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Ti3SiC2/Al2O3 multilayered composites were prepared by the combination of tape casting and hot pressing sintering. The slurry was produced by adjusting the amounts of each organic material, including triethyl phosphate (TEP) as a dispersion, polyvinyl butyrate (PVB) as a binder, dioctyl phthalate (DOP) as a plasticizer, and anhydrous ethanol as an organic solvent. When TEP content was 3 wt.%, PVB content was 4.5 wt.%, R‐value (DOP/PVB) was 1.4, and solid content was 38 wt.%; the cast film with a smooth surface, good flexibility, and uniform thickness was obtained after defoaming, tape casting, and drying. Three samples were prepared, namely, S1–S3. The S1 was monolithic Ti3SiC2/Al2O3 (mass ratio is 1:1) composites. S2 and S3 were Ti3SiC2/Al2O3 multilayered composites, which matrix layers were Ti3SiC2/Al2O3 composites (mass ratio is 1:1) and Al2O3, respectively, and their interface layer was Ti3SiC2. S1–S3 were also sintered at 1550°C. The bending strength of multilayered materials were lower than that of monolithic material, but the fracture toughness of multilayered materials significantly increased. Due to the introduction of Ti3SiC2 interface layer, the friction coefficient and wear rate of Ti3SiC2/Al2O3 multilayered composites were reduced by 30.7% and 33.8%, respectively, compared with monolithic material. [ABSTRACT FROM AUTHOR]

Ti 3 SiC 2 /Al 2 O 3 composites attract attention because Ti 3 SiC 2 and Al 2 O 3 have complementary advantages in mechanical properties. However, the high temperatures (≥1400 °C) required for densification of the Al 2 O 3 lead to the decomposition of Ti 3 SiC 2. To address this issue, Ti 3 (Al 1-x Si x)C 2 /Al 2 O 3 composites were fabricated via current-assisted sintering of Ti 3 AlC 2 /SiO (TM sample) and Ti 3 AlC 2 /SiO 2 (TD sample) at 1100–1300 °C. After sintering, most Al atoms in Ti 3 AlC 2 were substituted by Si atoms, forming Ti 3 (Al 1-x Si x)C 2 with values of x greater than 0.85. However, the morphologies of Al 2 O 3 produced from Ti 3 AlC 2 /SiO and Ti 3 AlC 2 /SiO 2 were different. Spherical Al 2 O 3 produced by Al–Si substitution in SiO 2 was difficult to densify at low temperatures, whereas the reaction between Ti 3 AlC 2 and SiO disintegrated the matrix of SiO and produced dense Al 2 O 3. As a result, the relative densities and mechanical properties of TM samples were less affected by a reduction in sintering temperature than those of TD samples. As sintering temperature declined from 1300 °C to 1100 °C, flexural strength, hardness, and fracture toughness of TM samples decreased by 35.9% (from 546.2 MPa to 350.0 MPa), 27.4% (from 4.56 GPa to 3.31 GPa), and 33.4% (from 7.45 MPa m0.5–4.96 MPa m0.5), respectively. Meanwhile, the flexural strength, hardness, and fracture toughness of TD samples were reduced by 81.2% (from 466.1 MPa to 87.6 MPa), 85.4% (from 6.50 GPa to 0.95 GPa), and 68.6% (from 6.94 MPa m0.5–2.18 MPa m0.5), respectively. Therefore, Ti 3 AlC 2 /SiO is more suitable for fabricating Ti 3 (Al 1-x Si x)C 2 /Al 2 O 3 composites at low temperatures. [ABSTRACT FROM AUTHOR]

Al/SiC composites with different Al contents were prepared by high-energy ball milling with Al powder and SiC powder as raw materials at a temperature of 1800 °C, a pressure of 50 MPa, and heat preservation for 5 min. The microstructures and phase compositions of the Al/SiC composites were observed using scanning electron microscopy and X-ray diffraction. The results showed that the Al/SiC composites prepared by adding 10 vol% aluminum had the best properties: the strength was 310 MPa, the apparent porosity was 6.50%, and the density was 2.9192 g/cm3. Furthermore, the corrosion rate of the Al/SiC composites gradually decreased with increasing corrosion time when the Al/SiC composites were placed in a 3.5 wt% NaCl solution at room temperature. However, the corrosion rate differed for varying Al contents. The experimental results showed that the Al/SiC composites with 10 vol% Al have the best properties, including the smallest porosity, the largest density, and the highest corrosion resistance. [ABSTRACT FROM AUTHOR]

