This work presents a coherent beam combining system achieving constructive interferences of 8 arms seeded by 4 wavelength-division multiplexed (WDM) channels modulated at 10 Gbit/s each. The whole spectrum spans over 2.4 THz (19 nm) in the C-band. Phase-locking of one channel, combined with an accurate equalization process of the optical path differences (OPD) of the arms, allows us to maximize the combining efficiency of all the channels simultaneously. Each channel achieves a combining efficiency higher than 95%. Supported by an analytical description of the system, tolerancing rules underline the need for precise OPD equalization accuracy: a 5 µm OPD mismatch results in a 1% combining efficiency loss. Bit error rate and eye diagram analysis demonstrate the reliability of the system to transmit data without penalties. This marks a step toward the development of innovative WDM laser sources for high-power, high-bit-rate free-space optical telecommunications.

Robocasting is an extrusion-based additive manufacturing (AM) process widely used to produce porous structures. It enables to build three-dimensional (3D) ceramic parts, thanks to computer numerical control of the filament deposition path onto a fabrication substrate. Despite its high potential, robocasting is much less explored than other AM techniques for producing dense parts. This work focused on the robocasting of dense alumina parts by varying the filament deposition path of an environmentally friendly paste. Taguchi method was used to establish a correlation between the printing parameters and the microstructural and mechanical properties of the sintered parts. Closed pores located between adjacent filaments were found to dictate crack propagation mechanisms, depending on the infill pattern. The optimal printing strategy led to 93% dense alumina samples having a flexural strength of 140 MPa, a Young's modulus of 355 GPa and a Poisson's ratio of 0.23.

Hollow block masonry is a widely used building technology in many countries. These blocks are handcrafted and have unknown thermal properties; therefore, their overall thermo-physical performance is also poorly studied scientifically in single and double wall configurations. In this work, experimental measurements and numerical simulations are performed for a better understanding of heat transfer in masonry walls. First, the thermal properties of the materials constituting the wall were first determined separately. Then, a thermal characterisation on a hollow masonry block sample wall (0.1 m x 1 m x 1 m) was realised by imposing different thermal conditions on one side of the wall using a control heating box with an adjustable interior temperature with the other side remaining exposed to the ambient condition of the laboratory. The experimental results were first compared to a numerical 3D model for validation; then the effects of the geometric and thermal properties of the wall components were analysed in order to recommend some qualitative and quantitative improvements. The results showed that the masonry blocks thermal properties have the major impact on the masonry block thermal performance allowing to reach around 178% of thermal improvement.

Robocasting stands as a pertinent additive manufacturing technique for producing intricate ceramic parts. Amidst stricter environmental regulations, the adoption of natural additives becomes imperative. This study investigates the influence of plant-based additives on the rheology and printability of eco-friendly pastes.Various 50 vol%-alumina pastes were formulated using natural binders, plasticizers and dispersants (e.g., lignosulfonate, polysaccharides, glycerol) and then assessed through oscillation and flow rheological analyses. Paste viscosity and rigidity often deviated from printability maps reported in the literature, showing the complexity of defining universal printability criteria. A comprehensive investigation was conducted on the water retention capabilities of additives, liquid phase migration and paste drying kinetics.This paper highlights the critical importance of constraining liquid phase migration within eco-friendly ceramic pastes and the crucial role of polymer chain reorientation under shear. Consequently, this research lays diversifying formulations, offering sustainable solutions for industrial ceramic applications.

The improvement of the thermal and energy efficiency of buildings, regardless of their geographical location, is an objective that needs to be achieved quickly. The objective of this work is to develop a method to evaluate the thermal performance of a hollow block masonry double wall under controlled and pseudo-random experimental conditions. First, the thickness of the air space separating the two walls was varied to see the influence of the gap on this type of wall. Then, this technology was filled with polystyrene beads to improve the thermal performance at the wall scale. Finally, each case studied at wall scale was modeled and simulated numerically in 3D using COMSOL Multiphysics under the same conditions, properties, and dimensions as the one tested experimentally. The conclusions confirm that the double wall filled with polystyrene has excellent thermal behavior compared to the one without the addition of polystyrene beads and that the comparison between numerical and experimental results gave very satisfactory results.

