Constituent Powders Research Articles

Experimental investigation of mechanical and tribological properties of Aluminium metal matrix composites fabricated by powder metallurgy route – A review

Additive manufacturing is being viewed as the future of manufacturing and is one of the most actively explored cutting edge research area in manufacturing. Powder metallurgical technique has the unique advantage of near net shape manufacturing, getting rid of finish machining processes and hence material wastage. Mechanical alloying is the solid state alloying technique that combines constituent metal powders, via powder metallurgical route, ending up with alloys that are quite comparable to traditionally manufactured alloys. Metal powders are blended with a help of ball mill to achieve a standardised distribution, prior to compaction. Hybrid metal matrix composites exhibit two different secondary phases distributed in the primary phase, exhibit interesting behaviour and are worthy to be explored in the area of composite research. This review delineates various such literatures about mechanical alloying of aluminium with different constituent alloying metals and compounds and the outcomes of such works, in comparison to traditionally fabricated alloys.

Facile green synthesis of silver oxide nanoparticles and their electrochemical, photocatalytic and biological studies

In the recent times, cost-effective and eco-friendly processes of synthesizing nanoparticles (NPs) have emerged as a substitute to conventional synthetic methods. Several research groups in the past have synthesized silver oxide (Ag2O) nanoparticles from various plant extracts and have been extensively reported. A first of its kind facile green combustion method has been adopted here to synthesize Ag2O NPs using Centella Asiatica and Tridax plant powder. The unique pentacyclic and triterpene constituents of Centella Asiatica and tridax powder has kindled our curiosity to explore their electrochemical, photocatalytic and biological activities that may contribute to various environmentally benign industrial applications. The cyclic voltammetric studies show that the cathodic and anodic peak potentials for the synthesized Ag2O NPs exhibit hysteresis in the range of 0.3 V to −0.1 V. A high percentage of degradation of acid orange 8 (AO8) dye by the synthesized Ag2O NPs offers new hope on its potential photocatalytic activity. Finally, their anti-bacterial and anti-fungal activities carried out against S. epidermidis and S. aureus and A. fumigates and A. aureus respectively, have shed new light on the ability of the synthesized Ag2O NPs to inhibit the growth of various disease-causing pathogens. Hence, it is believed that this research work will act as a fundamental basis to various researchers and industrialists working in the energy, water and biological fields to carry out advanced studies in the aforementioned domains.

Phase evolution, structure, and magnetic characterization of mechanosynthesized Co40Fe30Ni30 medium-entropy alloy

We demonstrate Co40Fe30Ni30 medium-entropy alloy is a suitable Co-rich ternary CoxFeyNiz (x ≥ y ≥ z) alloy precursor for designing high-entropy magnetic alloys having superior semi-hard magnetic properties. Mechanical alloying of the constituent metal powders 40 at.% Co, 30 at.% Fe, and 30 at.% Ni for 12 h resulted in a nanocrystalline Co40Fe30Ni30 alloy comprised of the γ phase. The alloy exhibited semi-hard magnetic behavior at ambient temperature; the intrinsic coercivity (HCI) and saturation magnetization (MS) was ~4.35 kA/m and ~141 Am2/kg, respectively. At sub-ambient temperatures, the alloy maintained semi-hard magnetic behavior; both HCI and MS increased by ~1.4 times and ~4%, respectively, from 300 K to 60 K. The estimated μH (the maximum magnetic moment per atom) was ~1.51 μB. At elevated temperatures, up to T ≤ ~570 K, the as-prepared alloy powder maintained the γ phase, and after that α phase precipitated out. Thermal-treatment increased MS by ~13% and decreased HCI by ~31%, yet the alloy retained semi-hard magnetic behavior. At cryogenic temperatures, the thermally-treated alloy powders exhibited magnetic behavior similar to that of as-prepared alloy powder, i.e., both HCI and MS increased with the decrease in T. Grey relational analysis proposed Co40Fe30Ni30 as a suitable medium-entropy alloy precursor for designing novel high-entropy magnetic alloys having superior semi-hard magnetic properties.

