Powder Blends Research Articles

Reactive deposition of CYSZ coatings using PS-PVD technology

CYSZ (CeO2-Y2O3-ZrO2) coatings were prepared via PS-PVD (plasma spray physical vapor deposition) using untreated YSZ and CeO2 blend powders instead of commercially CYSZ powders. 8YSZ was mixed with different proportions of CeO2 (10, 20and 30 wt%). CYSZ agglomerated composite powders were then produced via spray drying and CYSZ coatings were deposited through PS-PVD spraying. Microstructures of composite powders and coatings were observed using SEM and EDS, and characterization of powders and coatings were evaluated via XRD, laser particle size measurement and XPS. Results showed agglomerated composite powders possessed high percentages of particles with optimum size and were suitable for subsequent PS-PVD process. The coatings prepared with reactive deposition had a typical columnar structure as current coating method. The coatings exhibited uniform distribution of all elements and consisted mainly of the t-ZrO2 phase. Crystal structure and properties of coatings were identical to coating deposited via solid phase reactive powder.

Binder Jetting 3D Printing of Binary Cement-Siliceous Sand Mixture.

Three-dimensional printing allows accurate geometries to be obtained across a wide range of applications and it is now also moving into the architecture and construction industry. In the present work, a unique binary mix composed of ordinary Portland cement (OPC) and quick-setting cement (QSC) was combined with silica sand aggregate in different proportions for a customized binder jetting 3D printing (BJ3DP) process. Specimens were printed using the blended dry powders and deionized water to determine the impact of the processing variables on the properties of the realized specimens. The results show that the properties are influenced by the binary mix proportions and the layer thickness. The investigation found significant improvement in mechanical performance on increasing the proportion of OPC and optimal conditions were identified with proportions of 35 wt% OPC and 5 wt% QSC. Notable enhancements were also observed as the layer thickness was reduced.

African Breadfruit Seed Oil as Lipid Phase of Self-Emulsifying Drug Delivery System for Improved Gastrointestinal Fluid Solubility of Ibuprofen: Design and Evaluation

Introduction: Rain forest vegetations all over the world produce large quantity of economically important seed oils which, in most developing countries are utilized only as food condiments but hardly employed in pharmaceutical formulations.
 Objectives: The purpose of this work was to formulate ibuprofen-loaded self-emulsifying drug delivery system for the enhancement of the gastrointestinal fluid solubility of this poorly water soluble drug.
 Methods: The breadfruit seed oil was extracted by the soxhlet extraction technique and characterized for various physicochemical properties including acid, iodine, peroxide, saponification values and organoleptic properties. The super saturation solubility process, water titration studies and pseudo ternary phase diagrams were used to select and quantify the components of the emulsion systems. The liquid self-emulsifying drug delivery systems were converted to solid forms by adsorption onto a blend of miceocrystalline cellulose and Aerosil-200 powders. The resulting wet mass was dried and processed for encapsulation.
 Results: The percentage yield of the oil from the extraction process was 20.68 % while the acid, iodine, and saponification values were, 4.12 ± 1.24, 21.91 ± 0.88, and 302.45 ± 1.22 respectively. The ibuprofen exhibited higher solubility in the hydrolysed oil than in the crude form. Fourier transform infrared analysis did not reveal existence of component incompatibility. The optimized liquid and solid emulsions exhibited standard characteristics that were compatible to previous literature reports. The formulations also exhibited superior drug release properties over two control samples.
 Conclusion: It was concluded that Breadfruit seed oil has the potential to function as the lipid component of ibuprofen-loaded self-emulsifying drug delivery system formulated to enhance the aqueous solubility of the drug.

Effect of bimodal size distribution on the behavioural properties of powders used in the LPBF process

The adoption of the Laser Powder Bed Fusion (LPBF) process faces challenges due to a low productivity and high powder costs. Improvements in productivity can be achieved by increasing the laser power and the layer thickness. The present work explores an alternative approach by investigating the use of coarser particle size distributions in conjunction with thick powder layers. This approach potentially allows the valorisation of currently unexploited powder fractions in the LPBF process. In this work, blends of AISI 420 stainless steel powders are characterised in terms of their compaction dynamics and flow properties. The results obtained show that different levels of cohesion and compaction rate are found depending on the size ratio, the absolute size of the fine powder and its fraction. This work provides guidance for the selection of powder blends and opens up the possibility of their use in the LPBF process.

Removal of heavy metals in water-extracted solution through adsorption by palygorskite and stabilization by comilling.

