Saint-Gobain (United States)

The sintering consolidation and thermal damage of an alumina mullite zirconia refractory is modelled during a thermal cycle. The dynamic Modulus of Elasticity (MOE) of the material is assumed to be a function of two variables representing sintering and damage degrees. Two evolution laws are proposed for these internal variables and the model is calibrated to describe properly the MOE of the refractory during a reference thermal cycle. The model is then validated by experimental confrontation for other thermal treatments. The model predicts reasonably well the evolution of the dynamic MOE for thermal cycles with different sintering temperatures, dwell times or heating/cooling rates. This phenomenological model provides the variation of the associated sintering and damage degrees and could be used in thermomechanical simulations to account for the thermal history dependence of the material mechanical behaviour.

Abstract In this work, the electrical properties of a semi-industrial dielectric barrier discharge (DBD) system, characterized by a single thin dielectric, were investigated over a one-hour operation period. The discharge, generated in nitrogen, operated in the classical filamentary regime. While the discharge operated over an hour, measurements at low applied voltage, i.e. without discharge, have been introduced. The applied voltage and the charge were recorded during the non-discharge period. These measurements, analyzed using Lissajous figures and an equivalent circuit model of the setup, allowed extraction of several electrical parameters. Using basic PSIM simulations, it is first shown that the parasitic resistance (Rp) and capacitance (Cp) induce changes in the area and slope of the Lissajous figures, respectively. Those are usually used to estimate the power (Poff) and the cell capacitance (Ccell). The results demonstrated that both Poff and Ccell are increasing over one hour. Such trends are seen to be occurring whatever the electrical conditions chosen for the discharge operation. Simultaneous time resolved temperature measurements on the polymer present the same evolution than Poff and Ccell. From the strongest variation, Cp is estimated to increase from 5 pF to 64 pF, while Rp is decreasing from 14 MΩ to 3 MΩ. Such modifications are not trivial. No change in power was observed during the one-hour discharge operation. Therefore, several hypotheses are proposed to explain the observed phenomena, particularly regarding the relationship between temperature and the charge storage properties of PTFE, as discussed in recent literature.

Abstract Marine microbial communities govern many of the biological and chemical processes in the ocean, including element cycles, ecosystem health, and disease. Marine organisms are surrounded by microbes and complex molecular interactions occur between bacterial symbionts, eukaryotic hosts, and their pathogens or prey. Trace metals in the ocean can be either beneficial or detrimental to marine life depending on their concentrations and bioavailability. Multiple marine tunicate species are known to bioaccumulate trace metals in their mantel, and research suggests tunicate microbiota plays an important role in this process.Botryllus schlosseri, a marine colonial tunicate, has become a model organism for cellular and developmental studies, yet its ecological interactions are still not well understood. Using an integrated multidisciplinary approach, we established a comprehensive baseline and explored correlations between members of theB. schlosserimicrobiome, metabolome, and metallome to elucidate the ecological effects of trace metals in host-microbe-pathogen interactions. We identified significant correlations between metals, including manganese, nickel, cerium, zinc, and cobalt, with various metabolites and bacterial taxa. These findings offer insights intoB. schlosseribiological and chemical interactions with their symbionts and their environment, contributing to bridging the knowledge gap of host-microbiome-environment interactions and establishing a foundation for continuing research on the ecological effects of trace metals in these biological systems.Graphical AbstractHighlightsBotryllus schlosseritissue was highly enriched in metals compared to seawaterB. schlosserimicrobiome ß-diversity significantly different from seawaterPan-metabolome indicated microbial metabolites in core and flexible metabolomeMulti-omics revealed interactions between metals, metabolites, and microbes

