Powder Processing Technique Research Articles

Synthesis and Characterization of Hematite Fe2O3 Nanofiller for Enhanced Dielectric and Microwave-Absorbing Properties in PTFE Composites

This paper presents the synthesis of hematite Fe2O3 nanofiller from mill scales and its application in polytetrafluoroethylene (PTFE) composites for enhanced dielectric and microwave-absorbing properties. The nanofiller was obtained through 9 hours of high-energy ball milling, resulting in a particle size reduction 43.6 to 11.05 nm. The PTFE/Fe2O3 composites were fabricated by dispersing different concentration of Fe2O3 nanofillers using the dry powder processing technique. The structural and morphological characterization of the nanofiller and PTFE/Fe2O3 composites was carried out using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The composites’ microwave absorption properties were analyzed utilizing vector network analyzer (VNA) measurements in the 8–12 GHz frequency range. Based on the findings from the results, as the percentage of filler increased from 5 to 15%wt, the composites' loss tangent and dielectric constant increased from 0.0272 to 0.0478 and 2.12 to 3.25, respectively, while their reduced signal transmission speed was between 2.21 and 2.07 x 108 m/s at 8 GHz and from 2.24 to 2.11 x 108 m/s at 12 GHz. These findings demonstrate that Fe2O3 nanoparticles are a suitable material for developing microwave-absorbing polymer composites within the 8–12 GHz frequency range.

Equibiaxial flexural strength determination of UO2 using a ball-on-ring test

To increase nuclear fuel performance and reliability, their mechanical properties require an accurate and statistically relevant assessment. Biaxial flexural strength tests provide an alternative to bend bar techniques for assessing mechanical behavior; namely, the transverse rupture strength (TRS) of ceramic samples. Biaxial test samples require simple geometries and minimal surface preparation, reducing fabrication costs and handling hazards. This study investigated the TRS of polycrystalline UO2 fuel forms at room temperature using a ball-on-ring test fixture. Pellets were fabricated from UO2 powder using conventional powder processing and sintering techniques. The TRS and Weibull parameters were obtained through Weibull statistics on over 60 UO2 samples tested under equibiaxial flexure. The larger sample size in this study enabled a more robust Weibull statistical analysis than alternative test methods, which may not capture the stochastic failure of typical ceramics. Furthermore, two different loading ball diameters were employed to assess the impact of contact damage on fracture strength. While Hertzian contact damage was observed with the smaller loading ball, the fracture strength remained unaffected. A fracture analysis of the tested UO2 samples indicated a mixture of intergranular and transgranular fracture that transitions to transgranular fracture with increasing distance from the fracture origin. The characteristic strength of the combined data sets was determined to be 148 MPa, and the Weibull modulus was determined to be 9.1. The TRS values and Weibull parameters were close to values found in the literature for alternative testing techniques using samples with similar microstructure and density. The findings in this study validate the ball-on-ring method used to obtain the TRS of UO2 with a sample geometry more representative of nuclear fuels. Additionally, experimental TRS results from this study can be implemented in modeling codes to predict fuel performance, which is critical to fuel burnup extension and advanced nuclear fuel technologies.

Inhalation Dosage Forms: A Focus on Dry Powder Inhalers and Their Advancements.

In this review, an extensive analysis of dry powder inhalers (DPIs) is offered, focusing on their characteristics, formulation, stability, and manufacturing. The advantages of pulmonary delivery were investigated, as well as the significance of the particle size in drug deposition. The preparation of DPI formulations was also comprehensively explored, including physico-chemical characterization of powders, powder processing techniques, and formulation considerations. In addition to manufacturing procedures, testing methods were also discussed, providing insights into the development and evaluation of DPI formulations. This review also explores the design basics and critical attributes specific to DPIs, highlighting the significance of their optimization to achieve an effective inhalation therapy. Additionally, the morphology and stability of 3 DPI capsules (Spiriva, Braltus, and Onbrez) were investigated, offering valuable insights into the properties of these formulations. Altogether, these findings contribute to a deeper understanding of DPIs and their development, performance, and optimization of inhalation dosage forms.

