对试样液氮脆断后进行扫描电镜观察是研究材料微观结构的常用方法，但应用于磁性羟基铁粉填充的磁敏弹性体试样时，却很难获得理想效果。通过对橡胶高分子结晶现象和低温脆断理论的分析，揭示脆断截面无法形成裸露的羟基铁粉链的机理；提出机械切割和抛光相结合的截面处理方法，得到的样品截面可满足扫描电镜对磁敏弹性体表面微结构的表征要求。通过对扫描电镜工作原理和成像理论的分析，阐述磁性材料产生的杂散磁场与扫描电镜磁透镜的磁场、入射电子束、收集器电压产生的耦合作用。这种耦合作用使在样品表面按一定时间和空间顺序做光栅式逐点扫描的入射电子束发生畸变，改变磁敏弹性体发射的二次电子的运行轨迹，使二次电子收集器收集效果变弱，降低图像质量。根据绝缘电阻测试得到不同体积分数羟基铁粉的磁敏弹性体的电导率，确定金属离子真空溅射和粘贴导电胶的试样处理方法。提出磁敏弹性体样品的退磁方案，并得到理想的微观形貌图像。%scanning electron microscope observation is a common method to study microstructure of materials after brittle failure of sampled liquid nitrogen. However,it is difficult to obtain an ideal effect when the method is applied for the magnetic-sensing elastomer filled with magnetic hydroxy iron powders. The analysis on polymer crystallization phenomenon of rubber and low temperature brittle fracture theory revealed the mechanism that brittle fracture cross section can not form an exposed hydroxy iron powder chain and proposed a method of combination of mechanical cutting and polishing for cross section processing and the cross section obtained in this way can meet the representation requirements of scanning electron microscope on surface microstructure of magnetic-sensing elastomer. Based on the analysis of working principle and imaging theory of scanning electron microscope, it explained the stray magnetic field of magnetic materials and the coupling effect generated by magnetic field and incident beam of magnetic lens of scanning electron microscope and collector voltage. This coupling effect will make incident beam that is in point-by-point raster scanning state as per a proper time and space sequence on sample surface distorted,which can change the moving path of secondary electron launched by magnetic-sensing elastomer,making the collection effect of secondary electron collector weaker and reducing image quality. According to insulation resistance test, the conductivity of magnetic-sensing elastomer filled with magnetic hydroxy iron powders with different volume fractions was obtained and procesing method for metal ion vacuum sputtering and pasting conducting resin sample were proven effective. Besides, demagnetization plan for magnetic -sensing elastomer sample was proposed and ideal microstructure image was also obtained.
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