Influence of SiC Content on Microstructure, Dislocation Density and Mechanical Behavior of Cu/SiC Composite

The present investigation has examined the impact of micro-SiC on microstructure, dislocation and mechanical behavior of Cu/SiC composite. The micro-composite samples have been fabricated under a constant pressure (480 MPa) and sintered temperature (860oC) for 2 h. The sintering process was performed under argon gas. The microstructure examination was conducted using SEM/EDS and XRD diffraction. The SiC contents were 0, 5, 10,15,20,25 and 30 volume fraction. The outcomes showed that the density was significantly decreased with an increase of silicon carbide content. The relative densities of Cu and Cu/SiC composites was ranged from 91.24% to 83.56% for pure Cu and Cu/30 vol%SiC composites. The copper crystallite size was reduced with growing SiC content while the hardness, ultimate and yield compressive strength increased with increment of SiC volume fraction to 20% vol. The values of hardness, ultimate and yield compressive strength increased to 231 HV,343 and 176 N/mm2 , respectively for the composite sample containing 20% SiC particles with a percentage increase of 75%,26.6% and 57.2% compared with pure Cu.

Mg/Al-CH, Ni/Al-CH and Zn/Al-CH, as adsorbents for Congo Red removal in aqueous solution

In this study, chitosan was extracted from shrimp shells by demineralization and deproteination processes. The extracted chitosan was used to modify the layered double hydroxide and used as an adsorbent for the removal of congo red from aqueous solutions. Composites were successfully synthesized using M2+/Al (M2+ = Zn, Mg, Ni) and chitosan (CH) and the samples obtained were characterized using XRD and FTIR. The X-ray diffraction (XRD) pattern appeared at the layered double hydroxide peak of 2? = 11.63°; 23.00°; 35.16°; and 61.59° and chitosan at 2? = 7.93° and 19.35. The composite appearing in the layered double hydroxide and chitosan indicated that the composite material has been successfully synthesized. The XRD diffraction patterns of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH showed low crystallinity. The Fourier Transform Infrared (FTIR) spectra verifying absorption spectrum showed the presence of two bands at 3448 cm-1, 1382cm-1 characteristic to both chitosan and LDH. Adsorption of Congo Red (CR) followed the pseudo-second-order and Langmuir isotherm models. The adsorption capacities of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH were 181.818 mg/g, 227.273 mg/g, and 344.828 mg/g, respectively. The layered double hydroxide-chitosan composite adsorption was endothermically characterized by positive enthalpy and entropy values. On the other hand, the adsorption spontaneously was characterized by a negative Gibbs free energy value. The composites in this study were formed from LDH modified from chitosan extracted from shrimp shells to form Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH. The results of the characterization showed a number of characteristics that resembled the constituent materials in the form of LDH and chitosan. After being applied as an adsorbent to absorb Congo red dye, it then showed the most effective results using Mg/Al-CH adsorbent with an adsorption capacity of 344.828 mg/g.

High Crystalline Quality Conductive Polypyrrole Film Prepared by Interface Chemical Oxidation Polymerization Method

The authors report that polypyrrole (PPy) films with large area and high crystalline quality have been achieved using an interfacial chemical oxidation method. By dissolving different reactants in two immiscible solvents, the PPy is synthetized at the interface region of the two solutions. The PPy films have sharp XRD diffraction peaks, indicating that the molecular chains in the film are arranged in a high degree of order and that they reflect high crystalline quality. High crystal quality is also conducive to improving electrical conductivity. The conductivity of the as prepared PPy film is about 0.3 S/cm, and the carrier mobility is about 5 cm2/(Vs). In addition, the biggest advantage of this method is that the prepared PPy film has a large area and is easy to transfer to other substrates. This will confidently broaden the application of PPy in the future.

