Advanced Materials Research Vol. 856

Abstract: Nanosized fibrous cerium phosphates, Ce (HPO₄)₂.2.9H₂O (nCeP_f), wa prepared. was characterized by chemical , XRD, TGA analysis, Scanning electron microscope (SEM) and transmission electron microscope (TEM). Novel supported polybenzimidazole/ fibrous cerium phosphate nanocomposite membrane was prepared via in-situ chemical oxidation of the monomer that was promoted by the reduction of Ce (iv) ions present in the inorganic matrix. The presence of Ce (iv) ions allows redox reactions necessary to oxidative polymerization to occur. The resultant material was characterized by XRD, TGA, elemental (C,H,N) analysis and by FT-IR spectroscopy. Image SEM of the resulting nanocomposite reveals a uniform distribution of the polymer on the inorganic matrix }. Amount of polymer present in the composites found to be 11%.

Abstract: Novel nanosized lamellar germanium phosphate, α-Ge (HPO₄)_2.1.84H₂O(nGeP), with interlayer spacing (d₀₀₁) = 7.71Ǻ, was prepared. Preparations of polystyrene/lamellar germanium phosphate nanocomposite membranes were carried out by mixing slurry tetrahydrofuran (THF) solution of (nGeP) , of different weight percentages (2.5, 5 and 15 wt %), with (THF) solution of 5% polystyrene (PS) in concentration at 45°C with stirring for 48 hours. The resultant mixtures were poured into flat surface containers, of desired thickness, respectively, and allowed to dry in air. The resulting fully dried composites were pealed from the glass containers. The composite membranes were transparent flexible thin films and were characterized by XRD, TGA, FT-IR, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Size particles of lamellar germanium phosphate calculated from XRD broadening method using the Scherrer^,s equation, found to be 44.6 nm . TEM images of nanocomposites show that the (nGeP) in the nanometer scale, in the range 38-53 nm. The composite materials show to have mechanical and thermal stability properties superior to that of the original polymer, which a result of the enhancement of the thermal properties of PS/nGeP nanocomposites. The exchange capacities of the resultant composite membranes were investigated.

Abstract: In this study friction stir welding of Al-Cu laminated composites were carried out by two different tool geometries. Welding procedure was carried out from both sides of Al and Cu. Analyzing cross section of welds showed that different contact conditions between shoulder and material, offers different material flow behavior which is dependent on the tool geometry. SEM analyses showed that mixing of materials in nugget region is more pronounced in the advancing side. Also XRD results indicated that welding from Cu side, leads to intermetallic formation in mixed regions.

Abstract: The present study is an attempt to synthesize N-doped TiO₂ nanophotocatalyst using sonochemical method, having photocatalytic activity in the visible region. Non-metal doped nanocatalysts have been successfully synthesized and characterized structurally and physiochemically by using XRD, SEM, TEM, EDX, UV-VIS, FT-IR, Raman and PL. The photocatalytic activity of the synthesized photocatalyst was investigated for the degradation of 2-CP as model compound. The result confirms the successful synthesis of N-doped photocatalyst with particle size 34 nm having anatase phase and shows new peak in a visible region at 587 nm..

Abstract: A new class of Epoxy Emulsion modified Engineered Cementitious Composite (EM-ECC) has been developed for enhanced pipeline protection. The performance of typical ECC materials, such as flexural strength, anti-corrosion and early strength, has been improved by the addition of epoxy emulsion and rapid hardening cement. Our results indicated that the flexural strength of as-made EM-ECC increases with the increase of the EM/cement ratio after curing for 28 days. The retention rate of flexural strength of specimens remains analogical after immersed in water, 5 wt% Na₂SO₄ and 5 wt% NaCl solutions, respectively. The flexural strength reached ca. 16 MPa at 60 wt% replacement rate of rapid hardening cement after curing for 3 days. This new class of EM-ECC will shed light to the design of new applications for the oil and gas industry.

Abstract: The paper studied the effects of single addition of ultrafine fly ash (UFA) and mixed addition of silica fumeultrafine fly ash (SF-UFA) on powder pressure entity dense packing density, mechanical performance and microstructure structure of composite cement paste. The results show that, the ternary system of mixed addition of SF-UFA can effectively further reduced the compacting voidage and more increased packing density of composite powder, compared with the binary system of single addition of UFA. And when the content of SF is 8%, the compacting voidage is the lowest. Next, in the ternary system of mixed with silica fume, ultrafine fly ash and cement (SF-UFA-C), with the increase of silica fume (SF), the total porosity and pore diameter of hardened cementing paste decreased further compared with binary system, and with 8% content of SF and 17% content of UFA, the total porosity of hardened cement paste is the lowest, decreased by 60% than that of reference sample. At last, mixed addition of SF-UFA can improve the long-term strength of composite cement paste either, the compressive strength of 60 days hydration increased by nearly 9% compared with UFA-C and increased 41% compared with the reference sample.

Abstract: Short potassium titanate fibers were selected as the reinforcements to obtain the machinable aluminum alloy composites. The composites were fabricated by squeeze casting, and the turning machinability of the composites was investigated. The whisker-reinforced composites were also fabricated to compare their properties with the fiber-reinforced composites. The cutting force was lowered by the reinforcement, and that of the fiber-reinforced composite was lower than that of the whisker-reinforced composites. The roughness of the machined surface was lowered by the reinforcement. This result and the in situ observation of cutting process indicate that the reinforcements in the composite suppress the formation of the built-up edge. Continuous chips were formed after cutting the unreinforced alloy, while serrated chips were formed after cutting the composites. Under the standard condition for the finishing cut of nonferrous metals, the composite can be machined for a long time without changing the carbide tool.

Abstract: This study investigated the synthesis and catalytic properties of silver, platinum, and mixed Ag-Pt dopants into the 5A zeolite host. The prepared materials were tested toward the photodecomposition of the pesticide naptalam. The results indicate strong catalytic activities for the Ag-Pt-5A catalyst whereas, the Ag5A was found out to be the only doped zeolite that adsorbs the pesticide as soon as it came in contact with its surface. a-naphtylamine and phthalic acid were determined to be major photodecomposition products.

Abstract: Monometallic gold and bimetallic gold-iron catalysts supported on alumina were prepared in order to check their activity and selectivity in the reaction of cyclohexene oxidation. Au/Al₂O₃ was prepared by a deposition precipitation with urea (DPU) method, while the bimetallic catalyst Au-Fe/Al₂O₃ was prepared by under potential deposition (UPD). The characterization by ICP and EDS showed that very small amount of iron are deposited near gold nanoparticles. However, TEM images showed that the deposition method of iron induced gold nanoparticles sintering. All catalysts were tested in the reaction of cyclohexene oxidation in order to check the influence of both the size of gold particles and the presence of iron on the catalytic activity and selectivity. Small gold nanoparticles were shown be efficient in cyclohexene oxidation where the presence of iron influenced widely the selectivity towards the formation of cyclohexene oxide.