Crystal growth mechanism of nano nSc-Y/ZrO2 ceramic powders prepared by co-precipitation method

Abstract

The method of co-precipitation is shown to yield nSc-Y/ZrO₂ composite nanopowders with high density, good dispersion and crystallinity. Furthermore, the samples without Sc doping were mainly comprised of monoclinic ZrO₂ phase and trace amounts of tetragonal ZrO₂, whereas with the addition of Sc, the powders showed a great deal of tetragonal ZrO₂ structure and a minor quantity of cubic phase ZrO₂. By comparing the sintered specimens with undoped Sc and other sintered specimens with different dopant contents, it was found that the sintered samples with a doping ration of 6Sc-2Y-92Zr have denser microstructures as well as smaller activation energies for grain growth (162.48 kJ/mol). Notably, the sintering shrinkage of nSc-Y/ZrO₂ ceramic powders with different dopant contents increases first and then decreases. The maximum linear shrinkage (41.67 %) and volumetric shrinkage (3.11 %) are observed at 6Sc-2Y-92Zr. Therefore, the addition of Sc helps to promote the degree of sintering of the Sc₂O₃-Y₂O₃-ZrO₂ samples, but too much Sc leads to a smaller final shrinkage. The nSc-Y/ZrO₂ nanopowders prepared in this experiment can be used to prepare nanoceramics with high density, high dispersion, and good crystallinity, which are good candidates for defense industry, thermal barrier coating.