The effects of powder size and sintering temperature on the microstructure and properties of modified MA6000 alloy produced by spark plasma sintering

ABSTRACT The present study investigates the properties and microstructure evolution of MA 6000, a nickel-based alloy produced by mechanical alloying and spark plasma sintering (SPS), a powder processing technique in metallurgy. This study aims to explore the potential of MA 6000 as a high-temperature material for industrial applications. Modified MA 6000 samples of different powder sizes were sintered in a high-vacuum environment at temperatures ranging from 800 to 1100°C. At 800°C, the cohesion between powder particles was not significant, resulting in low-density samples. However, at 1000°C, the samples consisted of many fully sintered regions related to finer powder particles, while no specific morphology was observed at 1050°C. The image quality and inverse pole figure (IQ-IPF) map indicated that the grains were distributed randomly in all sintered samples, and the average distribution of grain size of samples sintered at 1050°C was larger than that of those sintered at 1000°C.

PROSPECTS FOR TURMERIC AGROINDUSTRY IN LAMTEUBA, SEULIMUM SUB-DISTRICT ACEH BESAR DISTRICT

Turmeric is a medicinal plant that has many benefits. There are more turmeric production centers in Indonesia in Java and Sumatra, it does not rule out the possibility of turmeric production centers in Aceh Province, one of which is in Seulimum District. The limited knowledge possessed by turmeric farmers, both technology and the market, makes turmeric farmers prefer to sell directly their turmeric harvests rather than processing them first into other products. The purpose of this study was to determine the processing techniques, costs and benefits derived from the turmeric powder processing industry in Lamteuba, Seulimum District, Aceh Besar District. The scope of this research is limited to processing techniques, business feasibility analysis of turmeric powder. Based on the research results, it was found that the turmeric powder processing techniques in Lamteuba already used machine technology such as washing machines, slicing machines, ovens and milling machines. Production costs incurred amounting to Rp. 22,047,273/month with a monthly profit of Rp. 4,952,727. The R/C Ratio value is 1.22, meaning that the business is feasible to run. The ROI value is 22.46% and the BEP price and BEP the amount of production obtained are Rp. 48,993/Kg and 367 Kg/month. 46% and BEP price and BEP the amount of production obtained respectively Rp. 48,993/Kg and 367 Kg/month. 46% and BEP price and BEP the amount of production obtained respectively Rp. 48,993/Kg and 367 Kg/month.

Effect of Surface Dispersion of Fe Nanoparticles on the Room-Temperature Flash Sintering Behavior of 3YSZ

Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the flash sintering behavior of a ceramic surface (3 mol% yttria-stabilized zirconia (3YSZ)) onto which loose metal (iron) powder was spread prior to flash sintering at room temperature (25 °C). The iron powder acts as a conductive phase that accelerates the start of flash sintering while also doping the ceramic phase during the sintering process. Notably, the iron powder substantially reduces the transition time from the arc stage to the flash stage from 13.50 to 8.22 s. The surface temperature (~1600 °C) of the ceramic substrate is sufficiently high to melt the iron powder. The molten metal then reacts with the ceramic surface, causing iron ions to substitute Zr4+ ions and promoting rapid densification. The YSZ grains in the metal-infiltrated area grow exceptionally fast. The results demonstrate that spreading metal powder onto a ceramic surface prior to flash sintering can enable the metal to enter the ceramic pores, which will be of significance in developing and enhancing ceramic-metal powder processing techniques.

Fabrication of highly transparent thulium-doped Al2O3 nanocrystalline ceramics with broadband emission at 1.8 μm

Rare earth (RE) doped polycrystalline Al2O3 ceramics have attracted increasing research interest in the past decade for lasing and lighting applications because of their outstanding thermal conductivity and fracture strength enabling power scaling. However, the optically anisotropic nature of Al2O3 causes birefringent scattering in polycrystals, limiting the in-line transparency across visible and NIR wavelength range. To improve the transparency of Al2O3 ceramics, great control over powder processing and densification techniques are required to optimize its nanostructure. In this work, we present the first report of thulium incorporated nanocrystalline Al2O3 ceramic. The Tm:Al2O3 ceramic presented has the highest transparency among RE:Al2O3 reported to date, with a total loss coefficient of 0.6 cm−1 at the major emission wavelength 1.78 μm.

