Laser sintering of Al₂O₃‐based green ceramics prepared by different pre‐sintering temperatures

Abstract

Al2O3‐based green ceramics are prepared by isostatic cold pressing technology. The prepared green ceramics are pre‐sintered at the temperature from room temperature to 1100°C, and then Al2O3 ceramics are prepared by laser sintering. The effects of pre‐sintering temperatures and laser parameters on mechanical properties and the sintering quality are analyzed. The results show that good crystallinity of Al2O3 particles is obtained at a higher pre‐sintering temperature. The flexural strength and density of green ceramics increase with the temperature of heat treatment. The flexural strength decreases slightly at ∼200°C due to the paraffin binder disintegration. The pre‐sintering temperature and laser processing parameters have a significant influence on the sintering quality. With the increase of laser power and laser frequency, dynamic grain growth occurs, and then grains are refined. The majority of plate‐like grains are transformed into long cylindrical‐like grains in the severe densification process. However, porous flocculation microstructures are generated on the samples pre‐sintered at 1100°C after laser sintering, which is due to the material gasification in atmospheric environment during sintering by infrared laser. More uniform microstructure and better sintering quality of samples pre‐sintered at 500°C can be achieved after laser sintering with a relatively narrower grain size distribution.

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