Abstract

Composite ZrO2-SiO2 powders, with different ZrO2 contents, including pure ZrO2 powders, were prepared by precipitation in SiO2 suspensions, of zirconia gels from solutions of zirconyl chloride at pH = 11. These products were investigated in connection with the phase changes in ZrO2 caused by heat-treatments. ZrO2-SiO2 mixtures containing 0–100% mol ZrO2, were studied by differential thermal analysis (DTA), X-ray powder diffraction (XRD), temperature programmed desorption combined with mass spectroscopy (TPD-MS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), to obtain information on the morphological and structural features of the particles before and during the heat treatment up to 1200°C. Specific surface areas were determined using nitrogen adsorption by the BET method. The results offer an explanation about some of the factors which can be influencing on the stabilization of metastable-cubic/tetragonal (C/T) phase of ZrO2 and the evolution of surface areas (“vulcano” profile) observed in the composites.

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