研究目的
To analyze the experimental densi?cation kinetics of 7.8 mol% Y2O3-stabilized zirconia during isothermal sintering in the ?nal stage and to explore a possible value of the grain-size exponent n by taking concurrent grain growth into account.
研究成果
The grain-size exponent n in the ?nal stage must be around 1～2 for the present nano-sized ZrO2 powder, contradicting the conventional prediction of n = 4 for the Coble’s corner-pore model. The experimental kinetics of densi?cation could be explained by using the di?usive model, supported by microstructural observation.
研究不足
The study was conducted in a limited temperature range of 1200 °C to 1300 °C. The grain size definition used may differ from conventional methods, and the pore structure observed may not be representative of all nano-sized powders.
1：Experimental Design and Method Selection:
The study involved isothermal sintering of 7.8 mol% Y2O3-stabilized zirconia powder compacts at temperatures of 1200, 1250, and 1300 °C. The densi?cation rate and grain growth were measured and analyzed theoretically.
2：8 mol% Y2O3-stabilized zirconia powder compacts at temperatures of 1200, 1250, and 1300 °C. The densi?cation rate and grain growth were measured and analyzed theoretically.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Commercial ZrO2 powder containing 7.8 mol% Y2O3 (TZ-8Y, Tosoh; 8YSZ) was used. The powder was pressed into compacts and then isostatically pressed at 392 MPa in water.
3：8 mol% Y2O3 (TZ-8Y, Tosoh; 8YSZ) was used. The powder was pressed into compacts and then isostatically pressed at 392 MPa in water.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A dilatometer (DIL 402C, Netzsch) was used for isothermal shrinkage measurements. SEM (SU-8000, Hitachi) was used for microstructural observation.
4：Experimental Procedures and Operational Workflow:
The shrinkage measurement was conducted at specified temperatures, and the measured shrinkage was corrected with the thermal expansion of the fully densi?ed 8YSZ. The polished surface of the sample after prescribed densi?cation was observed using SEM.
5：Data Analysis Methods:
The densi?cation behavior was analyzed by evaluating the density-dependent f(D) and the grain-size exponent n. The experimental kinetics of densi?cation was compared with existing theoretical models.
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