Ultrasonic Preparation of Submicron Low Melting Point Alloy Powder

2020 ◽  
Vol 993 ◽  
pp. 333-343
Author(s):  
Qing Qing Shu ◽  
Jing Tao Shi ◽  
Jing Liu ◽  
Zhong Shan Deng
Keyword(s):  
Melting Point ◽  
Alloy Powder ◽  
Smooth Surface ◽  
Particle Surface ◽  
Particle Diameter ◽  
Experimental Conditions ◽  
Rapid Cooling ◽  
Spherical Powder ◽  
Ultrasonic Atomization ◽  
Powder Diameter

In order to study the preparation of low-melting alloy powder in phase change materials, three sets of control experiments were set up in this paper. To explore the effects of ultrasonic oscillation, ultrasonic atomization technology and rapid cooling had an effect on the particle size, surface morphology and powder shape of ultrasonic powder making. In the experiment, ultrasonic atomization, rapidly cooling ultrasonic atomization, and ultrasonic vibration generated powder were tested. The results showed that the surface of fog droplets generated by ultrasonic atomization was smooth, with distinct particles. The powder diameter was large, ranging from 20-60 μm. The surface of the powder obtained by ultrasonic shock existed an aggregation phenomenon. The powder diameter was small ranging from 5-10 μm. The ultrasonic atomized powder obtained by rapid cooling was mostly spherical with a smooth surface. After the screening, spherical powder with a diameter of 15-25 μm and the smooth surface could be obtained. The results showed that the particle diameter is small and uniform, while the uneven surface was difficult to eliminate. The experimental conditions of rapid cooling were favorable for the smoothness of the particle surface and the roundness of powder shape. Spherical powder with a diameter of 15-25 μm can be obtained by screening the rapidly cooled powder after ultrasonic atomization. Different experimental conditions and technological approach can produce high-performance low melting point alloy powder.

Operation Performance of a Small Air-Lift Pump for Conveying Solid Particles

2003 ◽  
Vol 125 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Hitoshi Fujimoto ◽  
Satoshi Ogawa ◽  
Hirohiko Takuda ◽  
Natsuo Hatta
Keyword(s):  
Particle Density ◽  
Gas Injection ◽  
Particle Diameter ◽  
Solid Particles ◽  
Operation Performance ◽  
Two Phase ◽  
Experimental Conditions ◽  
Injection Point ◽  
Pump Performance ◽  
Air Lift

The pump performance of a small air-lift system for conveying solid particles is investigated experimentally. The total length of the vertical lifting pipe is 3200 mm, and the inner diameter of the pipe is 18 mm. The gas injector is set at a certain point of the pipe. The flows in the lifting pipe are water/solid two-phase mixtures below the gas injection point, and air/water/solid three-phase mixtures above it. The time-averaged characteristics of the flows are examined for various experimental conditions. The effects of particle diameter, particle density, the gas-injection point, and the volume flux of air on the pump performance are studied systematically. The critical boundary at which the particles can be lifted is discussed in detail based upon one-dimensional mixture model.

Boundary interactions for two-dimensional granular flows. Part 1. Flat boundaries, asymmetric stresses and couple stresses

1993 ◽  
Vol 247 ◽  
pp. 111-136 ◽  
Author(s):  
Charles S. Campbell
Keyword(s):  
Stress Tensor ◽  
Granular Flow ◽  
Particle Surface ◽  
Particle Diameter ◽  
Type A ◽  
Steady Flows ◽  
Two Dimensional ◽  
Type B ◽  
Continuum Scale ◽  
Small Change

The behaviour of a granular flow at a boundary cannot be specified independently of what is happening in the rest of the flow field. This paper describes a study of two fictitious, but instructive, flat boundary types using a computer simulation of a two-dimensional granular flow with the goal of trying to understand the possible effects of the boundary on the flow. The two boundary conditions, Type A and Type B, differ largely in the way that they apply torques to the flow particles. During a particle–wall collision, the Type A boundary applies the force at the particle surface, thus applying the largest mechanistically possible torque to the particle, while the Type B boundary applies the force directly to the particle centre, resulting in the application of zero torque. Though a small change on continuum scales (i.e. the point at which the force is applied has only been moved by a particle radius) it makes a huge difference to the macroscopic behaviour of the system. Generally, it was found that, near boundaries, large variations in continuum properties occur over distances of a particle diameter, a non-continuum scale, throwing into doubt whether boundaries may be accurately modelled via continuum mechanics. Finally, the large torques applied to the particles by the Type A boundary induce asymmetries in the stress tensor, which, in these steady flows, are balanced by gradients in a couple stress tensor. Thus, near boundaries, a frictional granular material must be modelled as a polar fluid.

scholarly journals Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Markus Petters ◽  
Sabin Kasparoglu
Keyword(s):  
Particle Size ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Point ◽  
Critical Role ◽  
Particle Diameter ◽  
Cloud Formation ◽  
Melting Point Depression ◽  
Wide Range

