Thermal analysis of the components used in the fabrication of Al2O3–Ni and Al2O3–Mo composites via vat photopolymerization followed by spark plasma sintering

In this study, thermal analysis (including differential thermal analysis and thermogravimetric analysis coupled with mass spectrometry) was used to design the sintering process of alumina as well as Al 2 O 3 –Mo and Al 2 O 3 –Ni green bodies obtained by digital light processing (DLP) 3D printing. The measurements were performed for selected organic additives, which are commonly used in the DLP technique, such as photoinitiators, dispersing agents, and organic monomers. Additionally, metallic powders (Ni, Mo), as well as ceramic and composite green bodies, have been subjected to thermal analysis. The obtained results allowed us to determine proper sintering conditions for a two-step sintering program. Firstly, the organic phase was burnt out at 400 °C in the air. At this temperature, metallic powders have not yet started to oxidize, and most of the organic additives have already been eliminated from the sample. The second step was performed using spark plasma sintering at 1150 °C with a pressure equaling 60 MPa in an argon atmosphere to prevent the oxidation of metals. The samples were gradually cooled down to 800 °C at a cooling rate of 35 °C min −1 and then furnace-cooled to room temperature, preventing the formation of intrinsic defects (microcracks) in a multicomponent ceramic–metal composite. The XRD and SEM–EDS analysis allowed us to conclude that the obtained composites are well densified, no other phases apart from alumina and metals are present in the samples, and that the alumina grain growth is smaller than for conventional sintering. An increase in fracture toughness for the composite samples was observed compared to pure alumina.