Reactive flash spark plasma sintering of high-entropy ultrahigh temperature ceramics

A new Reactive Flash Spark Plasma Sintering (ReaFSPS) method has been developed to synthesize high-entropy ultrahigh temperature ceramics (UHTCs), using (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2 and (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)C as examples. X-ray diffraction, energy dispersive X-ray spectroscopy, and electron backscatter diffraction collectively show the formation of a single high-entropy phase within ~2 min. Notably, adding 3 wt.% of carbon can promote the formation and homogenization of a high-entropy diboride phase without aggressive mechanical alloying, achieving a >99% relative density. This work has established a new rapid and potentially scalable method to use ReaFSPS to synthesize homogenous high-entropy UHTCs from commercial powders of individual constituents.

Phyto-Chemicals of Some Plants Powder as Anti-Insects Agents against Cowpea Weevils Callosobruchus Maculatus Coleoptera: Bruchidae

In this study, leaves powder of Lamium purpureum, Cyperus retrorsus, Lantana camara, Helianthus annuus, Citrus aurantifolia and Cestrum nocturnum were screened for secondary metabolite constituents and insecticidal activity against Cowpea weevils (Callosobruchus maculatus).Phytochemicals screening of the powder revealed the presence of alkaloids, terpenoids, flavonoids, tannins, saponnins, phytosteroids, phenolic compounds, proteins and aminoacids, oil and fats as well as reducing sugars in the plants investigated. Alkaloids were absent only in C. retrorsus, H. annuus and C. nocturnum, Flavonoids were absent in L .purpureum, C. retrorsus, H. snnuus and C. nocturnum, Terpenoids were absent in C. retrorsus and C. nocturnum, saponnins were absent in C. retrorsus only, Phenolic compounds were absent only in H. annuus, Phytosterols were absent in L.purpureum, C. retrorsus and C. nocturnum. Proteins and amino acids were present only in L. purpureum and H. annuus. Oil and fats were absent in C. retrorsus and C. nocturnum while reducing sugars were absent in L. purpureum, C. retrorsus and C. nocturnum. The plants powder indicates insecticidal activity in a dose dependent manner, higher doses has stronger effect, all the experimental plants caused significant mortalities (p<0.05) of the C. maculatus. LD50 (g) showed thatH. annuus (6.2)andC .nocturnum (6.2) were most toxic to C. maculatus than L. purpureum (9.7), C. aurantifolia (12.8) andL. camara (12.8) were more toxic than C. retrorsus (18.2) which was least toxic to adults of C. maculatus. Therefore, these phytochemical constituents of plants powder have potential to be used as control agents of C. maculatus infestations and could be use as replacement or supplements to conventional chemical insecticides which price, availability and technology of applications may be out of reach to poor farmers.

Metal Constituents of E-Waste Black Powder and Its Potential Utilization

Metal Constituents of E-Waste Black Powder and Its Potential Utilization

Black soldier fly (Hermetia illucens) larvae powder as a larval diet ingredient for mass-rearing Aedes mosquitoes.

The mass production of mosquitoes is becoming more wide-spread due to the increased application of the sterile insect technique (SIT) and other genetic control programmes. Due to the variable availability and high cost of the bovine liver powder (BLP) constituent of many current larval diets, there is an urgent demand for new ingredients in order to support sustainable and efficient mosquito production while reducing rearing cost, without affecting the quality of the insects produced. Two black soldier fly (BSF) powder-based diet formulations (50% tuna meal, 35% BSF powder, 15% brewer’s yeast and 50% tuna meal + 50% BSF powder) were tested for their suitability to support the development of Aedes aegypti and Ae. albopictus mosquitoes in mass-rearing conditions. Overall, the results indicate that the use of the BSF powder did not negatively impact the development and quality of the produced insects in terms of time to pupation, adult production and male flight ability. Furthermore, depending on the species and diet formulations, there were improvements in some parameters such as female body size, egg production, egg hatch rate and male longevity. BSF powder is a valuable ingredient that can effectively replace costly BLP for the mass production of high quality Ae. aegypti and Ae. albopictus mosquitoes. Both diet formulations can be used for Ae. aegypti showing high plasticity to nutrition sources. However, for Ae. albopictus we recommend the combination including brewer’s yeast.

