Co-precipitated synthesis of Al2O3–ZrO2 composite ceramic nanopowders by precipitant and drying method regulation: A systematic study. Issue 1 (January 2015) - Han, Xianglong
Abstract: Uniform Al2 O3 –ZrO2 composite ceramic nanopowders containing 13.1–25.5 wt% ZrO2 were prepared by coprecipitation method using various precipitans (NH4 HCO3, NH3 ·H2 O, and (NH3 )2 CO3 ) and drying methods (vacuum drying, spray drying, and freeze drying). The effects of precipitants and drying methods on Al2 O3 –ZrO2 nanopowderswere were explored systematically by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results showed that it is proper to use NH4 HCO3 as precipitant and freeze drying as drying method when taking into account extent of agglomeration, degree of crystallinity, and elements distribution of Al2 O3 –ZrO2 ceramic nanopowders, which had a narrow particle size distribution concentrating on 30–60 nm with an average sphere diameter of 47 nm. Those findings are also elucidated at micro level to give insight into the underlying mechanism under various precipitants and dry methods. In addition, the moisture of the preparation of Al2 O3 –ZrO2 nanopowders was first used to predict the extent of aggregation in the subsequent calcination process. In summary, these systematic works study the influence of two key factors on properties of Al2 O3 –ZrO2 ceramic nanopowders and guide for the further research of high performance ceramics.