Physico-chemical properties of fine-grained powder in Al2O3-ZrO2-Y2O3-CeO2 system produced by combined method
Maria Y. Smyrnova-Zamkova, Oleksii K. Ruban, Oleksandr I. Bykov, Olena V. Dudnik
Quarterly No. 4, 2018 pages 234-240
DOI:
keywords: ZTA, nanocrystalline powder, fine-grained powder, solid solution based on ZrO2, phase transition, microstructure design
abstract At present due to the emergence of new methods of synthesising starting powders and their consolidation, Al2O3 based high-strength ceramic materials toughened by ZrO2 (ZTA) are widely used as structural materials for various purposes. It is known that the material properties depend on the properties of the starting powders. Combined methods of powder preparation essentially extend the possibility to vary the powder properties. The purpose of this work is to produce a finegrained powder of the composition (mol%) 58.5 α-Al2O3 - 41.5 ZrO2 (Y2O3, CeO2) by a combined method (hydro-thermal synthesis in an alkaline medium/mechanical mixing). The resultant fine-grained powder was heat-treated at 400, 550, 700, 850, 1000, 1150, 1300, and 1450°C with holding for 2 hours at each temperature. The properties of the synthesized powders were characterized by differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and specific surface measurements (BET). The microstructural and phase analyses were conducted by petrographic study. The powder morphology varies continuously topologically. The agglomerates after mechanical mixing had an irregular shape up to 1450°C. A tetragonal solid solution based on ZrO2 (T - ZrO2) and α-Al2O3 was identified in the powder after mechanical mixing. T-ZrO2, as well as a monoclinic solid solution based on ZrO2 (M-ZrO2) and α-Al2O3 were identified after heating at 1450°C. The research results will be used for the microstructural design of ZTA composites.