An Experimental Investigation on the Effect of Sintering Temperature and Holding Time to the Characteristics of Fecual Powder Compacts Formed at Elevated Temperature

This paper presents the experimental investigation on the effect of sintering schedule to the final properties of FeCuAl powder compacts formed at elevated temperature through a lab-scale uniaxial die compaction rig. Iron (Fe) powder ASC100.29 was used as a main powder constituent and mixed with elemental powders which are copper (Cu) and aluminum (Al). The weight percentage of powder mass was divided into four, i.e., iron (91.7 wt%), copper (7.5 wt%), aluminum (0.5 wt%), and zinc stearate (0.3 wt%) as lubricant. All the powders were mixed through mechanical blending at a rotation speed of 30 rpm for 30 min. The mixed powder mass was compacted at 150˚C by 425 MPa of axial loading from upward and downward simultaneously. Subsequently, the defect-free green compacts were sintered under controlled argon gas atmosphere at three different sintering temperatures, i.e., 800˚C, 900˚C and 1000˚C for 120 min, 150 min and 180 min, respectively at constant sintering rate of 10˚C/min. Afterwards, the sintered samples were characterized for their physical properties, electrical properties, mechanical properties and their microstructures were evaluated. The results revealed that higher flexure stress was acquired by sample sintered at 1000˚C for 120 min and their microstructures were found to be better, i.e., the particles were bonded perfectly.

Analysis and classification of smokeless powders by GC–MS and DART-TOFMS

Partially burned smokeless powder particles may be present as a form of evidence following a shooting or explosive event, such as the explosion of a pipe bomb. The characterization and classification of residual smokeless powers may allow for a known sample, i.e. sample collected from a suspect, to be connected to an unknown sample, i.e. sample obtained from a crime scene. In this study, thirty-four (34) smokeless powders were analyzed using GC–MS and DART-TOFMS to determine how comparable the discriminatory power of each instrument was based on the smokeless powder constituents identified within each sample. Analysis of smokeless powders by DART-TOFMS generated comparable results to GC–MS in a fraction of the time (∼30seconds). Most peaks observed between the instruments were the same; however, N-nitroso-DPA was only observed in the DART-TOFMS spectra but was not a significant contributor. Samples were naturally grouped together using hierarchical cluster analysis and principal component analysis, based on underlying features in the resulting spectra. Samples were placed into groupings based on significant peaks observed and relative intensities. Classification models were presented for both GC–MS and DART-TOFMS and subsequently tested and compared. The classification models used in this study were linear discriminant analysis, k-nearest neighbors, and random forest modeling. The groups observed were similar between the two instruments, indicating that DART-TOFMS provides comparable data to GC–MS and could be used as a rapid screening technique.

Synthesis and Characterization of WC-6Co Nanocrystalline Composite Powder

WC-6Co nanocrystalline composite powders without excess C and decarburization phases were synthesized via a facile route including spraying conversion, calcination and in situ reduction-carbonization processes. The phase constituents obtained by XRD show that the as-prepared powders after each step of the preparation are amorphous, WO3 and Co3O4 phases, WC and Co phases, respectively. Pure WC-Co composite powders could be obtained by a reduction-carbonization process heat treated at 900 °C for 1 h under a hydrogen atmosphere due to the catalytic effect of Co on the carbonation reaction. The effects of heat treatment temperature on phase constituents of powders were investigated in a range of 700∼900 °C. Morphology and microstructure of powders were observed by SEM and HRTEM. The results indicate that the morphology of powder is spherical. The grain size of WC is about 0.36 μm, and the crystalline size of WC is about 56 nm, which indicates that the WC grain is polycrystalline and composed of many crystallites. It is also found that the individual particles of WC are bonded together under the action of Co. Furthermore, a few sintering necks could be observed in the composite powders due to the contacts between WC particles. The stoichiometry of WC-Co composite powders could be adjusted easily. Moreover, the formation process and mechanism of the sphere structure were also discussed in this paper.