Abstract Atmospheric aerosols can assume liquid, amorphous semi-solid or glassy, and crystalline phase states. Particle phase state plays a critical role in understanding and predicting aerosol impacts on human health, visibility, cloud formation, and climate. Melting point depression increases with decreasing particle diameter and is predicted by the Gibbs–Thompson relationship. This work reviews existing data on the melting point depression to constrain a simple parameterization of the process. The parameter $$\xi $$ ξ describes the degree to which particle size lowers the melting point and is found to vary between 300 and 1800 K nm for a wide range of particle compositions. The parameterization is used together with existing frameworks for modeling the temperature and RH dependence of viscosity to predict the influence of particle size on the glass transition temperature and viscosity of secondary organic aerosol formed from the oxidation of $$\alpha $$ α -pinene. Literature data are broadly consistent with the predictions. The model predicts a sharp decrease in viscosity for particles less than 100 nm in diameter. It is computationally efficient and suitable for inclusion in models to evaluate the potential influence of the phase change on atmospheric processes. New experimental data of the size-dependence of particle viscosity for atmospheric aerosol mimics are needed to thoroughly validate the predictions.

Maximizing the Use of Platinum Catalyst by Ultrasonic Spray Application

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Robb Engle
Keyword(s):  
Surface Area ◽  
Platinum Catalyst ◽  
Particle Surface ◽  
Particle Surface Area ◽  
Ultrasonic Atomization ◽  
Ultrasonic Spray ◽  
Industry Standard ◽  
Platinum Particles ◽  
Deposition Density ◽  
Conductive Properties

The following discusses the method and advantages of ultrasonic deposition of carbon-based platinum ink solution onto catalytic membranes in the manufacture of platinum-based fuel cells, doubling industry standard performances. Using patented ultrasonic atomization technology (Ultrasonic atomization technology provided by Sono-Tek) conductive properties are compared to those of films created with hydraulic deposition and paste printing methods, using comprehensive analysis of morphology characteristics, deposition density, and distribution of platinum particles throughout the thickness and surface area of the coating. Results indicate significant increase in uniform distribution of platinum particles using the ultrasonic deposition method. Measured electrochemically active Pt surface area using ultrasonic atomization was recorded as high as 71% of the total Pt particle surface area.

Maximizing the Use of Platinum Catalyst by Ultrasonic Spray Application

2011 ◽  
Author(s):  
Robb Engle
Keyword(s):  
Surface Area ◽  
Platinum Catalyst ◽  
Particle Surface ◽  
Particle Surface Area ◽  
Ultrasonic Atomization ◽  
Ultrasonic Spray ◽  
Industry Standard ◽  
Platinum Particles ◽  
Deposition Density ◽  
Conductive Properties

The following discusses the method and advantages of ultrasonic deposition of carbon-based platinum ink solution onto catalytic membranes in the manufacture of platinum-based fuel cells, doubling industry standard performances. Using patented ultrasonic atomization technology, conductive properties are compared to those of films created with hydraulic deposition and paste printing methods, using comprehensive analysis of morphology characteristics, deposition density, and distribution of platinum particles throughout the thickness and surface area of the coating. Results indicate significant increase in uniform distribution of platinum particles using the ultrasonic deposition method. Measured electrochemically active Pt surface area using ultrasonic atomization was recorded as high as 71% of the total Pt particle surface area.

Effects of Fluid Properties and Surface Parameters on Pool Boiling of Porous and Pin-Fin Surfaces

2008 ◽  
Author(s):  
Liang-Han Chien ◽  
Shu-Che Lee ◽  
Hon-Zen Wang ◽  
Shao-Wen Chen
Keyword(s):  
High Speed ◽  
Smooth Surface ◽  
Pool Boiling ◽  
Particle Diameter ◽  
Saturation Temperature ◽  
Porous Surface ◽  
Average Particle ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Fluid Properties

The present experimental study investigated the effect of heater size on pool boiling performance for various fluids. Water, methanol and FC-72 were tested at 50 and 70°C saturation temperature on a smooth surface, a porous surface, a pin-fin surface and a structured surface. The boiling test vessel has a 31 mm by 31 mm internal base area and 100 mm height. The sizes of the heating area are: 31×31, 12×12, 9×9, or 6×6 mm2. The test results of all the three fluids showed that boiling performance is independent on heater size for 31mm × 31mm, 12mm × 12 mm heaters, but the boiling heat transfer coefficients for the smooth surface having 6 mm × 6 mm heating area is approximately 70∼100% higher than those for the 12 mm × 12 mm heating area. The 0.2 mm thick square pin-fins, having 0.2 mm depth and 0.4 mm pitch, yields 2-to-3 folds enhancement of boiling performance in FC-72. For methanol and FC-72, the porous surface yields up to seven folds boiling enhancement as compared with the smooth surface. However, the enhancement ratio of the porous surface, having 0.15 mm average particle diameter, is only 2.3 for water. Boiling phenomena observation by a high speed video system showed that the bubble size depends on surface geometries and fluid properties.

