Sintering of a nano-crystalline metastable alumina: influence of the firing parameters on the phase development and microstructural evolution

The influence of the heating rate on phase transformation and microstructural evolution during sintering of a de-agglomerated nanocrystalline, transition alumina was investigated. A low heating rate treatment allowed to decrease the α-Al2O3 crystallization temperature as well as to displace densification at lower temperatures, also implying a refinement of the fired microstructures. In addition, the set-up of sintering cycles in which the heating rate changed in the range 0.5–20°C min−1 starting from intermediate, selected temperatures resulted in a further retention of a very fine and homogeneous grain size in final materials.