Powder Blends Research Articles

Influence of Mixers on Dry Dispersion of Nanoparticles in the Cementitious Composites

Nanomaterials are gaining prominence in industries such as construction and medicine. Several parameters like durability and early strength development can be enhanced through the incorporation of nanomaterials into cementitious composites. The major challenge is to achieve uniform dispersion of nanomaterials within the composite’s matrix. The present study is an interdisciplinary research which combines concrete technology and nanotechnology with powder technology to develop a blended binary mixture in powder form with uniform dispersion of nano-silica (NS) as the active ingredient with the cement as the primary ingredient. The fundamental idea of this research is to understand the influence of mixers on the mixing pattern and the dead zones. For this purpose, the powder blending in conical mixer and mortar mixer were simulated using discrete element method (DEM) based software and it was capable predicting the mixing pattern and dead zones of the mixers.

Mechanochemical synthesis investigations on the ternary and quaternary B2O3/TiO2/Mg/C systems

In this study, mechanochemical synthesis (MCS) was performed on the ternary and quaternary B2O3/TiO2/Mg/C system in order to investigate the probable reaction products. As being a high-energy ball milling (HEBM) technique, MCS was conducted on the B2O3–TiO2–Mg, B2O3–Mg–C and B2O3–TiO2–Mg–C powder blends. Various milling times were applied for MCS optimization. Besides, the effect of excess amount of Mg on the MCS process was investigated. Subsequently, a purification step was carried out on the milled powders to remove MgO by-product. The MgO content in the as-synthesized powders was leached out using 6 M HCl solution. Thermodynamic evaluations were made utilizing both the FactSage 7.1 and HSC thermochemical software to predict the reactions and products for each system. The as-synthesized and purified powders were characterized by using X-ray diffractometry (XRD), scanning electron microscopy/energy dispersive spectrometry (SEM/EDS), transmission electron microscopy (TEM), particle size analysis (PSA) and differential scanning calorimetry (DSC) techniques. Pure TiB2, B4C and TiC–TiB2 powders were synthesized from stoichiometric B2O3–TiO2–Mg, B2O3–Mg–C and B2O3–TiO2–Mg–C powder blends after MCS for 4 h, 10 h and 6 h, respectively. High purity TiB2, B4C and TiC–TiB2 powders were obtained with an average particle size of 50.20 nm, 330 nm and 17 nm, respectively.

Pharmaceutical tablet compression: measuring temporal and radial concentration profiles to better assess segregation

Concentration monitoring inside a tablet press feed frame is important not only to assess the composition of the powder blend compressed into tablets but also to detect quality affecting phenomena such as powder segregation. Near infrared spectroscopy has been successfully used to monitor powder concentration inside the feed frame; however, so far, this methodology does not provide information on local spatial variability, since it probes a very small area of powder sample. Near infrared chemical imaging (NIR CI) has the potential to improve process monitoring because it can simultaneously acquire a plurality of spectra covering nearly the entire width of the feed frame, thereby making it possible to detect local variations in powder concentration. The present work uses both NIRS and NIR CI to monitor the concentration of Ibuprofen and Ascorbic acid in multi-component mock pharmaceutical blends flowing through the feed frame of an industrial tablet press. The concentrations of Ibuprofen and Ascorbic acid were successfully monitored in multi-component powder blends. NIR spectral wavelength ranges and pre-treatments were simultaneously optimized via a genetic algorithm. N-way PLS approach for concentration monitoring was found to be more suitable than regular PLS when analyzing spectral images and provided the ability to visualize spatial segregation.

