Source Powder Research Articles

Mechanically milled powder from cotton gin trash for diverse applications

There are very few reports, if any, on the physicochemical changes during the powder fabrication of cotton gin trash (CGT), an abundant source of lignocellulose. This particular study can be very informative for the production of new CGT composite materials. In our current study, we investigated the changes in particle size, morphology, surface area, chemical structure, crystallinity, thermal and moisture properties of CGT at different stages of the milling operation. An attritor milling of CGT up to 4 h reduced the particle size (from 144.2 μm to 6.2 μm) and enhanced the surface area up to 2.5 times without damaging its original properties, including crystallinity and chemical structure. Milling operation beyond 4 h did not further reduce the particle size effectively, though affected the thermal stability of CGT. Overall, it is suggested that the milled CGT can be a sustainable source of lignocellulose powder for use in a wide area of applications.

Numerical simulation of the effect of fine fraction on the flowability of powders in additive manufacturing

Additive manufacturing (AM) is a rapid and flexible technique for the production of metal parts and prototypes from metal powders. The quality of parts manufactured using AM is a strong function of powder physical and mechanical properties. Previous work has shown that powders with a large fraction of fine particles produce better parts in terms of smooth finished surface and high mass density. However, an excessive fine fraction in the source powder causes serious flowability issues, leading to unexpected voids or discontinuities in the finished product. This effect of the fine fraction on the flowability of metal powder is widely encountered but poorly understood in the AM industry. This study presents a three-dimensional (3D) discrete element method (DEM) model to simulate the microscale mechanisms of powder flow considering the effects of van der Waals force. This microscale force has a negligible influence on the flowability of coarse grains, but the effect becomes the dominant factor governing the behavior of fine fractions (micrometer scale). The results show that the numerical model presented in this paper is capable of reproducing the experimental dependency of the powder flowability on the fine fraction. Moreover, it also successfully captures the characteristics of particle flow under the influence of microscale van der Waals force.

Role of ion substitution and lattice water in the densification of cold-sintered hydroxyapatite

High-density hydroxyapatite (HA) compacts were achieved by cold sintering of co-precipitated powders at temperatures lower than 200 °C without addition of any solvent. Critical factors affecting the densification behavior including the source of powders, the type of solvent, applied pressure, sintering temperature and time were investigated. The presence of lattice water together with ion substitution in the co-precipitated HA powders has a significant effect on the densification. A novel viewpoint that is essentially different from classical dissolution−precipitation mechanism in cold sintering was proposed; i.e., the formation of hydrogen bonds between the HA particles plays a critical role in the densification.

Optimization of the SiC Powder Source Material for Improved Process Conditions During PVT Growth of SiC Boules.

We have studied the influence of different SiC powder size distributions and the sublimation behavior during physical vapor transport growth of SiC in a 75 mm and 100 mm crystal processing configuration. The evolution of the source material as well as of the crystal growth interface was carried out using in situ 3D X-ray computed tomography (75 mm crystals) and in situ 2D X-ray visualization (100 mm crystals). Beside the SiC powder size distribution, the source materials differed in the maximum packaging density and thermal properties. In this latter case of the highest packaging density, the in situ X-ray studies revealed an improved growth interface stability that enabled a much longer crystal growth process. During process time, the sublimation-recrystallization behavior showed a much smoother morphology change and slower materials consumption, as well as a much more stable shape of the growth interface than in the cases of the less dense SiC source. By adapting the size distribution of the SiC source material we achieved to significantly enhance stable growth conditions.