Synthesis and Photocatalytic Evaluation of Nanocrystalline ZnO Obtained by High Energy Milling

2016 ◽  
Vol 869 ◽  
pp. 789-794
Author(s):  
Jeferson Almeida Dias ◽  
Vera Lúcia Arantes ◽  
Alfeu Saraiva Ramos ◽  
Tania Regina Giraldi ◽  
Marília Zani Minucci ◽  
...  
Keyword(s):  
Particle Surface ◽  
High Energy ◽  
Semiconductor Surface ◽  
Photocatalytic Efficiency ◽  
Particle Surface Area ◽  
Visible Radiation ◽  
Experimental Conditions ◽  
High Energy Milling ◽  
Media Milling ◽  
Nanocrystalline Zinc Oxide

Photocatalytic processes have been applied to treatment of organic effluents through the mineralization of these pollutants on a semiconductor surface. Obtaining nanosemiconductors is desirable for the increasing of particle surface area and improvement in photocatalytic efficiency. In this paper, it was evaluated the influence of High Energy Milling (HEM) as a technique to produce nanocrystalline zinc oxide. The photocatalytic activity of the milled powders to degrade Rhodamine-B dye when exposed to ultraviolet and visible radiation also was investigated. The powders were milled during 4 and 10 hours by dry media milling and 10 hours by wet media milling. The results indicated that there were no detectable powder contamination during the millings and the reduction of crystallite size was function of time and media of milling. All of the assessed samples demonstrate high degradation of the dye, which corroborates with the potentiality of this technique to photocatalysts production. The material milled during 10 hours by dry media milling showed the best results under the experimental conditions.

Supercritical carbon dioxide-assisted solid-phase free radical grafting of butyl acrylate onto PP

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Wang Jian ◽  
Wang Deng-Fei ◽  
Du Wei ◽  
Zou En-Guang ◽  
Dong Qun
Keyword(s):  
Free Radical ◽  
Butyl Acrylate ◽  
Solid Phase ◽  
Particle Diameter ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
Experimental Conditions ◽  
Water Contact ◽  
Melt Flow Rate ◽  
Grafting Reaction

AbstractFree radical grafting copolymerization of butyl acrylate (BA) onto polypropylene (PP) matrix was investigated using supercritical CO2 as a swelling agent and carrier solvent. The monomer BA and initiator AIBN were first dissolved in supercritical CO2, and then these small molecules were diffused into the grafting zones of PP matrix. As grafting reaction temperature (about 80 °C) was far below the melting point, PP was modified in the solid phase. The effects of different experimental conditions such as soaking time and temperature, supercritical CO2 pressure; monomer and initiator concentration; PP particle diameter; solid phase grafting reaction time and temperature on grafting percentage were studied. Fourier transform infrared spectroscopy (FTIR) results and gel content experiment prove that the monomers were indeed grafted onto PP chains. Scanning electron microscope (SEM) analysis of the grafted sample indicates that the grafting branches PBA were homogeneously distributed onto the surfaces and micropores of PP particles. Thermal gravimetric analysis (TGA) results show that the grafted samples had a higher onset thermal degradation temperature and a lower weight loss at a particular temperature than pure PP. The water contact angle of PP-g-BA decreased from 98° to 72°, indicating the polarity and hydrophilicity of PP were improved effectively. The melt flow rate (MFR) and mechanical analysis results show that the grafting sample remained its versatile physical properties though introducing the grafting BA branch chain. This is prominent when it was compared with normal solid grafting product.

Effects of Micro-Particle Diameters and Low Fluid Velocities on Effective Thermal Parameters of Micro-Particle Packed Bed as a Biothermal Reactor

2012 ◽  
Vol 516-517 ◽  
pp. 15-23 ◽  
Author(s):  
Yi Xu ◽  
Li Ping Wang ◽  
Yan Qian Zhong ◽  
Yi Hua Zheng
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Particle Diameter ◽  
Packed Bed ◽  
Thermal Parameter ◽  
Transfer Model ◽  
Filling Material ◽  
Experimental Conditions ◽  
Constant Wall Temperature ◽  
Fluid Velocities

The effects of micro-particle diameters (i.e. dp=0.4~1.1mm) and low fluid velocities (v=5ml/min, 3ml/min and 1ml/min) on the heat transfer behavior of water flowing through a micro-particle packed bed as a reactor of thermal biosensor were investigated experimentally under constant wall temperature conditions (i.e. 60°C). The effective thermal parameter is smaller with decreasing the particle diameter and fluid velocities. This is mainly due to the poor thermal conductivity of the filling materials which leads to a larger thermal resistance and hydraulic resistance. As such, it is very important to select a filling material with better thermal conductivity to enhance heat transfer, which is favorable to completely detect the heat created during the enzyme-catalyzed reaction. Comparing the correlations of both this work and those published in the literature, there are considerable discrepancies among them due to different experimental conditions. The two-dimensional heat transfer model that predicts the temperature distributions agree reasonably well with actual measurements except a slight over-prediction in the region close to the inlet.

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