直流电场对35钢盐浴渗氮的影响与动力学分析  

Effect of direct current field on salt bath nitrding for 35 steel and kinetics analysis

作　　者：陈尧[1] 周正寿[1,2] 孙斐[2,3] 戴明阳[1] 胡静[1,2] 

机构地区：[1]常州大学材料科学与工程学院,江苏省表面科学与工程技术重点实验室,江苏常州213164 [2]江苏省光伏科学与工程协同创新中心,江苏常州213164 [3]常州轻工职业技术学院机械工程系,江苏常州213164

出　　处：《中南大学学报（自然科学版）》2016年第5期1506-1512,共7页Journal of Central South University:Science and Technology

基　　金：江苏高校优势学科建设工程项目(2014006);江苏省研究生创新基金资助项目(SCZ100431322)

摘　　要：以35钢为材料,研究直流电场催渗盐浴渗氮技术。该技术在渗氮盐浴中通过在被渗样品间施加合适参数的直流电场予以实现。利用光学显微镜、显微硬度计和X线衍射仪对渗层的显微组织、渗层厚度、硬度及物相进行测试和分析。研究结果表明:直流电场可以显著提高渗氮速度,降低渗氮时间;在渗氮温度818 K,施加强度为7.5 V的直流电场时,可将常规渗氮时间100 min所得到的化合层厚度所需时间降低到50 min。同时,施加电场盐浴渗氮使35钢截面显微硬度得到明显提高。电场盐浴渗氮的扩散系数比常规盐浴渗氮提高1.9倍以上,扩散激活能从常规盐浴渗氮的220 k J/mol降低到181 k J/mol,从而达到增加渗层厚度的显著效果。同时对直流电场快速盐浴渗氮机理进行分析。Direct current field（DCF） assisted salt bath nitrding technology was developed, using 35 steel as the testing material. This technology was carried out by applying appropriate parameters of DCF between the treated samples in the nitrding salt bath. Characterization of modified surface layers was made by means of optical microscopy, Vickers micro-hardness test and X-ray diffraction analysis. The results show that DCF can significantly reduce the holding duration compared with the conventional process. When nitrding at 848 K with 7.5 V of DCF assisting, the time to get the same thickness of compound layer decreases to less than half by DCF assisting, while the higher surface hardness, modestly higher sub-surface hardness and superior hardness profile were obtained. The results show that the diffusion coefficient of nitrogen enhanced by DCF increases to more than 1.9 times higher than that of NM at each temperature. In addition, activation energy（Q） for the nitrogen diffusion decreases from 220 to 181 k J/mol. Moreover, the catalyzing mechanism of DCF for salt bath nitriding process was analyzed.

关 键 词：盐浴渗氮 直流电场 动力学 扩散 

分 类 号：TG156.8[金属学及工艺—热处理]