A comparative study of Mechanical, morphological and vibration damping characteristics of wood fiber reinforced LLDPE processed by rotational moulding

The present work investigates the mouldability of Linear Low-Density Polyethylene (LLDPE) with Wood Dust (WD) as a potential reinforcement with enhanced mechanical, morphological, and vibration damping characteristics. This was achieved by incorporating treated wood particles in rotomoulded grade into the LLDPE matrix with the help of a lab model rotomoulding machine. The incorporation of natural fibers finds difficult in the processing of rotomoulded parts since the process itself is a powder processing technique. The rotomoulded parts developed here is distinct from the previous works reported as it utilizes melt-compounded composite granules of a significantly larger size than the matrix material which is in the powder form. The need for natural fiber composite is come into existent because of its availability in abundance and is cheap. This project aims to come up with a solution of the best polymer composite material with a given percentage of natural fiber as filler. In rotational molding, several natural fibers have been used such as coir, flax, agave, sisal, palymira, etc. In the present study, LLDPE powder is used as a base material and mixed with a different weight percentage of WD fillers. The mechanical characterization and morphological study results proved that a sufficient hike in strength is obtained for 10% WD fiber added composites. The Experimental Modal Analysis (EMA) results also prove that the incorporation of WD is effective in improving the vibration damping characteristics of the composites developed.

Effects of Particle Size on the Dielectric, Mechanical, and Thermal Properties of Recycled Borosilicate Glass-Filled PTFE Microwave Substrates.

Low dielectric loss and low-cost recycled borosilicate (BRS) glass-reinforced polytetrafluoroethylene (PTFE) composites were fabricated for microwave substrate applications. The composites were prepared through a dry powder processing technique by dispersing different micron sizes (25 µm, 45 µm, 63 µm, 90 µm, and 106 µm) of the recycled BRS filler in the PTFE matrix. The effect of the filler sizes on the composites’ thermal, mechanical, and dielectric properties was studied. The dielectric properties of the composites were characterised in the frequency range of 1–12 GHz using an open-ended coaxial probe (OCP) connected to a vector network analyser (VNA). XRD patterns confirmed the phase formation of PTFE and recycled BRS glass. The scanning electron microscope also showed good filler dispersion at larger filler particle sizes. In addition, the composites’ coefficient of thermal expansion and tensile strength decreased from 12.93 MPa and 64.86 ppm/°C to 7.12 MPa and 55.77 ppm/°C when the filler size is reduced from 106 μm to 25 μm. However, moisture absorption and density of the composites increased from 0.01% and 2.17 g/cm3 to 0.04% and 2.21 g/cm3. The decrement in filler size from 106 m to 25 m also increased the mean dielectric constant and loss tangent of the composites from 2.07 and 0.0010 to 2.18 and 0.0011, respectively, while it reduced the mean signal transmission speed from 2.088 × 108 m/s to 2.031 × 108 m/s. The presented results showed that PTFE/recycled BRS composite exhibited comparable characteristics with commercial high-frequency laminates.

Dry Processing and Recycling of Thick Nacre–Mimetic Nanocomposites

AbstractBioinspired nanocomposites with high levels of reinforcement hold great promise for future, green lightweight, and functional engineering materials, but they suffer from slow, tedious, and nonscalable preparation routes, that typically only lead to very thin films. A rapid and facile dry powder processing technique is introduced to generate bioinspired nanocomposite materials at high fractions of reinforcements (50 wt%) and with millimeter scale thickness. The process uses powder drying of vitrimer‐coated nanoplatelets (nanoclay and MXene) from aqueous solution and subsequent hot‐pressing. As a method of choice in industrial lightweight composite materials engineering, hot‐pressing underscores a high potential to translate this approach to actual products. The use of the vitrimer chemistry with temperature‐activated bond shuffling is important to facilitate smooth integration into the nanocomposite design, leading to layered nacre‐inspired nanocomposites with nanoscale hard/soft order traced by X‐ray diffraction and excellent mechanical properties investigated using flexural tests. Recycling by grinding and hot‐pressing is possible without property loss. The compatibility with existing composite processing techniques, scalable thickness and dimensions, and recyclability open considerable opportunities for translating bioinspired nanocomposites to real‐life applications.

Review on soft magnetic metal and inorganic oxide nanocomposites for power applications

• Summary of the state-of-the-art soft magnetic materials and applications in power electronics. • Characteristics of oxide-based, metal-insulator, and insulator-insulator type composites. • Overview on thermodynamics and kinetics of self-assembled nanocomposites. • Microstructure engineering of soft magnetic composites based on traditional and advanced powder processing techniques. Oxide-based nanocomposites have potential to offer much higher switching frequencies compared with state-of-the-art soft magnetic materials for applications in power electronics. However, scalable techniques for synthesizing high performance bulk oxide-based nanostructured and nanocomposite systems with superior performance compared to traditional materials are limited. This review aims at identifying existing and potential opportunities for the development of high performance nanocomposite systems through microstructure engineering specific to soft magnetic property optimization by traditional processing routes. The review begins with general introduction about soft magnetic properties of different classes of materials, followed by a detailed description of crystal structures and the underlying physics responsible for their magnetic performance. These include; soft ferrites, bulk crystalline alloys, metal-amorphous nanocomposites, and metal-oxide nanocomposites of various nature such as metal-insulator and insulator-insulator type composites. An overview on powder metallurgy techniques is provided and aspects relevant to optimizing the balance between competing requirements of high effective electrical resistivity to mitigate eddy current losses and high saturation magnetization are highlighted.