Removing water-soluble chlorides (WSCs) through water extraction is a common pretreatment technology for recycling municipal solid waste incineration (MSWI) fly ash (FA). However, the extracted solution often contains heavy metals, the concentrations of which exceed standards for effluent. This study aims to investigate the adsorption of heavy metals by palygorskite in water-extracted solution and explore the feasibility of stabilizing heavy metals through comilling palygorskite-adsorbed heavy metals (PAHMs) with water-extracted fly ash (WFA). The experimental parameters include: two-stage water extraction with a liquid-to-solid ratio of 5, adding 0, 0.125, 0.25, 0.5, 1, 2 or 3 g of palygorskite to 100 mL of water-extracted solution, and comilling the mixture of PAHMs and WFA for 0, 0.5, 1, 2, 4, 8, 12, 24 or 96 hours. The experimental results revealed that 3 g of palygorskite in 100 mL of extracted solution could absorb Pb, Cd, Cr, Cu and Zn, meeting the effluent standards. The total amount of Pb, Cd, Cr, Cu and Zn removal rate reached 99.7%. Moreover, 98.44% of the WSCs were not adsorbed, the water extraction process for removing WSCs was not compromised. After the comilling of PAHMs and WFA, the distribution of the heavy metals in the milled blended powder was greater than 99.44%; moreover, toxicity characteristic leaching procedure concentrations were determined to conform to regulatory standards, and the sequential extraction procedure revealed that the heavy metals tended to be in stable fractions. This achieves the goal of preventing secondary pollution from heavy metals during the MSWI FA recycling process.

UV–VIS imaging-based investigation of API concentration fluctuation caused by the sticking behaviour of pharmaceutical powder blends

Surface powder sticking in pharmaceutical mixing vessels poses a risk to the uniformity and quality of drug formulations. This study explores methods for evaluating the amount of pharmaceutical powder mixtures adhering to the metallic surfaces. Binary powder blends consisting of amlodipine and microcrystalline cellulose (MCC) were used to investigate the effect of the mixing order on the adherence to the vessel wall. Elevated API concentrations were measured on the wall and within the dislodged material from the surface, regardless of the mixing order of the components. UV imaging was used to determine the particle size and the distribution of the API on the metallic surface. The results were compared to chemical maps obtained by Raman chemical imaging. The combination of UV and VIS imaging enabled the rapid acquisition of chemical maps, covering a substantially large area representative of the analysed sample. UV imaging was also applied in tablet inspection to detect tablets that fail to meet the content uniformity criteria. The results present powder adherence as a possible source of poor content uniformity, highlighting the need for 100% inspection of pharmaceutical products to ensure product quality and safety.

In-situ alloying laser powder bed fusion of Ni-Mn-Ga magnetic shape memory alloy using liquid Ga

Ni-Mn-Ga-based magnetic shape memory alloys can exhibit large magnetic field induced strains (MFIS). Recently, additive manufacturing techniques, especially laser powder bed fusion (L-PBF), have been successfully used to manufacture functional polycrystalline Ni-Mn-Ga with complex geometries, such as ‘bamboo-grained’ lattice structures. However, previous approaches of L-PBF of Ni-Mn-Ga have used pre-alloyed powders, which can limit the compositional freedom of the manufactured devices. This study explores, for the first time, the feasibility of an in-situ L-PBF alloying approach using a powder blend of elemental Ni, Mn, and Ga. Promising results were obtained despite the significant differences between the elemental Ni and Mn powders and the liquid Ga. The microstructure of the as-built sample showed distinct stripe patterns from the 14 M structure confirmed by XRD analysis. Heat-treatment significantly improved chemical homogeneity, dissolved the Ni-rich phase but couldn’t dissolve MnO hindering the shape memory effect.

Work hardening of quaternary powder metallurgy Ti alloys

The concurrent addition of Al as α stabiliser and Nb and Cu or Mn as β stabilisers was used to design new powder metallurgy quaternary Ti alloys and investigate their manufacturability and consequent performance. It is found that the powder blend's compressibility decreases with the total amount of alloying elements due to the characteristics of the powders used. Consequently, the sintered density of the quaternary Ti alloys decreases and slightly higher values are achieved if Mn instead of Cu is used, despite the higher diffusivity of Cu at the sintering temperature. The quaternary Ti alloys are characterised by a lamellar microstructure comprising α grain boundaries and α+β lamellae where the amount and type of alloying elements determine the coarseness of the microstructural features. This results in stronger and harder but less ductile quaternary Ti alloys for higher alloying elements contents and for stronger β stabilisers, although of their overall elastoplastic behaviour. Because of their lamellar microstructure, the quaternary Ti alloys show similar deformation behaviour but the actual work hardening rate is governed by the fineness of the microstructure.