Development and Evaluation of a Polyherbal Tablet for Polycystic Ovarian Syndrome (PCOS)

The main objective of the present study was to develop and evaluate polyherbal tablet for the treatment of Polycystic Ovarian Syndrome (PCOS). For the formulation of tablet, the herbs were selected based on the concepts of pathophysiology and Ayurvedic perspective of the disease. The extracts of <em>T. foenum graceum, C. longa, B. aristata, S. asoka, B. variegata</em> and Guggul purified in cow’s urine was used for the preparation of polyherbal tablet. The physicochemical, phytochemical evaluation and quantification of markers by HPTLC of crude drugs and extracts were performed. The guggul was used as binder in different proportion for the preparation of tablet. Pre-formulation study of the powder blend and post compression evaluation of tablet was done by various parameters like weight variation, friability, hardness, thickness, diameter, disintegration time, in-vitro dissolution and accelerated stability study. The physicochemical evaluations of crude drugs yielded results which were in accordance with the monograph’s standard values. The phytochemical analysis of the extracts revealed the presence of variety of phytoconstituents. From the results of HPTLC quantification the amount of curcumin (7.14%) in <em>C. longa</em>, diosgenin (40.6%) in <em>T. foenum graceum ,T. foenum graceum</em>, berberine hydrochloride (4.83%) in <em>B. aristata</em>, catechin (3.48%) in S. asoka, lupeol (0.11%) in <em>B. variegata</em> and Z-guggulsterone (0.140%) and E-guggulsterone (0.146%) in purified guggul was found. The micrometrics of the powder blend of all the formulations showed good flow properties. Formulation F3 showed better results compared to other formulations in post compression evaluation. Accelerated stability study showed that the formulation F3 was stable during the course of study.

A Ternary Model for Particle Packing Optimization

Powder packing in metal powders is an important aspect of additive manufacturing (otherwise known as 3-D printing), as it directly impacts the physical and mechanical properties of materials. Improving the packing density of powder directly impacts the microstructure of the finished 3D-printed part and ultimately enhances the surface finish. To obtain the most efficient packing of a given powder, different powder blends of that material must be mixed to minimize the number of voids, irrespective of the irregularities in the particle morphology and flowability, thereby increasing the density of the powder. To achieve this, a methodology for mixing powder must be developed, for each powder type, to obtain the maximum packing density. This paper presents a model that adequately predicts the volumetric fraction of the powder grades necessary for obtaining the maximum packing density for a given powder sample. The model factors in the disparity between theoretical assumptions and the experimental outcome by introducing a volume reduction factor. We outline the model development steps in this paper, testing it with a real-world powder system.

Microstructure and Mechanical Properties of a High-Strength Ti-4Al-2Fe-3Cu Alloy Fabricated by Sintering and Hot Extrusion

A Ti-4Al-2Fe-3Cu (wt pct) alloy containing only low-cost alloying elements was fabricated by vacuum sintering a blend of TiH2, Al, Fe, and Cu powders at 1200 °C for 1 hour followed by hot extrusion at the same temperature. The as-extruded alloy exhibited a microstructure consisting of mainly α/β lamellar colonies and Ti2Cu as a minor phase. The average colony size and lamella thickness were 118 and 12 µm, respectively, and Fe and Cu were predominantly distributed in the β lamellae. The as-extruded alloy had a high tensile yield strength (YS) and ultimate tensile strength (UTS) of 1248 and 1270 MPa, respectively, but a limited ductility (elongation to fracture: 2.3 pct). Annealing at 750 °C for 4 hour caused the average colony size and lamella thickness of the alloy to increase to 145 and 17 µm, respectively, and the volume fraction of the β phase decreased with the annealing. These microstructural changes resulted in a slight decrease of the YS and UTS to 1221 and 1253 MPa, but a clear increase of the ductility with the elongation to fracture reaching 4 pct. This work demonstrates that a combination of relatively low-temperature vacuum sintering, hot extrusion, and annealing can be effectively utilized to fabricate a low-cost Ti-4Al-2Fe-3Cu alloy with high strength and appreciable tensile ductility.

