A Nano-Bismuth-Silicone Polymer Composite as Shielding for X-Rays in Extreme-Environment Applications: Experimental and Simulation Studies.

Radiation shielding is an important consideration in the design and protection of spacecraft electronics and equipment, where conventional metallic shields can add considerable weight and are difficult to integrate with compact or non-planar components. Flexible polymer composites containing high-Z materials offer an alternative approach by combining radiation attenuation with the conformability of an elastomeric matrix. In this work, nano-bismuth is incorporated into a silicone elastomer at loadings of 0-30 wt.% to develop a flexible X-ray shielding composite. The shielding performance of the composites is evaluated experimentally under a 160 kV X-ray source at a total dose of 1 Mrad and compared using Geant4 Monte Carlo simulations. The simulation model is then used to investigate a broader range of bismuth concentrations and composite thicknesses and develop an empirical relationship to predict X-ray attenuation. The results show a clear improvement in X-ray attenuation with increasing nano-bismuth content, demonstrating the potential of silicone/nano-Bi composites as shielding materials for extreme-environment applications, including space.