In Vitro Profile of Hydrocortisone Release from Three-Dimensionally Printed Paediatric Mini-Tablets.

Three-dimensional (3D) printing is quickly being adopted in pharmaceutics due to the many advantages it offers, including treatment, adaptability, the reduction in waste and the accelerated development of new formulations. In this study, micro-extrusion printing was implemented for the production of modified-release hydrocortisone (HCT) mini-tablets for paediatric patients. For the developed formulations, Gelucire® 44/14 and Precirol® ATO 5 were used as the main inks at three different ratios: 70%/30%, 60%/40% and 50%/50%, respectively. The printing parameters (temperature and pressure) were altered accordingly for each ratio to achieve printability. The printed mini-tablets exhibited excellent printing quality, featuring consistent layer thicknesses and smooth surfaces. Dissolution tests were performed, and the results indicated a successful modified release of HCT from the mini-tablets. In summary, micro-extrusion exhibited favourable processing abilities for powder blends, facilitating quick printing and the fabrication of potential personalized dosages.

Additive Metallization of Alumina with Copper-Titanium Powder Blends for Power Electronic Applications

Additive manufacturing shows great potential to further increase the performance of power electronic modules through novel packaging concepts. Such an approach is the integrated manufacturing of metal-ceramic substrates by means of laser powder bed fusion of metals (PBF-LB/M). With this layered additive manufacturing process, planar ceramic substrates can be metallized and electrically functionalized for power electronic applications. In this paper Al2O3 ceramic substrates are metallized via PBF-LB/M by selectively melting applied powder layers with software defined geometries. The investigated powders are mixtures of copper and titanium powders with 1 wt.%, 5 wt.% and 10 wt.% titanium in order to enable bonding by creating a titanium-oxide reaction layer at the interface to the ceramic. Shear tests and microstructural investigations show that a subsequent heat treatment increases the adhesion and density of the metallization. By energy dispersive X-ray microscopy (EDX) the partial formation of reaction layers is detected.

Analysis of initial stage of liquid-phase sintering by combined multi-phase-field/discrete-element method

A combined multi-phase-field/discrete-element method in two dimensions is applied to the liquid phase sintering process of blended elemental powders. The boundary migration, diffusion of elements, and phase transformation between two dissimilar particles are calculated using a multi-phase-field method for sintering based on Gibbs energy functions. The sintering shrinkage is computed with the discrete-element method taking account of the neck size and sintering force, which are obtained from a multi-phase-field simulation. In this study, a pair or small cluster consisting of two elemental powders in a binary eutectic alloy is used as a model system. First, the formation of a liquid phase around the contact area between two dissimilar particles above the eutectic temperature of the system, and the motions of the particles due to grain boundary sliding along the liquid films are confirmed. Second, an Sn–Bi system is selected as the real eutectic system, and the sintering behavior of powder compacts with various mixing ratios of Sn and Bi particles is demonstrated. Finally, transient liquid-phase sintering of Sn–Bi system is simulated, that is, the generation and extinction of the liquid phase due to interdiffusion between Sn and Bi particles are calculated.

Mixed-Material Feedstocks for Cold Spray Additive Manufacturing of Metal–Polymer Composites

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing as composite components for a wide variety of industrial and medical applications due to their excellent thermomechanical properties. However, conventional PEEK metallization methods can often lead to poor quality control, low deposition rate, and high cost. Cold spray is a promising potential alternative to produce polymer–metal composites rapidly and inexpensively due to its relatively mild operating conditions and high throughput. In this study, we investigated the deposition characteristics of metal–polymer composite feedstock, composed of PEEK powder and copper flake in varying ratios, onto a PEEK substrate. Copper-PEEK powder blends were prepared by both hand-mixing and cryogenic milling (cryomilling), which predominantly creates composite particles with micron-scale copper domains coating PEEK particle surfaces. This process non-monotonically affects the relative dominance and length scales of the multiple contributing deposition mechanisms present in mixed-material cold spray. In low-pressure cold spray, deposits showed significant changes in deposition efficiency and composition as a result of milling, with improvements in these characteristics most dramatic at lower Cu fractions. Deposits of a cryomilled blend of nominally 30 vol.% copper in PEEK exhibited minimal porosity under scanning electron microscopy, complete retention of powder composition, and the highest deposition efficiency among all samples tested. Notably, neither neat PEEK nor neat Cu meaningfully deposited at the same mild conditions as this 30 vol.% Cu blend, indicating a synergistic departure from linear mixing rules driven by the relative balance of local deposition interactions (e.g., hard–soft, soft–soft, etc.). Intentional powder and process design toward optimizing this balance may facilitate cold spray metallization applications.

