自纳米化电工纯铁表面合金化改性研究

Study on surface alloying of the self-nanocrystallizated electric iron

利用高能喷丸(high energy shot peening,HESP)法在电工纯铁表面获得了一定厚度的纳米晶层;同时采用在喷丸弹丸中添加镍粉和铬粉的方法,实现了电工纯铁表面自纳米化-合金化改性。运用金相显微镜、扫描电镜、X射线衍射分析以及电化学测试系统等手段对自纳米化层以及合金化层的组织结构进行了表征,重点对其耐蚀性进行了测试分析。结果表明,采用HESP方法,在0.6MPa喷丸压力下喷丸6min,即可在电工纯铁表面形成一定厚度晶粒大小为47.9nm、微观畸变为0.0431%的纳米晶层。由于表面自纳米化层中晶界数量急剧增加,变形产生的大量缺陷使电工纯铁表面具有较高的储存能,导致表面原子的活性提高,耐蚀性降低。而渗Ni合金化后试样的腐蚀电位Ecorr=-0.535V,渗Cr合金化后试样的腐蚀电位Ecorr=-0.459V,均大于原始试样的腐蚀电位,经过合金化改性以后,电工纯铁的耐蚀性有所提高。

The electric iron was surface nanocrystallizated by high energy shot peening（HESP） method.Ni and Cr were well mixed to the shot tank to accomplish them diffusion into the electric iron and the surface self-nanocrystallization of the electric iron at the same time.The microstructure and the corrosion properties of the self-nanocrystallizated layer and alloying layer of the electric iron were investigated by microscopy,scanning electron microscopy（SEM）,X-ray diffraction（XRD） and electrochemical measurement system.Experimental results showed that under a 0.6MPa shot pressure and 6min shot time,a self-nanocrystallizated layer with an average grain size of 47.9nm and a 0.0431% microstrain is obtained on the electric iron by HESP.Because of large number of grain boundaries and imperfects in the self-nanocrystallizated layer,which lead to increase of activity and decrease of corrosion properties of the self-nanocrystallizated layer.The corrosion potential of the Ni alloying layer is-0.548V while the Cr alloying layer is Ecorr=-0.514V,which are all larger than that of the electric iron.That means the corrosion properties of the electric iron are enhanced after alloying treatment.