Micron Powders Research Articles

Clinical Efficacy of Pathyadi Kwath Arka & Katphala Churna Nasya in the Management of Ardhavabhedaka with special reference to Migraine - A pilot Study

Ardhavabhedaka can be correlated with migraine having similar symptom as half-sided headache. It is mentioned as tridoshapradhana by Sushruta and vatakaphapradhana by Vagbhata. Pathyadi Kwath is a proven formulation for urdhwajatrugata disorders including Ardhavabheaka. In addition, importance of Nasya karma in shirogata vyadhi cann’t be ignored so here pradhamana nasya with kataphala churna mentioned in Yogaratnakara is selected to evaluate its efficacy. Aim & Objective: The present study aimed to evaluate the clinical efficacy of Pathyadi Kwath Arka & Katphala Churna Nasya in the management of Ardhavabhedaka with special reference to Migraine. Material and method: The fruit of haritaki, bibhitaki, Amalaki, stem bark of nimba, whole plant of bhunimba, rhizome of haridra and stem of guduchi were used for the preparation of Pathyadi Kwath and its extract (arka) was prepared using the same ingredients by the process of distillation. Course powder of Kataphala was prepared in grinder, then filtered from mesh size 500 micron (BS 30, ASTM 35) and smooth powder of Kataphala obtained. Botanists carried out authentication of drugs. The study conducted on 10 samples for the duration of 12 weeks. Pathyadi kwath given in the dose of 10 drops/ 10 ml of water and kataphala churna pradhaana nasya; morning and evening daily. Result: Statistically significant p value was noted i.e.(P<0.05), the null hypothesis is accepted, hence it is clear that all the parameters show a significant difference in the observations (before treatment and after treatment). Conclusion: Pathyadi Kwath Arka & Katphala Churna Nasya is effective in the management of Ardhavabhedak.

Iron Powders as a Potential Material for Arsenic Removal in Aqueous Systems

Iron powders due to their wide spectrum of applications is one of the potential materials of all time. Water remediation is one of the prominent and widely explored applications of iron. Arsenic is one of the most common and life-threatening pollutants present in the globe. Ingestion of arsenic contaminated products, especially water containing arsenic above 10 ppb results in acute health disorders. Due to its existence in various oxidation states such as As(V), As(III), As (0), As(-III), arsenic removal from aqueous systems is not a straightforward problem to solve. Among various materials which assist arsenic removal, iron powders due to their low cost, high reactivity, commercial availability, multiple mechanisms of removal, reusability and on-site usage, is one of the prominent and lucrative treatment medias. Iron powder employs one or combination of oxidation, reduction, adsorption, precipitation and co-precipitation mechanisms for the arsenic removal. Physico-chemical properties (purity, size, etc.) of powders along with aqueous system properties (pH, oxygen, contaminants, etc.) play a significant role in steering the arsenic removal. Iron powders from electrolytic and reduction routes are largely preferred for water remediation. This review is first of its kind work highlighting the potential of micron and macro scale iron powders in water remediation, especially arsenic removal. Special emphasis is given on the different routes of synthesis, mechanisms of removal, research evolution and commercial presence of iron powders for water remediation.

One-step mechanical exfoliation and deposition of layered materials (graphite, MoS2, and BN) by vacuum-kinetic spray process

The exfoliation of micron-layered materials to few-layered nanosheets is still a great challenge due to their widespread use in various applications. Herein, we provide a new approach for one-step mechanical exfoliation and deposition of graphite, MoS2, and boron nitride at room temperature. The essence of this technique is that the shock compaction wave produced by the micron powder impact with the hard substrate at a high velocity induces fragmentation and exfoliation of layered materials. The lattice expansion due to removal of stacked layers and reduction of crystalline domain size in nanosized thin films is identified using x-ray diffraction and a high-resolution transmission electron microscope. Raman spectra of the nanostructured thin film indicate the improvement of disorder-related modes due to the kinetic-induced layer separation and powder fragmentation. X-ray photoelectron spectra analysis indicates the transformation of bond configuration from sp2 hybridization of bulk hexagonal structure to sp3 in the nanostructured thin film.

The Facile Three-Dimensional Printing of the Composite of Copper Nanosized Powder and Micron Powder with Enhanced Properties.