Multi-Scale Cu-Cr Composites Using Elemental Powder Blending in Laser Powder-Bed Fusion

Cu-Cr-based alloys are good candidates for thermo-electrical applications because of their excellent combination of mechanical, thermal, and electrical properties. However, tailoring their microstructure via traditional processes such as sintering and casting remains a challenging task. Herein, we introduce a strategy to fabricate multiscale Cu-25Cr composites. This is achieved through in-situ alloying from elemental powder blending in laser powder-bed fusion. The process is monitored layer-by-layer using synchrotron X-ray microtomography. We show that by changing the melt-pool size and its overlap, one can produce multiscale Cu-Cr composites with coarse (∼50µm) and fine Cr-spheroids (<500 nm) while controlling their spatial distribution. Coarse Cr particles are preferentially located at the melt pool boundaries while fine spherical Cr particles are distributed in the melt pool interior. Spatial variations in mechanical properties are revealed using nanoindentation mapping. This strategy opens new opportunities to optimize multiscale metal matrix composite through the manipulation of the scanning strategy.

Powder characterisation and the impact on part performance in electron beam melted Ti6Al4V

Metallic powder for Additive Manufacturing (AM) typically varies between different batches, while being supplied to achieve the same customer specification. In order to reduce this variation and minimise waste, batches are often mixed together in both their virgin and used form. However, the properties of bulk components must have limited variance in order to be reliably used in an industrial setting. This manuscript is focused on the analysis of Grade 5 Ti6Al4V powders (3 virgin, plus 2 blends) and the associated mechanical properties of Electron Beam Melted (EBM) AM specimens. Measurements were performed in accordance with the principles defined in the MMPDS Handbook, ESDU database, and ASTM F2924. The tensile, and fatigue properties of the EBM specimens were found to be superior when compared with Ti6Al4V properties within these standards. This demonstrated that these powders are suitable for a wide range of commercial applications, and that these blended powders (including used powders) are able to achieve these requirements. Additionally, the results provide a systematic route for powder verification and highlight the importance of adhering to standardised principles and specifications to ensure quality and reliability in metallic AM materials.

Analyzing the Mechanical, Durability, and Microstructural Impact of Partial Cement Replacement with Pumice Powder and Bamboo Leaf Ash in Concrete

This study explores the physiomechanical and durability properties of C-25 concrete by partially replacing cement with blends of pumice powder (PP) and bamboo leaf ash (BLA). The combined amount of major oxides SiO2, Al2O3, and Fe2O3 in PP is 84.59%, while in BLA, it is 74.4%, classifying PP and BLA as class N and F pozzolans. Subsequently, the study examines the impact of different cement replacement percentages, emphasizing 5%, 10%, 15%, and 20% on C-25 with varying mixes of concrete: Mix-1 (100, 0, and 0), Mix-2 (90, 5, and 5), Mix-3 (85, 10, and 5), Mix-4 (85, 5, and 10), and Mix-5 (80, 10, and 10) which correspond to the proportions of OPC, VPP, and BLA used in each mix respectively and by using 1 : 2.34 : 2.68 (cement : sand : aggregate) with the water/cement ratio (w/c) of 0.491. The study’s findings indicate that as the proportion of PP and BLA increases in concrete, the workability of the mixture decreases. Moreover, on the 28th day, Mix-2 with (35.84 MPa) and Mix-3 with (33.55 MPa) met the desired mean compressive strength (33.5 MPa) required for C-25 concrete per the ACI standards. Additionally, the flexural strength of concrete produced with partial replacement of Mix-2 with a flexural strength of 3.86 MPa fulfills the minimum strength requirement of 3.5 MPa specified by the C-25 ACI standards. The PP and BLA blended concrete had lower water absorption than the control mix in Mix-2. It also improved resistance to sulfuric acid attack, and Mix-3 had the least strength reduction of 9.59%. In contrast, the control mix has a 33.34% strength reduction.

