Prediction of Densiftcation and Microstructure Evolution for alpha-Al_2O_3 During Pressureless Sintering at Low Heating Rates Based on the Master Sintering Curve Theory

摘要

The master sintering curve (MSC), in which the sintered density is a unique function of the integral of a temperature function over time, is insensitive to the heating path. Densification of alpha-Al_2O_3 with the mean particle size of 2.5 mu m was continuously recorded during heating at 0.5, 2 and 5°C/min. A MSC was successfully constructed using dilatometry data with the help of a combined-stage sintering model The validity of the MSC was verified by seveal experimental runs. The microstructural evolution with densification during different heating-rate sintering was explored. The sintered microstructure is a function of the time-temperature sintering conditions, and it is verified that there exists a link between sintered density and microstructure. The MSC can be used to predict and control microstfucture evolution during sintering of alpha-Al_2O_3 ceramics.