Preparation and characterization of zirconium-containing ceramic precursor used for impregnation

A kind of low cost and toxicity ceramic precursor with zirconium (PZC) used for impregnation was successfully synthesized with phenol, paraformaldehyde (PA), ZrOCl₂ • 8H₂O, acetylacetone (Hacac) and H ₂0₂ as raw materials. The precursor was air stable and can be diluted in ethanol to any expected viscosity. The composition, structure, viscosity and pyrolysis process of the precursor were analyzed by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), Fourier transform infrared spectra (FTIR), the cone and plate rheometer and thermogravimetric analyser-differential scanning calorimetry (TG-DSC). The results showed that incorporation of Zr - on to the polymer backbone was successfully done, using Hacac as complexing agent and ethanol as solvent, and the obtained precursor might be Zr - O and Zr - O - C chain polymer with acetylacetone and hydroxymethyl phenol as ligands. During reaction, the coordination compound [Zr] prepared by the coordination reaction between ZrOCl₂ • 8H₂O and acetylacetone (Hacac) was the main reactive group. And PZC was prepared by the coordination reaction of [Zr] and the hydroxymethyl phenol which was synthesized by reaction between phenol and formaldehyde. Results indicated that the precursor showed long temperature range of 40 - 80°C and low viscosity of 50 - 800 mPa • s, which was suitable for impregnation. The ceramic yield ratio of the precursor was 48% at 1400°C, pyrolysis products were ZrO₂ and ZrC, while initial formation temperature of ZrC was higher than 1200°C, and the precursor transformed into ZrC completely at 2000°C. Thus, it is a kind of ceramic precursor suitable for infiltration and pyrolysis to obtain ZrC modified carbon/carbon composites.