Comparison of LPBF processing of AlSi40 alloy using blended and pre-alloyed powder

Elemental powders or pre-alloyed powders can be blended to form a powder stock with new compositions. In-situ alloying of blended powder mixtures during LPBF processing speeds up the alloy development process as it allows composition adjustment. Pre-alloyed powder is typically used in industrial settings to ensure consistency of the built material, whereas blended powders are used to experiment with new alloy compositions. In this research, we compare a range of binary alloy compositions built from blended elemental powder and pre-alloyed powder to evaluate how the feedstock powder affects the built material. The alloy is a lightweight alloy with a low coefficient of thermal expansion, comprised of Al and Si. The following compositions were formed by mixing pure Al and Si powder: AlSi38, AlSi40 and AlSi42, and pre-alloyed AlSi40 powder was also used. Parametric studies were performed for both the blended and pre-alloyed powders. It was found that the optimum process parameters for the blended and pre-alloyed powder were different. The line energy for pre-alloyed powder was selected to be 0.150 J/mm (300 W, and 2000 mm/s) which yielded a density of 99.5% of the theoretical density. The optimal density for the blended powders was 99.07-99.16% which was also achieved with 0.150 J/mm (375 W, 2500 mm/s). The alloys are brittle, with Young's modulus 86-99 GPa. Coefficient of thermal expansion (CTE) reduced with increasing Si content, material built from pre-alloyed powder had 5% higher CTE than material built from blended powder.

FORMULATION AND EVALUATION OF ORODISPERSIBLE TABLETS OF ACECLOFENAC BY DIRECT COMPRESSION METHOD

Nowadays, Oro dispersible tablets are gaining much importance because it is easily approachable and due to its patient compliance. In this study, Formulation and evaluation of one such tablets of Aceclofenac by direct compression method using super disintegrants like Cross carmellose sodium (CCS) was performed.
 Due to low water soluble property of aceclofenac, it has poor dissolution and bioavailability. In order to minimize this property OTD’s are prepared. ODT’s were prepared by direct compression method using super disintegrant i.e Cross Carmellose Sodium (CCS) in different concentrations. The prepared powder blend was subjected to various evaluation studies like pre compression parameters like angle of repose, tapped density, and bulk density. Post compression parameters like weight variation, hardness, friability, drug content, wetting time, disintegration and dissolution studies were performed. The drug excipients compatibility was verified by FTIR.
 The precompression evaluation studies showed that the prepared powder blend has good flow property. The hardness and friability revealed that it has good mechanical strength with acceptable disintegration time. The optimized formulation indicated good in vitro drug dissolution profile with maximum drug being released at all the time intervals indicates an ideal profile for the development of ODT’s. The results of pre compression studies and post compression along with FTIR are presented.

Maca could improve endurance capacity possibly by increasing mitochondrial biogenesis pathways and antioxidant response in exercised rats.

The objective of this study was to shed light on the effect of a novel Lepidium peruvianum (Maca) blend on anti-fatigue capacities in exercised rats. Twenty-eight male albino rats were allocated into four groups (n=7) at random: (i) Control (vehicle), (ii) Maca: (40 mg/kg/BW), (iii) WL-FST: weight-loaded forced swimming test group, and (iv) WL-FST + Maca group. Maca supplementation increased swimming time to exhaustion (p < .01), while decreased serum lactate and liver glycogen concentrations. Maca addition resulted in lower levels of serum, liver, and muscle MDA (p < .05). Muscle GPx activity increased in both Maca groups (p < .001). Moreover, NF-κB levels were less in the WL-FST + Maca compared to the WL-FST group (p < .001). Nrf1, Nrf2, PGC-1α, SIRT1, and TFAM levels were augmented in the WL-FST + Maca compared to the WL-FST (p < .05). Consequently, our Maca blend increased endurance capacity and prevented exercise-induced oxidative stress and lactic acid buildup. PRACTICAL APPLICATIONS: The brassica species Lepidium peruvianum (maca) has been consumed in Peru for centuries to enhance mood, libido, and energy. Although the positive effects of this plant on energy metabolism are accredited, the underlying molecular mechanisms of these effects have not been sufficiently elucidated. The current study's findings suggest that this innovative, exclusive maca powder blend can boost endurance while preventing oxidative stress and lactic acid buildup during acute exercise. The mechanism of this efficacy is thought to be caused by maca's regulatory properties on energy metabolism signaling receptors and strong antioxidant scavenging effects on the free radicals that are produced by prolonged exhaustive exercise periods.

