Preparation of NbC, TaC and Mo2C fibres and films from polymeric precursors

Polymeric precursors for carbothermal reactions were prepared from niobium alkoxide, tantalum alkoxide and molybdenum ethylene glycolate, respectively , by simultaneous reaction with a chelating reagent (acetylacetone) and org anic compounds having two or more reactive OH groups, such as ethylene glyc ol, saccharose, tartaric acid or dihydroxybenzenes. The precursors exist in common polar and non-polar solvents mostly as linear polymers. The viscous solutions show rheological properties that allow for the preparation of po lymer fibres and films. At temperatures up to 1500 degrees C, bulk precurso rs as well as fibres and films were thermally converted into carbide powder s, fibres and coatings. The structural transformations of the polymeric mat eria Is into carbides were investigated using simultaneous thermogravimetri c-differential thermal ana lyses (TGA-DTA), X-ray diffraction (XRD) and sca nning electron microscopy (SEM). (C) 1998 Kluwer Academic Publishers.