Powder Weight Ratio Research Articles

Combustion Synthesis of Aluminum Oxynitride in Loose Powder Beds.

This paper describes combusting loose powder beds of mixtures of aluminum metal powders and aluminum oxide powders with various grain sizes under various nitrogen pressure. The synthesis conditions required at least 20/80 weight ratio of aluminum metal powder to alumina powder in the mix to reach approximately 80 wt% of γ-AlON in the products. Finely ground fused white alumina with a mean grain size of 5 μm was sufficient to achieve results similar to very fine alumina with 0.3 μm grains. A lower nitrogen pressure of 1 MPa provided good results, allowing a less robust apparatus to be used. The salt-assisted combustion synthesis upon addition of 10 wt% of ammonium nitrite resulted in a slight increase in product yield and allowed lower aluminum metal powder content in mixes to be ignited. Increasing the charge mass five times resulted in a very similar γ-AlON yield, providing a promising technology for scaling up. Synthesis in loose powder beds could be utilized for effective production of relatively cheap and uniform AlON powder, which could be easily prepared for forming and sintering without intensive grounding and milling, which usually introduce serious contamination.

Molten Salt Synthesis of Core-Shell Heterostructure Cathode Materials for Solid Oxide Fuel Cells

Core-shell La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) – La0.8Sr0.2MnO3 (LSM) heterostructure crystalline materials have been synthesized in a simple, one-step feeding method via a KNO3 molten salt solvent. Two-phase perovskite composites can be synthesized in times as short as 10 minutes, and is demonstrated for the first time in a molten salt. A combination of X-ray diffraction and S/TEM energy dispersive X-ray spectroscopy has been utilized to confirm the formation of an LSM shell on LSCF cores in all samples when adjusting dwell time, core size, weight ratio between core and shell precursors, and weight ratio of powder to salt. Specifically, decreasing the LSCF core size increases core-shell yield. Smaller cores introduce a greater density of facets on the crystal surface, and provide more favorable sites for LSM heterogeneous nucleation. Decreasing the weight ratio of shell precursor to core decreases shell thickness, reduces the number of homogeneously nucleated LSM nanoparticles, and increases core-shell yield. Increasing the amount of salt relative to powder decreases supersaturation in the melt and results in less uniform, isolated shell deposition on the cores. Overall, the molten salt synthesis of core-shell perovskite oxides is investigated and demonstrated as an expeditious method to synthesize core-shell composites for energy applications. Considering the parameters of molten salt synthesized LSCF-LSM, optimized core-shell cathodes are then fabricated and used as electrodes in symmetric cells as a preliminary insight into their efficacy for solid oxide fuel cells.

Flexible asymmetric solid-state supercapacitor of boron doped reduced graphene for high energy density and power density in energy storage device

Environment safe, cost-effective, reusable and portable asymmetric solid-state supercapacitor (ASSC) device, working at higher operating potential with high energy density was the challenging criteria for practical application. To satisfy all these we fabricated the ASSC device with boron doped reduced graphene (BRG) as positive and reduced graphene oxide as negative electrode with H2SO4/PVA solid gel electrolyte. Using three different precursors at different weight ratio of boric acid (HBG), boron powder (BG) and boron trioxide (BTG) boron doped reduced graphene oxide was prepared by hydrothermal treatment followed by pyrolysis at 1000 °C in CVD for 2 h. All electrode material exhibits a EDLC and pseudocapacitance in CV and GCD with high capacitance, HBG exhibits 225 Fg−1, BG shows 216 Fg−1 and BTG exhibits 266 Fg−1. Our BTG2//rGO ASSC device exhibits the specific capacitance of 122 Fg−1 with an energy density of 67.8 Wh Kg−1, also exerts an excellent stability of 94% capacitance retention with 99% of coulombic efficiency even after 5000 cycles. Using the device 5 mm red light emitting diode (LED) and DC motors was demonstrated for potential applications.

