No abstract

The processing of boron carbide by pressureless sintering with nano-sized rare-earth compounds additives to obtain dense pellets for use as neutron absorber in fast breeder reactors is investigated. The effect of dysprosium aluminum garnet (DAG) and dysprosium titanate nanopowders on density and mechanical properties was studied. The addition of DAG and dysprosium titanate nanopowders was found to be beneficial in the densification of B4C powders. B4C with 5 wt. % of DAG or dysprosium titanate nanopowders, exhibiting bulk density of 2.14g/cm3 and 2.35 g/cm3, could be prepared by pressureless heating at 2120°C and 2160°C.

Boron carbide is an attractive neutron absorbing material used both in Fast Breeder Reactors (FBR) and in Pressurised Water Reactors (PWR) owing to its very high absorption cross section for thermal neutrons, chemical stability and refractory character. In the present paper, 10B enriched B4C ceramics are prepared by pressureless sintering at 19602160°C, under argon, using 10B boron carbide powder as raw material, 18 wt% phenolic resin as sintering aid. In the sintering temperature range, with the increasing of sintering temperature, both the relative density and flexural strength increase linearly, the average particle sizes increase from about 3μm at 1960°C to more than 30μm at 2160°C. The sample sintered at 1960°C has a 91.7% of relative density and 192 MPa of flexural strength and a homogeneous texture with 3-4μm particle size, which are enough for pellet application of reactors.