Transition　metal　carbon-nitrides,　typically　represented　by　HfCN,　have　become　the　latest　progress　among　the　ultra-high　temperature　ceramics.　In　this　study,　single-phase　solid　solution　HfCN　coating　was　successfully　synthesized　from　spray　granulated　HfC-HfN　composite　powder　followed　by　employing　the　dual　solid　solution　effects　of　radio　frequency　inductively　coupled　plasma　spheroidization　and　supersonic　atmospheric　plasma　spraying　processes.　The　coating　was　nearly　dense　(only　2.3　%　in　porosity)　with　a　high　thickness　of　∼　270　μm.　Compared　with　HfC　coating,　the　HfCN　coating　exhibited　higher　hardness　and　elastic　modulus.　After　plasma　ablation　at　a　high　heat　flux　of　8.2　MW/m2　for　200　s,　the　HfCN　coating　exhibited　a　surface　temperature　of　up　to　2600　°C　and　can　firmly　protect　the　refractory　tungsten　substrate　from　oxidation　failure.　This　outstanding　performance　illustrates　that　doping　N　element　in　HfC　crystal　can　effectively　improve　the　energy　barrier　for　oxidation　reaction　and　oxygen　adsorption　compared　with　typical　HfC　coating.　©　2024