Reactive Hot Pressing of B4C-CrB2 Ceramics and its Mechanical Properties
D. V. Dik1,2, T. S. Gudyma2, A. A. Filippov1, V. M. Fomin1, Yu. L. Krutskii2
1Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: ceramics, boron carbide, chromium diboride, nanofibrous carbon, hot pressing, sintering, microstructure, phase composition, microhardness, elastic modulus
Abstract
Ceramic composites based on B4C with a mole fraction of CrB2 0-30% were obtained by reactive hot pressing of a mixture of B4C, Cr2O3, and nanofibrous carbon at a press force of 17.5 MPa, a temperature of 2000 °C and an exposure time of 10 min. The possibility of the chemical reduction reaction of metal oxide with boron carbide 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%. The dependences of the microhardness and elastic modulus of samples on the concentration of the plastic phase were obtained. The dependence of the elastic modulus of the heterogeneous material on the volume fraction of chromium diboride taking into account porosity was determined by sequentially using the Reuss and Voigt averaging schemes
|
