Impact of the hollow microspheres' filling degree on the electrical dc breakdown field strength of syntactic foam

This paper deals with theoretical and experimental investigations on an innovative insulation material called syntactic foam. Syntactic foam is a composite dielectric consisting of a polymeric matrix with embedded hollow microspheres. The main focus of the present study is on the electrical breakdown process of syntactic foam under electrical dc field stress. Furthermore, the study deals with the impact of the hollow microspheres' filling degree on this process. In the experiments, the electrical breakdown field strength of syntactic foam under electrical dc stress is determined. The microspheres' filling degree varies in a range of 10...50 vol.%. The results show, that the breakdown field strength decreases, if the microspheres' filling degree is increased. Numerical 3D field simulations of syntactic foam with different filling degrees verify the material's behavior observed in the experiments. A model of the breakdown mechanism in syntactic foam under electrical dc stress is presented. The impact of the hollow microspheres' filling degree on the breakdown mechanism is given.