Effects of Substrate Geometry on Performance of Twin-Fluid Atomizer in Metal Powder Production

2008 ◽  
Vol 594 ◽  
pp. 138-149 ◽  
Author(s):  
Muh Ron Wang ◽  
Che Jui Yang ◽  
Jian Duen Huang ◽  
Tien Chu Lin ◽  
Ming Shen Sheu
Keyword(s):  
Particle Size ◽  
Metal Powder ◽  
Industrial Applications ◽  
Transmission Ratio ◽  
Metal Powders ◽  
Small Particles ◽  
Ring Type ◽  
Powder Production ◽  
The Mean ◽  
Almost All

Uniform and spherical metal powders have been widely used in many industrial applications. This paper investigates the control of particle size and size distribution by the impingement of the molten spray on the substrate with different geometries. The idea is to combine the atomization process with the classification process. Result shows that a significant reduction of the particle size occurred when the substrate was placed in the spray jet. The mean particle size was lowered to 8.0μm with a low transmission ratio of the spray jet in the existence of the ring type substrate. The particle size increased from 8.78μm to 12.67μm as the transmission ratio was increased from 13.92% to 75.80%. The reduction in particle size was due to the effect of the blockage of the substrate on the spray. The particle size increased from 6.72μm to 6.98μm when the disk-type substrate was placed at Z = 150mm and 200mm, respectively. The particle size of this case was smaller than the case with ring type substrate because the transmission ratio of the disk type substrate was lower. The percentage of small particles (i.e., V15-) were higher than 60% and the percentages of V25-45 were 4.19% and 0.37% when the disk-type substrate was placed at Z=150mm and Z=200mm, respectively, indicating that almost all of the particles were below 25μm under these conditions. Hence this technique is very effective in controlling the particle size in the metal powder production.

Combination of Spray Forming and Metal Powder Productions by the Internal Mixing Atomizer with a Substrate

2006 ◽  
Vol 505-507 ◽  
pp. 1237-1242 ◽  
Author(s):  
Muh Ron Wang ◽  
Pin Jen Chen ◽  
Je Rei Yang ◽  
Jin Shen Chiu ◽  
Tien Chu Lin ◽  
...  
Keyword(s):  
Particle Size ◽  
Production Rate ◽  
Metal Powder ◽  
Deposition Rate ◽  
Spray Forming ◽  
Metal Powders ◽  
Two Phase ◽  
Powder Production ◽  
Internal Mixing ◽  
Impinging Flow

This paper describes the performance of an atomizer coupled with a substrate which produces metal powder and spray forming materials simultaneous in the spray chamber. Ultra fine metal powders are produced from this process. The melt is atomized by a twin-fluid atomizer with internal mixing mechanisms. The molten spray injected from the swirling chamber of the atomizer is then impinged upon the substrate to form the two phase impinging flow. The deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in turn determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the substrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as 3μ m level has been achieved, a level which is not achievable by the conventional gas atomization processes.

scholarly journals THERMAL ANALYSIS OF LIGNOCELLULOSE COMPOSITES FILLED WITH METAL POWDERS

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Miroslav M. Pavlović ◽  
Vladan Ćosović ◽  
Zoran Janković ◽  
Jasna Stajić-Trošić ◽  
Miomir G. Pavlović
Keyword(s):  
Thermal Analysis ◽  
Particle Size ◽  
Composite Materials ◽  
Silver Powder ◽  
Experimental Studies ◽  
Thermal Characteristics ◽  
Industrial Applications ◽  
Metal Powders ◽  
Natural Polymers ◽  
Renewable Materials

Composite materials are gaining increasing industrial applications worldwide. Composites based on polymers with conductive fillers have been recently in the focus of extensive research primarily because of their growing importance from the point of view of application. Natural polymers based on renewable materials with selected fillers can be used directly as contemporary materials in: electronics, medicine, industry, as contact conductive materials, electromagnetic and radio wave shields, photothermal optical recorders, electronic noses sensitive to certain chemicals, as well as economically acceptable catalysts. In this paper the results of experimental studies of the properties of composite materials based on lignocellulosic matrix (LC) filled with electrolytic copper powder and chemically obtained silver powder are presented. Volume fractions of metal fillers in the composite materials in tested samples were varied in the range of 1.6-30% (v/v), and the samples were prepared by compression – cold pressing. Characterization included examination of the influence of particle size and morphology on the conductivity and percolation threshold of the composites using a variety of testing techniques: SEM, TGA, DSC, particle size distribution and conductivity measurements. The thermal analysis of the prepared composites showed the improvement of the thermal characteristics of the composites. This was due to the presence of the metallic fillers which are very good thermal conductors, hence accumulating the emitted heat during TGA measurements primary to lignocellulosic matrix. On the other hand, there is no difference in the response with different metallic fillers and particles with different morphologies. Glass transition temperature is improved by 20 ºC for all the composites.

