Properties comparison of pure Al2O3 and doped Al2O3 ceramic cores fabricated by binder jetting additive manufacturing

Binder jetting additive manufacturing (BJAM) was widely used for fabricating complex ceramic cores due to its low cost and convenient process. In this study, the effects of layer thicknesses (50-100 mu m) and sintering tem-peratures (1300-1400 degrees C) on the properties of pure Al2O3 and 95 wt% Al2O3-4 wt.% TiO2-1 wt.% CuO ceramics (doped Al2O3 ceramics) were investigated, respectively. For the green parts with a layer thickness of 50 mu m, the maximum density, porosity, and bending strength values of doped Al2O3 ceramic increase by 14.9%, 6.3%, and 39.6% when compared with those of pure Al2O3 ceramic. When the green parts were sintered from 1300 degrees C to 1400 degrees C, the optimal values of doped Al2O3 ceramic with a layer thickness of 50 mu m were 2.377 +/- 0.036 g/cm3, 39.34 +/- 1.20%, and 27.44 +/- 1.29 MPa, respectively, and the increase rates were 23.0%, 27.2%, and 86.8% compared with those of pure Al2O3 ceramic. The dimensional shrinkage of each axis gradually increased with the increase of the layer thicknesses and sintering temperatures, and the Z-axis was always larger than X-axis and Y-axis. When the sintered part was 50 mu m and 1300 degrees C, the minimum values of pure Al2O3 ceramic were 2.00 +/- 0.15%, 1.86 +/- 0.15%, and 1.59 +/- 0.15%, and those of doped Al2O3 ceramic were 13.57 +/- 0.20%, 12.46 +/- 0.57%, and 12.60 +/- 0.17%, respectively. Additionally, when the sintered part was 100 mu m and 1400 degrees C, the maximum values of pure Al2O3 ceramic increase to 4.90 +/- 0.20%, 3.94 +/- 0.13%, and 3.61 +/- 0.25%, and those of doped Al2O3 ceramic were 18.81 +/- 0.19%, 17.27 +/- 0.75%, and 16.77 +/- 0.39%, respectively. These results indicate that adding sintering aids can promote low-temperature sintering and improve the mechanical strength of ceramic cores.