A Metal-Ceramic-Rubber Composite for Hybrid Gamma and Neutron Radiation Shielding

Abstract In this study, silicone rubber (polydimethylsiloxane) matrix was incorporated with bismuth (III) oxide and hexagonal boron nitride (hBN) functional fillers to develop a flexible composite material that can shield both neutron and X/gamma radiations. Bismuth, as having a high atomic element weight is a very effective material for X/gamma electromagnetic radiation shielding, while hBN has a very high neutron cross-section due to its boron and nitrogen contents. On the other hand, the matrix material that is high temperature vulcanized (HTV) silicone rubber has superior properties of good flexibility, high transparency, and mechanical properties. Hexagonal boron nitride has unique properties and has a similar structure with graphite that is used for neutron moderation. Mechanical test results showed that the elastic modulus of the optimum sample has improved 4 times compared to control sample. Thermal, X ray and neutron attenuation tests were carried out for the developed composite materials. The curing behaviour was investigated in detail using Moving Die Rheometer. Kinetic studies of the vulcanization process were carried out in a very detailed way and high regression values up to 0.98 has been achieved. Non-destructive radiography images were taken to investigate the particle distribution and radiation attenuation of the prepared composites. It was seen that the composite material developed has a considerable attenuation ratio for both neutron and X/gamma radiations. X-ray attenuation test results for silicone rubber containing 20% Bi2O3 and 20% hBN with thickness of 6.4 mm were shown that the intensity of the incoming rays attenuated by 84.1%. Metal-ceramic-rubber composite material with 6.6 mm thickness shielded 65.8% of incoming neutrons.