Development of Deterioration Diagnostic Technique of Polymer Electric Insulating Materials Using the Dielectric Measurements with Surface Depth Resolution

研究人员一直在利用表面深度分辨率介电测量技术研究聚合物电绝缘材料劣化诊断技术的发展。在硅橡胶等聚合物材料的指尖电极上施加交流强场，可以检测水的吸、脱、ATH填充量以及填料处理过程中介电性能的变化。通过测量样品的质量、疏水性和表面粗糙度的变化来比较样品的降解情况。结果表明：(1)在样品表面使用叉指电极进行介电测量可以检测样品的介电损耗和电容的变化。介电性能的评价深度与电极指间距成正比。因此，不与样品表面直接接触的介电性能是可测量的。(2)高场交流工频可以测量每一周期的介电性能，而低场作用只能在高频(KHz及更高)下检测到聚合物状态的变化。(3)样品表面粗糙度的测量可以确定材料的ATH填充量，但样品在脱水过程中表面粗糙度的变化无法检测到。(4)样品表面疏水状况的图像分析可以评价材料的状况，(5)随着测量温度的改变，疏水能级随温度的变化而变化。随着样品温度的升高，疏水程度增加。表面亲水性越强，Hc值变化越大。(6)综合以上测试结果，可以更准确地评价聚合物材料的降解情况。

The investigator has been studying the development of deterioration diagnostic technique of polymer electric insulating materials using the dielectric measurements with surface depth resolution. Application of AC high field to the inter-digital electrodes on the polymeric materials, such as silicone rubber, can detect the change in dielectric property during the absorption and de-sorption of water, the amount of ATH filler and the treatment of fillers. Changes in weight, hydrophobicity and surface roughness of the samples are also measured to compare the degradation condition of the specimens.The results are summarized as follows :(1)Dielectric measurement using inter-digital electrodes on a sample surface can detect the change in dielectric loss and capacity of the specimen. The evaluation depth of the dielectric property is proportional to the interval of the electrode fingers. Therefore, dielectric property without direct contact to the sample surface is measurable.(2)High field application of AC commercial frequency can measure the dielectric property for every one cycle of the applied field, however, low field application can detect the changes of polymer condition only at high frequencies(kHz and higher).(3)The measurement of the surface roughness of the samples can define the amount of ATH filler of the materials, however, the change in surface roughness during the de-sorption of water of the samples can not detect.(4)Image analysis of the hydrophobic condition of the sample surface can evaluate the condition of the materials, successfully.(5)Temperature dependence of the hydrophobic level is changed when the measurement temperature is changed. Increasing the sample temperature, hydrophobic level is increased. The changes in HC value are larger when the surface is more hydrophiric.(6)Combination of all above measurement results can evaluate the degradation condition of the polymer materials more accurately.