An investigation of the long-range and local structure of sub-stoichiometric zirconium carbide sintered at different temperatures

• Published in: Scientific reports Vol. 10; no. 1; p. 3096
• Main Authors: Rana, Dhan-sham B. K., Solvas, Eugenio Zapatas, Lee, William E., Farnan, Ian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20.02.2020; Nature Publishing Group
• Subjects: 639/301; 639/301/1023/1024; 639/301/1023/303; Carbon; ceramics; Combustion; High temperature; Humanities and Social Sciences; Magnetic resonance spectroscopy; MATERIALS SCIENCE; mechanical properties; multidisciplinary; NMR; Nuclear magnetic resonance; Physical properties; Raman spectroscopy; Science; Science (multidisciplinary); Spectroscopy; Spectrum analysis; Stoichiometry; Zirconium
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-59698-6

ZrC 1−x (sub-stoichiometric zirconium carbide), a group IV transition metal carbide, is being considered for various high temperature applications. Departure from stoichiometry changes the thermo-physical response of the material. Reported thermo-physical properties exhibit, in some cases, a degree of scatter with one likely contributor to this being the uncertainty in the C/Zr ratio of the samples produced. Conventional, methods for assigning C/Zr to samples are determined either by nominal stochiometric ratios or combustion carbon analysis. In this study, a range of stoichiometries of hot-pressed ZrC 1−x were examined by SEM, XRD, Raman spectroscopy and static 13 C NMR spectroscopy and used as a basis to correct the C/Zr. Graphite, amorphous, and ZrC 1−x carbon signatures are observed in the 13 C NMR spectra of samples and are determined to vary in intensity with sintering temperature and stoichiometry. In this study a method is outlined to quantify the stoichiometry of ZrC 1−x and free carbon phases, providing an improvement over the sole use and reliance of widely adopted bulk carbon combustion analysis. We report significantly lower C/Zr values determined by 13 C NMR analysis compared with carbon analyser and nominal methods. Furthermore, the location of carbon disassociated from the ZrC 1−x structure is analysed using SEM and Raman spectroscopy.