LaMnO3 coatings have been obtained by spraying a perovskite suspension injected in a d.c. plasma jet working with an arc current of 300 A and three different plasma forming gases: Ar (45,8slm), Ar/H2 (45/15slm) and Ar/H2/He (45/10/40slm). A perovskite stable suspension was prepared with ethanol as the liquid phase and submicronic particles of perovskites. These particles have been prepared through a solid state reaction at 1100 °C during 6 h. Before the suspension preparation, particles were milled during 5 h in a ball mill. The best results for coatings with perovskite were obtained with Ar, the other plasma forming gases resulting in perovskite decomposition.

A preliminary study was carried out on the morphological design of tubular single-channel alumina membranes prepared by stereolithography, an additive manufacturing process. The geometry of the ring-patterned inner surface of membranes was optimized using computational fluid dynamics calculations and validated in microfiltration tests with aqueous suspensions of P. aeruginosa. Patterning of the inner surface of tubular membranes helped reduce cake formation at a higher value of the average crossflow velocity. The results highlight benefits of stereolithography-based approach to the morphological design of ceramic membranes.

In this work we demonstrate the fabrication and characterization of TiO2 ceramics material with high refractive index and low losses in the 300- 1400 GHz range. The optimized fabrication process, based on Spark Plasma Sintering, allows for the elaboration of high-density materials whose dielectric properties make them good candidates for the design of fully dielectric metamaterials.

To meet industry’s expectations for manufacturing ceramic parts by stereolithography, a better comprehension of the process, in particular laser scattering through the ceramic slurry is mandatory. This knowledge makes it possible to define adapted printing conditions to control the dimensions, homogeneity of the conversion and mechanical properties of the green parts, in order to achieve better resolutions and optimize the properties of sintered parts. This approach is focused on the development of a 3D polymerization modeling for stereolithography process able to predict curing and associated thermal phenomena. First, a design of experiments is carried out to identify material-dependent parameters, calibrate and validate the model, then able to predict monomer conversion rates and dimensions after curing depending on manufacturing parameters. Finally, temperature variation and exposure homogeneity have been evaluated. These results will allow, in future studies, to interpret the differences of deformations and mechanical properties of green parts.

Mid-infrared absorption spectroscopy is nowadays considered as a routine analysis and sensing tool providing highly discriminatory information on organic and inorganic molecules. The specific needs of the transport, aerospace or energy industries may involve applications for which the spectroscopic sensor has to withstand high temperatures. This paper reports the design and fabrication of a silica hollow-core anti-resonant fiber with 8 non touching capillaries primarily designed for mid-infrared COx sensing inside engines. Numerical and analytical simulations performed to ensure fiber transparency in the 4-5 µm region are reported. Optical transmission between 3.9 µm and 4.7 µm is observed and demonstrate attenuation below 1 dB/m for single capillary ring fibers in this range. A preliminary scheme for CO2 sensing using a quantum cascade laser operating in one of the fiber’s transmission windows (λ=4.3 µm) is depicted.

Additive manufacturing processes make it possible to produce increasingly complex 3D parts. In addition, these numerical processes can be usefully used to manufacture ceramic/metal parts of high dimensional resolution with thermal, electrical and electronic properties of interest for applications in the field of power electronics. In this context, a hybrid additive machine was developed to manufacture ceramic/metal parts. This machine consists in the combination of two additive manufacturing processes: stereolithography and robocasting. Using this hybrid process, the feasibility of HTCC components has been demonstrated by building dielectric alumina by stereolithography and molybdenum conductive network by robocasting. Molybdenum-based metallic formulation adapted to the process and allowing to obtain a high conductive metallic network has been developed. The co-debinding and co-sintering cycles have been optimized to minimize the content of residual carbon and to prevent the oxidation of molybdenum. The alumina/molybdenum interface has also been observed to conclude about a possible delamination between these two materials with different thermal expansion co-efficients (CTE). Sintered HTCC parts have been characterized in the domain of hyperfrequency. The frequency responses deviate from the simulation due to a lack of dimensional accuracy of the metallic network.

This article presents the basis of ceramic formulations emphasizing the specific actions of organics to adapt the raw powder properties to ceramic processing requirements. More attention is paid to the triptych dispersant, binder and plasticizer, which confers fundamental properties, i.e., stability, adapted rheology with low viscosity at high solid loadings, and green cohesion. Finally some challenges are stated for the future of ceramic formulations, which will come along the developments of new manufacturing methods, in a century where new rules will be imposed by a higher environmental awareness.