Preparation of В4С/ZrB2 Ceramics via Boron Carbide Reduction

In this paper, we report boron carbide preparation of В4С/ZrB2 composite ceramics. The ceramics have been prepared via pressing of B4C + ZrB2 powder mixtures and by reaction pressing. The content of the ZrB2 phase was varied from 10 to 30 mol %. Increasing the percentage of ZrB2 has been shown to reduce the open porosity of the composite ceramics and increase their relative density. Visual inspection showed that simultaneous boron carbide synthesis and hot pressing made it possible to obtain a B4C/10 mol % ZrB2 material with ZrB2 grains uniformly distributed over the bulk of the B4C phase. The microhardness and fracture toughness of this material were 38.3 GPa and 3.9 MPa m1/2, respectively, and its relative density was 99.9%. In the case of hot pressing of a presynthesized powder mixture, such results were obtained at a higher modifying additive content, corresponding to 30 mol % zirconium diboride. The composite ceramic containing 30 mol % ZrB2 has been shown to have a larger thermal neutron absorption cross section in comparison with the unmodified ceramic.