摘要
利用TD盐浴法,在42Cr Mo合金钢表面制备多孔碳化钒层,并探究多孔结构的形成机理。设计4%、6%、8%、10%和12%五种不同质量分数Al含量的盐浴剂。采用SEM、EDS、XRD和显微硬度计等,对950℃×4 h渗钒后试样的渗层形貌、横截面、成分、表面硬度和盐浴剂粉末进行检测分析。结果表明:4%和12%Al含量的盐浴剂会严重腐蚀材料基体,表面未生成VC层;6%,8%和10%Al含量的盐浴剂可在基体表面生成多孔状VC层,厚度分别为8,8和6μm,渗层维氏硬度在950~1 150,约为基体硬度(450)的2.5倍;VC层的生长过程为:微量的V原子进入基体,使奥氏体中C原子的固溶度降低,溢出的C原子聚集在晶界处并沿着晶界向外迁移,从而与盐浴剂中的V原子生成VC晶粒,进而在晶界处形成"凸"型VC形貌,多孔组织结构也随之形成;随Al含量增加,VC晶粒择优向I(200)晶面生长,孔洞尺寸逐渐增大。
The porous vanadium carbide layer was prepared on the surface of42CrMo alloy steel by TD salt bath method and the formation mechanism of the porous structure was discussed.The salt bath agent with five different mass fractions of Al(4%,6%,8%,10%,12%)were designed.The surface and cross-section morphology,elements composition,surface hardness and salt bath agent of the speciment processed by vanadinizing at950℃for4h were analyzed by SEM,EDS,XRD and microhardness tester,respectively.The results show that the matrix immersed in the salt baths with Al content of4%and12%are corroded seriously and the VC layer is not formed on the surface.The porous VC layers with thickness of8,8and6μm can be prepared by the salt bath with Al content of6%,8%,10%on the matrix surface respectively.The hardness of the coating is950to1150HV,which is nearly2.5times of the matrix alloy.The growth process of VC layer is that trace amounts of V atoms diffuse into the matrix,reducing the solid solubility of carbon atoms in austenite(450).The overflowing carbon atoms gather in the grain boundary and migrate along it,then combine with V atoms in salt bath agent to form VC grains.And“convex”VC morphology and porous structure come into being.With the increase of Al content,the VC grains tend to grow to the I(200)crystal plane and the size of the pores increase.
作者
杨松
韩天
许晓静
阮鸿雁
戈晓岚
何志盛
刘庆辉
YANG Song;HAN Tian;XU Xiaojing;RUAN Hongyan;GE Xiaolan;HE Zhisheng;LIU Qinghui(Engineering Institute of Advanced Manufacturing and Modern Equipment Technology,Jiangsu University, Zhenjiang 212013, China)
出处
《粉末冶金材料科学与工程》
北大核心
2017年第5期662-667,共6页
Materials Science and Engineering of Powder Metallurgy
基金
江苏省科技计划产学研联合创新资金(BY2015064-01)
江苏大学拔尖人才工程基金(1211110001)
江苏省2015年度普通高校研究生实践创新计划(SJLX15-0481)