Effect of Varying Parameters on the Properties of Effervescent Paracetamol Tablets for Paediatrics

Aims: This study was aimed to determine the effect of varying parameters on the properties of effervescent paracetamol tablets for paediatrics.&#x0D; Study Design: This analytical study was carried out on effervescent paracetamol tablets formulated with differing formulation parameters.&#x0D; Place and Duration of Study: This study was carried out in the Faculty of Pharmacy, Delta State University and Abraka from April 2017 to November, 2017.&#x0D; Methodology: Different formulations of effervescent paracetamol tablets were produced through wet granulation method using varied concentrations of citric acid (15, 20 and 25 %) and sodium bicarbonate (15, 20 and 25 %) as the major effervescent ingredients. The powder blends were evaluated for angle of repose, tapped and bulk density to determine its flow property. The prepared tablets were further evaluated using the unofficial test for hardness, friability and thickness as well as the official tests for weight uniformity, disintegration time, carbon dioxide (CO2) content, water content and pH.&#x0D; Results: Angle of repose ranged from 23.96 ± 1.97o - 28.84 ± 0.91o, Hausner’s ratio ranged from 1.16 ± 0.02 – 1.25 ± 0.02 while Carr’s index ranged from 14 ± 1.73 - 20 ± 1.15. All the granules had good flow properties while granules for F3 was the optimized formulation. Friability values were from 0.38 - 0.39 %. Tablets disintegrated between 3 ± 43.06 to 5 ± 16.3 min. The effervescence time in all formulations was between 3 to 5 mins with batch F3 giving the best effervescence time.&#x0D; Conclusion: Granules made with Formulation F3 had the optimized flow characteristics. Effervescent paracetamol tablets containing 25% each of citric acid and sodium bicarbonate had the most desired properties as increase in both the concentration of the citric acid and sodium bicarbonate led to a decrease in the disintegration and effervescence time.

Comparative study on the real-time monitoring of a fluid bed drying process of extruded granules using near-infrared spectroscopy and audible acoustic emission

The process of fluidized bed drying of granules was comparatively evaluated by on-line real-time measurements of granule moisture content (MC) using near-infrared spectroscopy (NIR) and audible acoustic emission (AAE). The extruded granules were prepared by kneading a powder blend containing lactose, starch, crystalline cellulose, and riboflavin, with water. The MC of the granules (while they were dried at 35 °C in a fluidized bed dryer) was monitored simultaneously with NIR and AAE. The prediction accuracy of the NIR and AAE using partial least squares (PLS) was verified by measuring MC of the granules. The best calibration models following NIR and AAE evaluations consisted of five latent variables with correlation coefficients of 1.000 and 0.998 and root mean square error of 0.259 and 0.615, respectively. As a result of external verification, the accuracy of MC analysis by AAE was slightly lower than that of NIR; however, it was still applicable in practice. Furthermore, the end point of fluidized bed drying process was automatically determined using the PLS discriminant analysis. From the above results, it can be concluded that the AAE-mediated granule drying process can be monitored with sufficient accuracy (compared with NIR).

Al-matrix composites reinforced with quasicrystals consolidated at room temperature using HPT

High-Pressure Torsion (HPT) was used to consolidate Al-matrix composites reinforced with Al-Cu-Fe quasicrystals at room temperature. Gas-atomized Al and Al-Cu-Fe powders were mixed, in different proportions, using high-energy ball milling. The powder blends were consolidated using HPT and characterized using X-ray diffraction, Optical and Scanning Electron Microscopy. The samples were then mechanically characterized using Vickers microhardness, plane strain compression and sliding wear tests. The resulting composites showed that HPT processing at room temperature is a suitable route for manufacturing high quality quasicrystal-reinforcing Al-matrix composites, as they presented a substantial increase in the mechanical strength of the Al-based material and, additionally, a significant high wear resistance.

Manufacturing of Textured Bulk Fe-SmCo5 Magnets by Severe Plastic Deformation.