A strategy for designing microencapsulated composite phase change thermal storage materials with tunable melting temperature

Thermal energy storage technology with high temperature phase change materials (PCMs) plays an increasingly important role in the concentrated solar power plants and industrial waste heat recovery systems. In this study, a novel displacement reaction between tetraethoxysilane as SiO2 source and molten raw Al powder was purposed to successfully prepare Al-Si/Al2O3 high temperature composite PCMs. Interestingly, by proposed synthetic methodology, we not only achieved the in-situ synthesis of Al-Si alloy PCM and Al2O3 shell, but also realized the controllability of Al-Si alloy composition and Al2O3 shell layer thickness. Our results indicated that the melting temperature of the prepared composite PCMs depended on the composition of Al-Si alloy, and could be designed within a certain temperature range (from 574.0 °C to 641.4 °C), instead of a particular temperature point. The melting temperature adjustability of the prepared composite PCMs provided an additional flexibility in different working temperature conditions. Moreover, the prepared composite PCMs exhibited a relatively high thermal storage capacity (248.6 J/g to 331.0 J/g), good thermal stability, excellent repeatable utilization property and certain shell layer self-repairing ability in the working temperature range. Therefore, the prepared composite PCMs can prove to be promising thermal energy storage materials for improving the energy efficiency in various systems under different working temperature conditions.

Ca diffusion in K-Feldspar

Diffusion of Ca has been characterized in natural K-feldspar under dry, 1 atm conditions using a 44Ca tracer. Polished sections of feldspar were surrounded by source powders in Pt capsules and annealed in air, or with solid buffers to buffer at NNO or IW. One hydrous experiment was conducted in a piston-cylinder device at 800 °C and 1 GPa. In all cases, the source of diffusant was pre-synthesized anorthitic powder doped with 44Ca. Prepared sample capsules were held at run conditions for times ranging from a few hours to a few months, at temperatures from 750 to 1050 °C. The 44Ca distributions in the feldspars were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Ca diffusion in K-feldspar for diffusion normal to (001):D = 3.91 × 10−9 exp.(−276 ± 41 kJ/mol/RT) m2 sec−1.Diffusivities normal to (010) appear similar, suggesting little anisotropy for Ca diffusion. Diffusion coefficients for experiments buffered at NNO and IW agree within experimental uncertainty with those for experiments run in air, indicating little dependence of Ca diffusion on oxygen fugacity under the investigated range of conditions. On the basis of the single high-pressure experiment, neither pressure nor the presence of H2O appear to affect Ca diffusion.Ca diffusion in K-feldspar is slower than the diffusivities of the larger divalent cations Sr and Pb, and also slower than Ca diffusion in plagioclase, which may be attributable to the large size mismatch of Ca in the K-feldspar structure.Ca diffusion is 7–8 orders of magnitude slower than Ar diffusion in K-feldspar, indicating that K-feldspars will be much more retentive of Ca chemical signatures than of Ar. As an example, 1 mm diameter feldspar grains will experience ∼50% Ar loss in 1500 years at 500 °C, while Ca loss of only 1% would require 100 million years at this temperature.

The Effect of Reduced Graphene Oxide (rGO) Coating on Electrical Conductivity of Lithium Ferro Phosphate (LFP) as an Alternative Cathode for Li-Ion Battery

In this study an investigation has been conducted on the effect of reduced graphene oxide (rGO) coating on increasing the value of Lithium Ferro Phosphate (LFP) electrical conductivity. This coating process uses a variation of the mass ratio of LiFePO4/rGO by 90%:10%, 70%:20%, and 67%:33%. The LiFePO4 precursor was prepared using the sol-gel rute from the main commercial materials, namely Li2CO3 powder as a source of lithium ions, FeCl2.4H2O as a source of iron and NH4H2PO4 powder as a phosphate source. As for the coating used rGO extracted from coconut shell waste. The samples were calcined with temperature variations of 600°C, 650°C and 700°C in an argon environment for 10 hour. The phase purity and crystal structure of LiFePO4 were analyzed using XRD. The analysis of data from XRD was done using the the Match!, Rietica, and MAUD software. Based on the results of XRD analysis, LiFePO4 with high purity and good crystallinity was obtained when the sample was calcined at temperature of 700°C. The results of the MAUD analysis show that the best size of LiFePO4 crystal is 86,54 nm. LiFePO4/rGO nanocomposite was successfully synthesized by mechanical ultracentrifugation method. The characterization of the value of electrical conductivity, carried out using a four-point probe. The results show that the greater the percentage of rGO, the higher the value of electrical conductivity. The mass ratio of 67% LiFePO4 and 33% rGO shows an increment in good conductivity values, from the original order of 10-8 S/cm to the order of 10-4 S/cm.