Deformations in Cement Pastes during Capillary Imbibition and Their Relation to Water and Isopropanol as Imbibing Liquids

The traditional approach for evaluating capillary imbibition, which describes the phenomena as a linear relationship between mass gain and the square root of time, considers a rigid pore structure. The common deviation from the linearity when using the square-root law (manifested in a downward curvature, i.e., slower water ingress) can be explained by considering a changing pore structure during the process caused by the swelling of calcium silicate hydrate (C-S-H) during water ingress. Analysing how the combination of deforming phase (C-S-H), non-deforming phase, and porosity affects the capillary water ingress rate is relevant for a deeper understanding of concrete durability. In this research, the C-S-H content was quantified by means of XRD diffraction coupled with Rietveld + PONKCS, dynamic water sorption (DVS), and SEM/BSE images coupled with phase mapping using PhAse Recognition and Characterization (PARC) software. The porosity was assessed by mercury intrusion porosimetry, water absorption under vacuum, and DVS. Furthermore, to assess deformations occurring with water and a non-aqueous imbibant, capillary imbibition tests with water and isopropanol as invading liquids were performed along with simultaneous deformation measurements. The relation between the relative C-S-H content and porosity has a great impact on the transport process. Samples exposed to isopropanol presented a much larger liquid uptake but significantly fewer deformations in comparison to imbibition with water. The effects of the changing pore structure were also evaluated with the Thomas and Jennings model, from which calculations indicated that pore shrink during imbibition. A comprehensive description of the relation between deformations and capillary imbibition in cement pastes reveals that liquid ingress is highly influenced by deformations.

Crystallization Behaviors of Composites Comprising Biodegradable Polyester and Functional Nucleation Agent

In this study, a thorough study of the crystallization behaviors of the biodegradable polymer composites of poly(ethylene succinate) (PESu) and hexagonal boron nitride (h-BN) was carried out. We found that h-BN had a significant nucleation effect on crystallization behaviors. DSC isothermal crystallization results demonstrated that the crystallization time of the PESu/h-BN composites became shorter after adding h-BN. The rate constant k values calculated from the Avrami equation were larger for the composites, demonstrating that PESu’s crystallization rate was increased by adding h-BN. TEM and SEM images showed the well-dispersed h-BN in the PESu matrix. Optical microscopy revealed that the PESu/h-BN composites formed more and smaller spherulites than neat PESu did, which confirmed that h-BN caused the nucleation effect. H-BN also accelerated non-isothermal crystallization kinetics. We discussed the behaviors of the Mo model, which demonstrated that h-BN promoted the kinetics of non-isothermal crystallization. The XRD diffraction patterns showed that h-BN in the composites would not obviously change the crystalline structure of PESu.

Mo-Doped CuO Nanomaterial for Photocatalytic Degradation of Water Pollutants under Visible Light

Recently, metal oxide-based nano-photocatalysts have gained much attention in waste water remediation due to their outstanding properties. In this report, a novel Mo-doped CuO nanomaterial was successfully prepared and utilized for the degradation of methylene blue water pollutant. The molybdenum content was varied from 1–5 wt.% to obtain the desired modified CuO based nanomaterials. The crystalline structures of as prepared materials were investigated by XRD diffraction technique, which explored the successful fabrication of monoclinic structure based CuO nanomaterials. For morphological study, SEM and HRTEM techniques were probed, which had also proved the successful preparation of nanoparticles-based material. SAED is used to check the crystallinity of the sample. The EDX and XPS analysis were performed to evaluate the elemental composition of Mo-doped CuO nanomaterials. The optical characteristics were explored via UV-vis and PL techniques. These studies have showed that the energy bandgap of CuO was decreased from 1.55 eV to 1.25 eV due to Mo doping. The photocatalytic efficiency of Mo-doped CuO nanomaterials was evaluated by degrading methylene blue (MB) under visible light-irradiation. Among different Mo-doped CuO based nanomaterials, the 4 wt.% Mo-doped CuO sample have shown highest degradation activity against MB dye. These results verified that the optimized material can be used for photocatalytic applications, especially for the purification of waste water.

