Open porosity cellular SiC-based ceramics have a great potential for energy conversion, e.g. as solar receivers. In spite of their tolerance to damage, structural applications at high temperature remain limited due to high production costs or inappropriate properties. The objective of this work was to investigate an original route for the manufacturing of porous SiC ceramics based on 3D printing and chemical vapor infiltration/deposition (CVI/CVD). After binder jetting 3D-printing, the green α-SiC porous structures were reinforced by CVI/CVD of SiC using CH3SiCl3/H2. The multiscale structure of the SiC porous specimens was carefully examined as well as the elemental and phase content at the microscale. The oxidation and thermal shock resistance of the porous SiC structures and model specimens were also studied, as well as the thermal and mechanical properties. The pure and dense CVI/CVD-SiC coating considerably improves the mechanical strength, oxidation resistance and thermal diffusivity of the material.

In order to demonstrate that digital material engineering methodology is able to address the design and optimisation of architectured ceramic materials, solar volumetric receivers employed in Solar Thermal Power Plants (STPP) have been studied. A digital design approach for obtaining new receivers, at the macroscopic structural scale, is proposed. This approach couples virtual structure generation, ray tracing and thermal simulations at the scale of the base structural components (microscopic scale). Then, a recently developed process for manufacturing silicon carbide (SiC) parts by binder jetting is used to elaborate three optimised structures which are tested on-sun at high temperature in a solar concentrator reproducing the STPP operation conditions. The results obtained with these structures, having original shapes, are promising: the average experimental outlet air temperature reaches a maximum of 1133 K, energy yields can reach 0.49 despite high experimental heat losses, and all the SiC structures, made with a new material based on 3D printing, withstood the high temperatures reached, up to 1500 K. Comparison between digital and experimental results shows that the approach presented in this paper paves the way to a new digital material engineering approach.

CEA laboratory has developed an additive manufacturing technique with SiC powders and the material obtained need to be characterized. Therefore, we studied the change of optical properties and oxidation kinetics of SiC samples for the last step of the elaboration process. In this investigation, the optical properties and the oxidation kinetics of two SiC materials of two different densities and post-treated at LCTS laboratory have been compared. Their roomtemperature optical properties were measured and both materials were oxidized using solar facilities at PROMES laboratory. It was observed that a higher porosity would increase both the solar absorptivity  and total emissivity  of the SiC. Nevertheless, the  ratio is improved with the density, increasing from 1.04 to 1.22. The less dense SiC presents also a faster oxidation kinetics, the determined activation energy increasing from 110 to 270 kJ mol -1 .