Revisiting the structure of SiC–B4C–MedB2 systems and prospects for the development of composite ceramic materials based on them

Resumo

The liquidus surface in SiC–B₄C–Me^dB₂ quasi-ternary eutectic systems (where Me^dB₂ is CrB₂, VB₂, NbB₂, TaB₂, ZrB₂, HfB₂, and W₂B₅) is modeled in the approximation of the regular solution model based on the experimental data on bordering systems and individual compounds. The calculated and experimental data are compared. Regularities of the structure of phase diagrams of SiC–B₄C–Me^dB₂ systems are analyzed. It is noted that the diboride concentration appropriately decreases in the triple eutectic with an increase in its melting point. Correlation dependences between the eutectic temperature and melting point \({t_{eut}} = f\left( {t_m^{M{e^d}{B_2}}} \right)\) and formation enthalpy of diboride \({t_{eut}} = f\left( {\vartriangle H_f^{M{e^d}{B_2}}} \right)\) are constructed. The character of dependences is close to previously observed similar dependences in SiC–Me^dB₂ and B₄C–Me^dB₂ bordering quasi-binary systems. It is concluded based on the analysis of the structure and parameters of analyzed systems that it is promising to develop a broad series of construction and functional ceramic materials and coatings fabricated by “free” sintering and by pulsed methods of heating and consolidation based on the considered systems.