Characterization of Novel Cement-Based Carboxymethyl Chitosan/Amorphous Calcium Phosphate

Objective This study aimed to analyze, evaluate, and characterize novel cement-based carboxymethyl chitosan/amorphous calcium phosphate (CMC/ACP). Materials and Methods The three cement groups studied were gypsum (Gyp), and CMC/ACP—gypsum cement-based 5% (5% CAG) and 10% (10% CAG). The groups were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), setting time, and scanning electron microscopy (SEM) data. The characterization results were analyzed qualitatively, but the data for setting time were analyzed using SPSS (p < 0.05). Statistical Analysis Data were statistically analyzed. One-way analysis of variance was used to compare numerical (parametric) data between more than two separate groups followed by post hoc Tukey. Results FTIR showed phosphate groups indicate the presence of calcium phosphate in the form of amorphous (ACP) in the CMC/ACP, CMC/ACP post-milled powder, and CMC/ACP cement-based (5% CAG and 10% CAG). XRD showed no difference in the diffraction spectra among the Gyp, 5% CAG, and 10% CAG groups. SEM images revealed that the CMC/ACP cement-based groups (5% CAG and 10% CAG) showed CMC/ACP cluster filled with hollow spaces between the gypsum crystals and aggregations surrounding the gypsum crystals. The CMC/ACP showed envelopes and attached to the crystalline structures of the gypsum. Setting times of 5% CAG and 10% CAG showed significant differences compared with Gyp (p < 0.05). Conclusion The result of our study showed that CMC/ACP cement-based (5% CAG and 10% CAG) demonstrated amorphous characteristic, which can stabilize calcium ions and phosphate group (ACP). In addition, the modification of gypsum using CMC/ACP as cement-based extended the time of setting.

The Contribution of G-Layer Glucose in Salix Clones for Biofuels; Comparative Enzymatic and HPLC Analysis of Stem Cross-Sections

Background Interest on the use of short-rotation willow as a lignocellulose resource for liquid transport fuels has increased greatly over the last ten years. Investigations have shown the advantages and potential of using Salix spp. for such fuels but have also emphasized the wide variations existing in the compositional structure between different species and genotypes in addition to their effects on overall yield. The present work studied the importance of tension wood (TW) as a readily available source of glucose in two-year-old stems of four Salix clones (Tora, Björn, Jorr, Loden). Studies involved application of a novel approach whereby TW-glucose and residual sugars and lignin were quantified using stem cross-sections with results correlated with HPLC analyses of milled wood. Compositional analyses were made for four points along stems and glucose derived from enzyme saccharification of TW gelatinous (G) layers (G-glucose), structural cell wall glucose (CW-glucose) remaining after saccharification and total glucose (T-glucose) determined both theoretically and from HPLC analyses. Comparisons were also made between presence of other characteristic sugars as well as acid-soluble and -insoluble lignin. Results Initial studies showed good agreement between using stem serial sections and milled powder for determining total sugar and lignin. Therefore, sections were used throughout the work. HPLC determination of T-glucose in Salix clones varied between 47.1–52.8%, showing a trend for higher T-glucose with increasing height (Björn, Tora and Jorr). Using histochemical/microscopy and image analysis, Tora (24.2%) and Björn (28.2%) showed greater volumes of % TW than Jorr (15.5%) and Loden (14.0%). Total G-glucose with enzyme saccharification of TW G-layers varied between 3.7–14.7% increasing as the total TW volume increased. CW-glucose measured after enzyme saccharification showed mean values of 41.9–49.1%. Total lignin between and within clones showed small differences with mean variations of 22.4–22.8% before, and 22.4–24.3% after enzyme saccharification. Calculated theoretical and quantified values for CW-glucose at different heights for clones were similar with strong correlation: T-glucose = G-glucose + CW-glucose. Pearson´s correlation displayed a strong and positive correlation between T-glucose and G-glucose, % TW and stem height, and between G-glucose with % TW and stem height. Conclusions The use of stem cross-sections to estimate TW together with enzyme saccharification represents a viable approach for determining freely available G-glucose from TW allowing comparisons between Salix clones. Using stem sections provides for discrete morphological/compositional tissue comparisons between clones with results consistent with traditional wet chemical analysis approaches where entire stems are milled and analyzed. The four clones showed variable TW and presence of total % G-glucose in the order Björn > Tora > Jorr > Loden. Calculated in terms of 1 m3, Salix stems Tora and Björn would contain ca. 0.24 and 0.28 m3 of tension wood representing a significant amount of freely available glucose.