Three-dimensional (3D) printing of Cu items is a new way to build up the structured Cu materials, but 3D printing of Cu items is usually a challenge because of the high melting point, high thermal conductivity, and high light reflection rate of Cu material. In this study, the composite of Cu microspheres powder and Cu nanoparticles (micro/nano Cu powder) is used to realize the 3D printing of Cu items with the selective laser melting technology. The sintering temperature and the thermal conductivity of micro/nano Cu powder are evidently decreased due to Cu nanoparticles' addition in the micron Cu powder. The results reveal that the 3D printing of 50%/50% micro/nano Cu powder needs laser power range of 100-240 W, which is in contrast to 200-340 W for 3D printing of 100% Cu microspheres powder. Furthermore, the conductivity, mechanical strength, and density of 3D-printed Cu items are improved with the addition of Cu nanoparticles into the micron Cu powder. The increasement of 34% on electrical conductivity and 17% on tensile strength are reached by the addition of 50% Cu nanoparticles with the laser power of 240 W.

Morphology characteristics and mechanical properties of hot-pressed micron/sub-micron boron carbide ceramics

Boron carbide (B4C), an important armored ceramic material with poor sinterability, is regarded as a potential bulletproof material for personnel and vehicles. Introducing sub-micron B4C powder into composite ceramics could be one approach to achieve promising high mechanical properties instead of micron and nano-grained B4C powders. Herein, sub-micron B4C powder was introduced into micron B4C powder as a “toughened phase” to construct additive-free sub-micron/micron mixed B4C ceramic via a hot-pressing process. The influence of sub-micron powder content on the relative density, microstructure and mechanical properties of the ceramics was investigated. For instance, the specimen containing 20% sub-micron B4C powder possessed enhanced mechanical properties with flexure strength of 488 MPa and fracture toughness of 3.48 MPa m1/2. Furthermore, transmission electron microscopy (TEM) analysis reveals that the pores of the obtained sub-micron/micron B4C specimens were round instead of triangular and smaller compared with no sub-micron powder added specimens, which guarantee the high relative density and enhanced mechanical properties. These findings clarify the importance of sub-micron B4C powder in increased mechanical properties and may pave a new way to design of armored protective ceramics.

Characterization of nano / micro bimodal 316L SS powder obtained by electrical explosion of wire for feedstock application in powder injection molding

Bimodal nano / micro powders are in demand in powder injection molding (PIM) and additive manufacturing (AM) technologies. Feedstocks with bimodal powder have a higher flowability, and the resulting products have a higher density.In this work, a bimodal 316L steel powder obtained by the electric explosion of a wire (EEW) was investigated. The bimodal powder is formed directly during the explosion and does not require a mixing step. The powder was obtained at different explosion energy densities. A feedstock was obtained with a powder content of 94 wt%.The powders have a different micro: nano ratio depending on the energy density. Feedstocks with these powders have different rheological behavior. The morphology and chemical composition of the powders and the homogeneity and rheological properties of feedstock with bimodal powder were studied and discussed. A comparison of feedstock properties with bimodal and micron powder is carried out.

Enhancing Mechanical Properties of Various Sintered Pellets with Nano-Additives

The impact of Fe, Co, Ni nano-additives on the density, microhardness and bending strength was investigated for several sintered pellets. Fe, Co, Ni nanopowders (NP) were prepared in the size range 67-94 nm using chemical metallurgy techniques. These powders (0.5 wt. %) were dispersed into three sets of micron powders: Co (+0.5 wt. % Co NP); Fe (+0.5 wt. % Fe NP); Fe+0.5wt. % C (+0.5 wt. % Co and 0.5 wt. % Ni NP). Mixtures were further mixed and processed using a magnetic mill and a turbulent mixer. Sintering was carried out using spark plasma sintering (SPS) as well as pressureless sintering (PS). The densities of sintered pellets were found to increase by 2.5-3% (SPS) and 3-5% (PS) in the presence of nano-additives; corresponding increases in microhardness and bending strength were determined to be 7.9-11.1% and 17.9-38.7%, respectively. These results are discussed in terms enhanced packing due to interparticle sliding and the filling of free spaces with the nanodisperse phase.

Efficiently production of micron-sized polyethylene terephthalate (PET) powder from waste polyester fibre by physicochemical method

Polyester has the highest share of world fibre market, which also leads to a large volume of polyester waste. In this study, a compact process combining alkali treatment and stone milling was used to recycle waste polyester fibre into ultrafine powder efficiently. The morphology of the original polyester fibre, alkali modified fibre and milled polyester powder were observed by Scanning electronic microscopy (SEM) and atomic force microscope (AFM). The particle size, crystallinity and strength loss were also studied. It was found that the alkali treatment greatly reduced fibre strength and the crystallinity of the fibre largely decreased after stone milling. The waste polyester fibre was converted into micron powders easily and efficiently. About 700 g dry ultrafine powders with particle size of around 60 µm were achieved in 2 h. This method shows a great potential for industrial application of waste polyester in the future.