Crack reduction in electron beam cladding of AlCoCrFeNiCu high entropy alloy coatings by resistance seam welding pre-alloying

A major drawback in the application of AlCoCrFeNiCu high-entropy alloy (HEA) coatings is a susceptibility to hot-cracking, which is closely related to a grain boundary segregation due to the low melting point Cu component. Reducing or eliminating the grain boundary segregation of Cu is an effective means of reducing cracking in the HEA coating. In this study, blended and partial pre-alloyed powders were used as feedstock to fabricate the AlCoCrFeNiCu coating. The application of electron beam (EB) cladding to partial pre-alloyed powders, prepared by resistance seam welding (RSEW), resulted in an appreciable reduction of crack density in the coating. This response is attributed to the formation of Ni3Al and Al4Cu9 promoted by the relatively low heat generated during the RSEW process. In subsequent EB cladding, nanoscale Me3Al (Me = Cu, Ni) replaced the Cu-rich phase at grain boundaries. The hardness and wear resistance of coatings using partially pre-alloyed powders were 17.2 % and 15.8 % higher, respectively, than blended powders. The findings of this study indicate that the use of partial pre-alloyed powders can offer a new effective approach to reducing the hot cracks in EB cladding AlCoCrFeNiCu HEA coatings.

Dry Recycling of Lithium‐Containing Material by Forced Tribocharging and Electrostatic Separation

AbstractLithium‐containing components in batteries, electronics, and renewable energy pose material and waste challenges. Ongoing research focuses on eco‐friendly recycling, emphasizing electrostatic separation as a method to recover, for instance, lithium, especially in battery recycling. This study investigates forced dry triboelectric charging and electrostatic separation of powdered materials, with a focus on the charging behavior of lithium aluminate and talcum. The electrostatic separation efficiency for a blend of powders is also evaluated. Collected samples are analyzed via inductively coupled plasma‐mass spectrometry testing to assess component enrichment. Results show successful lithium enrichment from a talcum‐lithium aluminate mixture, highlighting significant separation success.

Microstructural and tribological properties of high-performance Inconel 625 alloy-WS2 self-lubricious composite coating by laser assisted cold spray

A hard and self-lubricious composite coating of tungsten disulfide (WS2) blended Inconel 625 alloy was deposited on AISI 304 stainless steel substrate by laser assisted cold spray (LACS) process through optimizing the laser power and gas pressure of the supersonic jet. Effects of the laser power which determined the deposition temperature and the gas pressure of the cold spray on powder deposition were studied. The surface temperature during laser heating was maintained below the evaporation temperature of WS2 for avoiding depletion of the WS2, but sufficiently high to soften the hard Inconel 625 powder. This facilitated deposition of the blended powder through plastic deformation at a relatively low gas-jet velocity in comparison to that typically employed in a conventional cold spray process. XRD and XPS results confirmed the presence of WS2 in the coating. The coefficient of friction was found to be 5 times lower (0.11) and the wear rate 42 times lower (8.5 ×10-6 mm3/N-m) than those of the substrate. The coating exhibited a hardness more than two times that of the substrate (490 HV) due to presence of nano-sized tungsten dispersed in the matrix.

Features of Microstructural Evolution and Corrosion Behavior of Ti6Al4V Titanium Alloy Fabricated from Elemental Powder Blends

Sintered Ti6Al4V titanium alloys prepared from TiH2/60Al40V powder blends under various technological conditions were studied. The microstructural evolution was investigated by X-ray diffraction, scanning electron microscopy, optical microscopy, and energy dispersive X-ray analysis. The corrosion resistance of sintered titanium alloy was evaluated by the static immersion test in 40 wt.% H2SO4 acid, according to ASTM standard G31-72(2004). Depending on powder metallurgy processing parameters (compaction pressure or sintering temperature), the Ti6Al4V alloy was obtained with various structural features (porosity and structural heterogeneity). It was shown that those structural features of sintered Ti6Al4V titanium alloy are a key microstructural factor that determines their corrosion resistance. For instance, an increase in porosity leads to enhanced corrosion resistance. Based on the current research, the optimal manufacturing regimes of powder metallurgy of Ti6Al4V titanium alloy ensure the achievement of characteristics sufficient for practical use in aggressive conditions of the chemical industry were obtained.

Optimization of sustainable concrete properties modified with blends of date palm ash and eggshell powder using response surface methodology.

Agricultural waste products are one of the major solid wastes disposed into landfills without treatment or recycling. In this study, date palm ash (DPA) was processed from date tree waste and used to partly substitute cement in dosages of 0 %, 10 %, 20 %, 30 %, and 40 %. To counteract the slow pozzolanic reaction of the DPA, eggshell powder (ESP) was added in amounts of 0 %, 1 %, 2 %, 3 %, and 4 % by mass of binder. Response surface methodology (RSM) was used for designing experimental mixes, optimization and establishing statistical models for predicting the properties of the concrete. Blending DPA and ESP as hybrid binder materials in concrete improved its mechanical properties and reduced its water absorption. The RSM models established were very significant, having high accuracy and average error lower than 6 %. From the optimization, blending 14.77 % DPA and 2.2 % ESP gave the best performance in the concrete properties with desirability of 91.1 %.