Novel refractory high-entropy ceramics: Transition metal carbonitrides with superior ablation resistance

• Published in: Corrosion science Vol. 184; p. 109359
• Main Authors: Peng, Zheng, Sun, Wei, Xiong, Xiang, Zhang, Hongbo, Guo, Fangwei, Li, Jiaming
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 15.05.2021; Elsevier BV
• Subjects: Ablation; Ablation resistance; Acetylene; Ball milling; Carbon nitride; Carbonitride; Ceramics; Entropy; High-entropy material; Metal carbides; Plasma sintering; Scale (corrosion); Spark plasma sintering; Transition metals; Ultra-high temperature ceramic; Ultrahigh temperature; Zirconium; Ultra-high temperature ceramic; Carbonitride; High-entropy material; Ablation resistance
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2021.109359

•Novel ultra-high-temperature-ceramic (UHTC) as well as high-entropy material with superior ablation resistance was proposed.•Special micro-segregation is found in the HECN, where Ta, Hf, Zr, Ti elements aggregated inside of grains and Nb segregated at the grain boundary.•There is the compact multi-oxide scale that involves Hf-Zr-rich grains skeleton and continuous molten-like phase with Ta-Ti-Nb segregation. A novel high-entropy material as well as ultra-high temperature ceramic (Ta0.2Hf0.2Zr0.2Ti0.2Nb0.2)C0.8N0.2 was synthesized from ten kinds of transition metal carbides and nitrides, via high-energy ball-milling and spark plasma sintering. Besides, the ablation behavior of high-entropy ceramic was first studied by oxy-acetylene torch system at 2500 K. The results showed that optimized nitrogen substituted in sublattice could remarkably improve the ablation resistance by an impressive 57±1 % and 72 ±1 % in mass ablation rate and linear ablation rate compared to high-entropy carbides, since the highly dense multiple oxides scale with large Hf-Zr-rich grains skeleton surrounded by continuous secondary-phase in the boundaries that was able to retard the diffusion of oxygen.