Single layered hollow NiO–NiS catalyst with large specific surface area and highly efficient visible-light-driven carbon dioxide conversion

A sea urchin-shaped, single-layer, and hollow NiO–NiS photocatalyst with a large surface area was designed for carbon dioxide (CO2) conversion in this study. A d-glucose polymeric hollow frame was fabricated using a d-glucose monomer, and NiO particles were stably grown on it using the hydrothermal method to form a hollow NiO surface. The d-glucose frame was removed by heat treatment to create hollowed NiO; hollowed NiO–NiS (h-NiO–NiS) was subsequently obtained through ion exchange between the O ions in NiO and S ions in the sulfur powder. Additionally, we attempted to determine the correlation among the surface area of the h-NiO–NiS catalyst, CO2 gas adsorption capacity, and catalyst performance. The surface area of the h-NiO–NiS catalyst was ten times larger than that of the nanometer-sized NiO–NiS (n-NiO–NiS, 21.2 m2 g−1) catalyst. The CO2 photocatalytic conversion performance of the hollowed catalyst was approximately seven times larger than that of the nanosized catalyst. As the amount of ion-exchanged S increased, methane selectivity increased, and optimal methane production was obtained when the weight ratio of NiO and sulfur powder was 1 : 4. Using temperature-programmed desorption (TPD) analyses of CO2 and H2O, the adsorption of water molecules on the Ni–S surface and that of CO2 gas on the Ni–O surface during CO2 conversion reaction were confirmed. The h-NiO–NiS catalyst facilitated an effective charge separation through a well-developed interfacial transition between the linked NiS and NiO, and resulted in increased CO2 photoreduction performance under sunlight.

Characterization of mechanochemically synthesized ZrB2 nanocrystals with Zr/ZrO2, B2O3, and Mg reactants

Pure forms of Zirconium diboride (ZrB2) nanocrystals could successfully be synthesized by mechanochemical method. Synthesis of ZrB2 nanocrystals from Zirconium route was tried for the first time. The importance of zirconium sources is a cardinal factor to obtain the purity of the crystalline forms of ZrB2. All past methods involved ZrO2 source for the synthesis which always entrained the traces of ZrO2 due to the incomplete reduction. The present study also revealed the factors like ball to powder weight ratios on the final product properties. In this study synthesis of ZrB2 nanocrystals were compared using both Zr and ZrO2 routes. Products were characterized by XRD, scanning electron microscopy, transmission electron microscopy, BET method, and specific density analysis. The synthesis using Zr produced slightly larger nanocrystallites compared the sizes obtained via ZrO2 route. Surface areas of the products were found 32–88 m2/g depending upon the milling parameters used.

Microhardness Optimization of Al–TiC Nanocomposite Produced by Mechanical Milling and Heat Treatment

In this study, the Al–TiC nanocomposite was produced by the mechanical milling and sintering process. Also, the optimization of the milling parameters was performed by the Taguchi method. The X-ray diffraction analysis, scanning electron microscopy, and microhardness test were used to analyze the phase characterization, microstructure, and mechanical properties of the Al–4% TiC nanocomposite. At first, the milling speed, milling time, and ball to powder weight ratio were considered as the input data, and the microhardness was considered as the output value of the Minitab software. According to the design of the experiment, 27 experiments must be performed, which were reduced to 9 by the Taguchi method. After the milling, the powders were subjected to the cold pressing and subsequent sintering at 450 °C. The microhardness results showed that the Al–4% TiC nanocomposite was formed with a maximum microhardness of 271 HV. Furthermore, a proper model was proposed and the results indicated that there was a good agreement between the experimental and predicted microhardness.

