Granulated Powder Research Articles

Magnetic biochar particles prepared by ion cross-linking to remove phosphate from water

In this study, the ionic cross-linking method was used to synchronize the granulation and magnetization of biochar powder. A precursor of Ca/Mg modified, tobacco stalk biochar combined with sodium alginate as the functional monomer, CaCl2 solution as the cross-linking agent, and a Fe3O4 magnetic fluid dopant were used to prepare magnetic biochar particles (EMCSB3), which were easy to separate and recover. The adsorption performance of phosphate by these EMCSB3 was explored. The Langmuir model fitted adsorption capacity of phosphate on the EMCSB3 was 8.93 mgP g−1, which was comparable to other materials at the same concentration. The process of phosphate adsorption by magnetic particles followed a pseudo-second-order model, and the adsorption mechanism was chemisorption. EMCSB3 was suitable for use in environments with pH ≤ 8, the best dosage was 6.67 g l−1, and its removal rate was maintained at about 85%. Phosphate adsorption was greatly affected by coexisting CO3 2−. This study provides a technical approach for the granulation and magnetization of powdered biochar and improves its feasibility of use.

Surface Micromorphology and Structure of Stainless and Maraging Steel Obtained via Selective Laser Melting: A Mössbauer Spectroscopy Study

Selective laser melting (SLM) as an additive manufacturing method makes it possible to quickly produce complexly shaped three-dimensional (3D) metal specimens from a powder. This work describes how SLM affects the surface phase composition of a 3D printed specimen, as analyzed with conversion electron Mössbauer spectroscopy (CEMS), conversion X-ray Mössbauer spectroscopy (CXMS) and X-ray diffraction (XRD). Both stainless 1.4404 (CL20ES) steel and maraging 1.2709 (CL50WS) steel have been investigated. A transformation of the phase composition from the ferritic phase into an austenitic one was proven by comparing the initial CL50WS powder and the final specimen using CXMS. This transformation takes place during the SLM process. No transformation was identified in stainless steel. The differences identified via CEMS between the surface phase composition of the final non-annealed specimens and the surface of the final annealed specimens demonstrated the oxidation of the surface layer. The oxidation occurs during the annealing of the sample in surface layers less than 1 μm thick. The quality of the surface was examined using scanning electron microscopy (SEM), which presented imperfections on the face of the final specimen. Granules of the initial powder bonded to the surface of the specimen and both irregular and spherical pores were observed.

X‐ray diffraction, differential scanning calorimetry and evolved gas analysis of aged plutonium tetrafluoride (PuF4)

A 30 year-old PuF4 sample consisting of brown powder (PuF4-b) and pink granules (PuF4-p) was analyzed. X-ray diffraction shows the bulk is comprised of three compounds: PuF4, PuO2, and PuF4·1.6H2O. Broadening of PuF4 XRD peaks suggests possible $$\upalpha$$ -damage. After annealing at 650 °C, crystalline PuF4 and PuO2 remain. Thermogravimetric analysis and differential scanning calorimetry—with simultaneous evolved gas analysis—of the separated PuF4-p and PuF4-b components reveal a distinct sequence of reactions. Dehydration occurs between ~ 90 and 300 °C. Exothermic annealing of the $$\upalpha$$ -damage occurs in two stages: at 350–355 °C and at 555–558 °C. Hydrofluoric acid, fluorine and helium desorb during the first exotherm. Above 700 °C, PuF4 reacts with PuO2, resulting in oxygen release and mass loss.

Phase control of WC–Co hardmetal using additive manufacturing technologies

ABSTRACT Three-dimensional WC–Co hardmetal samples were fabricated using WC–Co nanopowder via two methods: selective laser melting (SLM) and fused deposition modelling (FDM). The carbon loss and phase transition during processing were controlled to minimise the degradation of mechanical properties of the cemented carbide. The SLM samples were manufactured from granule powder produced via spray drying, whereas the FDM process was carried out on a filament produced via injection moulding. During SLM, carbon loss occurred due to the high energy involved in the process. Owing to carbon loss, the relative density and Rockwell hardness of SLM processed samples were low. To overcome this, a stable WC phase cemented carbide was manufactured via FDM. The density of the sintered FDM samples was improved by increasing the packing density of the filaments. The carbide sintered samples had a relative density of 96.3%, hardness of HRA 89.06 and carbon content of 5.47–5.52 wt-%.

