AFM as a tool for probing HV insulation systems involving nanodielectrics

In this work, Atomic Force Microscope (AFM) was used in various contextual situations where nanodielectrics are involved. Only polymer systems containing some nanometric inorganic phase are presented here. Also, measurements have been carried out directly on the insulating phase. First, an epoxy-based nanocomposite sample has been prepared for study. The effect of sample preparation prior to imaging is found to be critical. The mode of scrutiny and choice of parameters including the probe were found to affect the fine details of the imaging. The data type was in relation to the height sensor and unraveled explicitly agglomerated state of nanosilica when a large content (20 wt%) was added. Next, Graphene Oxide (GO) powder was studied with the aim of unraveling conductive characteristics of the powder with a controlled acidity (pH=3). Peak-force TUNA mode was selected in order to characterize ultra-low currents. When a certain voltage level was attained at the probe tip, e.g. 2 volts, a step of current would rise and maintain itself. This situation was imaged and thus, it was shown by the AFM that the powder is conducting. The conduction behavior is possibly associated with the threshold of electrical field.