Ultrahigh hardness of carbon steel surface realized by novel solid carburizing with rapid diffusion of carbon nanostructures  

作　　者：Qing Tao Jian Wang Liming Fu Zheng Chen Chengjin Shen Dekun Zhang Zhi Sun 

机构地区：[1]School of Materials Science and Engineering, China University of Mining and Technology [2]School of Materials Science and Engineering, Shanghai Jiao Tong University

出　　处：《Journal of Materials Science & Technology》2017年第10期1210-1218,共9页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51641109);the National Basic Research Program of China (No. 2014CB046303);the Fundamental Research Funds for the Central Universities of China (Grant No. 2015XKQY01)

摘　　要：In this study, a novel rapid solid carburizing process with a large diffusion depth using nano-diamonds（NDs） was conducted for low carbon steel. Changes of annealed NDs were obtained by Raman spectroscopy and transmission electron microscopy（TEM）, and the results suggested that the NDs experience a stripping process before a special solid-reaction with surface iron atoms from steel substrate. Onionlike carbon（OLC） derived from the annealed NDs provided broken graphitic ribbons as carbon sources that accelerated the rate of adsorption and diffusion. Examination of the surface layer at equilibrium using TEM and X-ray photoelectron spectroscopy（XPS） also revealed the special state of carbon, and an ultrafine mixed phase microstructure was obtained by rapid solid-phase transformation. As a result, a surface hardened layer with ultrahigh hardness and a smooth transition region were realized. We believe that these kinds of diamond or graphitic structures with high activity states have an important influence not only on adsorption and diffusion but also on this special solid-phase transformation.In this study, a novel rapid solid carburizing process with a large diffusion depth using nano-diamonds（NDs） was conducted for low carbon steel. Changes of annealed NDs were obtained by Raman spectroscopy and transmission electron microscopy（TEM）, and the results suggested that the NDs experience a stripping process before a special solid-reaction with surface iron atoms from steel substrate. Onionlike carbon（OLC） derived from the annealed NDs provided broken graphitic ribbons as carbon sources that accelerated the rate of adsorption and diffusion. Examination of the surface layer at equilibrium using TEM and X-ray photoelectron spectroscopy（XPS） also revealed the special state of carbon, and an ultrafine mixed phase microstructure was obtained by rapid solid-phase transformation. As a result, a surface hardened layer with ultrahigh hardness and a smooth transition region were realized. We believe that these kinds of diamond or graphitic structures with high activity states have an important influence not only on adsorption and diffusion but also on this special solid-phase transformation.

关 键 词：Solid carburizing Onion-like carbon（OLC） DIFFUSION Solid-phase transformation Ultrahigh hardness 

分 类 号：TG178[金属学及工艺—金属表面处理]