Mechanical characteristics of Si/SiC graded ceramic lattice structures with a triply periodic minimal surface fabricated by laser powder bed fusion

Abstract

SiC graded ceramic lattice structures (GCLSs) have attracted rising attention owing to outperformed merits including ultra-lightweight and excellent specific strength compared with uniform ceramic lattice structures (UCLSs). In this study, Si/SiC Gyroid GCLSs with variable relative densities (35 % and 45 %) and different gradient directions were designed and fabricated via laser powder bed fusion combined with liquid silicon infiltration techniques. 35 % and 45 % UCLSs were also prepared as a reference. The manufacturing precision and mechanical responses of these CLSs were systematically investigated through compressive tests and micro-computed tomography analysis. The mechanical performances of 35 % GCLSs are lower than that of 35 % UCLSs. The weaker load-bearing capacity in the upper portion and the stress concentration in the inclined load-bearing surface lead to the knockdown of mechanical properties for 35 % GCLSs. The nonlinear superposition of mechanical properties in 45 % GCLSs is the main reason for the superior mechanical performance of 45 % GCLSs compared to 45 % UCLSs. Besides, various theoretical models and finite element simulations were implemented to evaluate the mechanical properties of SiC CLSs. The comparison of compressive strength with other ceramic porous structures emphasized the exceptional mechanical properties (16.07 MPa for 35 % UCLSs and 22.91 MPa for 45 % GCLSs) of Si/SiC CLSs.