| Abstract Scope |
Recently there have been focus on developing Ultra High Temperature Ceramics (UHTCs) combining the high hardness (>20 GPa) of carbides and thermal properties of di-borides making them suitable for hot structures in hypersonic vehicles. Herein, an innovative dual-layer UHTC system are sintered with ZrB₂-20 vol% SiC, as top layer (thickness~0.5 mm) for heat dissipation, and bottom layer consisting of three-carbide system (Zr,Ti,Ta)C and five-carbide system (Zr,Ti,Ta,W,Si)C offering thermal insulation. Microstructural examination confirmed crack-free, sharp, and seamless interfaces along with single-phase formation in (Zr,Ti,Ta)C and multi-phase formation in (Zr,Ti,Ta,W,Si)C. Nano-indentation demonstrated similar hardness (~25GPa) in top layer of ZrB₂-SiC whereas higher hardness of ~36 and ~34 GPa are obtained at interface and matrix layer for (Zr,Ti,Ta)C and (Zr,Ti,Ta,W,Si)C system, respectively. Thermal conductivity of these dual layer UHTC systems is also evaluated making this combination of boride top and carbide bottom layer suitable for leading edges and nose cone of hypersonic vehicles. |