The effect of boron, copper, and magnesium on the ignition of HEM containing aluminum powder

The use of metal powder as fuel in high-energy materials (HEM) for propulsion is the most energy-efficient method to increase the burning rate, combustion temperature, and specific impulse. Typically, various dispersity aluminum powders are used in the HEM composition. To improve the ignition and combustion characteristics of the HEM composition it is advisable to use the catalysts (nonmetals, metals or their oxides). This paper presents the experimental data of the HEM samples ignition containing ammonium perchlorate, butadiene rubber, micron powders of aluminum, aluminum-magnesium alloy, as well as nanopowders of amorphous boron, aluminum-copper, and aluminum-boron mixtures. The use of aluminum-copper or aluminum-boron nanopowders in the HEM composition decreases the ignition delay time by 1.3–2.0 times in comparison with Al-based HEM during CO2 laser initiation. In the case of Al-Mg powder use, the ignition delay time is changed slightly.

Pressure-less joining of SiCf/SiC composites by Y2O3–Al2O3–SiO2 glass: Microstructure and properties

In this study, Y2O3–Al2O3–SiO2 (YAS) glass was prepared from Y2O3, Al2O3, and SiO2 micron powders. Thermal expansion coefficient of as-obtained YAS glass was about 3.9 × 10−6, matching-well with that of SiCf/SiC composites. SiCf/SiC composites were then brazed under pressure-less state by YAS glass and effects of brazing temperature on microstructures and properties of resulting joints were investigated. The results showed that glass powder in brazed seam sintered and precipitated yttrium disilicate, cristobalite, and mullite crystals after heat treatment. With the increase in temperature, joint layer gradually densified and got tightly bonded to SiCf/SiC composite. The optimal brazing parameter was recorded as 1400 °C/30 min and shear strength of the joint was 51.7 MPa. Formation mechanism of glass-ceramic joints was proposed based on combined analysis of microstructure and fracture morphology of joints brazed at different temperatures. Thermal shock resistance testing of joints was also carried out, which depicted decline in shear strength with the increase of thermal shock times. The strength of the joint after three successive thermal shock cycles at 1200 °C was 35.6 MPa, equivalent to 69% of that without thermal shock.

The issue of regeneration of metal powder DLMS 3D printing

The subject of the article is a comparison of new and used powder for 3D metal printing. The powder is 316L stainless steel manufactured by Renishaw. The powder used was taken from the RENISHAW AM250 printer after use. Powder manufacturer Renishaw recommends using 15-45 micron powder in their 3D metal printers. An im-portant parameter of monitoring is the chemical composition of the metal powder and its changes during the thermal treatment during laser sintering. Another important parameter of a metal powder is its mechanical prop-erties, which determine the flowability, consistency and uniformity of powder application. By using an inert at-mosphere for sintering and storing the powder, these chemical changes can be prevented, especially against the formation of nitrides and oxides at elevated temperatures.