Architectural design of MWCNT reinforced AlSi10Mg matrix composites with comprehensive mechanical properties

In the present study, we reported a powder processing technique for fabricating a heterogeneous AlSi10Mg matrix reinforced by CNTs with enhanced comprehensive mechanical properties. The as-designed composite with 2 wt.% CNT exhibited excellent compressive yield strength of 211 MPa, which was 384% higher than that of the as-received AlSi10Mg (44 MPa), and similar ultimate strain (31.5%) to that of the matrix (32.5%). It was found that the combination of low-energy wet-milling and high-energy dry-milling as well as addition of the as-received matrix powders/CNTs in the dry-milling stage resulted in non-homogeneous dispersion of CNTs in the matrix, facilitating the development of heterogeneous architecture, and finally giving rise to high strength and acceptable ductility. The applied strategy shed light on the development of strong and ductile composites with different metallic matrices and reinforcements.

Effect of powder manufacturing process on characteristics of nanostructured MCrAlY coatings: dry vs. wet ball milling

Metallic MCrAlY coatings have been widely utilized to protect the high-temperature materials operating in aggressive conditions of gas turbines. However, with more demands on the turbine inlet temperature rise for efficiency gains, there is a need to further improve the high-temperature performance of the MCrAlY coatings. A possible way to meet this challenge is by microstructure modification. The aim of this study is to produce nanocrystalline MCrAlY powders via wet and dry mechanical milling techniques and deposit the obtained feedstock powders by high-velocity oxygen fuel (HVOF) spraying method. A comprehensive characterization and comparison of the different powder processing techniques and the corresponding coatings were studied. It was established that the nano-scaled MCrAlY feedstock powder with low contamination levels could be achieved by mechanical milling. Moreover, the powder samples were well-deposited by the HVOF process and the correlation between powder properties and coating characteristics was investigated.

Refractive Imaging of Air Shock Above Microscale Defects in Pentaerythritol Tetranitrate (PETN) Films

AbstractPhysical vapor deposition (PVD) of high explosives can produce energetic samples with unique microstructure and morphology compared to traditional powder processing techniques, but challenges may exist in fabricating explosive films without defects. Deposition conditions and substrate material may promote microcracking and other defects in the explosive films. In this study, we investigate effects of engineered microscale defects (gaps) on detonation propagation and failure for pentaerythritol tetranitrate (PETN) films using ultra‐high‐speed refractive imaging and hydrocode modelling. Observations of the air shock above the gap reveal significant instabilities during gap crossing and re‐ignition.

Three-dimensional phase field sintering simulations accounting for the rigid-body motion of individual grains

Sintering is a widely used powder processing technique in industrial applications. During sintering, atoms migrate to decrease the energy of the system via two main mechanisms: coarsening and densification, both of which lead to significant morphological variation of the sintered microstructure. When simulating sintering dynamics, the phase-field method has been broadly utilized because of its convenience in tracking morphology evolution. When a large number of grains is involved, it is common to use the same order parameter to describe multiple grains that are not in direct contact with one another (in order to reduce the computational memory demands). However, with this treatment it is difficult to handle the rigid-body motion of individual grains during densification. In this work, an implementation scheme is introduced to overcome the challenge of calculating individual particle motion based on existing equations. It uses a grouping algorithm and sets a cutoff radius on each grain for calculating the particle velocity during densification. This method allows for the incorporation of the densification mechanism, which has been commonly ignored in previous work, into phase-field sintering models in three-dimensional simulations with a large number of particles/grains. Moreover, through combination with the smoothed boundary method, material properties of sintered microstructures, such as the effective diffusivity and Young’s modulus, can be calculated during the sintering processes.

