Linking rheology, process parameters and formability for material extrusion and photo-polymerization combined process aiming at high-density ceramics

Material extrusion and photo-polymerization (MEX-PPM) process is a great potential for ceramic components in the aerospace field, while the uncertain formability of ceramic parts and rheological property of slurry limit its further application. In this work, using spherical alumina powder with particle size of 1 μm, prepolymer 1, 6-hexanediol diacrylate, surfactant oleic acid and photo-initiator diphenyl (2, 4, 6-trimethylbenzoyl) phosphate oxide as raw material, a series of 60wt % and 70wt % Al2O3 ceramic slurry with different viscosities were obtained by aging, and their comprehensive properties such as the rheology, flow behavior and formability through experiments were evaluated. The comprehensive forming model linking formability and rheology of slurry, process parameters such as printing speed and radiation power was established. The results showed that the predicted dimension (Dpre) and printing dimension (Dp) of the green body formed by adjusting the process parameters were close to each other. The printing speed and radiation power were adjusted to 5 mm/s and 23.5 J/s, respectively. The Dp and Dpre were approximated to design dimension (Dd) of the green body formed using 70wt % slurry. The internal structure of sintered body was uniform without obvious defects, the density could reach at 96.2% (theoretical density of 3.96 g/cm3), and the hardness was at 15.67 GPa. In sum, the effectiveness of this new model was proved, and the dense ceramic structures could be formed well by regulating parameters of MEX-PPM process under the limited slurry rheology.