ДЕЙСТВИЕ ГАММА-ОБЛУЧЕНИЯ НА ПАРАМЕТРЫ АКТИВНОСТИ МИКРОПОРОШКОВ АЛЮМИНИЯ

Актуальность исследования.Один из лидеров по производству алюминиевых порошков в России ООО «СУАЛПМ» перешел от выпуска грубодисперсных порошков к производству микронных порошков, имеющих более высокую реакционную способность. Микропорошки алюминия применяются во многих отраслях промышленности:порошковой металлургии, самораспространяющемся высокотемпературном синтезе новых материалов,водородной энергетике, пиротехнике иракетных топливах. Повышение реакционной способности порошков алюминия в различных процессах приводит к понижению энергозатрат и экономии ресурсов. Цель: получение и объяснение экспериментальных данных по изменению параметров активности микропорошков алюминия после их облучения в зависимости от дозыγ-облучения. Объекты: микропорошки алюминия АСД-6, АСД-6М. Методы:дифференциальный термический анализ, рентгенофазовый анализ, методика облучения микропорошков алюминия γ-излучением, методика расчета параметров активности порошков алюминия. Результаты. Получены количественные показатели реакционной способности микропорошков алюминия АСД-6 и АСД-6М до и после облучения γ-излучением изотопа Со60 с энергией 1,17 и 1,33 МэВ, т.е. энергией существенно ниже порога фотоядерных реакций. Дозы облучения образцов порошков составляли 1, 2, 4, 8 и 10 Мрад. После γ-облучения температура начала окисления микропорошков снизилась максимально на 90 и 85 °С; максимальная скорость окисления возросла на 83 и 36 %; степень окисленности (при нагревании до 1250 °С) повысилась на 5,1 %, и минимально понизилась на 1,3 % для микропорошков АСД-6 и АСД-6М, соответственно. Удельный тепловой эффект окисления после γ-облучения всеми дозами был больше, чем для необлученных порошков.Максимальные значения удельного теплового эффекта для АСД-6на 199,5 кДж/моль, а для АСД-6М – на 134,8 кДж/моль больше тепловых эффектов, чем для необлученных порошков, что существенно превышает стандартную теплоту плавления алюминия (10,8 кДж/моль). Следовательно, такое состояние системы «алюминий – оксид алюминия» характеризуется запасенной энергией в 9 раз больше стандартной теплоты плавления алюминия, что с позиции классической термодинамики невозможно. В то же время известно, что запасание энергии в нанопорошках происходит за счет формирования двойного электрического слоя в частицах алюминия.

An Apparatus for Research on Processes of Selective Laser Sintering of Powder Materials with High Spatial Resolution

Abstract—An apparatus for selective laser sintering of micron and submicron fraction powders is described. The apparatus allows studies with small volumes of polymer powders, as well as aqueous and alcoholic suspensions to refine the sintering process in order to achieve high spatial resolution (on the order of 10 μm). Thin (approximately 20 μm) layers of spherical microparticles of polymethylmethacrylate (PMMA) with an average diameter of 0.5 to 3 μm were formed. Optimization of the parameters of selective laser sintering and stepwise formation of single layers of PMMA allowed us to obtain 3D structures with a resolution of less than 100 μm.

Preparation and Photocatalytic Performance of Porous ZnO Micron Powders

Preparation and Photocatalytic Performance of Porous ZnO Micron Powders

Effect of sample morphology on the spectral and spatiotemporal characteristics of laser-induced plasmas from aluminum

Species stratification and local plasma composition can affect microsecond-timescale oxidation reaction rates of metals such as Al in an oxidizing atmosphere. Here, we utilize fast, gated emission spectroscopy and a high-speed framing camera to determine the intensity and spatiotemporal evolution of various Al ablation products within a laser-induced plasma. Using a high-purity Al plate, micron- and nano-sized Al powders, and inert micron Al2O3 powder, we studied the effect of Al morphology and reactivity on the oxidation characteristics and plasma hydrodynamics in air at 1 atm over two temporal regimes (2–10 μs and 20–100 μs). We observed an increase in the spatial distribution and intensity of emission from vaporized Al within the plasma for powder-based samples compared to plate Al due to enhanced material dispersion. In nano-Al, AlO emission forms at, and propagates along, the surface of the powder bed from 2–10 μs, whereas for micron powder, there is a delay in AlO formation within the bulk of the plasma until tens of microseconds. We measured electron densities from a variety of spectral lines, which can range from ~ 2 × 1015 to 2 × 1018 cm−3, and which scale inversely with the rate of plasma expansion across morphologies. The Al I and Al II species temperatures from 2 to 10 μs calculated via Boltzmann plots are similar (from ~ 10,000 to 14,000 K), and we performed a suite of local thermodynamic equilibrium (LTE) validity calculations to establish that these two species are in LTE, while H is not. Using image co-registration, we calculated the thickness of the AlO layer surrounding the expanding Al cloud at times > 20 μs, which can range from ~ 50 to 300 μm. These results allow us to begin to understand the complexities of laser ablated metal powder reactions at microsecond timescales.