Comparison of Flowability and Sinterability Among Different Binder Jetting Feedstock Powders: Nanopowder, Micropowder, and Granulated Powder

Abstract Feedstock powders used in binder jetting additive manufacturing include nanopowder, micropowder, and granulated powder. Two important characteristics of the feedstock powders are flowability and sinterability. This paper aims to compare the flowability and sinterability of different feedstock powders. Three powders were compared: nanopowder (with a particle size of ∼100 nm), micropowder (with a particle size of 70 μm), and granulated powder (with a granule size of ∼70 μm) made from the nanopowder by spray freeze drying. Flowability metrics employed included apparent density (AD), tap density (TD), volumetric flow rate (VFR), mass flow rate (MFR), Hausner ratio (HR), Carr index (CI), and repose angle (RA). Sinterability metrics employed included sintered bulk density (SBD), volumetric shrinkage (VS), and densification ratio (DR). Results show that the granulated powder has a higher flowability than the nanopowder and a higher sinterability than the micropowder. Moreover, different flowability metric values of the granulated powder are close to those of the micropowder, indicating that these two powers have a comparably high flowability. Similarly, different sinterability metric values of the granulated powder are close to those of the nanopowder, indicating that these two powders have a comparably high sinterability.

The investigation of dynamic properties of 3D-printed steel parts

Additive technologies are promising for manufacturing parts of metal navigation devices with complex shapes. Finite element analysis is used during the designing of such items. The modeling accuracy is determined by the correctness of the specified physical properties of materials. The properties of materials used in 3D printing significantly differ from the ones used in the traditional manufacturing. Researchers focus on such characteristics as Young’s modulus, Poisson’s ratio, hardness and strength. Meanwhile, some applications require dynamic properties. The paper presents the investigation and comparison of damping properties of three steel parts produced by different methods. The first part is manufactured by 3D printing with melting in the transverse direction, and the second part is done by melting in the longitudinal direction, while the third one is traditionally manufactured. The parts are shaft shaped with constant cross-section and have the same geometric dimensions. The TIRA TV 5220 / LS-120 stand is used. A piezoelectric accelerometer is installed at the loose end of the part. The tests are carried out in the frequency range from 15 to 3500 Hz and with an acceleration of 19.6 m/s2 (2 g). The accelerometer output is used to calculate the damping coefficient. The results are verified by comparison with the finite element modeling results. The damping coefficients of transverse and longitudinal 3D-printed parts are 0.022 and 0.006, respectively. The damping coefficient of the traditional manufactured part is 0.023. The difference of 3D-printed parts damping coefficients can be explained by the denser fusion of powder granules when printing one layer than between layers. In this case, a crystal structure with greater rigidity in the printing plane is formed and it limits the dissipation of vibration energy due to internal friction. Finite element modeling shows mismatch between the experimental and calculated values of the printed parts natural frequencies. Considering that the values of natural frequencies are largely determined by Young’s modulus, a parametric optimization of its value is carried out. It was found that the value of Young’s modulus does not correspond to the values determined during tensile tests for similar samples. Thus, 3D-printed parts have different vibration and static stiffness. This is not typical for metals and should be taken into account in simulations. The research results can be used in the simulation model development of steel 3D-printed parts and in the design of digital twins for navigation devices. It allows one to estimate vibration resistance of promising products at the early stages of their design and to optimize the construction minimizing stress.

Studying the Possibility of Obtaining Titanium Powder of Various Sizes by Alumino-Thermic Reduction

The main aim of this work is to obtain a compact spherical titanium powder by the metallo-thermic reduction. The feedstock is TiO2 (rutile), and aluminum shavings are used as the reducing metal. In the reduction process granules of titanium powder and corundum were obtained. For cleaning titanium powder from corundum, various alkaline and acid processing methods were used. When using the alkaline treatment method of the powder, obtained after reduction of sand and floury rutile by aluminum shavings, its weight decrease was 36-37%.

Synthesis of Highly Dispersed Spherical Metal Granules by Laser Ablation Method

The work is devoted to the problem of synthesis of highly dispersed spherical powder granules by laser ablation. The formation of microspheres is carried out by the action of femtosecond laser radiation on the surface of a titanium target in a two-component reaction medium. The process of titanium treatment in n-hexane by ultrashort laser pulses is investigated. It is shown that the use of n-hexane as a working medium component allows the synthesis of micro-and nanopowders containing titanium carbide, which are resistant to atmospheric environment during prolonged exposure. The presented method provides the possibility of synthesis of high-purity powder materials with typical sizes from 1 to 3 microns.

