High-entropy carbide ceramic and rare earth-containing high-entropy carbide ceramic, fibers and precursors thereof, and methods for preparing the same

A method for preparing the high-entropy carbide ceramic precursor comprising steps of:

• (1) obtaining metal alkoxide complexes:
• adding dropwise a complexing agent into metal alkoxides M(OR)n, followed by stirring for 0.1-5 hours to obtain the metal alkoxide complexes;
• (2) cohydrolysis:
• selecting at least four metal alkoxide complexes comprising different metal elements prepared according to step (1), and mixing the same uniformly, followed by dropwise adding of a mixture of water and a monohydric alcohol, refluxing for 1-5 hours, and then atmospheric distillation to obtain a first metal alkoxide copolymer;
• or,
• selecting at least four transition metal alkoxide complexes comprising different metal elements prepared according to step (1), and mixing the same uniformly with a rare earth element-containing compound, followed by dropwise adding of a mixture of water and a monohydric alcohol into the resulted system at a temperature ranging from room temperature to 90° C., refluxing for 1-5 hours, and then atmospheric distillation to obtain a second metal alkoxide copolymer;
• and
• (3) preparing the precursor:
• mixing the first metal alkoxide copolymer or the second metal alkoxide copolymer prepared in step (2) uniformly with allyl-functional novolac resin, followed by heating to 50-90° C. for 0.5-4 hours, and then cooling to obtain the high-entropy carbide ceramic precursor or the rare earth-containing high-entropy carbide ceramic precursor.