Pharmacokinetic study of the major chemical constituents in Xanthoceras sorbifolia wood after oral administration of methanol extract, wood powder, and single constituents

ABSTRACTThe wood powder and extract of Xanthoceras sorbifolia are used to treat rheumatism, gout, and other diseases in Mongolian medicine. Information on the pharmacokinetic differences between various forms of the herb drug is needed. Eight Xanthoceras constituents were examined simultaneously in rat plasma by ultra liquid chromatography-triple quadrupole mass spectrometry. In vitro experiments were performed to determine the influence of digestive juices on the pharmacokinetic profiles. Epicatechin and dihydromyricetin had higher AUC values in rats that were gavaged with X. sorbifolia extract versus the pure compounds. The AUC value of epicatechin in rats that were gavaged with X. sorbifolia wood powder was higher than that with the methanol extract. The nonextractable epicatechin polymer in the wood powder could be degraded to epicatechin by gastric juice, consequently elevating the epicatechin levels in blood.

Enhanced reaction velocity and diluent homogenization in Redox Foils using arrested reactive milling thermite powder

Fully dense thermite foils, commonly referred to as Redox Foils, provide a unique opportunity to enable exothermic brazing of components by utilizing the molten metallic product of the thermite reaction as a braze. Due to the propensity of thermites to produce gas, however, Redox Foils must be diluted to eliminate metal vapor formation. This dilution can lead to foils that react too slowly to fully propagate in a bonding configuration, and therefore the reactivity of the foils must be improved. To do so, we milled the constituent powders (Al, Cu2O, and Cu) before we mechanically consolidated them into dense Redox Foils. The milling process decreases the reactant spacing, or the distance between the fuel (Al) and oxide (Cu2O), thereby enhancing oxygen transfer between the fuel and the oxide. Two fabrication strategies are employed: milling the thermite reactants (Al and Cu2O) without the Cu diluent, then adding the diluent before consolidation into Redox Foils, and the second is milling all components (Al, Cu2O, and Cu) together before consolidation. Both milling processes results in foils that propagate faster and release heat earlier than foils consolidated from unmilled, single-phase powders of Al, Cu2O and Cu, due to decreased reactant spacings. However, only the second milling strategy is capable of suppressing the production of Cu metal vapor during the reaction of the foils, as confirmed using emission spectroscopy. The lack of Cu vapor in these foils is attributed to a more uniform distribution of Cu diluent that is verified using digital analysis of foil microstructures.

Effect of Mechanical Activation on the In Situ Formation of TiB2 Particulates in the Powder Mixture of TiH2 and FeB

AbstractThe in situ formation of TiB2particulates via an interface reaction between Ti and FeB powders was studied. The effects of mechanical activation by high-energy milling on the decomposition of TiH2and the interface reactions between Ti and FeB powders to form TiB2were investigated. Powder mixtures were fabricated using planetary ball-milling under various milling conditions. The specific ball-milling energy was calculated from the measured electrical power consumption during milling process. High specific milling energy (152.6 kJ/g) resulted in a size reduction and homogeneous dispersion of constituent powders. This resulted in a decrease in the decomposition temperature of TiH2and an increase in the formation reaction of TiB2particulates in the Fe matrix, resulting in a homogeneous microstructure of nanoscale TiB2evenly distributed within the Fe matrix. In contrast, the powder mixture milled with low specific milling energy (36.5 kJ/g) showed an inhomogeneous microstructure composed of relatively large Fe-Fe2B particles surrounded by a thin layer of Fe-TiB2within a finely dispersed Fe-TiB2matrix region.

