Two-dimensional nucleation growth of stepped ZrC skeleton with controllable morphology

Porous zirconium carbide (ZrC) ceramics with stepped morphology were successfully prepared by evaporating solvent combined with high-temperature sintering. Step morphology with different slopes on the skeleton can be tuned by optimizing the sintering temperature. SEM, TEM and in-situ scanning probe image characterizations confirmed that the stepped ZrC ceramic followed a two-dimensional nucleation growth mechanism. Herein a three-dimensional model based on Burton-Cabrera-Frank theory of crystal growth was established to explain the reasons for stepped growth. After 5 thermal shock cycles between 1500 °C and room temperature, the stepped morphology has a positive role on improving the adhesion strength between pyrocarbon and ZrC skeleton in the form of mechanical interlocking. This work provides a strategy for improving the interfacial bonding strength of ultra-high temperature composites by morphology design.