Prediction of the JC (B) Behavior of Bi-2212 Wires at High Field

Bi-2212 wires have been produced for much of the last decade with varying architectures, powder sources, and great variability of final J C (B) properties. As Bi-2212 transitions from an R&D materials development to a magnet technology, means to predictably forecast J C (B) becomes increasingly valuable. Here we report on characterizations of short samples having J C (15 T, 4.2 K) varying from 1210 to 6560 A/mm 2 , measured in fields up to 31 T, and drawn from 10 billets. Using both 4 K transport and variable temperature vibrating sample magnetometer measurements, capable of probing the 20 K irreversibility field, B irr = μ 0 H k , we found that the vortex pinning properties are very stable across these wires, which all used the same standard powder composition (Bi 2.17 Sr 1.94 Ca 0.89 Cu 2.00 O 8+ x ), even though it has been made by three different manufacturers over nine years. We conclude that a power-law fit J C ∝ B -α , where α = 0.280 (σ = 0.015), works well at 4.2 K over the field range of at least 3-30 T and that μ 0 H k (20 K) remains stable at 8.6 ± 0.4 T. We conclude that the dominant current limiting mechanism predicting J C (B) in Bi-2212 is the effective filament connectivity. J C (B) at high fields may thus be predicted by simple I C measurements at easily accessible fields in the 3-15 T range.

Polytype Control by Pretreatment of SiC Source Powder for 4H-SiC Single Crystal Growth

4H-SiC single crystal was successfully grown with source powder modified by the pretreatment process in order to improve polytype stability of SiC crystal. To increase C/Si ratio in SiC source powder, SiC source powder was mixed with liquid carbon source and then pre-heated at 1200°C. SiC single crystal grown with modified source powder exhibited complete 4H polytype and the crystal quality of SiC crystal grown by modified source power was definitely better than conventional source powder

Optimization of the SiC Powder Source Size Distribution for the Sublimation Growth of Long Crystals Boules

The influence of four different SiC source powder size distributions on the sublimation behavior during physical vapor transport growth of SiC was studied. The growth processes were carried out in a 3 inch crystal growth setup and observed in situ using advanced 3D computed tomography X-ray visualization. The single modal D90 size distribution of two source powders was 50 μm and 200 μm, respectively, with a corresponding average powder density of 1.17 g/cm3. The third source powder consisted of a blend of the previously named powders and exhibited an average powder density of 1.66 g/cm3 with a bimodal particle size distribution. The last source was composed of a solid polycrystalline SiC cylinder. The bimodal powder source exhibited a smoother morphology change and material consumption during the growth run and led to a much more stable shape change of the growth interface compared to the single modal source powders. The solid source featured the least morphology change. Therefore, with a careful adaption of the source material stable growth conditions can be achieved.

Variation of Vanadium Incorporation in Semi-Insulating SiC Single Crystals Grown by PVT Method

Two SiC crystals were grown using SiC source powder with different level of purity and then the effect of the purity of SiC source materials on the final electrical properties has been systematically observed. Furthermore, the variation of vanadium amount according to the growth direction of vanadium doped semi-insulated SiC single crystals has been investigated. The quality of SiC crystal grown using SiC source powder with higher purity was definitely better than SiC crystal with lower purity. SiC crystals having an average resistivity value of about 1×1010 Ωcm were successfully obtained. In the result of COREMA measurement, the use of high purity SiC powder was revealed to obtain wafers with better uniformity in resistivity value.