Influence of Cobalt Substitution in LaMnO3 on Catalytic Propylene Oxidation

Perovskite-type structures LaBO3 with the compositions of LaMn1-xCoxO3 (x = 0.0, 0.3, 0.5, 0.7, and 1.0) were synthesized at 800 °C by a modified co-precipitation precursor technique for total oxidation of propylene, as a model test of the hydrocarbon oxidation reaction. Details concerning the evolution of the crystal structure, morphology, and crystallite size were performed by X-ray diffraction (XRD), Thermo Gravimetry Analysis (TGA)/Differential Scanning Calorimetry (DSC), Fourier Transform Infra-Red (FTIR), Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM), and Electron Spin Resonance (ESR) techniques. All compositions were identified to be single-phase and are indexed to rhombohedral structures. TG/DSC technique evidenced a temperature of 330 °C needed for the precursor as the start point and 800 °C completion for perovskite phase formation. Slight distortion in XRD diffraction peaks was observed on substituting manganese with cobalt in B-site, and new peaks emerged. An attempt has been made to understand the effect of the B-site substitution of Co3+ ions in the lattice of LaMnO3 and their influence on catalytic total propylene oxidation efficiency. These compounds show a considerable increase in the activity of propylene oxidation to carbon dioxide and water and could be explored for hydrocarbon pollution control.

Properties of multicomponent (Mn-Ni-Co-Al-Si-Ti) oxide spinel hierarchically organized nanostructures deposited by magnetron sputtering in two temperatures.

Multicomponent spinel films were deposited on Ag/Si substrates by magnetron sputtering. Two substrate temperatures were used. XRD diffraction measurements show that the layers are composed of three metals oxides (Mn2O3, NiO, CoO). The presence of spinel phase is poorly visible. However, electron diffraction measurements (RHEED) clearly confirmed the presence of nanostructured spinel structure on top of the samples. Moreover, AFM measurements show that nanostructured spinel islands are present on the sample surface. The measurements validated that indeed, hierarchically organized spinel-oxides nanostructures were obtained. A possible model growth of the spinel nanostructures at different temperatures is discussed.

Influence of Cobalt Substitution in LaNiO3 Nanoperovskite on Catalytic Propylene Oxidation

Perovskite-type oxides with transition elements offer promising potential as catalysts in total oxidation reactions. The present work reports the synthesis of crystalline lanthanum nickelates and cobaltates and their intermediate nanomaterials compositions LaNi1-XCoXO3 (x = 0.3, 0.5, and 0.7) at 800 ºC by co-precipitation precursor technique for structural, morphological, and total propylene oxidation catalytic activity. The evolution of the crystal structure and formation of the perovskite phase were analyzed by X-ray diffraction, Thermo Gravimetry Analysis (TGA) / Differential Scanning Calorimetry (DSC), Fourier Transformed Infra-Red (FTIR), Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), Electron Spin Resonance (ESR) techniques. The terminal compounds LaNiO3, LaCoO3, and their intermediates compositions were identified to be single-phase and are indexed to rhombohedral structures. The bonding characteristics were studied by FTIR spectroscopy. On substitution of Ni with Co in B-site, the slight distortion in XRD diffraction peaks were observed. These compounds show a considerable increase in the activity of propylene oxidation to carbon dioxide. This study aims at understanding the effect of B– site substitution in the lattice of LaNiO3 and their influence on catalytic propylene oxidation efficiency.

Synthesis and Characterization of Photoluminescent Ce(III) and Ce(IV) Substituted Hydroxyapatite Nanomaterials by Co-Precipitation Method: Cytotoxicity and Biocompatibility Evaluation

Improved compounds of Ce(III) and Ce(IV)-doped hydroxyapatite (Ca10-xCex(PO4)6(OH)2) with different concentrations such as x = 0.5, 1, 2.5, 5, and 10%, obtained by the simple co-precipitation method were synthesized. The cerium (3+) and cerium (4+)-doped hydroxyapatite were evaluated for biocompatibility and fluorescence properties. It was found that the cerium-HAp powders were non-toxic, even at higher level of concentration. The synthesized powders were further characterized by FTIR spectrometry, UV-Vis spectroscopy, XRD diffraction, SEM and TEM analysis. Therefore, the present study proves that the developed cerium (3+) and cerium (4+)-doped hydroxyapatite, respectively can be widely used as luminescent labeling materials, with improved biological properties.