Preparation of spherical Ti-6Al-4V powder by RF induction plasma spheroidization combined with spray granulation

Spray granulation was used to control morphology and particle size of raw materials for spheroidization in this work. Effects of dispersant (PAA-NH4OH) addition, pH value and solid content on stability of slurry for granulation was investigated. Influence of solid content of the slurry and atomizer speed on spray granulation were also investigated. Furthermore, difference in spheroidization effect between Ti-6Al-4V powder spheroidized from the granulated powder and irregular powder was compared. Results show that zeta potential of the slurry can be controlled at -44 mV to by addition of dispersant when pH value is 9.3. Granulated powder prepared with 50 wt% solid content and 10,000 rpm atomizer speed was best for plasma spheroidization. Ti-6Al-4V powder spheroidized from the granulated powder has better properties than that spheroidized from irregular powder. Spheroidization ratio, flow properties and apparent density of the spheroidized Ti-6Al-4V powder from granulated powder are 98%, 35.4 g/50s and 3.2 g/cm3, respectively.

Critical quality attribute assessment of big brand traditional Chinese medicine: process quality control method of Suhuang Zhike Capsules intermediate based on physical properties of powder and granules

The physical properties of powder and granules are the critical quality attributes for the process control of Suhuang Zhike Capsules, a big brand traditional Chinese medicine. This paper took the production of 25 batches of real-world Suhuang Zhike Capsules dry extract powder and granules intermediates as the research object. Firstly, a method for testing the physical properties of Suhuang Zhike Capsules powder and granules with 19 physical indicators was established. The results showed that the granules of dry extract powder after granulation had a smaller particle size, wider particle size distribution range and poor fluidity, which easily caused the problem of over-limit capsule loading. Secondly, correlation analysis, principal component analysis and cluster analysis were used for mathematical statistics. The correlation analysis showed that the density of dry extract powder could affect the chroma and fluidity. At the same time, the particle size in the granules had a stronger effect on the chroma and fluidity than the density. The study also found that the particle size and hygroscopicity of dry extract powder were potentially key physical properties that affected the physical properties of granules. Furthermore, the results of principal component analysis and cluster analysis showed that the consistency of the physical properties between the dry extract powder and intermediate granules was relatively poor. To this end, similarity analysis was carried out, and the quality control method of powder and granules based on physical fingerprint was established. The results showed that the physical fingerprint similarity of 25 batches of dry extract powder was 0.639-0.976, and the physical fingerprint similarity of the gra-nules was 0.716-0.983. With the similarity of 0.85 as the threshold, the batches with abnormal physical properties could be identified. In this study, the process quality control method of Suhuang Zhike Capsules based on the physical properties of powder and granules was established finally, which realized the identification of abnormal batches, and provided a reference for the process quality control of Suhuang Zhike Capsules.

Porous structures printed by fused deposition of granules processed from a novel polyamide/alumina‐based system

AbstractAlumina ceramic porous structures were shaped by the fused deposition of alumina/polyamide 612 composite granules using an FDM 3D printer with a modified extruder to process granulated powder instead of a filament. The composite granules were prepared via thermally induced phase separation (TIPS). Firstly, in order to determine the proportion of polymer/solvent to be used in the TIPS process, different volume fractions of PA612 in dimethyl sulfoxide (DMSO) were studied (0.01 to 0.20), and the granules obtained were characterized by SEM, DSC, and Raman spectroscopy. Secondly, the addition of different ceramic loadings to the PA612/DMSO solution was studied with the aim of determining the amount to be used for preparing the composite granules by TIPS. In particular, the effect of the alumina content on the morphology and size of the obtained composite granules was studied. In addition, rheological properties (oscillatory and rotational tests) of the feed materials were studied. Finally, the printing conditions, including the nozzle temperature and nozzle diameter, and the extrusion process, were optimized in order to obtain porous structures with good quality. Alumina porous structures were successfully printed, debinded, and sintered. Adequate bonding between layers was achieved, and no defects at interfaces were detected.

