Study On High Temperature Phase Stability And Corrosion Resistance Of Dy₂O₃ Stabilized ZrO₂ Ceramic Materials

The rapid phase transformation and molten salt corrosion of rare earth oxide stabilized zirconia thermal barrier coating in high temperature service environment have become the bottleneck of its use at higher temperatures.In order to find a new thermal barrier coating material with good performance and service life at higher temperature,dysprosium oxide stabilized zirconia（DySZ）nano powder material was synthesized by improved chemical coprecipitation method.The high temperature phase stability and CMAS corrosion behavior of 10DySZ ceramic materials were systematically studied,and the high temperature phase transformation mechanism and CMAS corrosion mechanism of 10DySZ ceramic materials were clarified.The main results are as follows:（1）DySZ nano powder with metastable tetragonal structure was synthesized.The difference of Dy³⁺concentration in the micro region of the precursor polymer led to the formation of embedded DySZ structure.（2）After high temperature heat treatment at 1300℃-1400℃,the final phase transformation products of DySZ powder and ceramics are mainly composed of nearly equal volumes of m-DySZ and c-DySZ phases,which are only related to the doping amount of stabilizer in DySZ.（3）Compared with the powder state,there are asynchronous nucleation phenomena of m-DySZ and c-DySZ in the transformation process of DySZ ceramics.The combined effect of steric hindrance and internal stress inhibits the martensitic transformation of t→m in the initial stage of transformation.The rapid nucleation of m-DySZ and the growth of m/c-DySZ grains lead to a relatively high transformation rate in the phase transformation explosion period of DySZ ceramics.（4）The inherent characteristics of the initial material lead to the rapid increase of phase change products of DySZ ceramic materials in the initial stage.The aframi fitting results show that DySZ ceramic materials have atypical diffusion phase transformation dynamics,and the new phase nucleation and grain growth are the dominant mechanisms before and after DySZ phase transformation,respectively.（5）The increase of corrosion temperature and time significantly exacerbated the corrosion degree of DySZ ceramics.The CMAS corrosion of DySZ ceramic materials is mainly completed by the dissolution precipitation of DySZ in CMAS melt.The phase transformation of DySZ ceramic materials is the result of the migration and segregation of Dy stabilizer caused by high temperature environment and dissolution precipitation.