Dry Sliding Wear Behavior of the Reinforced by Graphite Particle and Heat Treated of Recycled Aluminum AA6061 Based MMC Fabricated by Powder Metallurgy Method

The micro-hardness and compression of recycling aluminum alloy AA6061 were investigated as a function of the different microstructure and constituent powder metallurgy method. Five specimens were selected to investigate the compression strength and microhardness. The first, as fabricated specimen (as compacted), the second was as heat treated by quenching and aging process. Three specimens were mixed with Graphite particles as a reinforcement material. Compression strength values were tested for the specimens as fabricated and heat treated which were 195 and 300 MPa, respectively. The improvement ratio was 52% for the specimen as heat treated. On the other hand, high wear resistance was given by the specimen as heat treated, whereas, the lower wear strength was at the specimen mixed with 4.5% Graphite. These results were attributed to that the wear resistance related to the microhardness value.

Microstructural characterization and properties of Ti-28Ta at.% powders produced by plasma rotating electrode process

Ti-28 at.%Ta powders were produced by rapid solidification via plasma rotating electrode process (PREP). It is found that microstructure, morphology and phase constituents of Ti-28Ta powders are particle size dependent. Small powder particle exhibit the formation of predominant martensitic α” and minor metastable β, whilst large particles consist of primary metastable β with minor martensitic α” phase. The amount of martensitic α” increases while the amount of metastable β phase decreases with decreasing the particle size. The martensitic α” lath with the size of about 50 nm wide and 1 μm long are formed preferentially at the β grain boundaries. The martensitic transformation start temperature (Ms) and peak temperature (Mp) are ∼390 °C and ∼340 °C respectively for the Ti-28Ta powders with the particle size between 40 and 65 μm. An increased Vickers micro-hardness is obtained and is associated with decreasing particle size.

Modulating Oxidative Stress Relieves Stress-Induced Behavioral and Cognitive Impairments in Rats.

Background:Persistent psychological stress often leads to anxiety disorders and depression. Benzodiazepines and selective serotonin reuptake inhibitors are popular treatment options but have limited efficacy, supporting the need for alternative treatment. Based on our recent preclinical work suggesting a causal link between neurobehavioral deficits and elevated oxidative stress, we hypothesized that interventions that mitigate oxidative stress can attenuate/overcome neurobehavioral deficits.Methods:Here, we employed the rat social defeat model of psychological stress to determine whether increasing antioxidant levels using grape powder would prevent and/or reverse social defeat-induced behavioral and cognitive deficits. Furthermore, a hippocampal-derived HT22 cell culture model of oxidative stress was employed to identify the individual beneficial constituent(s) of grape powder and the underlying mechanism(s) of action.Results:Grape powder treatment prevented and reversed social defeat-induced behavioral and cognitive deficits and also decreased social defeat-induced increase in plasma corticosterone and 8-isoprostane (systemic and oxidative stress markers, respectively). And grape powder treatment replenished social defeat-induced depleted pool of key antioxidant enzymes glyoxalase-1, glutathione reducatse-1, and superoxide dismutase. Grape powder constituents, quercetin and resveratrol, were most effective in preventing oxidative stress-induced decreased cellular antioxidant capacity. Grape powder protected oxidative stress-induced cell death by preventing calcium influx, mitochondrial dysfunction, and release of cytochrome c.Conclusions:Grape powder treatment by increasing antioxidant pool and preventing cell damage and death prevented and reversed social defeat-induced behavioral and cognitive deficits in rats. Quercetin and resveratrol are the major contributors towards beneficial effects of grape powder.

Development of Carrot Medium Suitable for Conidia Production of Venturia nashicola.

The causal fungus of pear scab, Venturia nashicola, grows slowly and rarely produces conidia on artificial media in the laboratory, but it produced conidia on the Cheongah medium containing Cheongah powder. V. nashicola grew too slow to produce conidia until 15 days after cultivation but produced conidia with 4 × 104 conidia/plate 30 days after cultivation on the Cheongah medium containing 1% Cheongah powder. V. nashicola showed a peak production of conidia with 4.5 × 105 conidia/plate 60 days after cultivation on the carrot medium containing 2% carrot powder, one of the constituents of Cheongah powder. The carrot medium is considered to be the best medium to obtain conidia of V. nashicola in the laboratory until now. This is the first report on the development of a suitable medium for conidia production of V. nashicola, as far as we know.