Microstructural and Magnetic Behavior of Nanocrystalline Fe-12Ni-16B-2Si Alloy Synthesis and Characterization

The nanocrystalline Fe70Ni12B16Si2 (at.%) alloy was prepared by mechanical alloying (MA) of elemental powders in a high-energy planetary ball mill. Phase evolution, microstructure, thermal behavior and magnetic properties were investigated. It was found that a body-centered cubic structured solid solution started to form after 25 h milling and a faced-centered cubic structure solid solution started to form after 50 h of milling; its amount increased gradually with increasing milling time. The BCC and the FCC phases coexisted after 150 h of milling, with a refined microstructure of 13 nm and a 10 nm crystallite size. The as-milled powder was annealed at 450 °C and 650 °C and then investigated by vibrating sample magnetometry (VSM). It was shown that the semi-hard magnetic properties are affected by the phase transformation on annealing. The saturation magnetization decreases after annealing at 450 °C, whereas annealing at 650 °C improves the magnetic properties of 150 h milled powders through the reduction of coercivity from 109 Oe to 70 Oe and the increase in saturation magnetization.

Experimental investigation and parameter optimization of Cr2O3 atmospheric plasma spray nanocoatings

In this research, Cr2O3 ceramic nano-sized powder particles were prepared using ball milling and then were granulated to reach the proper size for spraying. Afterward, Cr2O3 nano-coatings were deposited by atmospheric plasma spraying (APS) process onto stainless steel substrates. To optimize APS parameters, spraying was carried out under six conditions with different parameters. Microstructures of the elemental/milled powder and coatings were characterized via a field emission scanning electron microscope (FESEM) equipped with energy-dispersive spectroscopy (EDS). In this research, Cr2O3 coatings were deposited under different spraying conditions to understand the effect of APS parameters on the splat formation, deposition efficiency, and porosities of the coatings. After parameter optimization, spraying was performed under a high deposition efficiency of 46.0±1.3%. The optimized Cr2O3 coatings showed porosity content, Knoop microhardness, and adhesive strengths of 8.7±2.2%, 823±27 HK0.2, and 49±4 MPa, respectively; making them a good candidate for industrial use.

Effect of Aqueous Milling on the Total Carbon Content of Hard Metal Powders

Materials consisting of a hard phase, usually WC, and a tough binder, traditionally Co, form the most successful class of composite materials, also known as Hard Metals (HM) or Cemented Carbides. Powder metallurgy routes are employed generally for the production of such [1]. The typical processing route of such materials involves mixing the components, kneading and consolidation. Alcohols, alkanes and alkenes are commonly used to limit any excessive heating and oxidation of powders during mixing the components. In this study, we report the results of milling in a more environmentally friendly aqueous milling media. The obtained results are presented comparatively with milling under a traditional media, such as isohexane and acetone. The characterization of the milled samples has been done from the structural, compositional and morphological point of view. Considering our previous results, an important aspect of the milled powder is the carbon content, which dictates the sintering behavior of such parts. The carbon balance investigation performed on a carbon analyzer has revealed no significant differences upon changing the milling media. This work emphasizes the influence of the milling media on the HM powder. HM powders with similar properties have been obtained both by traditional and aqueous milling. The comparative study has revealed that the substitution of the traditional milling media does not influence the carbon content in the HM powder.

Recovery of Cr from chrome-containing leather waste and its utilization as reinforcement along with waste spent alumina catalyst and grinding sludge in AA 5052-based metal matrix composites

