Open Ceramics最新文献

Photocatalytic water treatment is an appealing concept to mineralize organic contaminants in contaminated water. In this study, the UV-resistant drug paracetamol (PCT) in aqueous solution is degraded by using a solar irradiated loop-reactor equipped with a TiO₂ (P25) photocatalyst. The catalyst powder was dispersed in a geopolymer surface coating applied to aluminum-U-profiles connected by filament-printed polymer elements. Different assays with variations in initial PCT concentration were performed under natural solar radiation to determine the degradation kinetics of the PCT and correlate it to applied solar radiation energy density. Depending on experimental conditions, degradation efficiencies of 37.0–75.1 % were achieved within 3 h. Control samples without catalyst show no degradation. No degradation of the catalyst activity was observed within 42 h of operation time. The study shows the feasibility of this simple and scalable reactor design and coating technology for water purification under off-grid conditions provided sufficient solar radiation is available.

Digital Light Processing (DLP) enables intricate ceramic part production from photosensitive ceramic slurry. While ZrO₂ and Al₂O₃ are commonly studied, their composites are underexplored despite diverse applications. This study investigates fabricating high-strength, fully dense alumina-toughened zirconia (ATZ) parts using a low-cost desktop DLP printer designed for polymer printing. Various ATZ-based ceramic slurries (30, 35, 42.5 vol%) with different binders and dispersants were prepared and evaluated for curing and rheological properties. Promising formulations underwent debinding and sintering, resulting in homogenous microstructures with a well-distributed blend of the two phases. For the doped samples, SEM analysis revealed a good distribution of dopants and elongated dopant grains infused at higher temperatures. The 35 vol% ATZ exhibited exceptional average flexural strength of 1321 MPa, surpassing previous DLP-fabricated composites. This suggests no need for increased solid loading content. The findings demonstrate the potential of DLP in producing high-performance ceramic parts with tailored properties.

This work proposes the processing of porous ceramic lattices via three polymer-derived ceramic routes, namely powder bed fusion and infiltration, fused filament fabrication and replica, and a direct replica of a foamed polymer. A common feature in the processing of these lattices is the use of the same polysilazane as the preceramic source for the Si-C-N-O network that builds up during ceramization.

We adopted rotated cube, honeycomb and randomized cellular geometries as a matter of comparison for thermal exchange when an air flow is forced through the structures up to 1050 °C. The three procedural pathways are discussed in their limitations regarding geometry, polymer-to-ceramic conversion, high-temperature heat exchange performance and durability. In this regard, while rotated cube geometry results in the best thermal exchange and highest pressure drop, we show a correlation between chemical composition and high temperature oxidation of the Si-C-N-O network, possibly attributed to the selection of the processing routes.

Plasma electrolytic oxidation (PEO) is one of the most promising methods for synthesizing ceramic coatings on metallic substrates. Recently, PEO in molten salt electrolytes was found to be advantageous due to overcoming system heating and the formation of contaminants. However, the PEO in molten salt was conducted at a high temperature (T_m∼220 °C), limiting the introduction of different components such as Ca and P. This study realizes the employment of a low-temperature electrolyte based on a ternary eutectic system of Ca(NO₃)₂–NaNO₃–KNO₃ (T_m∼130 °C) jointly with the in situ introduction of Ca/P in the form of ammonium dihydrogen phosphate (ADP). The surface morphology, phase and chemical composition, wettability, and anti-corrosion performance were examined. The results indicate improved surface performance with the addition of 1 wt% ADP to the electrolyte. This surface preferably comprises the anatase phase of TiO₂ and exhibits enhanced biocompatibility and corrosion resistance in a biological environment.

Here we present a novel study of Calcium hydroxide and iron-nickel co-doped Calcium hydroxide nanoparticles. Calcium hydroxide (CH) and iron-nickel doped Calcium hydroxide (INCH) nanoparticles (NPs) were synthesized by a simple chemical precipitation method. XRD, FESEM-EDX, and FTIR were used to characterize the structural and morphological characteristics, while UV–Vis spectroscopy was used to study the optical alterations. The average crystallite size is estimated to be 63.75 nm and 66 nm for the CH and INCH nanoparticles, respectively. The FESEM analysis revealed that CHNPs form a hexagonal-like shape, whereas INCH NPs produce highly agglomerated dispersed particles. The UV–Vis spectroscopy revealed that the band gap changes with average crystallite size concurrently.