Comparative Study on Improving the Ball Mill Process Parameters Influencing on the Synthesis of Ultrafine Silica Sand: A Taguchi Coupled Optimization Technique

Taguchi-based experimental design technique has been a major research area for making systematic approaches to understand the complex process of ball mill process parameters influencing on the synthesis of ultrafine silica sand monolayer degradation. To determine an optimal setting, Taguchi coupled optimization technique has been applied with a novel approach as there is no previous work focusing on the synthesis of ultrafine silica sand taking in account the ball milling process parameters and Taguchi coupled optimization techniques. The high-grade silica was milled in planetary ball mill and the selected samples were passed through washing, crushing, dehydrating, meshing and drying operations. The samples were analyzed using Malvern Instruments for particle size distribution. The experiments were conducted as per Taguchi’s L9 orthogonal array. Process parameters were analyzed using the signal-to-noise ratio based on the-smaller-the-better approach. To minimize the effect of uncontrollable variables, The ANOVA results determined the significance of the influential controllable variables so that the variability in the response is small. Optimization results confirmed that the balls to powder weight ratio were the most influential process parameter. The optimum process parameters setting concluded that balls to powder weight ratio are 20:1, the optimum ball mill working capacity is 2 L while the optimum speed of the ball mill is 105 rpm. Using SEM characterization, the improved particles of silica sand presented a spherical shape with a cluster. Using TEM of different structures of the ultrafine silica sand containing asymmetrical characteristics of particles confirmed the solid form of the ultrafine silica sand.

Experimental and Numerical Study on the Effect of Creep Behavior on Epoxy Composites Reinforced with Yttrium Oxide Powder

The creep test is one of the important approaches to determining some mechanical properties of composite materials. This study was carried out to investigate the creep behaviour of an epoxy composite material that was reinforced with Y<sub>2</sub>O<sub>3</sub> powder at weight ratios of <i>2</i>%, <i>7</i>%, <i>12</i>%, <i>17</i>% and <i>22</i>%. Each volume ratio was subjected to five loads over the range of <i>1N</i> to<i>5N</i> at a constant temperature of <i>16 ± 2°C</i>. In this work, creep behaviour, stress and elasticity modulus were studied through experimental and numerical analyses. Results showed that increasing the weight ratio of Y<sub>2</sub>O<sub>3</sub> powder enhanced creep characteristics.

Preparation of Fluoramphibole Glass Ceramics by The Mechanochemistry Method

The fluoramphibole glass ceramics were successfully prepared by mechano-chemistry method using waste glass and fluormica powder. The effects of ball milling parameters on synthesis of fluoramphibole glass ceramics were studied by means of XRD and SEM. The mechanical properties of the samples were discussed. The results show that the optimum preparation conditions were as follows: the processing of 10 to 1 ball to powder weight ratio, rotation speed of 800 rpm and milling of 45 minutes. Under these conditions, the highest value of modulus of rupture for fluoramphibole glass ceramics is 41.73 MPa.

Study of Ultimate Tensile Strength of Borosilicate Reinforced Metal Matrix Composite

Application of composite materials are increasing remarkably because of its much advantage compared to base matrix alloys properties like reduced weight, increasing strength, increasing wear resistance capacity etc. Reinforcement particles play a very important role for preparing metal matrix composite and ultimately improve its properties. In the present experiment, Al6063 designated aluminium alloy is used as matrix material and borosilicate glass powder is used as reinforcement. Specimens are prepared by stir casting method. Borosilicate glass is collected from scientific laboratory scrap to support disposal as well as recycle of the waste glass materials. In order to reduce the experimental run, the design of experiment is incorporated as per Taguchi’s L9 orthogonal array. It is observed that glass reinforcement in Al6063 aluminium alloy is compatible to form metal matrix composite. Secondly, ultimate tensile strength of the composite increases in selected combination of grain size and weight ratio of the borosilicate glass powder to the metal matrix.

