Applied Mechanics and Materials Vol. 749

Abstract: The compression characteristics of open-cell aluminum foams were experimentally and numerically investigated. It is found that the mechanical parameters, such as collapse stress and absorbed energy, are dependent on the porosity of aluminum foams material. During simulation of metal foam compression, the finite elements distort severely at the local regions with high gradient of physical field. The procedure integrates Explicit solver of Abaqus FEA, 3D Optiformmesher and Python script program transfer to execute step by step the incremental deformation of deformable body.

Abstract: The DFT method was used for modeling a partial decomposition of the structure of the thaumasite mineral. The four models with a consecutive decreasing of water content were prepared (T12 – 100 %, T9 – 75 %, T6 – 50 %, T3 – 25 %) and corresponding decomposition enthalpies were calculated. The results showed a good agreement with available experimental data for the decomposition reaction of the thaumasite structure.

Abstract: Models of smart materials and structures are derived through rigorous mathematical methods. We establish a classification of piezoelectric and piezomagnetic crystalline materials and propose simplified but accurate models of thin structures made of piezoelectric or electromagneto-elastic materials.

Abstract: Microporous carbons prepared from commercial activated carbon WG12 by KOH and/or ZnCl₂ treatment were examined as adsorbents for CO₂ capture. The micropore volume and specific surface area of the resulting carbons varied from 0.52 cm3/g (1374 m²/g) to 0.70 cm3/g (1800 m²/g), respectively. The obtained microporous carbon materials showed high CO₂ adsorption capacities at 40 bar pressure reaching 16.4 mmol/g.

Abstract: Bisphenol of 4,4’-dihydroxy-N-benzylidene-4-aminophenol containing azomethine group was synthesized via condensation of an aromatic amine namely 4-aminophenol with p-hydroxybenz aldehyde. It’s epoxy derivate and epicholorohydrin produced the new liquid crystalline diglycidyl ether of 4,4’-dihydroxy-N-benzylidene-4-aminophenol. A new type of liquid crystalline epoxy and azoemthine hardening agent are characterized at 300°C for 10 min, using c11z as a catalyst. The chemical structures were confirmed by FT-IR, ¹H-NMR. The curing reaction with 4,4’-dihydroxy-N-benzylidene-4-aminophenol were carried out in the ratio of glycidyl ether of 4,4’-dihydroxy-N-benzy lidene-4-aminophenol/azomethine hardening 1:0.8. The degree of crystallinity studied by X-ray diffractometer, differential scanning calorimetry (DSC) and polarized optical microscope (POM).

Abstract: Hydroxyl sodalite (Na₈Al₆Si₆O₂₄(OH)₂) was investigated to develop a new ecofunctional material having removal performance for toxic substances including in combustion gas. Hydroxyl sodalite has nanometer-sized micro pore (β-cage) in the structure, and Cl^- ions derived from HCl gas were fixed in the pores above 400 °C. The amount of Cl^- ion fixed increased with increasing reaction temperature, and was the greatest, 7.3 wt% at 800 °C. In addition, it was found that Cu²⁺ ions were fixed in sodalite structure by substitution with Na⁺ ions by solid (hydroxyl sodalite) - gas (gaseous CuCl₂) reaction. The substitution quantity increased with increasing reaction temperature. The amount of Cu²⁺ ion substituted was 10.5 wt% as CuO at 900 °C. From the above results, it was concluded that hydroxyl sodalite is an ecomaterial which is useful for combustion gas purification in the high temperatures.

Abstract: Bi₃Ni₂Ta₃O₁₄ pyrochlores and related materials were prepared by solid state reaction at sintering temperatures ranging from 900°C to 1150°C. The BNT cubic pyrochlores could be represented by a general formula Bi₃Ni_2-xTa₃O_14-x and phase pure sample was obtained at temperature 1050°C with x = 0.6. This was confirmed by X-ray diffraction analysis and detailed lattice refinement. The single phase material crystallized in a cubic system, space group Fd3m with a = b = c = 10.5134 Å, α = β = γ = 90o, respectively. The sample was further characterized using a combination of techniques including Fourier-Transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA), thermogravimetric analysis (TGA) and inductively coupled plasma – atomic emission spectrometry (ICP-AES). The material was thermally stable without any thermal events being observed. Electrical properties of the single phase material were studied by ac impedance spectroscopy starting from room temperature to 800 ^oC over a frequency range of 5 Hz to 13 MHz. The phase formation and solid solutions of cubic pyrochlores in the Bi₂O₃-NiO-Ta₂O₅ (BNT) ternary system were studied thoroughly via combination of characterization techniques.

Abstract: Large quantity of iodinated charcoal (I-AC) is firstly prepared by simple ball-milling activated chargoalin the presence of iodine. The resultant I-AC contains iodine of 0.59 at.% (EDS) and shows that the morphology is changed from random powder into flake-like platelet. It is uased as electrocatalyst for oxygen reduction reaction (ORR), exhibiting outstanding electrocatalytic activities with higher selectivity, better tolerance to methanol crossover than those of the starting AC and commercial Pt/C electrocatalysts.

Abstract: The conditions of adsorption of Cr^{3 +} ions at the surface of diatomite are optimized. It was shown that the adsorption of Cr^{3 +} ions on diatomite depending on the initial concentration is 1,8-6,9 mg /g, which is caused by the occurrence of the ion exchange reaction between the silanol groups of diatomite and Cr (III) ions. The effect of pH on the binding of Cr^{3 +} ions with diatomite was studied. It was established that acidification of the medium leads to a decrease in the degree of extraction of Cr^{3 +} ions from solutions, due to protonation of SiOH-groups of the diatomite surface with H ⁺ ions of acids to SiOH₂^+. It is suggested that, along with the adsorption of Cr^{3 +} ions on the surface of diatomite heterocoagulation of diatomite particles and hydroxocomplexes of Cr^{3 +} ions is possible.