Microstructure, mechanical and neutron shielding properties of aluminum borate ceramics obtained from alumina and boric acid

In this study, a series of aluminum borate ceramics (ABCs) with needle-like whiskers were obtained using a low-cost, solid-state, pressureless sintering ceramic route, without any additives during the preparation process. The effects of different alumina/boric acid molar ratios and sintering temperatures on the phase composition, microstructure, mechanical properties, specific surface area, pore size distribution, and sub-cadmium neutron shielding properties of ABCs were studied using orthogonal experiments. It was observed that pure phase aluminum borate (Al₁₈B₄O₃₃) ceramics could be obtained at 1100 ℃, forming a mass of needle-like whiskers. The whiskers’ aspect ratio, fracture work, specific surface area, and pore size distribution of ABCs are maximized when ABCs are sintered at 1100 ℃ with 9:6 alumina/boric acid molar ratio. In this condition, ABCs (0.5 cm) can shield 70% of sub-cadmium neutrons (E<0.4 eV). These findings demonstrate the great potential of aluminum borate ceramics for neutron shielding applications.