Investigation on Mechanical and Electrical Properties of Cu-Ti Nanocomposite Produced by Mechanical Alloying

In this paper, Cu-Ti nanocomposite synthesized via ball milling of copper-titanium powders in 1, 3, and 6 of weight percentage compounds. The vial speed was 350 rpm and ball to powder weight ratio kept at 15:1 under Argon atmosphere, and the time of milling was 90 h. Obtained powders were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Crystallite size, lattice strain, and lattice constant were calculated by Rietveld refinement with Maud software. The results show a decrease in the crystallite size, and an increase in the internal strain and lattice parameter. Furthermore, the lattice parameter grew by increasing the percentage of titanium. Then, the powders compressed by the cold press and annealed at 650˚C, and finally, their micro-hardness and electrical resistance were measured. These analyses show that via increasing the proportion of titanium, Cu-6wt%Ti with 312 Vickers had the highest micro-hardness; due to the increasing the work hardening. Moreover, the results of the electrical resistance illustrate through increasing the amount of alloying material, the electrical resistance grew which the highest electrical conductivity was Cu-1wt%Ti with 0.36 Ω.

Modified Mechanical Coating Technique for the Preparation of Nanohydroxyapatite Coated Ti–6Al–4V Dental Implants

To improve the mechanical and biological properties and also to increase the lifetime and performance of Ti–6Al–4V dental implants they were coated by hydroxyapatite nanoparticles using a modified mechanical coating technique. A novel milling vial was developed to simultaneously coat hydroxyapatite nanoparticles on the Ti–6Al–4V substrates. The modified dimensions of the milling vial and optimized milling operation parameters were presented. The coating operation was applied for 4 hours with a ball to powder weight ratio of 30 : 1. Furthermore the bioactivity of the coatings was studied by placing the coating in a simulated body fluid for 14 days. SEM and FTIR analysis indicated the bone bonding ability of the coating by its capability of forming hydroxyapatite on the surface of the coating. The coating operation resulted in the formation of a uniform nanoparticle containing coating and significantly decreased the cost and complexity of the nanohydroxyapatite coating process on Ti–6Al–4V substrates.

Microstructure and properties of n-type Bi2Te3-based thermoelectric material fabricated by selective laser sintering

An n-type Bi2Te3-based thermoelectric material Bi2Te2.85Se0.15 was prepared through an SLS (Selective Laser Sintering) process with E12/Bi2Te2.85Se0.15 as composite powder (weight ratio 1:7), from which E12 was degreased after the SLS process. It was studied the effect of laser power, scanning speed and scanning interval on the density and thermoelectric properties of the sintered samples. The laser power was found the most important influential factor, while the scanning interval was the second and the scanning speed the least. The maximum dimensionless thermoelectric figure of merit ZT is about 0.88 in the condition when the laser power, scanning interval and scanning speed were 20 W, 0.26 mm and 3000 mm s−1, respectively.

Clinical flexible needle puncture path planning based on particle swarm optimization

Background and objectivePercutaneous puncture with flexible needle has important value in clinical application for its low trauma and flexible path. However, it is difficult to guarantee accuracy and avoid obstacles in puncture process. Therefore, developing a viable path planning method is particularly important. In this research, the bending deformation law of flexible needles during puncture was studied and the puncture path was planned to provide a feasible method for clinical application of flexible needles. MethodsAccording to the researchs that have been conducted, the path of the flexible needle in the tissue could be considered as a circular arc stitching. This research studied the calculation method of arc radius and obtained its actual value by the puncture experiments. Based on the arc model, the spatial transformation method of three-dimensional path planning was studied. In addition, a simplified particle swarm optimization (PSO) was applied into the process of path planning by changing the central angle of arc and the rotation angle of the needle body. ResultsThe results of Experiment 1 showed that the path radius of the flexible needle pierced into gelatin prosthesis was influenced by four parameters, which were needle diameter, tip angle, puncture speed and the weight ratio of gelatin powder. As the needle diameter and tip angle increased, the radius of needle path tended to increase, but when the puncture speed and gelatin mass ratio increased, the radius of needle path decreased. The results of Experiment 2 showed that the distances of needle tip apart from target point were 3.2 mm (barrier-free experiments) and 1.8 mm (obstacle experiments). ConclusionsThis research links the intelligent algorithm with the flexible needle puncture tissue process, which has high value in future clinical application. By setting the correct boundary conditions and parameters, the flexible needle can be planned to reach the target point accurately.

