The unique multi-layer, multiscale structures of teakwood allow for excellent mechanical and long-term environmental stability, providing inspiration for the biomimetic design of the environmental barrier coating (EBC) structures. However, achieving the desired biomimetic structure control in high-temperature plasma spraying is a challenging task that requires new technological breakthroughs. In this study, a multi-scale nano Yb₂Si₂O₇-Yb₂SiO₅ (YbDS-YbMS) composite EBC with a teakwood-like lamellar structure has been realized by a novel alternating vapor/liquid phase deposition method in plasma spraying-physical vapor deposition (PS-PVD). Volatilized waste SiO₂ from Yb₂Si₂O₇ (YbDS) was reused and deposited on the coating surface during the spraying process, where a regularly arranged multi-layer structure was formed in the coating by the alternate deposition of gaseous SiO₂ and droplet YbDS. In addition, SiO₂ on the coated surface formed nanoclusters and dome-shaped nanocrystals by homogeneous and heterogeneous nucleation, respectively, and some of them gradually formed a continuous nanofilm as the arc current increased. The deposited SiO₂ reacted in situ with the decomposed phase YbMS in the coating to form YbDS preserved its multi-scale nanostructure after heat treatment, enabling the preparation of YbDS-YbMS composite coating. This work provides a new design strategy and method for the preparation of coatings using YbDS and other spray powders with similar decomposition and volatilization characteristics during plasma spraying process.

Fabricating SiC ceramics via the digital light processing (DLP) technology is of great challenge due to strong light absorption and high refractive index of deep-colored SiC powders, which highly differ from those of resin, and thus significantly affect the curing performance of the photosensitive SiC slurry. In this paper, a thin silicon oxide (SiO₂) layer was in-situ formed on the surface of SiC powders by pre-oxidation treatment. This method was proven to effectively improve the curing ability of SiC slurry. The SiC photosensitive slurry was fabricated with solid content of 55 vol% and viscosity of 7.77 Pa·s (shear rate of 30 s⁻¹). The curing thickness was 50 μm with exposure time of only 5 s. Then, a well-designed sintering additive was added to completely convert low-strength SiO₂ into mullite reinforcement during sintering. Complex-shaped mullite-bond SiC ceramics were successfully fabricated. The flexural strength of SiC ceramics sintered at 1550 ℃ in air reached 97.6 MPa with porosity of 39.2 vol%, as high as those prepared by spark plasma sintering (SPS) techniques.