Search

3D printing of transparent ceramics has attracted great attention recently but faces the challenges of limited compositional system and low transparency. Herein, transparent Y2O3-MgO nanocomposite ceramics with transmittance reaching 98.5 % of the theoretical limit are successfully fabricated using a materials extrusion-based 3D printing method assisted by hot isostatic pressing and the critical factors governing the superior printability and transparency are revealed. Various complex-shaped transparent nanocomposite ceramics are printed at a high resolution of 200 µm. The 3D printed transparent ceramics demonstrate fairly good infrared imaging ability, which significantly enhance its temperature resistant compared with classical infrared transparent sapphire ceramics. Compared with other 3D printed single phase transparent ceramics, the printed multi-phases transparent nanocomposite ceramics have the advantages of design complex microstructure for a targeted set of improved properties, including but not limited to mechanical properties, thermal stability, chemical resistance and optical properties, have great potential to be used in various advanced optical device under harsh environments.

The synergistic effect of vermiculite and the submerged macrophytes Vallisneria spiralisand Hydrilla verticillataon lake sediment was studied using diffusive gradients in thin films (DGT) technology. The dynamics of phosphorus (P) fractions in sediment, the labile-P and labile-S in the water-sediment continuum, and the microbial community in the rhizosphere were studied. Vermiculite effectively promoted reproduction of microorganisms in the sediments Microbial abundance in treatments containing V. spiraliswith sediments containing 10% added vermiculite, and H. verticillatacontaining 50% added vermiculite being 1.7 and 3.5 times higher than the controls which contained no added vermiculite. Acidobacteriaand Proteobacteriapopulations, which are both beneficial for the sediment microenvironment, were higher in treatment groups containing vermiculite. The bioavailable-P in treatment groups containing added vermiculite was lower at the sediment-water interface, with a correlating decrease of TP by between 63% and 91% in the overlying water. This suggests that vermiculite can affect the release of labile P and facilitate the assimilation of nutrients by macrophyte roots. Additionally, vermiculite can improve the Oxidation-Reduction potential and further reduce sulfide toxicity to plants. These results provide theoretical guidance and technical support for the application of vermiculite combined with submerged plants for the remediation of eutrophic lakes.

Fabrication of transparent ceramics with complex geometric structure by 3D printing break through the limitations of traditional ceramic molding process, thus gained increasing research interest. Till now, 3D printing transparent ceramics are limited to visible transparent systems. Herein, 3D printed infrared transparent 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia) ceramics are achieved for the first time by material extrusion (MEX). We developed an aqueous ceramic ink with high solid content (ϕ) up to 50 vol% and excellent shear thinning properties (n = 0.1975) for MEX. By using this ceramic ink, a hemispherical dome cover with a convex radius of curvature (R) of 6.5 mm, a concave radius of curvature (r) of 5.5 mm, and thickness of 1 mm and a flat disc (R=10 mm) with were successfully printed. The relative density up to 99.85% was obtained after de-binding and two-step sintering process including pre-sintering and hot isostatic pressing (HIP). Such high relative density enables its high transparency (>70%) in the mid-infrared (3–5 µm) region. Vickers hardness for the 3D printed infrared transparent ceramic was determined as 14.583 ± 0.379 GPa.