Enhanced ferromagnetic and electric properties of multiferroic BiFeO3 by doping with Ca

We report the dependence of magnetic and electric properties with the substitution of Bi3+ by Ca2+ into the crystal structure of multiferroic calcium doped BiFeO3 for obtaining Bi1-xCaxFeO3, 0 ≤ x ≤ 0.10 Stoichiometric mixtures of Bi2O3, Fe2O3 and CaO were mixed and milled for 5 h using a ball to powder weight ratio of 10:1 by high-energy ball milling. The obtained powder was pressed at 900 MPa to obtain cylindrical pellets and sintered at 800 °C for 2 h. X-ray diffraction and Rietveld refinement were used to evaluate the effect of Ca2+ on the crystal structure and to determinate the phase transition from rhombohedral α-BiFeO3 (R3c) to orthorhombic β-BiFeO3 (Pbnm). In addition, vibrating sample magnetometry (VSM) was used to have knowledge of magnetic order: antiferromagnetism and ferromagnetism were identified for α-BiFeO3 and β-BiFeO3, respectively. Dielectric tests determinate Debye-type relaxation for samples with the rhombohedral crystal structure and no Debye type relaxations for orthorhombic samples. Differences in AC conductivity of rhombohedral samples show different mechanism compared with the conductivity of orthorhombic samples. Ferromagnetic and electrical properties of synthesized materials show a strong correlation with the lattice distortions induced by the ionic ratio between Ca2+ and Bi3+. The effect of Ca2+ over leakage current has an interesting response, an increase of Ca2+ reduce one magnitude order the leakage current for α-BiFeO3 samples; though for β-BiFeO3 samples increase of Ca2+ raise the leakage current in one magnitude order.

Optimization of the tensile strength of sintered Al6061/SiC nanocomposites using response surface methodology

In the present work, silicon carbide (SiC) nanoparticles applied as reinforcement material to enhance the tensile characteristics of aluminium-based nanocomposites. The experimental design was selected as per the response surface methodology to optimize the effect of balls to powder weight ratio (6–10), milling speed (200–400 rpm), milling time (120–180 min) and SiC concentration (20–40 wt.%). From the ANOVA (analysis of variance) results, it was found that all the four parameters played a significant role on the tensile strength of Al-SiC nanocomposites. The tensile strength was maximized simultaneously and the optimal values of SiC concentration, balls to powder weight ratio, milling time and milling speed was found to be 24.27 wt.%, 10, 180 min and 200 rpm respectively. From the predicted vs. actual and 3D surface plots, it is also observed that there is a good agreement between the developed quadratic model and experimental results. From the scanning electron microscope, it is observed that there is a uniform dispersion of SiC nanoparticles in the matrix, which caused the improvement in tensile strength.

Electrochemical Studies on the Ca-Based Hydrogen Storage Alloy for Different Milling Times

The CaNi4.8Mn0.2 powder was synthesized by mechanical alloying, under an atmosphere of argon at room temperature, at different milling times (2, 10, 20, 30, 40, 50 and 60 h) with ball to powder weight ratio of 8:1. The structural and morphological characterizations of the CaNi4.8Mn0.2 powder were carried, respectively, by scanning electron microscopy and X-ray diffraction. After 2 h, all the alloys had a biphasic structure, two major phases, Ni and Ca2Ni7, remained virtually unchanged when a small amount of Mn was added. After more than 40 h of milling, the same peaks of the Ni and Ca2Ni7 phases appeared, while the intensity of the peaks decreased, indicating an additional amorphization process. After 50 h of milling, this damping was followed by the crystallization amorphization. The electrochemical properties of CaNi4.8Mn0.2 electrodes were studied at different milling times (10, 20, 30, 40, 50 and 60 h) and in KOH electrolyte concentrations (1 M and 6 M) at ambient temperature, as anodes in the Ni–MH battery. Different techniques were used, such as galvanostatic polarization, potentiostatic polarization and potentiodynamic polarization.