Abstract Many energy systems demand heat transfer at high temperatures to keep up with high demand for power, so high‐temperature material that can perform and last under these harsh conditions is needed for heat exchangers. The engineering requirements for these high‐temperature heat exchanger material call for high thermal conductivity, high resistance to fracture, high resistance to creep deformation, environmental stability in environments associated with the application, and high modulus of elasticity while maintaining low cost to make and maintain. Naturally, ceramics are a good solution for this endeavor. In the past, high‐temperature heat exchangers made from ceramics have been used. We provide examples of ceramics in relevant heat exchange applications and provide motivation where additive manufacturing (AM) can improve efficiency. AM for the relevant material is under development, and we provide insight on the AM of ceramic materials and examples of AM heat exchangers keeping cost in mind. The motivation of the review paper is to provide a framework for material and manufacturing selection for high‐temperature heat exchangers for AM to keep up with the demand for better efficiency, better material, better manufacturing, and cost moving forward with AM technology in high‐temperature ceramic heat exchangers.

Most previous studies about halide solid-state electrolytes have used pellets prepared by uniaxial pressing, which is a good approach for materials development but is not suitable for commercialization. Thinner electrolyte layers that can be scaled up to large cell areas are required, and tape casting is a promising approach. It is challenging, however, as halide materials are reactive with most of the conventional solvents used in the process. In this study, solvents with low polarity, such as toluene, are found to be compatible with the Li3YBr6 halide material. A wide variety of candidate binders that are soluble in toluene are studied. MSB1–13 binder is preferred, based on the ionic conductivity and mechanical properties of the tape. Electrolyte tapes (<70 μm) are successfully cast on Al substrates, using 2 wt% binder. The resulting room temperature ionic conductivity is 2 × 10−4 S cm−1. Two composite cathodes including active material (LiFePO4 or LiNi0.82Mn0.07Co0.11O2) and 1 to 1.5 wt% MSB1–13 are tape cast as proof-of-concept for a scalable cell fabrication approach. A LiFePO4 cell shows good retention at 25 °C. The performance of NMC cells with tape electrolyte or pellet electrolyte is similar. This study demonstrates the feasibility of tape casting halide-based electrolytes and cathodes.

Due to their chemical inertness and low friction coefficient, fluoropolymers are today widely employed in sectors of activity as diverse and distinct as the textile industry, architectural sector, and medicine. However, their low surface energy results in poor adhesion, for example, when used for a component in a composite device with multiple other materials. Among the techniques used to enhance their adhesion, atmospheric pressure discharges provide a fast and low-cost method with a reduced environmental impact. Although this approach has proven to be efficient, the different chemical and physical processes in the discharge remain not fully understood. In this study, fluoropolymer surfaces were modified using an atmospheric pressure dielectric barrier discharge in a nitrogen and organic precursor environment. To prevent any damage to fluoropolymer surfaces, the dissipated power in the discharges was tuned by applying a duty cycle. Evidence shows that plasma treatment allows for the incorporation of oxygen and nitrogen in the surface resulting in the formation of hydrophilic functionalities such as carbonyl groups both in ketone and amide form, amine, and hydroxyl groups after 180 s of treatment. Overall, the data reveal that the discharge duty cycle has more effect on the oxygen and carbon content in the coating than the precursor concentration. In addition, increasing the precursor concentration limits the molecular fragmentation and nitrogen incorporation into the coating. These experiments enable the building of a better fundamental understanding of the formation mechanism of such chemical moieties at the fluoropolymer surface.

Simultaneous multilayer coating techniques are widely known, but their industrial application remains limited to narrow market sectors. One barrier to adoption may be the mismatch between industries that are familiar with such processes but have no need, and industries that have need but are not familiar. Moreover, there are application-specific technical challenges to developing multilayer-coating processes. In this article, we describe our resolution of two specific issues in simultaneous multilayer coating of all-aqueous highly loaded slurries for new and emerging energy applications. The first issue is particle jamming (associated with shear-thickening) of the highly loaded slurries in the die internals, which we alleviated by adding small amounts of viscosity modifiers without reducing the solid loading. The second issue is a Marangoni-driven surface instability that resembles top layer de-wetting, which we solved by carefully selecting surfactants to tune the dynamic surface tensions of each slurry. Both issues were resolved early in a step-wise development, saving significant development cost which in our case was driven by expensive materials.