Structure Formation in Syntactic Foam Based on Metal-Coated Glass Microspheres and Polysiloxane under the Action of a Nanosecond Relativistic Electron Beam

Changes in the chemical and phase compositions, as well as the formation of micro- and nanostructured objects in syntactic foams consisting of tungsten-modified glass microspheres and a polymeric binder based on a phenylsilsesquioxane—b-dimethylsiloxane block copolymer, caused by the action of a single relativistic electron beam with an average energy in the range of 180–260 keV and a peak current power in the range of 4.5–6.8 GW were studied by scanning electron microscopy and X-ray phase analysis. It was demonstrated that tungsten and tungstic acid hydrate react with products of polysiloxane decomposition to give WO3, WO2, δ-WO2, and Na2WO4 under extreme conditions (T > 1600 K and pressures in the range of 3–8 GPa) near the surface of the microspheres. The observation of irregularly shaped droplets and “solidified foam” structures found on the inner surface of collapsing microspheres suggests that the formation of filamentous structures is preceded by high-temperature reactions involving products of high-temperature pyrolysis of polysiloxane and tungsten compounds.