The article describes the formation of samples into pipes with NiAl₂O₄ and TiAl₂O₅ spinel phases with different metallic phase content. The centrifugal slip casting method was used to form the composites. All suspensions used were shear thinning and were characterized by slight thixotropy. The analysis of the phase composition and chemical composition showed the presence of Al₂O₃, TiAl₂O₅ and NiAl₂O₄ in the produced samples. The produced materials were characterized by brittle fracture behaviour. The obtained life cycle assessment results clearly showed that as the content of the metallic phase increases, the environmental footprint of sinters in the A1 phase increases, which is a direct consequence of the increased use of raw materials.

MXenes, a rapidly growing family of two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (M_n+1X_nT_x, where M is a transition metal, X is carbon, nitrogen, or both, and T represents surface functional groups), have captured the scientific community's interest due to their exceptional physicochemical properties and diverse technological applications. This comprehensive review explores the latest breakthroughs in MXene synthesis and characterisation, emphasising their multifaceted applications in energy storage, catalysis, sensing, and other cutting-edge domains. This review examines the most widely used MXene synthesis strategies, including selective etching and delamination, and highlight recent advancements in controlling surface terminations, composition, and morphology. The influence of these synthetic parameters on MXene properties is discussed in detail. Characterisation techniques, ranging from spectroscopic methods to electron microscopy, are essential for elucidating MXenes' structure-property relationships. Research into energy storage leverages MXenes' high electrical conductivity, large surface area, and chemical tunability. This has led to significant progress in the field. This paper presents research efforts focused on optimising MXenes for both battery and supercapacitor applications. Additionally, the catalytic prowess of MXenes, particularly in electrocatalysis and photocatalysis, is explored, emphasising their role in green energy technologies and environmental remediation. MXenes' remarkable sensitivity and selectivity make them promising candidates for sensing various gases, biomolecules, and ions, offering exciting possibilities in healthcare and environmental monitoring. Importantly, this review underscores the need for continued optimisation of MXene synthesis protocols to achieve large-scale production, enhanced stability, and precise control over properties across various fields.

Dense tantalum-based carbonitride materials featuring >95 % relative density, TaC, Ta₂C_1.5N_0.5, Ta₂CN, Ta₂C_0.5N_1.5 and TaN, were prepared by Spark Plasma Sintering (SPS) at 1873 K with a dwell time of 10 min and a pressure of 50 MPa. Despite the presence of an oxide phase (i.e. 5 vol%) and some W inclusions (i.e. 1 vol%), the mechanical properties of such ultra-high temperature ceramics (UHTC) show promising values. Indeed, the Young's moduli measured by nano-indentation were approx. 600–700 GPa, which is higher than literature values reported for similar UHTC. The hardness values increased from 16.4 ± 0.8 GPa for TaC to 27.9 ± 1.3 GPa for TaN, with an approximately linear trend for the carbonitride samples while the ratio of plastic deformation work over the total indentation work followed the opposite trend.

The Master Sintering Curve (MSC) model is traditionally used to describe the densification kinetics of a specific material and allows to determine the activation energy of the dominant mechanism. In this study, this approach is applied to the Cold Sintering Process (CSP) of ZnO with the addition of acetic acid. The result was compared with SPS sintered samples from the same dry powder. The apparent activation energy of the ZnO powder sintered by CSP with acetic acid is 4 times lower than the same dry powder (338 kJ/mol versus 83 kJ/mol). This low value confirms the low energy surface interactions between liquid and solid phases involved in mechanisms of ZnO. MSC model applied to CSP presents different interests to detect similarities or differences in sintering mechanism with different liquid phases. It allows to determine the densification trajectory of the material, then to select the optimum processing parameters to control its microstructure.

In the steel industry, a large amount of diverse waste is generated, including carbon-bonded magnesia-rich waste originating from refractories. This study focused on the development and characterization of composite material based on magnesium oxychloride cement (MOC), with an emphasis on incorporating MgO–C-based refractory waste (CBMW) as a sustainable filler. To reach the best possible material properties, two different size fractions were applied in various ratios, completely replacing quartz sand. A comprehensive analysis of all composite material samples was conducted utilizing various analytical techniques, XRD, SEM, EDS or STA-MS. Mechanical properties such as compressive strength, flexural strength, and Young's modulus of elasticity were evaluated. Even though even the best sample did not surpass the mechanical properties for the reference, compressive strength 78.1 MPa was achieved, which is a more than sufficient value for most indoor applications.