REACTIVE HOT PRESSING OF B₄C–CrB₂ CERAMICS AND ITS MECHANICAL PROPERTIES

Ceramic composites based on B₄C with a CrB₂ mole fraction of 0–30% were obtained by reactive hot pressing of a mixture of B₄C, Cr₂O₃, and nanofibrous carbon at a uniaxial pressure of 17.5 MPa and a temperature of 2000 °C for 10 min. The possibility of boron carbide reduction of metal oxide during hot pressing was studied. During the synthesis of CrB₂, the density of B₄C was found to increase due to the formation of the CrB₂–B₄C eutectic liquid phase. The relative density of all B₄C–CrB₂ composites obtained under these conditions exceeds 90%. Experimental dependences of the microhardness and elastic modulus of samples on the concentration of the CrB₂ plastic phase were obtained. The dependences of the elastic modulus of the heterogeneous material on the volume fraction of chromium diboride were determined taking into account porosity by sequentially using the Reuss and Voigt averaging schemes.