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PurposeThis study aims to provide understanding of the influence of external factors, such as gravity, during sintering of three dimensional (3D)-printed parts in which the initial relative density and cohesion between the powder particles are lower compared with those present in the green parts produced by traditional powder technologies. A developed model is used to predict shrinkage and shape distortion of 3D-printed powder components at high sintering temperatures. Design/methodology/approachThree cylindrical shape connector geometries are designed, including horizontal and vertical tubes of different sizes. Several samples are manufactured by binder jetting to validate the model, and numerical results are compared with the measurements of the sintered shape. FindingsSimulations are consistent with empirical data, proving that the continuum theory of sintering can effectively predict sintering deformation in additively manufactured products. Originality/valueThis work includes the assessment of the accuracy and limits of a multiphysics continuum mechanics–based sintering model in predicting gravity-induced distortions in complex-shaped additively manufactured components. 

In the binder jetting (BJ) process, as in most of powder bed additive manufacturing technologies, the powder is periodically recoated onto the substrate layer-by-layer. The elements of the current deposited layer corresponding to the part being manufactured are bonded together using a polymeric binder. In all cases that require a thermal process for sintering, the internal structure of the finished part is defined by the internal structure of the powder bed. This article focuses on the discrete element modelling (DEM) of various powder spreading methods during recoating and their impact on the powder bed structure particularly applied to binder jetting technology. The article demonstrates that despite the thinness of the deposited layers, they typically exhibit porosity and particle and pore size non-uniformities along the build-up direction. These irregularities contribute to the anisotropic sintering shrinkage observed in green BJ bodies during experiments. However, the experiments presented confirmed by modelling show that without binder deposition, the powder bed – except for a narrow surface layer – remains relatively uniform, regardless of the recoating method used. It is the binder injection into the porous structure of the powder bed that disrupts this homogeneity, locks in large surface pores, and exacerbates the effects of powder segregation during spreading. Finally, several strategies, explored via simulation, are proposed to reduce porosity variations during BJ: using a combined roller-wide blade method for powder spreading and a two-hopper approach, where each layer consists of small particles deposited over larger ones. 

Warm pressing of organosilicon polymers is often challenging due to the formation of cracks due to release of volatile compounds during the warm pressing process. The focus of the present study is to warm press crosslinked SMP‐10 powders into crack‐free compacts and to pyrolyze them to get bulk SiC monoliths. Crack formation during warm pressing is addressed by optimizing the crosslinking temperature, and the loss of formability of the powders crosslinked at higher temperatures is overcome with the use of uncured polymer as a binder. The crosslinking temperature of the preceramic polymer plays a crucial role in developing crack‐free green bodies. The amount of binder used is varied to study its effect on the bulk density of the pyrolyzed product. The warm pressed green bodies pyrolyzed at 1400 °C result in the formation of bulk silicon carbide ceramics and are characterized using X‐ray diffractometer and FTIR spectroscopy. Warm pressing is performed at a lower temperature than reported in the literature, and this limits the incorporation of oxygen during the warm pressing.