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] The HfCxN1−x has been assessed to possess the following properties:[2]