The present investigation deals with the development of AA 5052-based metal matrix composites (MMCs) by utilizing industrial wastes, spent alumina catalyst, chrome-containing leather waste, and grinding sludge as a reinforcement material. The chrome-containing leather waste has been utilized to extract the collagen powder, which is a form of chromium oxide. The presence of Al2O3, Fe2O3, and SiO2 phases in the spent alumina catalyst and grinding sludge ball-milled powder encourages its utilization as reinforcement material (in the form of Cr) for the development of MMCs. The stir-casting technique has been used to develop the aluminum-based MMC with waste spent alumina catalyst, chrome-containing leather waste, and grinding sludge. Further, results revealed that the matrix material mechanical properties compressive strength, tensile strength, and hardness were significantly increased by 12.93%, 5.34%, and 31.81% after adding spent alumina catalyst, Cr, and grinding sludge with the weight percentage (wt.%) of 4.5%, 1.5%, and 4.5%, respectively, but the toughness was reduced. The microstructural investigation indicated the uniform distribution of reinforcing elements spent alumina catalyst (4.5 wt.%), GS (4.5%), and Cr (1.5%) in the aluminum matrix material. Further, the influence of given reinforcement elements on the thermal expansion and corrosion weight loss properties of aluminum alloy matrix material has also been investigated.

Fabrication and Structural Properties of Ni50 Al50 Alloy by Mechanical Alloying

In the present study, mechanical alloying process was employed for preparation of the nanocrystalline Ni50Al50 alloy through ball mill method. The structure properties of the alloy at various milling times of 0, 2, 4, 6 and 8hr were studied by X-ray diffraction and scanning electron microscopy (SEM) measurements. Several phases was formed successfully after 4hr of milling. At 6hr of milling, new intermetallic compound type (Ni3AI) was observed prospering, The particle size for various milling times decreased significantly, with increasing time of milling. The resulted morphology the milled powder shows a reduction of particle size which is in accordance with the XRD patterns. The results of EDX shows clearly atypical spectrums of both Ni and Al peaks.

Dependence of Magnetic Properties with Structural/Microstructural Parameters of Ball-milled Fe15Co2P3 Powder Mixture

This research work aims to investigate the mechanically alloyed Fe15Co2P3. Parametric Rietveld refinement method, of the obtained X-ray patterns, was performed for qualitative and quantitative phase analysis, structural, microstructural and mechanical properties. The ball-milled powder mixture crystallized within the face-centred cubic α-Fe(P) solid solution in equilibrium with Co75Fe25 phase. The crystallite size decreases reaching 100 and 200 nm respectively after 3h of milling. The highest values of the dislocation density, microstain and stored energy are registered for the α-Fe(P) solid solution. The studied mechanical properties manifest the brittle nature of the α-Fe(P) solid solution compared to the Co75Fe25 phase. The squareness ratio Mr/Ms and the coercivity values of the milled powders increase with increasing milling time and reach steady state after 2 h. The hysteresis loss energy and maximum permeability reach minimal values of 45*10− 4 W/m3 and 49*10− 3 H/m respectively, after 1 h of milling at the opposite of the switching field distribution.

THE USE OF (Mg0.9Zn0.1)TiO3+2wt.% Bi2O3 CERAMICS AS A DIELECTRIC RESONATOR OSCILLATOR MATERIAL AND CHARACTERISATION OF STRUCTURE, MICROSTRUCTURE, AND DENSITY

Magnesium titanate (MgTiO3)-based ceramics have the potential for use in the telecommunications industry at microwave frequencies, including as a resonator in dielectric resonator oscillator (DRO) circuit. This research is intended to study the application of (Mg0.9Z0.1)TiO3+2wt.% Bi2O3 (abbreviated MZT01-2) ceramics as DRO material and characterize the structure, microstructure, and bulk density. Fabrication was carried out by ball milling between (Mg0.9Z0.1)TiO3 crystalline powder and 2wt.% Bi2O3 powder. The milled powder was compacted at certain pressure using a die press to become pellets. All pellets were sintered at 1000, 1100, 1200°C for 4 h to obtain ceramics. The structural characterization using XRD showed that the three ceramics contained the main MgTiO3 phase, each 93.63, 93.83, and 90.78% molar, the rest was the MgTi2O5 phase. The increase in sinter temperature causes the lattice parameter and the unit cell volume to decrease. The Archimedes bulk density was 2.928; 2.832 and 2.736 g/cm3. The microstructure is solid surfaces with a grain diameter of 1.9-2.3 μm accompanied by pores. As DRO materials, the three ceramics exhibited a resonant frequency at 5.11, 5.08, and 5.12 GHz which shows that the ceramics can be applied as DRO materials at microwave frequencies. The sinter temperature variation tends not to affect the resonant frequency position.