机械能助渗法制备Zn-Mg合金渗层的显微组织及耐蚀性

Microstructure and Corrosion Resistance of Zn-Mg Alloy Coating Prepared by Mechanical Energy Aided Diffusing Method

采用机械能助渗法,在铁路垫片上制备了Zn-Mg合金渗层,采用扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)和失重法,分析了渗层的表面和截面形貌、物相组成及其在中性盐雾环境中的耐蚀性.结果表明:Zn-Mg合金渗层致密、均匀;随着盐雾腐蚀时间从120 h延长至2000 h,Zn-Mg合金渗层表面白色腐蚀产物逐渐增多,但未出现红色锈蚀产物;经盐雾腐蚀2000 h后,Zn-Mg合金渗层试样的质量损失为0.0484 g/(m^(2)·h),表明Zn-Mg合金渗层试样具有较好的耐蚀性;Zn-Mg合金渗层主要由FeZn_(10.98),FeZn_(6.67),MgZn_(2),MgZn_(2)和Mg_(2)Zn_(11)组成,镁元素渗入形成的Mg_(2)Zn_(11)和Mg_(4)Zn_(7)是Zn-Mg合金渗层耐蚀性较好的主要原因.

Zn-Mg alloy coating was prepared on railway gasket by means of mechanical energy aided diffusing method.The surface and cross section morphology,phase composition and corrosion resistance of the permeable layer in neutral salt spray environment were analyzed by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS)and weight loss method.The results showed that Zn-Mg alloy coating was compact and uniform.With the salt spray corrosion time extending from 120 h to 2000 h,the white corrosion products on the surface of Zn-Mg alloy coating gradually increased,but no red corrosion products appearred.After 2000 h salt spray corrosion,the mass loss of Zn-Mg alloy coating sample was 0.0484 g/(m^(2)·h),which indicated that Zn-Mg alloy coating sample had good corrosion resistance.The Zn-Mg alloy coating was mainly composed of FeZn_(10.98),FeZn_(6.67),MgZn_(2),Mg_(2)Zn_(11) and Mg_(4)Zn_(7) alloy phases.The MgZn_(2) and Mg_(2)Zn_(11) formed by the infiltration of magnesium element were the main reason for the relatively good corrosion resistance of Zn-Mg alloy coating.