Principle and Practice of Conductive Epoxy Resin to Eliminate Charging Problem in Scanning Electron Microscope Images

Charging problem often causes the artifacts such as uneven brightness, stripes, etc. on scanning electron microscopic (SEM) images. A method was proposed to eliminate the charging problems of samples with lower strength and porous loose structures by impregnating the samples in the conductive epoxy resin. The adaptability of this solution and the conventional method for the three lower strength and porous loose structural samples, namely the fiber reinforced concrete exposing to high temperature of 1 000 ℃, ceramic soil and archology soil of Henan Shuanghuaishu archeological site, were comparatively studied. The results showed that samples impregnated in the copper powder mixed conductive epoxy resin can effectively eliminate the charging problem induced artifacts of the SEM images. While, samples prepared by the traditional method showed severely charging artifacts. By improving the thickness of conductive layer not only can not reduce the charging problem, but also cover the nano- and micro-structure. The causes of the charging problem caused by the traditional sample preparation method and the improvement principle of the conductive epoxy resin on the charging problem were analyzed.