Synthesis of a novel single-source precursor for HfC ceramics and its feasibility for the preparation of Hf-based ceramic fibres

The growing popularity of ultra-high-temperature ceramics inspired us to prepare Hf-based ceramic fibres by sequential melt hand-drawing, ultraviolet (UV) crosslinking, and pyrolysis of a novel polymeric precursor synthesised by co-polymerisation of HfCl4, ethylenediamine, and allylamine. The above precursor featured a backbone comprising Hf–N and CH=CH groups and exhibited good melt spin ability due to having a relatively linear-chain structure, an optimal molecular weight (Mn = 2569 g/mol), and a suitable softening point (135–155 °C), being easily melt-drawn into green fibres (diameter = 25 µm) and exhibiting a high ceramic yield of 46.38 wt% at 1500 °C. UV curing of green fibres at room temperature and their subsequent pyrolysis in an inert atmosphere at 1200 and 1600 °C afforded Hf-based ceramic fibres (diameter = 13 µm), indicating the great potential of the above precursor and the prepared ceramic fibres for ceramic matrix composites used in high-temperature applications.