Additive manufacturing and characterization of complex Al₂O₃ parts based on a novel stereolithography method

Abstract

In this work, we prepared Al2O3 ceramic green parts with complex geometry and architecture using an additive manufacturing process based on stereolithography. The rheological and thermal behavior of Al2O3 slurry was firstly examined and used to establish the conditions for molding and debinding. As opposed to previous researches that only focused on manufacture techniques, the sintering behavior and densification process were systematically investigated. In addition, special attentions were paid to the evolution of microstructure between green bodies and sintered parts. The results showed that debound parts were equipped with uniform particle packing and narrow pore size distribution. The dimensions of the Al2O3 parts changed anisotropically with the different processing steps. The densification process was greatly accelerated by the decrease in pore size and annihilating of interconnected pores in which significant grain growth was observed above 1450°C. The sintered part also had a homogeneous microstructure and no interface between adjacent layers. High densification (relative density of 99.1%) and much desirable Vickers hardness (17.9 GPa) of Al2O3 parts were achieved at the sintering temperature of 1650°C.

Silica‐based ceramic core for aviation applications: Facile pore filling and flexural strength improvement

“…An open porosity has an opposite trend with regards to the shrinkage behavior. This is consistent with the sintering process because shrinkage is accompanied by the annihilation of interconnected pores. Although a large amount of cristobalite increases the cracks in the ceramic core material and accelerates the corrosion rate for the first 10 minutes, the existence of excessive cristobalite and alumina in the samples cannot improve the whole reaction process of the silica‐based ceramic core.…”

Nanoscale Plasticity Behavior of Additive-Manufactured Zirconia-Toughened Alumina Ceramics during Nanoindentation

“…Therefore, shear-induced deformation band and/or microcracking can be initiated by the sufficient stress during nanoindentation of ZTA10 and ZTA30 when τ max is ≥τ theo [28], and the initiation of localized plasticity events was observed throughout the loading process. Similarly to the empirical power law dependence of τ max with P c [29], a linear dependence of τ max on P c (Figure 3) was expected in the present work. Further evidence from SEM studies supported this speculation.…”

Rapid three-dimensional structuring of transparent SiO2 glass using interparticle photo-cross-linkable suspensions

“…hoto-curable suspensions have attracted extensive research attention as indispensable for designing complexstructured ceramics and glass components through additive manufacturing (e.g., digital light processing [1][2][3][4][5][6][7][8] , laser-based stereolithography 9,10 , mask projection stereolithography [11][12][13][14] , suspension-enclosing projection stereolithography 15 , and ultraviolet-assisted direct-write 16 ), in-situ solidification 17,18 , subtractive manufacturing 19 , three-dimensional micro-template replication 20 , fiber production 21 , and stop-flow lithography 22 . Thus far, various photo-curable suspensions have been designed up to date.…”

“…Thus far, various photo-curable suspensions have been designed up to date. While the simplest process involves direct dispersion of inorganic fine particles in photo-curable monomers with photo-radical initiators [6][7][8][9][13][14][15][16][17]21,[23][24][25][26] , many researches have also focused on multi-component mixtures containing solvents to control suspension viscosities [1][2][3][4][5][10][11][12] and to form porosity in photo-cured green compacts which was favorable to debind polymers in a controlled manner 18 . Many further attempts have also made, such as by designing monomer mixtures to tune the number of reactive functional groups for controlling the photocuring rates 23 ; selecting monomers/solvents to achieve a transparent suspension and avoid light scattering 1,[17][18][19]26 , which realizes high-resolution three-dimensional printing by microstereolithography 1 ; and adding light absorbers and/or radical inhibitors to optimize the printing resolution 2,3,9,17,24 .…”