China's Refractories

Abstract: Ceramics with proper pore sizes and geometry are critical to many applications, so that lots of efforts have been made to achieve the goal. Direct ink writing (DIW), an additive manufacturing technique, is cost-effective and accessible. It is interesting to study the ability to control the pore size and geometry by the DIW technique. In this study, alumina ceramics were prepared with special focus on the pore configuration and the performance of printed samples was tested. The porous structures with different pore sizes (minimum pore size of 200 μm) and different shapes (honeycomb, lattice and triangle) were printed. The printed structures shrunk uniformly and maintained the original geometry after firing, they did not show any visible defects or deformations, and the microstructure was uniform and dense. It was found the honeycomb structures exhibited superior mechanical strength at the same porosity compared to lattice and triangle structures, which reached 55 MPa with a porosity of 70%. The high strength with the high porosity was attributed to the highly controlled microstructure, i.e., uniform pore sizes, pore shapes and interconnectivity.

Key words: direct ink writing, porous structures, high porosity, mechanical strength