Sintering behaviour, solid solution formation and characterisation of TaC, HfC and TaC-HfC fabricated by spark plasma sintering

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• 作者：Omar Cedillos-Barraza^a ; ^{oc205@imperial.ac.uk" class="auth_mail" title="E-mail the corresponding author} ; ^{ocedillos@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Salvatore Grasso^b ; Nasrin Al Nasiri^a ; Daniel D. Jayaseelan^a ; Michael J. Reece^b ; William E. Lee^a
• 关键词：TaC ; HfC ; Spark plasma sintering ; UHTCs
• 刊名：Journal of the European Ceramic Society
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：36
• 期：7
• 页码：1539-1548
• 全文大小：3873 K

文摘

Solid solution formation and sintering behaviour of TaC–HfC ceramics made from commercial TaC and HfC powders prepared using spark plasma sintering (SPS) at temperatures up to 2450 °C was investigated. Phase analysis and lattice parameter measurements using X-ray Diffraction (XRD) showed mutual diffusion of Hf and Ta with increasing sintering temperature. High Resolution Transmission Electron Microscopy (HRTEM) confirmed that solid solution formation and densification were achieved by a solid-state mechanism. Solid solutions were achieved for 4TaC–1HfC, 1TaC–1HfC and 1TaC–4HfC powders after sintering at temperatures of at least 2350 °C. Fracture toughness (K_IC) values were in the range of 2.7–3.4 MPa m^1/2 for all ceramics measured using Vickers indentation. Thermal conductivity of TaC was 55.8 W/m K at 1400 °C. Coefficients of thermal expansion (CTE) varied from 7.08–7.66 × 10⁻⁶/K (in the range of 25–2000 °C), with TaC at the lower end.