Ce–P/γ-Al 2 O 3 coatings applied with the freeze-drying technique were deposited on foam ceramics before being further prepared as Pd catalysts. According to the research, phosphoric acid replaced the hydroxyl on the surface of γ-Al 2 O 3 to produce polyhydroxy P-containing sites that readily attracted cerium oxide. The palladium oxide was then embedded into the cerium oxide vacancy. The impacts of the drying technique on the catalysts were investigated, and the results indicated that freeze drying created a special coating with a large specific surface area and uniform mesoporous structure by inhibiting nanoparticle agglomeration. H 3 PO 4 's altering action was augmented to boost the number of active sites and the percentage of weakly acidic sites. Due to better P–Ce interactions, more Ce3+ was added into CeO 2 , which created numerous oxygen vacancies. By adjusting the P-containing sites, the dispersion of cerium oxide and the active phase could be controlled, which aided the activation and spillover of hydrogen. Furthermore, the capacity for oxygen adsorption and desorption was enhanced, and the amount of adsorbed oxygen species increased. As a result, the freeze-drying technique improved the advantages of the Ce–P/γ-Al 2 O 3 coating, increasing the conversion and selectivity of CO 2 methanation to 81% and 94%, respectively, and lowering the complete conversion temperature of CO oxidation to 116 °C. This research has a guiding influence on the development of foam ceramic-loaded palladium catalysts in the fields of energy and the environment. [ABSTRACT FROM AUTHOR]

It's crucial to make inexpensive, effective palladium catalysts employing α-alumina in the realms of pollution remediation and drug synthesis. The α-alumina foam ceramics prepared by the template approach were modified by adding a thin coating of γ-alumina containing Ce and P elements to further prepare the palladium catalyst. γ-Alumina significantly raised the foam's specific surface area, multiplied the number of acidic sites, decreased the Pd–O bond strength in palladium oxide, and brought the active phase content closer to the ideal value. Phosphate radicals were adsorbed onto the alumina surface, reducing the proportion of strongly acidic sites on the surface, and facilitating the desorption of oxygen species adsorbed by surface defects. As P and Ce elements interacted, the Ce4+/Ce3+ ratio decreased, increasing the number of oxygen vacancies in cerium oxide to improve the oxygen storage capacity of cerium oxide. In addition to acting as an oxygen storage material, the Ce elements increased the electron density of Pd and weakened the binding strength of the oxygen species bound to the individual metal Pd. There was a strong interaction between cerium and palladium, resulting in a mixed state of Pd0, PdO, and Pd2+ after the reaction. On the other hand, the surface of the foam was rough enough to facilitate the adhesion of the thin coating, while the thin coating, with a thickness of less than 8 μm, improved its mechanical properties. The CO full conversion temperature was reduced by 135 °C in the Pd/CeP(γ/α-A) compared to the uncoated foam catalyst. [ABSTRACT FROM AUTHOR]

(Ti,Ta) 3 SiC 2 /Al 2 O 3 composite ceramics were prepared by hot-pressing sintering using TaC as Ta source. X-ray diffraction analysis showed that the maximum of solid solubility of Ta in Ti 3 SiC 2 were determined to be from 7.5 to 10 at%. With the increase of TaC contents, the grain size of Ti 3 SiC 2 reduced obviously. Combined Wulff theorem and first-principle calculations, the probable mechanism of this refinement phenomenon was revealed. When Ta atoms substitute Ti in surface atomic layers, the surface energy of (001) plane increased significantly compared to those of (100) plane, which restricted the growth of (001) facets. As it is the largest exposed surface, the lower growth rate of (001) facets lead to the grains refinement. The results will provide theoretical guidance for surface modification and morphological transformation of Ti 3 SiC 2 -based ceramics. [ABSTRACT FROM AUTHOR]

Abstract: In this work, an acrylic acid/vermiculite (AA/VMT) hydrogel was prepared by glow‐discharge‐electrolysis plasma initiated graft copolymerization, in which N,N′‐methylenebisacrylamide was used as a cross‐linker. The structure, thermal stability, morphology and surface area of AA/VMT hydrogel were characterized by FT‐IR, TG, SEM, and automated porosimeter. Cationic dyes such as Crystal violet (CV) and Methylene blue (MB) were used for testing the adsorption property. Factors influencing adsorption such as pH, contact time, concentration were investigated by batch experiments. Adsorption kinetics and adsorption isotherms were employed to illustrate the hydrogel‐dye interaction. The results showed that the best parameters for the adsorption of dyes were pH = 6 and contact time 2 h. The adsorption kinetic followed the pseudo‐second‐order model with multi‐step diffusion process. Both Langmuir and Redlich‐Peterson isotherms were well agreed with the experimental data. The maximum adsorption capacities of CV and MB on AA/VMT hydrogel were 2575.2 and 2674.0 mg g−1, respectively. [ABSTRACT FROM AUTHOR]

A highly absorptive resin was prepared by glow-discharge electrolysis plasma initiated suspension copolymerization, in which methyl methacrylate and butyl acrylate were used as monomers, N, N′-methylenebis(acrylamide) as crosslinking agent, polyvinyl alcohol as dispersant, and NaSO solution as supporting electrolyte. To optimize the synthesis conditions, the discharge voltage, discharge time, polymerization temperature, the ratio of monomers, the amounts of crosslinking agent and supporting electrolyte, as well as the ratio of water to oil, were examined in detail. The structure and properties of the obtained resin were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), respectively. The oil absorbency, absorption rate, absorption selectivity, and network parameters of the resin were also examined. Results showed that under the optimal conditions, the oil absorbency was about 28.5 g/g for benzene, 25.4 g/g for toluene, 28.0 g/g for xylene, 38.1 g/g for chloroform, and 37.0 g/g for carbon tetrachloride. [ABSTRACT FROM AUTHOR]