Preparation and characterization of spray‐dried granulated bioactive glass micron spheres

AbstractOwing to its superior bioactivity, biocompatibility, and biodegradability, bioactive glass (BG) has been attracting significant attention within biomedical science fields. However, BG powders with variable particle sizes are required targeting different applications, such as dermal fillers. Thus, in this study, granulated BG powders were prepared via the spray drying and granulation method. Size‐controlled BG micron sphere with diameters of up to tens of microns can be mass‐produced and their phase information, particle morphology, and specific surface area were characterized via X‐ray diffraction, scanning electron microscopy, and nitrogen adsorption/desorption isotherm, respectively. In addition, the in vitro bioactivity was evaluated following Kokubo's protocol, and the formation of a hydroxyapatite (HA) layer after immersion into the simulated body fluid was confirmed via energy‐dispersive and Fourier transform infrared spectroscopy. The cytotoxicity was examined using a 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide assay. Finally, the resulting morphologies and corresponding properties are shown, and the related mechanisms are discussed.

Fabrication of spherical WC-Co powders by radio frequency inductively coupled plasma and a consequent heat treatment

To obtain spherical cemented carbide powders suitable for the additive manufacturing process, granulated WC-Co powders made by spray drying were spheroidized by radio frequency inductively coupled plasma. The influence of powder feed rate on the sphericity of the obtained powders was investigated. Results show that spheroidization efficiency of near 100% was achieved at different applied feed rates. Applying plasma processing decreased the particle size, compacted the microstructure and caused obvious improvements in the apparent density and flowability. However, complete decomposition of WC and certain evaporation loss of Co were noted in these powders. The spheroidized powders consisted of W2C, C, Co3W3C, and contained higher Co at a higher applied feed rate. After conducting heat treatment at 950 °C for 3 h, the powder phase composition was regenerated as WC and Co. The heat-treated powders, due to their good sphericity, improved apparent density and flowability are suitable for the printing processes.

Magnetic Properties of Iron-Based Alloy Powder Coils Prepared with Screen Printing Using High-Solid-Content Magnetic Pastes

A molding coil is prepared by filling and dry pressing granulated alloy magnetic powders directly onto enameled wire. As the molding coil is developed toward miniaturization, the granules consisting of magnetic powder and organic binder cannot uniformly fill the small space in the coil center column during molding. This leads to a porous microstructure or cracks. The uneven packing problem in the coil center column was effectively solved in this study by applying a screen printing process using high-solid-content magnetic pastes. Bisphenol A epoxy resin has the benefits of excellent mechanical, bonding, electrical, corrosion resistance, low shrinkage and low cost properties. However, the viscosity is too high for use as a binder for high-solid-content magnetic paste. The magnetic paste viscosity can be reduced by substituting some low viscosity reactive diluent (butyl glycidyl ether) for Bisphenol A epoxy resin. It was observed that the relative density and magnetic properties (such as initial permeability, saturation magnetization, and core loss) can be effectively improved by increasing the monomer addition because the monomer acts as a lubricant that helps the magnetic particles rearrange during compaction. However, as monomer addition becomes greater than half the epoxy resin weight percent, the sample bending strength decreases.

Titanate coupling agent surface modification effect on the magnetic properties of iron-based alloy powder coil prepared using screen printing

A molded-type coil is prepared by filling and dry pressing granulated alloy magnetic powders directly onto enameled wire. As the molded-type coil is developed toward miniaturization, the granules consisting of magnetic powder and organic binder cannot uniformly fill the small space in the coil center column during molding. This leads to a porous microstructure or cracks. In this study, magnetic alloy powder coils were prepared using a screen-printing process using high-solid-content magnetic pastes. The magnetic powder was surface-modified with titanate coupling agent to improve the magnetic powder and epoxy resin compatibility, thereby improving magnetic powder mixing with epoxy resin and reducing the high solid content magnetic paste viscosity. The experimental results showed that the relative density and magnetic properties (such initial permeability, core loss, and coercivity) can be significantly enhanced using titanate coupling agent surface modification.

Study on the Influence of fly ash, mineral powder and silicon powder on the performance of high-performance concrete

To study the effect of fly ash, mineral powder, and silica fume on the working performance and mechanical properties of C70 high-performance concrete by adding the same amount of fly ash, granulated blast furnace slag powder, and silica fume as a composite admixture to replace the amount of cement. Influencing the law, at the same time, the optimal dosage ratio of various admixtures is determined through the orthogonal experiment. The results show that: when adding 6% silica fume, it can improve the performance of high-performance concrete. When the amount is increased, the viscosity of the concrete increases and the fluidity decreases. Incorporating an appropriate amount of silica fume can greatly increase the compressive strength of concrete. When blended with fly ash in the proportion of 20%, the performance of high-performance concrete is better. When the same amount of fly ash replaces cement, fly ash reduces hydration and improves the cohesion of concrete, 7d, 28d the compressive strength of the cube increases significantly. Adding 10% mineral powder, mineral powder can affect the early compressive strength of highperformance concrete, extend the setting time of concrete, and improve the pumping capacity of concrete.

