A novel approach to prepare high density SiC ceramics by powder extrusion printing (PEP) combined with one-step sintering method

High density (97 %) SiC ceramics containing in-situ synthesized Y4Al2O9 (YAM) have been successfully fabri-cated by a novel PEP additive manufacturing technology combined with a one-step sintering method without any post-treatments. The process of additively manufacturing SiC green body, debinding and sintering has system-atically studied. Meanwhile, the atomic structure of SiC and YAM was characterized, and the mechanical properties of sintered SiC ceramics were measured. The HRTEM results revealed the crystallographic orientation relationships between YAM and SiC as (0 4 0) YAM // (1 0 1 1) SiC and [1 0 2] YAM // [1 2 1 0] SiC for the first time. The density, Vickers hardness and three-point bending strength of the sintered SiC samples are 3.11 g/cm3, 19.35 +/- 0.28 GPa and 225 +/- 27 MPa, respectively. Thus, PEP combined with the one-step sintering method provides a new strategy for complex-shaped SiC ceramics with high density and mechanical properties.