Exchange-coupling between soft- and hard-magnetic phases plays an important role in the engineering of novel magnetic materials. To achieve exchange coupling, a two-phase microstructure is necessary. This interface effect is further enhanced if both phase dimensions are reduced to the nanometer scale. At the same time, it is challenging to obtain large sample dimensions. In this study, powder blends and ball-milled powder blends of Fe-SmCo5 are consolidated and are deformed by high-pressure torsion (HPT), as this technique allows us to produce bulk magnetic materials of reasonable sizes. Additionally, the effect of severe deformation by ball-milling and severe plastic deformation by HPT on exchange coupling in Fe-SmCo5 composites is investigated. Due to the applied shear deformation, it is possible to obtain a texture in both phases, resulting in an anisotropic magnetic behavior and an improved magnetic performance.

Elimination of Composition Segregation in 33Al-45Cu-22Fe (at.%) Powder by Two-Stage High-Energy Mechanical Alloying.

In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying was conducted in two stages: at the first stage, a Cu+Fe powder mixture was ball-milled for 90 min; at the second stage, Al was added, and the milling process was continued for another 24 min. The main products of mechanical alloying formed at each stage were studied using X-ray diffraction phase analysis, Mössbauer spectroscopy, transmission electron microscopy, and energy-dispersive spectroscopy. At the end of the first stage, crystalline iron was not found. The main product of the first stage was a metastable Cu(Fe) solid solution with a face-centered cubic structure. At the second stage, the Cu(Fe) solid solution transformed to Cu(Al), several Fe-containing amorphous phases, and a spinel phase. The products of the two-stage process were different from those of the single-stage mechanical alloying of the ternary elemental powder mixture; the formation of undesirable intermediate phases was avoided, which ensured excellent composition uniformity. A sequence of solid-state reactions occurring during mechanical alloying was proposed. Mesopores and a spinel phase were the features of the two-stage milled material (both are desirable for the target catalyst).

Comparison of Phase Evolution and Sintering Properties of Ti-10Mo Alloys Prepared using Bulk Scrap and Blended Elemental (BE) Powder

In this study, Ti-10Mo alloy powder and sintered bodies were successfully fabricated using a threestep process of acid/organic solvent cleaning, hydrogenation/dehydrogenation (HDH) of bulk Ti-Mo scrap, and pressureless vacuum sintering of the alloy powder. This process can be used to recycle valuable Ti alloy. And unlike remelting-based recycling processes, in which elements vaporize, this process maintains the original ratio of Ti and Mo and results in no loss of elements during HDH and sintering. We note, however, that the phases in the resulting Ti-Mo alloy were changed by HDH and the sintering processes, and as a result the phases of the alloy evolved differently than those of alloys prepared by the blending of Ti and Mo powders. XRD results of the processed sintered bodies revealed different pathways for the transformation of the crystal structure. As sintering temperature increased, the dominant phase changes in the crystal structure of the sintered bodies that used commercial powders were α' → α' + α'', while the phase changes for the recycled Ti-10Mo sintered bodies were α' + α'' → α'' + β. Although the density of the sintered body using commercial materials was generally higher at a lower sintering temperature than the density of the sintered body that used recycled powder, at 1673 K their respective densities were nearly identical. Moreover, the sintered body that contained scrap showed superior Vickers hardness after the dual phase (α + β) of Ti was reached, despite its relatively low density.

Use of Fumed Silica Nanostructured Additives in Selective Laser Melting and Fabrication of Steel Matrix Nanocomposites.

The advancement of additive manufacturing (AM) for metal matrix nanocomposites (MMNCs) is gaining enormous attention due to their potential improvement of physical and mechanical performance. When using nanostructured additives as reinforcements in 3D printed metal composites and with the aid of selective laser melting (SLM), the mechanical properties of the composites can be tailored. The nanostructured additive AEROSIL® fumed silica is both cost-effective and beneficial in the production of MMNCs using SLM. In this study, both hydrophobic and hydrophilic fumed silicas were shown to successfully achieve homogenous blends with commercial 316L stainless steel powder. The powder blends, which exhibited better flow, were then used to fabricate samples using SLM. The samples’ microstructure demonstrated that smaller grains were present in the composites, resulting in improvements in mechanical properties by grain refinement compared to those of 316L stainless steel samples.

