The impact of different alkali ion concentrated hollow glass microspheres on the electrical breakdown mechanism of syntactic foam

This paper deals with the experimental investigation on syntactic foam, a new composite insulation material consisting of an epoxy resin matrix filled with hollow glass microspheres. The investigations carried out focus on the impact of the glass composition of the microspheres on the dc breakdown field strength of syntactic foam. Two different breakdown test procedures are used to analyze the breakdown process. The breakdown properties of syntactic foam with microspheres with low alkali ion concentration depend on the breakdown step test procedure used, whereas for syntactic foam with microspheres of high alkali ion concentration no dependency on step test procedure is observed. The determined behavior is ascribed to the microscopic field distribution of syntactic foam, which depends on the alkali ion concentration of the hollow glass microspheres.