Effect of sintering temperature and time on composition, densification and electrical properties of InGaZnO4 ceramics

This paper studied the influence of sintering temperature on composition, density and electrical properties of InGaZnO4 ceramics synthesized by conventional solid-state reaction technique. Firstly, IGZO powders were prepared by mechanical ball milling of micron-scale In2O3, Ga2O3 and ZnO mixed powder and the effects of milling time, ball to powder weight ratio (BPR) and dispersant on the properties of mixed powders were investigated by XRD, SEM and laser diffraction particle size analyzer. Secondly, the green compacts formed by mixed powders were sintered at different temperatures (1100, 1200, 1300, 1400 °C) and time (0, 1, 3, 6 h), then the sintering behavior and electrical properties of the compacts were analyzed. The results showed that when the BPR was 10:1 and 2 wt % polyammonium acrylate was used as dispersant, the powder owed the best compression performance and the relative density of the green compact reached 67.14%. Owing to the decomposition of In2O3, obvious loss of mass phenomenon occurred during sintering process. When the compact was hold at 1400 °C for 150 min, the density of compact reached as high as 99.5%. The lowest resistivity of the compact reached 6.07 × 10−3 Ω cm when the compact was kept at 1400 °C for 3 h.

Study of the effect of milling parameters on mechanosynthesis of hydroxyfluorapatite using the Taguchi method

Hydroxyfluorapatite Ca10(PO4)6(OH)F (HFA) powders were prepared by mechanosynthesis method using planetary ball milling with various parameters. X-ray Diffraction (XRD), Infrared (IR) and Raman spectroscopies, Energy Dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) methods were employed to characterize the synthesized nanoparticles. Four factors (rotation speeds of disk, mass of balls, initial mass of powder and milling time) were investigated to understand their effect on the milling process and the formation of HFA nanocrystallite. Taguchi's design, with just 16 experiments (an L16 orthogonal array), was used to evaluate the impact of these parameters on six distinct properties, namely the crystallite size (nm), the percentage of crystallinity, the specific surface area (m2/g), the Ca/P atomic ratio, the percentages of the apatite and calcite phases. The average effects of the milling parameters and the signal-to-noise ratio (SN) were discussed. ANOVA analysis was used to determine the importance, the proportion of factor participation and also the influence of process parameters on responses. The Taguchi results indicated that the mass of balls and the rotation speed were found to be the most influential factors on the purity of compounds. The ball to powder weight ratio (BPR) was also introduced to study its effect on the synthesis process. Transmission Electron Microscopy (TEM), Scanning Electronic Microscopy (SEM) and Dynamic Light Scattering (DLS) revealed that milled HFA powders contained a nano-sized agglomerate.

Application of Simplex Lattice Design in Formulation Development of Lozenges Containing <i>Vernonia cinerea</i> Extract for Smoking Cessation

The aim of this work was to apply the simplex lattice design in the formulation development of lozenges containing Vernonia cinerea extract. The different ratios of three diluents; milk powder, xylitol, and inulin were investigated. The preformulation parameters of powder mixtures were evaluated. The compressed lozenges were evaluated for their weight variation, thickness, hardness, friability, and disintegration time. Results showed that the ratios of the three diluents affected the preformulation parameters. The angle of repose data revealed that all 12 powder mixtures had excellent flow property. The formulation containing milk powder had the highest values of Carr’s index and Hausner ratio, indicating the poor compressibility. While formulation containing inulin had the best compressibility. A formulation containing xylitol had the lowest moisture content. The compressed lozenges had a weight variation of less than 5%, a diameter of 1.5 mm, a thickness of 5-6 mm, and a hardness of 2-12 kP. The 8 of 12 formulations had friability of less than 1%. Use of milk powder provided the longest disintegration time. The desired properties of developed lozenge achieved when the medium amount of xylitol and inulin and low amount of milk powder were used. The optimal diluent ratio providing the weight variation not more than 5%, the hardness of 5-8 kP, friability not more than 1%, and disintegration time not more than 30 min was an equal weight ratio of milk powder, xylitol, and inulin.