振动助渗制备45钢表面铝化物涂层及其抗高温氧化性能

Preparation of Aluminide Coating on 45 Steel by Vibration Assisted Infiltration and Its High-temperature Oxidation Resistance

为降低渗铝温度以细化晶粒和提高45钢表面的抗高温氧化性能,采用振动助渗在其表面制备纳米结构铝化物涂层。采用X射线衍射仪分析涂层的相组成,采用扫描电子显微镜和原子力显微镜观察涂层的微观组织结构,采用能量色散光谱仪分析涂层微区化学成分,采用划痕仪检测涂层与基体的结合强度。结果表明:铝化物涂层主要由η-Fe_2Al_5和少量θ-FeAl_3相组成,且其具有单层、致密及均匀特性。120min振动助渗下形成的铝化物涂层表面呈现出凹坑和丘陵状两种典型纳米结构区域,且距表面越远,涂层的纳米晶越粗大;垂直加载载荷68N时出现噪声信号,涂层开始发生破损;涂层抗氧化试验中的氧化增重量和剥落量仅为未表面涂层处理45钢试样的1/60和1/160,说明铝化物涂层显著增强了45钢表面抗高温氧化的能力。

In order to reduce the aluminizing temperature to refine grain and improve the high-temperature oxidation resistance of 45 steel surface,nanostructured aluminide coating was prepared on the surface by vibration assisted infiltration.The phase composition of the coating was analyzed by X-ray diffractometer.The microstructure of the coating was observed by scanning electron microscopy and atomic force microscopy.The chemical composition of the coating was analyzed by energy dispersive spectrometer.The bond strength between coating and substrate was measured by scratch tester.The results show that the aluminide coating is mainly composed ofη-Fe 2Al 5 and a small amount ofθ-FeAl 3 phases,and having single,dense and uniform characteristics.At 120 min,the surface of the aluminide coating formed by vibration assisted infiltration has two typical nanostructure regions of pits and hills,the longer the distance from the surface,the larger the nanocrystalline of the coating.When the load is perpendicular to 68 N,the noise signal appears,and the coating is damaged.The oxidation weight gain and spalling capacity of the coating in the oxidation resistance test are only 1/60 and 1/160 of the 45 steel sample treated with the less surface coating,that is,the aluminide coating remarkably enhances the ability of the 45 steel surface to resist high temperature oxidation.