Fabrication and characterization of mesoporous Si/SiC derived from diatomite via magnesiothermic reduction

In the past few decades, SiC and Si have been widely researched via different methods due to their unique electrical conductivity, stable physical-chemical performance and good wear-resisting performance. In this paper, we firstly used diatomite as silica source and carbon powders as carbon source to synthesize mesoporous Si/SiC via magnesiothermic reduction reaction at relative low temperature (650 °C). All samples were characterized by XRD, SEM, TEM and N2 adsorption-desorption. The XRD patterns and TEM images confirmed that diatomite was fully transformed into Si and SiC. N2 adsorption-desorption isotherms shown that Si/SiC exhibited mesoporous structure. Brunauer-Emmett-Teller (BET) gas adsorption data showed that Si/SiC had a specific surface area of 69.09 m2/g and an average pore size about 10.82 nm. The results confirmed that diatomite can fully transformed into Si/SiC. The possible chemical reactions of magnesiothermic synthesis of mesoporous Si/SiC is also discussed.

Influence of the Mechanical Activation of Reaction Mixture on the Formation of Microstructure of ZrB2–CrB Composites Obtained by Electrothermal Explosions under Pressure

The ZrB2–CrB composites with a ceramic bond content of 80 wt.% and a relative density of 0.85 – 0.90 were obtained by the method of electrothermal explosion under pressure. It is shown that the mechanical activation of the source powder mixture decreases its heterogeneity and increases its reactivity.We also obtained a finely divided ceramic composite with homogeneous microstructure containing needle-like ZrB2 grains.

Determination of conversion factors of SPECT hot images respect to hot objects in bone medium: preliminary study using in house phantom

The purpose was to determine conversion factors (CF) of SPECT hot images respect to the original size of hot objects in the bone medium. In house phantom has been made in the form of a cubical acrylic (37cm x 15cm x 15cm) provided with cylindrical channel filled with bovine bone powder with the diameter (1.5; 3.5; 5.4; 7.4 cm). As hot objects, a mixture of bone powder and 99mTc source with various activity and diameter were embedded in filled bone channels. Image acquisitions were carried using Intevo Symbia E Siemens SPECT/CT and LEHR collimator, with surface collimator distance 9.6 cm. There were 6 different in activities and diameter of hot objects in each channel. Conversion factor (CF) was defined as the ratio between FWHM of hot object image profile and the original hot object size. CF value for each diameter channel was varied with the activity and size of the object diameter. The source activities used were 0.1-0.2 mCi and the observed object diameters were 7-12 mm. For hot object size less than resolution stated in SPECT specifications (4 mm), CF values were in the range 1.7-3.4 for 1.5 cm and 3.5 cm channel diameter. For hot objects diameter, 7.5-12 mm, CF value was mostly independent of channel diameters, with the value of (1.1 ± 0.2). This preliminary study informs that CF values of SPECT hot images independent with the size of the host bone medium. Whereas for object diameter ≤ 7.5 mm very relatively higher and influenced by the size of the host bone medium.

Influence of plasma spraying parameters on microstructure and corrosion resistance of Cr3C2-25NiCr cermet carbide coating