Experimental study on concrete using waste ceramic as partial replacement of aggregate

This research paper explains an experimental study on the utilization of waste material extracted from the Ceramic manufacturing plants and reused in concrete by replacing natural fine aggregate. Due to this ceramic waste, the natural fine aggregate extraction may be reduced, and the nominal cost of the river sand is high; compared to all the other alternate fine aggregate materials. Pulverized and granulated waste powder ceramic tiles are varies from 0%, 5%, 10%, 15%, and 20% replacement material for fine aggregate. The mix designs were prepared by replacing fine aggregate with different percentages of 0% to 20% pottery (crushed tiles) with M30 grade of concrete. Experimental investigations were conducted on fresh concrete for workability. In hardened concrete with various tests conducted like a Compression test, Young’s modulus, and Flexural strength on concrete beam with different percentages of waste crushed ceramic tiles at different stages of curing time at 7 28 days.

Influence of boulder machine-made sand powder on compressive strength of concrete

In order to recycle the boulder powder produced in the process of manufactured sand production and reduce the cost of engineering concrete, this article studied the influence of boulders powder on the compressive strength of concrete. The results show that in the early stage of concrete test, the compressive strength of rock powder concrete is slightly lower than of fly ash and mineral powder concrete. With the development of curing age, the strength of boulders powder concrete developed slower. As the increase of boulders powder content, the compressive strength of different curing age gradually decreased, and it was suggested that the content of boulders powder should be controlled within 20% of cementitious materials mass. The positive effect of boulders powder fineness on the strength of concrete is limited, so it is suggested to use unprocessed collected boulders powder in the project, which is economical and environmentally friendly. With the adjustment of water-to-binder ratio, boulders powder can be prepared with different strength grades of concrete to meet the needs of engineering; the composite of boulders powder with traditional mineral admixtures, such as fly ash, and especially granulated blast furnace slag powder, can significantly improve the strength of concrete.

ВЛИЯНИЕ РАЗМЕРНОСТИ МАТЕМАТИЧЕСКОЙ МОДЕЛИ ВНУТРЕННЕЙ БАЛЛИСТИКИ НА РАСЧЕТНЫЕ ПАРАМЕТРЫ ВЫСТРЕЛА ДЛЯ ЗАРЯДОВ ИЗ ЗЕРНЕНОГО ПОРОХА

The problem of the impact of the mathematical model dimension on the calculated intraballistic characteristics of a shot for the charges made of granulated powder is considered. Mathematical models of the shot are studied using the spatial (axisymmetric), one-dimensional, and zero-dimensional (thermodynamic) formulations. The thermodynamic model takes into account the distribution of the pressure and velocity of a gas-powder mixture behind the shot for a channel of variable cross-section. Comparison of simulation results is carried out in a wide range of loading parameters. It is shown that there is a range of the loading parameters for a thermodynamic approach to give satisfactory approximation to the parameters obtained using the gas-dynamic approach, which describes the flow of a heterogeneous reacting mixture with a separate consideration of phases and intergranular interactions between them. Notably that in the entire range of the charging parameters studied in this work, the one-dimensional and twodimensional gas-dynamic models only slightly differ from each other. Therefore, in the main pyrodynamic period, the actuation of the charge, made of granulated powder, can be simulated using a one-dimensional gas-dynamic model or a zero-dimensional thermodynamic model with allowance for spatial distribution of the pressure and velocity of the gas-powder mixture.

Evaluation of flowability for granulated powder using a test of powder discharge by pressurized air

This study experimentally and theoretically examined the flowability and the cohesiveness for powder using a test of powder discharge through an orifice by the pressurized air. The powder used consisted of two kinds of Calcium hydroxide which have different particle sizes by granulation. These sizes are 11µm and 176µm, those called Ca(OH)2 -A and -B. Cohesiveness is characterized by the Bond number which is the ratio of separation force to the gravity force. Flowability is evaluated by the relationship between the mass flow rate and the average air pressure acting on the powder bed. We found that the Bond number of Ca(OH)2 -B was much lower than Ca(OH)2 -A. The relation between the mass flow rate of the powder and the average air pressure indicates Ca(OH)2 -B is easily flowing at the lower pressure region, and Ca(OH)2 -A was scattered at the higher pressure region. This means Ca(OH)2 -B has good flowability by the particle granulation in comparison with Ca(OH)2 -A.