp(9.7–5237/T)。

In order to take advantage of the individual advantages of plasma nitriding and plasma nitrocarburizing,and overcome their shortcomings,plasma complex treatment combining both plasma nitrocarburizing and plasma nitriding(hereinafter referred to as complex treatment)was developed and compared with a single plasma nitriding.The nitrided layer thickness,phase microstructure,cross-sectional microhardness were investigated by means of optical microscope,X–ray diffraction and microhardness tester.The results show that the compound layer thickness after complex treatment is much thicker than that after plasma nitriding,thus the nitriding efficiency is improved remarkably.Fe_(3)C phase was occurred in compound layer after complex treatment,and the dominated phase of the compound layer was transformed fromγ′toεphase.Higher microhardness was obtained after a complex treatment.In addition,activation energy(Q)of forming compound layer decreases from 179.7 kJ/mol in plasma nitriding to 87.1 kJ/mol for the complex treatment.And the kinetics of plasma nitriding and complex treatment in the temperature range of 783 K to 843 K was obtained as the following formula d_(plasma nitriding)=exp(15.8–10810/T),d_(complex treatment)=exp(9.7–5237/T).