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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 α-Al2O3 with the mean particle size of 2.5μm 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 microstructure evolution during sintering of α-Al2O3 ceramics. [ABSTRACT FROM AUTHOR]

Master sintering curves (MSC) were constructed for dry pressed compacts composed of either a submicrocrystalline or a microcrystalline α-Al2O3 powder using constant heating rate dilatometry data containing lower heating rates only. The MSC constructed for two grain size α-Al2O3 were used to evaluate the sintered densities, which agreed well with the density obtained with different heating procedures and determined by Archimedes method. So the applicability of the MSC theory to alumina ceramic sintering under lower heating rates was validated. Apparent activation energies for submicrocrystalline and microcrystalline α-Al2O3 were determined to be 1035 and 1148 kJ mol-1 based on the MSC respectively. The calculated activation energies for densification are higher than the values reported in the literature concerning heating rates >5 K min-1. [ABSTRACT FROM AUTHOR]

One of the ultimate objectives for sintering research is to predict densification results under different thermal profiles for a given processing method. This paper studies the construction and validation of the master sintering curve (MSC) for rutile TiO2 for pressureless sintering. The MSC was constructed using dilatometry data at two heating rates and was then validated using isothermal holds at three different temperatures. The scanning electron microscopy (SEM) observation shows that the partially sintered samples have the same density under different heating procedures, which demonstrates that the assumptions of the model are reliable. The concept of the MSC could be used to predict the sintering shrinkage and final density and calculate the activation energy. A value of 105 kJ mol-1 for TiO2 was obtained. The MSC could be applied to predict the sintering profile to prepare ceramics with required density and a minimum of grain growth. [ABSTRACT FROM AUTHOR]