Hafnium carbonitride
| Identifiers | |
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3D model (JSmol) |
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InChI
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| Properties | |
Chemical formula | 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] |
Solubility in water | insoluble |
| Thermal conductivity | 19–24 W⋅m−1⋅K−1[2] |
| Structure | |
Crystal structure | Cubic crystal system, cF8 |
Space group | Fm3m, No. 225 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references | |
Chemical compound
Hafnium carbonitride (HfCN) is an ultra-high temperature ceramic (UHTC) mixed anion compound composed of hafnium (Hf), carbon (C) and nitrogen (N).
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
The 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]
- ^ a b For HfC0.3N0.7
- ^ a b For HfC0.7N0.3
- ^ a b For HfC0.5N0.35
References
- ^ "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.
