Effects of the Sintering Process on Al2O3 Composite Ceramics Fabricated Using Material Extrusion and Photo-Polymerization Combined Process

Abstract

The sintering process can improve the microstructure of Al2O3 composite ceramics and enhance their comprehensive properties, but the effects of the sintering process on Al2O3 composite ceramics are still unclear. Herein, a novel Al2O3 composite ceramic was printed using the material extrusion and photo-polymerization combined process, and the final ceramic was obtained using one-step sintering (TS) and two-step sintering technology (TSS). Based on the testing results, such as the relative density (Drel), average grain size (AGS), hardness, bending strength, and fracture toughness, TSS was suitable for the refinement of commercial Al2O3 ceramics. Moreover, the highest sintering temperature of the second step (T2) was at 1550 °C, while that of the shortest holding time (t) was at 4 h (TSS8), which was to ensure densification before rapid grain growth. The Drel and AGS of the best ceramics obtained via TSS8 were 97.65% and 1.52 µm, respectively. Their hardness, bending strength, and fracture toughness were also enhanced, and they were affected by T2, t, and the interaction. In sum, the TSS obtained better fracture toughness and bending strength, which had great potential in the application of the additive manufacturing field.