High entropy carbide (ZrNbTiCr)C ceramic composite coating with fine grains fabricated by plasma spraying

Despite the high hardness of high-entropy carbides, their applications are limited by their low fracture toughness. This study reports the successful preparation of two high-entropy carbide (ZrNbTiCr)C composite coatings by reactive plasma spraying. A comparison between the Zr-Nb-Ti-Cr-SiC and ZrO2-Nb2O5-TiO2-Cr2O3-Al-SiC system coatings reveals that the latter displays a lower porosity of 3.04 %, a higher microhardness of 1082 HV0.1 and an improved toughness of 4.16 MPa·m1/2. The presence of fine-grained (ZrNbTiCr)C, α-Al2O3 located between (ZrNbTiCr)C particles and metastable t-ZrO2 phases in the coating, can strengthen and toughen the ZrO2-Nb2O5-TiO2-Cr2O3-Al-SiC composite coating through synergistic effects. The research also outlines the reaction process of the two systems composite powders during the plasma spraying process. Overall, this work introduces a new approach to toughening high-entropy carbides by utilizing their compositional flexibility. •Two systems (ZrNbTiCr)C coatings were synthesized successfully.•The toughness of ZNTC-O coating reached 4.16 MPa·m1/2.•Fine-grained (ZrNbTiCr)C phase is beneficial for mechanical properties.•The formation mechanism of (ZrNbTiCr)C was explored.