Effect of Fiber Content on Mechanical and Morphological Properties of Bamboo Fiber-Reinforced Linear Low-Density Polyethylene Processed by Rotational Molding

Rotational molding or rotomolding is a powder processing technique used for the manufacturing of hollow plastic products. The present work investigates the moldability of long bamboo fiber as the reinforcement for linear low-density polyethylene (LLDPE) matrix. The temperature of the mold, oven and internal air temperature of the mold has been recorded to study the heat transfer rate while processing composites with different weight percentage. Mechanical properties were found to be improved by 5% fiber addition, and beyond that, the properties were reverted. Morphological characterization was done to analyze the interfacial properties of fiber and matrix. The present work successfully incorporated long bamboo fibers with LLDPE powders and uniformly distributed these fibers along the sides of the mold without applying any external pressure. Thus, it is concluded that fiber incorporation is possible in the rotomolding process and homogenous randomly oriented fiber dispersion can also be achieved by the rotational molding process.

Synthesis and characterization of brass–AlN composites synthesized by ball milling

Abstract Mechanical alloying is a powder processing technique in which repeated cold welding and fracturing of powder particles was done in high energy ball mill to produce a homogenous material. In this work, Brass matrix composites with different weight percentages of aluminium nitride (AlN) was synthesized through MA. The necessary amount of powders was milled to capitulate different compositions such as Brass-0 wt.% AlN, Brass-4 wt.% AlN, Brass-8 wt.% AlN and Brass- 12 wt.% AlN composites. The SEM and EDAX tests were conducted on the milled composite powders to investigate about their characterization. The SEM analysis established the homogeneous sharing of AlN in the Brass matrix. The green compacts were prepared and were sintered using electric muffle furnace under controlled atmosphere for a time period of 3 hr. The SEM images of the sintered composite samples ensured the uniform distribution of AlN in the matrix exclusive of pores. The outcome exposed that the adding together of AlN with the Brass matrix improved the mechanical properties of the brass matrix composites

Processing and interfacial effect of gelatin gel on coconut jute reinforced egg shell bio-composite

This research work presents novel coconut jute/ chicken egg shell (CJ/ES) bio-composite is made through using powder processing technique influenced by gelatin gel. Chicken egg shell in powder form is selected as matrix materials while coconut jute fibers act as reinforcing material is used to develop a novel processing technique. A successful incorporation of gelatin gel as a binder confirms the strong interface between egg shell and coconut jute. Developed composites are analyzed for interfacial effect by microstructural characterizations and mechanical properties.

Evaluation of Erosive Wear Rate of Al2O3-Cu Composite

This paper presents the analysis of erosive wear rate of Al2O3-Cu composite with 0, 1, 3, 5 and 7 wt% loading of Al2O3 particles. Composite samples were fabricated through cost effective powder processing technique. The surface morphology of the composites was analysed by Scanning Electron Microscope (SEM) and composition was examined by Energy Dispersive X-Ray (EDX). The density analysis show that the mass density increases with increase in wt% of Al2O3 particles up to 5 wt% and then decreases from 5 wt% to 7 wt% o. The decrease in mass density of composite at 7 wt% of Al2O3 particles may be due to agglomeration of Al2O3 particles. Hardness results show that the addition of Al2O3 particles, the hardness value increases up to an optimum level of wt% of Al2O3. The analysis of erosive wear shows that the erosive wear rate decreases with increasing wt% of Al2O3 from 0 wt% to 5 wt% of Al2O3 particles and then increases to 7 wt%. The erosive wear rate of the Al2O3-Cu composite depend on optimum level addition of Al2O3, sintered mass density, hardness value and distribution of Al2O3 particle in the composite.

Design of swellable ordered-mixed spherical drug particles (Swell-OM-spheres) using a dry powder milling and coating technique to improve dissolution behavior

A novel dry powder milling/ordered-mixing technique using a mechanical powder processor was previously developed to improve the dissolution properties of poorly water-soluble drugs. Mecanofused composite particles with an ordered-mixing principle, named OM particles, were designed using corn starch (CS) as a core particle and drug as a coating layer. In the present study this dry powder processing technique was modified to improve the dissolution behavior further by means of two approaches. First, wettable composite particles were produced by co-formulating the water-soluble waxy additive to enhance the hydrophilicity of the outer drug layer. Second, swellable composite particles were designed by replacing CS with a modified starch having expanding property as the core particle. It was found that the latter (swellable) approach was more effective than the former (wettable) one to improve the dissolution behavior of poorly water-soluble model drug. The swellable OM particles promptly expanded on contact with water and induced the effective detachment of fine drug particles from the core particles, resulting in rapid drug release. The present research suggests that the proposed contamination-free dry milling technique, which does not use hard milling balls or beads, can generate spherical drug particles with improved dissolution characteristics.