PurposeIn this work, Cr3C2-25NiCr coatings were deposited on 410 stainless steel substrate by using the atmospheric plasma spray technique, at varying spaying parameters. The porosity and microhardness, adhesion strength and corrosion behaviour of coatings were examined in relation to these spraying parameters.Design/methodology/approachThe microstructure of prepared coatings was examined by using scanning electron microscopy. The coating compositional analysis was performed by using X-ray diffraction (XRD) technique. The corrosion resistance of coated steel was investigated by potentiodynamic polarization. Results indicate that optimal factors for minimalizing the porosity were as follows: 10 g/min feed rate, 600 A plasma current and 100 mm spraying distance. The spraying factors influencing corrosion resistance of coating were also evaluated.FindingsUnder this optimal condition, the porosity of coating reached its minimal value of 3.1 per cent. The microhardness and adhesion of coatings also reached their maximum values of 64.8 Rockwell Hardness scale C and 60 MPa, respectively. XRD results indicated the transformation of Cr3C2originating from Cr3C2-25NiCr source powder into Cr7C3and Cr23C6crystalline phases, due to the high temperature during spraying process. The undetectable Cr3C2peaks indicating that this phase was remained in coating at very low concentrations. The potentiodynamic polarization and salt spray tests confirmed the highest corrosion resistance for the coating prepared by optimal spraying parameters.Originality/valueThe application of Cr3C2-NiCr cermet carbit coating for protection of steel from corrosion-erosion is very promising.

Suitability of electrical discharge machining debris particles for usage as a powder for selective laser melting: an explorative study

In this study, the properties of debris particles originating from Electrical Discharge Machining (EDM) processes are investigated. The question is addressed whether these particles are suitable to serve as a raw material for Selective Laser Melting (SLM). To this end, different EDM parameter sets were used to manufacture particles with different size distributions. After de-oiling, the resulting powders were examined by dynamic image analysis. Results show that EDM can produce particles with high sphericity. Moreover, particle size distribution can be controlled by EDM parameters. In summary, EDM-manufactured particles seem to be a promising source of powders for the SLM process.

Enhanced energy storage properties in A-site substituted Na0.5Bi0.5TiO3 ceramics

Detailed temperature-dependent structural, dielectric, piezo/ferroelectric, and energy storage properties were explored for the poled (Na0.5-xKxBi0.5-xLax)TiO3 (0 ≤ x ≤ 0.12) ceramics fabricated via a modified sol-gel method. Structural analysis of synchrotron source powder XRD data revealed the rhombohedral (R3c) phase for poled x ≤ 0.03 compositions. Whereas for x ≥ 0.06 samples confirmed structural transition, a mix of rhombohedral and tetragonal (P4bm) phase exists at room temperature. As a function of composition, a rhombohedral phase is found to be suppressed and the tetragonal phase promoted. Dielectric measurements corroborate that at room temperature; dielectric constant was increased with substitution. High-temperature dielectric measurement confirmed the reduction in phase transition temperatures and an increase in the diffuseness of dielectric anomalies with increasing content of K/La. Piezo/ferroelectric measurements revealed that x = 0.03 composition exhibits excellent piezo/ferroelectric properties (piezoelectric coefficient, d33 ∼ 115 pC/N, remnant polarization, 2Pr ∼ 56 μC/cm2, and coercive field, 2Ec ∼ 100 kV/cm) at room temperature. Antiferroelectric ordering improved the energy storage density and efficiency at room temperature (∼0.05 J/cm3, ∼2.6% (for x = 0) to ∼ 0.74 J/cm3, ∼87% (for x = 0.12)) and elevated temperature. For x = 0.06 sample, excellent energy storage density and efficiency ∼1.10 J/cm3 and ∼70% respectively, are obtained at 120 °C. Superior energy storage efficiency showed by x = 0.12 (∼87–∼93%, in the temperature range 30–140 °C) with almost thermally stable energy storage density (from ∼0.74 J/cm3 to ∼ 0.71 J/cm3). These drastic improvements in properties were explained in terms of structural changes as a function of composition and temperature. Observed properties suggest that substituted materials are promising candidates for piezoelectric (for x = 0.03) and energy storage (for x ≥ 0.06) applications.

