Drying kinetics and energy efficiency of Y2O3–CeO2 co-doped ZrO2 powder under microwave heating

Abstract

Abstract

Zirconia has important application prospects in the field of ceramics. However, during a high-temperature heating process, pure zirconia will undergo martensite transformation, which seriously affects its service performance. Metal oxides, such as Y2O3–CeO2 doping ZrO2, effectively improve the toughness and fire resistance of the material. Thus, the drying of Y2O3–CeO2 co-doped ZrO2 powder is an essential step before practical application. The study employs contemporary microwave drying techniques. The results of the experiment show that the average microwave drying rate increases with an increase in mass, water content, and microwave heating power. When the initial mass was 30 g, the initial moisture content was 12 %, microwave power was 720 W, and the drying rate was the fastest. We used four dynamic models: Modified Page, Quadratic, Wang and Singh, and Page to fit the experiment data. The best model was Modified Page, which describes the kinetic process most accurately. Fick's second law describes how, in the drying process, when microwave power is 720 W, initial mass is 15 g and initial water content is 8 %, the effective diffusion coefficient is 5.25 × 10−16 m2/s. Fourier Transforms of the infrared spectrum of the samples before and after drying were analyzed, the intensity of the O–H absorption peak located at 3442.03 cm/s, and O–H–O absorption peak located at 1594.48 cm/s. Both decreased significantly after drying. To discuss the relationship between the microwave power and the diffusion coefficient, the activating energy of microwave heating was 32.01 W/g. The experimental results show high heating efficiency and selective heating of the microwave method. This study provides a theoretical basis and research data for microwave drying of Y2O3/CeO2 co-doped ZrO2 powder in industry.