Microstructure and property evolution of 3D-printing multiscale porous YSZ ceramics sintered at various temperatures

Multiscale porous yttria-stabilized zirconia (YSZ) ceramics were fabricated via digital light processing (DLP), employing polymethyl methacrylate (PMMA) microspheres as a pore-forming agent. The evolution of microstructure and properties of ceramics, including compressive strength and thermal conductivity, was systematically investigated. The results showed that the porosity and density of the ceramics were 56.43-3.95% and 2.63-5.82 g/cm 3 , respectively, within the sintering temperature range of 1200-1600 °C. Correspondingly, the compressive strength and thermal conductivity of ceramics were 71.00-315.95 MPa and 0.51-2.68 W/(m·K), respectively. At lower sintering temperatures (≤ 1400 °C), multiscale pores formed inside the ceramics due to the decomposition of photosensitive resin and PMMA microspheres. The existence of multiscale pores further reduced the thermal conductivity by an average of 46.08%. In contrast, at higher sintering temperatures (≥ 1500 °C), the density and the mechanical properties of ceramics were significantly improved. In particular, the increase in porosity depended primarily on the increase in pore-forming agent content when the submicron pores disappeared.