Effect of increase in Nano-particle Addition on Mechanical and Microstructural Behaviour of HVOF and Cold-Spray Ni-20Cr Coatings on Boiler Steels

Abstract In the present work, Micron and nano-sized powders of Ni and Cr were blended in various proportions by mechanical milling, maintaining Ni (wt.% 80) and Cr (wt.% 20) as the overall weight %, to produce three different grain sized Ni-Cr nano-crystalline alloy powders. These in-house prepared nanocrystalline powders were sprayed on chosen SA 516 boiler steels in this study, using high-velocity oxy-fuel (HVOF) and cold spray (CS) processes. All the deposited coatings were found to have the nano-sized grains. Further the effect of different weight percentages of nano-particles on the microhardness and scratch resistance of coatings was studied. It was concluded that on enhancement in weight % nano-particle, the microhardness of the coatings enhanced. The maximum hardness was found to be 525 Hv and 601 Hv respectively for HVOF and CS coatings. XRD analysis was used to identify phases, SEM/EDS for microstructure analysis and X-ray mapping for elemental distribution in case of all the developed coatings.

A production of fine ferrotitanium powder by intensive planetary mill grinding

Micron and submicron size ferrotitanium powders were obtained by planetary ball milling. The fractional and phase composition and morphology of obtained powder after crushing and under various milling conditions were studied. The obtained powder with micron-sized particles has good prospects for application in metal-matrix composites “titanium carbide – iron-based binder” production by synthesis from reaction mixtures with carbon.

ИССЛЕДОВАНИЕ НА ПЕРСПЕКТИВНОСТЬ ИСПОЛЬЗОВАНИЯ НЕВОСТРЕБОВАННЫХ ПОРОШКОВ ПРИРОДНОГО АЛМАЗА

The processing of industrial diamonds is reduced to the extraction of conditioned powders of various grain sizes from them. At present the depth of such processing is limited to the fine-grained micron and submicron powders; as a result, which fall into the waste category. In reality, these are complete and usable diamond powders. However, due to the above mentioned reasons, they may be unclaimed for an indefinite period of time at the moment, and moreover with a tendency to accumulate. The article deals with the problem of using unclaimed natural diamond powders and explores the prospects for their use.

Investigation into the Influence of the Structure Dispersion and Homogeneity on the Properties of Powder Metastable Austenitic Carbide Steels and Diamond Tools

Diffusion and homogenization in “iron (5 μm–nickel (5 μm or 50 nm)” powder systems of various degrees of dispersion during sintering (900 and 1000°C), as well as spark plasma sintering, are investigated using the Matano–Boltzmann method. Calculated diffusivities in pairs of micron powders sintering without applying pressure (900°C, 6 h) and by the spark plasma method (900°C, 5 min) in these systems are equal to 7 × 10–10 cm2/s. It is shown that the use of nanodispersed nickel powder in diffusion pairs based on finely dispersed iron powder promotes a twofold increase in diffusivity at 900°C in contrast to the pair with the microdispersed nickel powder. Constants in the Ivensen sintering kinetics equation are calculated for the “iron–nickel” powder systems, by which the factors activating sintering of these systems are established. The dependences of the structural phase composition and physicomechanical properties of carbide steels of the Fe(base)–14 wt % Ni–8 wt % TiC system on the sintering temperature in range t = 900–1200°C and structure dispersity and homogeneity are determined. The dependences of the grain size, porosity, hardness, microhardness, fracture toughness, and bending ultimate strength on the sintering temperature are shown. Dependences of tribotechnical properties on the degree of homogeneity of the solid solution and volume of the phase transformation of metastable austenite into deformation martensite during abrasive friction turn out similar for carbide steels and diamond tools based on carbide steel. Optimal values of the variation coefficient of the nickel concentration in austenite and carbide steels of the same chemical composition but with different degrees of dispersity, which provide the maximal volume of the austenite decomposition and high values of the diamond-tool grinding coefficient, turn out equal to 5 in both systems, but the sintering parameters are different. It is shown that the physicomechanical properties of the studied systems depend on the structure porosity and dispersity, while tribotechnical properties depend on the structural homogeneity of steels.

Heat release in chemical reaction between micron aluminum powders and water

In this paper, the micron aluminum powders produced by the dispersion of liquid aluminum were characterized using the method of thermal analysis, scanning electron microscopy, low-temperature nitrogen adsorption (BET) method. The reactivity of the micron aluminum powders in a chemical reaction with an aqueous solution of NaOH was evaluated using the solution calorimetry method. The effect of the sample mass was investigated for different kind of the aluminum micron powder. The heat release is dependent on the aluminum mass in suspension aluminum-water. It is shown that the method of solution calorimetry is applicable for determining the thermal effects of the reaction between aluminum micropowders and water as well as the content of metallic aluminum after long-term storage of micropowders in the airtight containers.