扫描电镜和X射线能量色散谱仪在涂层脱落现象分析中的应用

Application of SEM and EDS in analysis of exfoliation of coating

通过对某型ZM5铸造镁合金产品表面防热涂层脱落实际案例的分析,介绍了扫描电镜(SEM)和X射线能量色散谱仪(EDS)在该类现象分析中的应用方法。在该案例的分析中,首先使用SEM对涂层脱落界面分别进行低倍和高倍显微形貌观察,确定脱落界面的位置以及各区域的粘接情况。而后利用EDS对脱落界面的粘接异常位置与粘接正常位置的表面元素成分进行分析。最终确定脱落界面上粘接异常位置过高的硫元素含量是导致涂层脱落的原因,而硫源自镁合金氧化处理槽液中硫酸镁的残留。

The application of scanning electron microscopy(SEM)and energy-dispersive X-ray spectroscopy(EDS)in the analysis of exfoliation of coating was introduced with the heat-resistant coating on a model of product made of ZM5 cast magnesium alloy as an example.In this case,the low-and high-magnification micromorphologies of the substrate side of the exfoliated coating were observed by SEM initially to determine the location of exfoliation interface and the adhesion of the coating at different local areas.The elements in the surficial areas with abnormal and normal adhesion were then analyzed by EDS.It was concluded that the exfoliation of coating was caused by the existence of excessive sulfur element,which was due to the residue of magnesium sulfate from the oxidation bath for treating the magnesium alloy substrate.