Hafnium carbonitride (HfCN) is an ultra-high temperature ceramic (UHTC) mixed anion compound composed of hafnium (Hf), carbon (C) and nitrogen (N).
| Identifiers | |
|---|---|
3D model (JSmol)
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| Properties | |
| CHf2N | |
| Molar mass | 204.51 g/mol[1] |
| Appearance | black odorless powder |
| Density | 12.65–13.073 g/cm3[2] |
| Melting point | 4,110 °C (7,430 °F; 4,380 K)[3] |
| insoluble | |
| Thermal conductivity | 19–24 W⋅m−1⋅K−1[2] |
| Structure | |
| Cubic crystal system, cF8 | |
| Fm3m, No. 225 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ab initio molecular dynamics calculations have predicted the HfCN (specifically the HfC0.75N0.22 phase) to have a melting point of 4,110 ± 62 °C (4,048–4,172 °C, 7,318–7,542 °F, 4,321–4,445 K),[3] highest known for any material.[3][4][5] Another approach based on the artificial neural network machine learning pointed towards a similar composition — HfC0.76N0.24.[3] Experimental testing conducted in 2020 has confirmed a melting point above 4,000 °C (7,230 °F; 4,270 K),[4][5] substantiating earlier predictions made with atomistic simulations in 2015.[6]
Properties
editThe HfCxN1−x has been assessed to possess the following properties:[2]
- Thermal conductivity:
- 19–24 W·m−1·K−1 at room temperature,
- 32–39 W·m−1·K−1 at high temperature and with increased nitrogen content.
- Electrical conductivity: (149×104)–(213×104) Ω−1 m−1
- Plasticity limit: 2,000 °C (3,630 °F; 2,270 K)[a]
- Fusion enthalpy: 150 kJ/mol (36 kcal/mol)[3]
- Flexural strength:[b]
- 638 ± 28 MPa at room temperature,
- 324 MPa at 1,000 °C (1,830 °F; 1,270 K),
- 139 MPa at 1,600 °C (2,910 °F; 1,870 K),
- 100 MPa at 2,000 °C (3,630 °F; 2,270 K).
- Fracture toughness: 6.73 ± 0.07 MPa·m1/2[a], 4.7 ± 0.3 MPa·m1/2[c][4]
- Vickers hardness: 19.08 GPa (2,767,000 psi)[b], 21.3 ± 0.55 GPa (3,090,000 psi)[c][4]
References
edit- ^ "Hafnium Carbonitride".
- ^ a b c Zhang, Xintao; Li, Xingchao; Zuo, Jun; Luo, Ruiying; Wang, Jinming; Qian, Yuhai; Li, Meishuan; Xu, Jingjun (20 February 2023). "Characterization of thermophysical and mechanical properties of hafnium carbonitride fabricated by hot pressing sintering". Journal of Materials Research and Technology. 23. Netherlands: Elsevier: 4432–4443. doi:10.1016/j.jmrt.2023.02.099. eISSN 2214-0697. ISSN 2238-7854. OCLC 9818302917. S2CID 257061872.
- ^ a b c d e Dai, Yu; Zeng, Fanhao; Liu, Honghao; Gao, Yafang; Yang, Qiaobin; Chen, Meiyan; Huang, Rui; Gu, Yi (15 October 2023). "Controlled nitrogen content synthesis of hafnium carbonitride powders by carbonizing hafnium nitride for enhanced ablation properties". Ceramics International. 49 (20): 33265–33274. doi:10.1016/j.ceramint.2023.08.035. eISSN 1873-3956. ISSN 0272-8842. OCLC 9997899259. S2CID 260672783.
- ^ a b c d Buinevich, V.S.; Nepapushev, A.A.; Moskovskikh, D.O.; Trusov, G.V.; Kuskov, K.V.; Vadchenko, S.G.; Rogachev, A.S.; Mukasyan, A.S. (17 March 2020). "Fabrication of ultra-high-temperature nonstoichiometric hafnium carbonitride via combustion synthesis and spark plasma sintering". Ceramics International. 46 (10). Elsevier: 16068–16073. doi:10.1016/j.ceramint.2020.03.158. ISSN 0272-8842. OCLC 8596178549. S2CID 216437833.
- ^ a b Science, The National University of; MISIS, Technology (27 May 2020). "Scientists develop the most heat-resistant material ever created". phys.org. Retrieved 2 April 2023.
- ^ Hong, Qi-Jun; van de Walle, Axel (2015). "Prediction of the material with highest known melting point from ab initio molecular dynamics calculations". Physical Review B. 92 (2): 020104. Bibcode:2015PhRvB..92b0104H. doi:10.1103/PhysRevB.92.020104. ISSN 1098-0121.