Phosphate solubilizing characteristics of Talaromyces aurantiacus and its growthpromoting effect on Phyllostachys edulis seedlings

To investigate phosphate-solubilizing characteristics and plant growth-promoting effect of Talaromyces aurantiacus (JXBR04) from Phyllostachys edulis rhizosphere soil, the influence of culture time, carbon sources, nitrogen sources, initial pH, liquid filling volume, and salt ions on phosphate solubilizing ability of strain JXBR04 were examined. The capability to solubilize different types of mineral phosphate was detected using a liquid fermentation method. A pot experiment was conducted to evaluate the effects of strain JXBR04 in promoting the growth of Ph. edulis seedlings. The results showed that strain JXBR04 displayed the highest phosphate-dissolving capacity when the cultivation period was 7 days, the initial pH reached 3.5, the volume of liquid was 1/5 or 2/5, and the NaCl concentration was 0 or 1.0 g·L-1. The phosphate-dissolving ability of the strain was the highest when using sugar as carbon source and yeast powder as nitrogen source. The strain had the greatest ability to solubilize CaHPO4 with 1304.04 mg·L-1, followed by Ca3(PO4)2 and FePO4. We found that available nutrients, leaf, stem, and root phosphorus contents in rhizospheric soil significantly increased in Ph. edulis after 180 days of inoculation with strain JXBR04. In addition, Ph. edulis inoculated with strain JXBR04 had 28.1%, 28.3%, and 51.5% higher ground diameter, seedling height, and biomass accumulation than that without JXBR04, respectively. Our findings suggested that T. aurantiacus has the potential to be applied as environment-friendly biofertilizers in maso bamboo forest in the acid soil in southern China.

Application of Particle Swarm Optimization (PSO) algorithm for Black Powder (BP) source identification in gas pipeline network based on 1-D model

Black Powder (BP) is a worldwide challenge that spans all stages of the natural gas industry from the producing wells to the consuming points. It can endanger the pipeline operations, damage instruments and contaminate customer supplies. The formation of BP inside natural gas pipeline mainly results from the corrosion of internal walls of the pipeline, which is a complex chemical reaction. This work aims to develop a novel algorithm for BP source identification within gas pipelines network based on a 1-D model of BP transport and deposition. The optimization algorithm for BP source identification is developed based on the well-known Particle Swarm Optimization (PSO) algorithm, which can solve constrained optimization problems. By applying this optimization algorithm on the gas transmission pipeline network, the BP source at different junctions could be identified and quantified simultaneously. Extensive simulation studies are conducted to validate the effectivity of the optimization algorithm.

Effect of Hydrocolloids on Rheological Properties and Printability of Vegetable Inks for 3D Food Printing.

In food ink systems in which the particles are dispersed in a hydrocolloid matrix, the source of the particles and the particle content are the main factors affecting the printability and rheological properties of the system. In this study, different contents (10% and 30% w/w) of vegetable (broccoli, spinach, or carrot) powders were added to hydrocolloid matrices with different hydration properties, and their influence on the printability and rheological properties was investigated. At low powder contents (10%), slight differences in the printability and rheological values were observed between the different vegetable sources in all hydrocolloids. When the powder content was increased to 30%, the hydrocolloid with the lowest water hydration capacity, hydroxypropyl methylcellulose, showed the greatest differences in rheology and printability when different vegetable sources were used. Xanthan gum, with its higher water hydration capacity, inhibited the swelling of the particles, thus minimizing the increase in the rheological values at high volume fractions of powder and reducing the differences in printability between different vegetable sources. Confocal laser scanning microscopy analysis of the vegetable inks showed that xanthan gum inhibited swelling of the particles regardless of the vegetable powder source. The mixtures using xanthan gum could be smoothly extruded from the nozzle due to their low extruded hardness (2.96 ± 0.23 to 3.46 ± 0.16 kg), and the resulting objects showed high resolution without collapse over time. PRACTICAL APPLICATION: The powder-based texturization technology introduced in this study provides a standardized method of preparing food ink that can be universally applied to all food materials that can be powdered. In addition, the present invention can be applied to a 3D printing technique in which a powder and a hydrocolloid matrix are independently stored and mixed immediately before printing. This technique can minimize the inherent rheological differences between formulations with different food sources and compositions.