Modulation of some markers of erectile dysfunction and malonaldehyde levels in isolated rat penile tissue with unripe and ripe plantain peels: identification of the constituents of the plants using HPLC

Context: Plantain fruit pulp has been used as a natural remedy to manage erectile dysfunction (ED) in traditional medicine. However, the potency of the peel has not been examined with respect to ED management. Objective: This study investigated and compared the inhibitory potential of unripe (UPP) and ripe (RPP) plantain peels on some enzymes associated with ED and Fe2+-induced oxidative stress in albino rat penile homogenate in vitro. Materials and method: Aqueous extract of the peels was prepared and the effect on phosphodiesterase-5 (PDE-5), arginase, acetylcholinesterase (AChE), angiotensin-I converting enzyme (ACE) and Fe2+-induced malonyladehyde in isolated albino rat penile homogenate were investigated. Phenolic constituents of the peels powder were characterized using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). Result: Extract from UPP had higher PDE-5 (IC50 = 3.10 μg/mL), arginase (IC50 = 0.96 μg/mL), AChE (IC50 = 6.30 μg/mL) and ACE (IC50 = 0.41 μg/mL) inhibitory ability compared with RPP (PDE-5, IC50 = 4.33 μg/mL; arginase, IC50 = 1.34 μg/mL; AChE, IC50 = 8.64 μg/mL; ACE, IC50 = 0.63 μg/mL). The extract from UPP also had higher inhibition of Fe2+-induced lipid peroxidation. HPLC-DAD analysis revealed that gallic and caffeic acids, rutin, quercitrin and quercetin were abundant in UPP, while catechin, kaempferol, chlorogenic and ellagic acids were the dominant phenolic compounds in RPP. Discussion and conclusion: Inhibition of enzymes associated with ED and lipid peroxidation could be linked with the phenolic compounds. However, UPP appeared to be more potent.

Mechanical properties of (TixW1−x)C–Co cermet prepared by carbothermal reduction of high energy ball milled TiO2–WO3–C

A series of solid–solution carbides, (TixW1−x)C (x=0.9, 0.8, 0.7, 0.6), was prepared by the high-energy milling of TiO2–WO3–C mixtures via subsequent carbothermal reduction. With high-energy milling, only the size reduction of the constituent powders was apparent without any chemical reaction. The milled mixture powder was transformed to a single–phase (TixW1−x)C solid solution by heat treatment in a vacuum at 1200°C. (TixW1−x)C–Co cermets were consolidated by isothermal sintering at 1300, 1400, and 1500°C. The powders were fully densified by liquid-phase sintering at 1500°C because the Co melted at 1430°C. The mechanical properties of the (TixW1−x)C–Co cermet (Hv: ~24GPa) were significantly better than those of the conventional WC–Co (Hv: ~13GPa) or TiC–Co cermets (Hv: ~16GPa). The use of a solid–solution carbide instead of conventional WC almost doubled its hardness values without a loss of toughness. It is indicated that the improved hardness of the (TixW1−x)C–Co cermet originates from the high hardness of (TixW1−x)C, and the solid–solution carbide would be a valuable substitute for conventional carbide cermets.

Direct observation of grain rotations during coarsening of a semisolid Al–Cu alloy

Sintering is a key technology for processing ceramic and metallic powders into solid objects of complex geometry, particularly in the burgeoning field of energy storage materials. The modeling of sintering processes, however, has not kept pace with applications. Conventional models, which assume ideal arrangements of constituent powders while ignoring their underlying crystallinity, achieve at best a qualitative description of the rearrangement, densification, and coarsening of powder compacts during thermal processing. Treating a semisolid Al-Cu alloy as a model system for late-stage sintering-during which densification plays a subordinate role to coarsening-we have used 3D X-ray diffraction microscopy to track the changes in sample microstructure induced by annealing. The results establish the occurrence of significant particle rotations, driven in part by the dependence of boundary energy on crystallographic misorientation. Evidently, a comprehensive model for sintering must incorporate crystallographic parameters into the thermodynamic driving forces governing microstructural evolution.