Lixia Cheng

Sintering kinetics window: an approach to the densification process during the preparation of transparent alumina

Abstract In this work, sintering kinetics window combined with microstructure development is adopted to understand the densification process of transparent alumina ceramic using submicrometre alumina powder. Alumina powder was densified via pressureless sintering and spark plasma sintering to explore the sintering behaviours of submicrometre alumina powder respectively. Sintering process could be divided into three typical stages, the criterion of which is based on whether the dominant mechanism is independent particle rearrangement or independent atomic diffusion. Through the investigation of sintering mechanisms of both sintering methods in the same way, it is found that it is necessary to remove the large pores (>100 nm) before grain growth is activated for complete densification. It suggests that at the temperature when the grain growth is activated, the corresponding pore structure proves to be the crucial factor influencing the complete densification of transparent alumina ceramic.

Optimisation of compositions of PEG/PMMA binder system in ceramic injection moulding via water debinding

In this study, we have made a comprehensive investigation on the optimisation of the compositions of polyethylene glycol (PEG)/polymethyl methacrylate (PMMA) binder system for water debinding. An orthogonal test was designed, and L9(33) table was chosen to investigate the influence of the molecular weight of low molecular PEG (L-PEG), high molecular PEG (H-PEG) and the percentage of L-PEG in PEGs on flaws of the injection moulded compacts after water debinding. In addition, the ratio of PMMA content to PEG content on flaws is also investigated. Four regions were defined as high stress region, safe debinding region, low binder removal rate region and unavailable injection region respectively. It is believed that our work could provide comprehensive and convincing principles for the manufacturing of injection moulded ceramic parts via water debinding.