Synthesis of Synthesis of ZrW₂O₈/ZrO₂ composites with low thermal expansion using chemical co-precipitation method

ZrW₂O₈/ZrO₂ composites were prepared by calcining the precursor synthesized by the chemical co-precipitation method at 1150℃ for 3.5 h. The precursor of ZrW₂O₈/ZrO₂ was studied by Fourier transform infrared spectroscopy(FTIR) and thermogravimetric and differential scanning calorimetry(TG-DSC). The crystal structure，section morphology and thermal expansion properties of the synthesized composites were investigated by X-ray diffraction (XRD)，scanning electron microscopy (SEM)，energy dispersive spectrometer(EDS) and dilatometry. The results indicate that the obtained composites contain only α-ZrW₂O₈ phase and m-ZrO₂ phase without other phases，which have good chemical uniform and sintering ability. The average thermal expansion coefficient of ZrW₂O₈/ZrO₂ composites decreases with the increase of mass fraction ofZrW₂O₈. Among all the samples，26%ZrW₂O₈/ZrO₂ composites exhibit nearly zero thermal expansion，and the average thermal expansion coefficient is -0.5649 10^-6K^-1 from 30℃ to 600℃.