Hafnium carbonitride
Hafnium carbonitride is an ultra-high temperature ceramic mixed anion compound composed of hafnium, carbon and nitrogen.
[Ab initio quantum chemistry methods|] molecular dynamics calculations have predicted the HfCN to have a melting point of 4,110 ± 62 °C, the highest known for any material. Another approach based on the artificial neural network machine learning pointed towards a similar composition — HfC0.76N0.24. Experimental testing conducted in 2020 has confirmed a melting point above, substantiating earlier predictions made with atomistic simulations in 2015.
Properties
The HfCxN1−x has been assessed to possess the following properties:- 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: – Ω−1 m−1
- Plasticity limit:
- Fusion enthalpy:
- Flexural strength:
- * 638 ± 28 MPa at room temperature,
- * 324 MPa at,
- * 139 MPa at,
- * 100 MPa at.
- Fracture toughness: 6.73 ± 0.07 MPa·m1/2, 4.7 ± 0.3 MPa·m1/2
- Vickers hardness:, 21.3 ± 0.55 GPa