Sintering kinetics of alumina/diopside composites

Abstract

Alumina matrix ceramic composites were fabricated by pressureless sintering. The effect of temperature and holding time, two of the most important pressureless sintering parameters, on the microstructures and grain growth of undoped and diopside doped alumina was researched. Experiments were performed at the temperature of 1420, 1520 and 1620°C, and with four holding times, i.e. 100, 140, 180 and 220 min. The results showed that temperature and holding time had different impacts on grain growth and microstructures. Grain growth was found to be strongly dependent on sintering temperature. The apparent activation energies of 19–20·5 kJ mol⁻¹ for alumina matrix ceramic composites were calculated by the least squares. The sintering kinetic equations were deduced. It was concluded that the sintering of pure alumina was controlled by volume diffusion, while that of alumina matrix ceramic composites doped with diopside was controlled by grain boundary diffusion and volume diffusion.

Keywords:

• Alumina
• Diopside
• Pressureless sintering
• Microstructures
• Sintering kinetics

The work described in this paper is supported by Research Award Fund for Outstanding Young Scientists of Shandong Province in China (No. BS2012ZZ002). The Natural Science Foundation of Shandong Higher Education Institutions of China (No. ZR2011EL026 and No. ZR2012EEL04). Science and Technology Development Plan of Yantai (No. 2011414).