X-ray microtomography investigations on the residual pore structure in silicon nitride bars manufactured by direct ink writing using different printing patterns

Printing bulk parts by Direct Ink Writing (DIW) is challenging. Aspects like the printing strategy (pathways followed by the nozzle) or drying parameters can have a significant influence on the quality of the resulting sample, besides the rheological characteristics of the ink. Different drying methods and building substrates were tested to avoid warping and cracks. Furthermore, bars were printed using different printing patterns, in terms of filament alignment and direction. The influence of these printing patterns on residual pore sizes and pore distributions were investigated by X-ray microtomography. In this way, it was possible to determine the size and distribution of pores for both green and sintered parts and to identify the presence of repetitive patterns as a function of the filament arrangement. The porosity was correlated to the density of the parts, and no influence of the printing strategy on the density of the final parts was detected.