Development of a B4C/Al Cermet for Use as an Improved Structural Neutron Absorber

Abstract An aluminum and boron carbide cermet was evaluated for possible application as a neutron absorbing material where structural strength and rigidity will be required. The boron carbide/aluminum composite possessed unique continuous interconnected ceramic and metal phases. Traditional bocon containing neutron absorbing materials have relied upon dispersions of particles in metal or polymeric matrices. The dispersion of boron carbide particles placed restrictions on the B10 concentration, introduced areal inhomogeneities, and necessitated the use of cladding to achieve desired strength. Utilization of two continuous phases allowed for considerable strength properties without having to include cladding. Boron concentrations in excess of 60 v/o were obtained in the cermet, a level that only hot pressing could surpass. Also, the boron carbide particle distribution could be adjusted to optimize strength and/or improve homogeneity of B10 within the material. A material with these characteristics will be ideal for demanding applications such as shipping casks and storage racks. The higher boron content provides for improved areal densities, thus reducing the shielding volume. Space can be conserved without sacrificing structural strength. This material can be fabricated in plates ranging in thickness from 0.076 to over 2.540 cm. Curved or complex shapes are also possible. The cost of this cermet can be expected to be much lower than hot-pressed boron carbide material. The evaluation was made on the basis of physical performance of the boron carbide/aluminum cermet. Properties were measured over a range of loadings and particle distributions of the boron carbide. A semi-guided bend test was performed on 0.254 cm thick plates to measure the ability of the cermet to withstand deformation. The B10 density was measured by neutron attenuation methods.