Fabricating antibacterial CoCrCuFeNi high-entropy alloy via selective laser melting and in-situ alloying

A quasi-equiatomic CoCrFeCuNi high-entropy alloy (HEA) with a broad-spectrum antibacterial ability and good mechanical properties has been fabricated by selective laser melting (SLM) and in-situ alloying of a blend of pre-alloyed CoCrFeNi powder and Cu elemental powder. The as-built HEA alloy has a homogeneous distribution of Cu and presents a single FCC phase. Compared with the same HEA fabricated using the traditional ingot metallurgy (IM) process, the HEA alloy fabricated by SLM releases more Cu ions to prevent growth and biofilm formation by gram-negative Escherichia coli and gram-positive Staphylococcus aureus, which enhances the applicability of the HEA alloy in potential applications that requires antibacterial ability. The results of this study confirm the feasibility of combining the antibacterial CoCrFeCuNi HEA alloy and SLM technology in fabricating complex shaped parts or structures with a strong antibacterial ability to be used in medical application or other environments desired for antibacterial ability.

Fire Behavior of Polyamide 12/Rubber Formulations Made by Laser Sintering.

In the present work, the processability and fire behavior of parts made by the laser sintering (LS) of polyamide 12/rubber powder blends is studied. In order to evaluate some of the interactions that could take place during LS, three acrylonitrile butadiene rubbers (NBRs) were used, which included two that had different acrylonitrile (AN) contents, and one that had carboxylated rubber. The results show that the flowability of the powders is strongly dependent on the rubber used. For the carboxylated rubber, a good flowability of the blend was observed, whereas the use of rubbers with different AN contents led to significant changes in the powder flowability, with a heterogeneous powder bed, and differences in the porosity as a function of the AN content. Furthermore, the addition of rubbers to polyamide 12 (PA12) entails an increase in the sintering window and, in particular, a change in the melting temperature of PA12 is noticed. Even though some changes in the crystallization and melting temperatures are observed, formulations containing 10 and 20 wt.% of rubbers could be processed using the same process parameters as PA12. Furthermore, the formulations containing carboxylated rubber show improved fire behavior, which is measured by a cone calorimeter, with reductions of about 45 and 65% in the peak of the heat release rate, compared to the PA12. Moreover, almost all of the samples evaluated in this study are classed as “Good” by the Flame Retardancy Index. This result can be partially explained by the formation of an amide linkage between the polyamide and NBR during processing, which could result in increases in the melt viscosities of these samples.

The microstructure and compressive properties of a sintered Fe–Mn–Al porous steel produced by blended elemental powder mixture

In this study, powder compacts produced by mixed elemental Fe, Mn, Al and C powders without ball milling were sintered at 640∘C and 1200∘C, respectively. The results revealed that intermetallic phases belonging to Fe2Al5 and Al8Mn5 appeared after pre-sintered at 640∘C. When the temperature increased to 1200∘C, only α-Fe phase existed. The total porosities of the sintered samples were ∼60 vol.% at 640∘C and ∼70 vol.% at 1200∘C, and the peak compressive strength of the 1200∘C-sintered samples was ∼1.6 MPa at the strain of ∼11%.

Electron Beam Powder Bed Fusion of Water Atomized Iron and Powder Blends.

In the present state of the art, highly spherical alloy powders are employed as feedstock in powder bed fusion processes. These powders are characterized by high flowability and apparent density. Their elaborate fabrication process is reflected in high powder price, adding a significant fraction to the cost of additively manufactured parts. Thus, the use of non-spherical powders, such as water atomized material, can lower costs significantly. Here, the electron beam powder bed fusion (PBF-EB) of standard water atomized iron powder used for press-and-sinter is studied. Despite raking problems, using the coating mechanism in standard configuration samples with densities exceeding 99% were fabricated. In a further step, the addition of alloying elements by powder blending is explored. Important powder properties of feedstock blended from irregular and spherical powders are characterized. The PBF-EB processing of two alloys is presented. The first represents a low carbon steel. Samples were characterized by metallographic cross-section, energy dispersive X-ray (EDX) mapping, and mechanical testing. The second alloy system is a FeCrAl. After PBF-EB processing of the powder mixture, chemical homogeneity was achieved. Besides the low cost, this approach of using water atomized powder mixed with master alloy offers the advantage of high flexibility for potential application.