Ablation-resistant high-entropy carbide-high-entropy diboride-silicon carbide multiphase ceramic and preparation thereof

A method for preparing an ablation-resistant high-entropy carbide-high-entropy diboride-silicon carbide (SiC) multiphase ceramic, comprising:

• (S1) mixing a transition metal oxide mixed powder, nano carbon black and a silicon hexaboride (SiB6) powder to obtain a precursor powder;
• and
• (S2) subjecting the precursor powder to pressureless sintering to obtain the high-entropy carbide-high-entropy diboride-SiC multiphase ceramic;
• wherein a relative density of the high-entropy carbide-high-entropy diboride-SiC multiphase ceramic is 96% or more;
• and
• wherein the transition metal oxide mixed powder comprises hafnium oxide (HfO2), zirconium dioxide (ZrO2), tantalum pentoxide (Ta2O5), niobium oxide (Nb2O5) and titanium dioxide (TiO2) in a molar ratio of 2:2:1:1:2;
• and
• the pressureless sintering is performed in a stepwise manner through the following temperature program:
• rising from room temperature to 1900-2100° C. at a rate of 10-50° C./min;
• 1900-2100° C. for 5-30 min;
• decreasing to 1600-1900° C. at a rate of 50-100° C./min;
• 1600-1900° C. for 1-8 h;
• and decreasing to room temperature at a rate of 10-50° C./min;
• wherein a vacuum degree of the pressureless sintering is controlled at 0.001-0.05 Pa.