scholarly journals Plasma Spheroidisation of Irregular Ti6Al4V Powder for Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1763
Author(s):  
Nthateng Nkhasi ◽  
Willie du Preez ◽  
Hertzog Bissett
Keyword(s):  
Particle Size ◽  
Additive Manufacturing ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Metal Powder ◽  
Weight Ratio ◽  
High Strength ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Powder Bed

Metal powders suitable for use in powder bed additive manufacturing processes should ideally be spherical, dense, chemically pure and of a specified particle size distribution. Ti6Al4V is commonly used in the aerospace, medical and automotive industries due to its high strength-to-weight ratio and excellent corrosion resistance properties. Interstitial impurities in titanium alloys have an impact upon mechanical properties, particularly oxygen, nitrogen, hydrogen and carbon. The plasma spheroidisation process can be used to spheroidise metal powder consisting of irregularly shaped particles. In this study, the plasma spheroidisation of metal powder was performed on Ti6Al4V powder consisting of irregularly shaped particles. The properties of the powder relevant for powder bed fusion that were determined included the particle size distribution, morphology, particle porosity and chemical composition. Conclusions were drawn regarding the viability of using this process to produce powder suitable for additive manufacturing.

SIEVING OF POWDERS ADDITIVE AND POWDER MANUFACTURINGS (review)

2020 ◽  
pp. 11-20
Author(s):  
A.E. Knyazev ◽  
◽  
A.V. Vostrikov ◽  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Metal Powder ◽  
Metal Powders ◽  
Technological Properties ◽  
Factors Affecting ◽  
Ultrasonic Cleaning

Considers the features of powders obtained by various methods, their technological properties in relation to additive and granular manufacturing. The sequence of operations upon receipt of metal powder compositions is presented. The factors affecting the process of vibration sieving of metal powders and granules are described. The features and advantages of vibratory sieving on horizontally arranged circular sieves using ultrasonic cleaning to obtain specified trajectories of motion are shown. Criteria for evaluating the sieving efficiency are given and explanations are given for determining the particle size distribution of powders and granules.

An initial test of a method for the estimation of real mean particle size from shadowed samples

1985 ◽  
Vol 31 (7) ◽  
pp. 604-607
Author(s):  
J. H. M. Willison
Keyword(s):  
Particle Size ◽  
Present Method ◽  
Particle Sizes ◽  
Initial Test ◽  
Small Particles ◽  
Mean Particle Size ◽  
Sample Rotation ◽  
Mean Diameter ◽  
The Mean

During shadowing, a "cap" of metal develops on small particles. This cap increases, apparent particle width (measured normal to the shadowing direction) by an extent which cannot be predetermined. The extent of this increase in particle size (here defined as the "cap," X) is estimated in the present method by using opposite (180° sample rotation) bidirectional shadowing. It is argued that the bidirectional cap is the sum of the two unidirectional caps, and therefore that X = 2A − (B + C), where A is the mean bidirectionally shadowed particle size, and B and C are the two mean unidirectionally shadowed particle sizes. As a validation of the method, the mean diameter of air-dried ferritin was estimated and the results appear to confirm the hypothesis (mean diameter by present method, 10.7 ± 0.2 nm; mean diameter by previous methods, 10.89 nm).

Methods for obtaining metal powder materials

2019 ◽  
pp. 137-145
Author(s):  
Ivan A. Shemberev ◽  
Vitaliy A. Zuyevskiy
Keyword(s):  
Metal Powder ◽  
Raw Materials ◽  
Research Purpose ◽  
Powder Materials ◽  
Metal Powders ◽  
Resource Saving ◽  
Important Place ◽  
Manufacturing Method ◽  
New Energy ◽  
Almost All

In practice, a large number of methods for obtaining metal powders are known, their diversity is due to the technological capabilities of manufacturing powders in several ways from different types of raw materials, as well as different requirements for the characteristics of powders for various fields and conditions of application. Metal powders in most cases are a secondary product, the properties of which are affected by the manufacturing method, so the theoretical foundations of their production occupy an important place in the processes of powder metallurgy. (Research purpose) The research purpose is in analyzing existing methods for obtaining metal powder materials and develop a new energy-and resource-saving method for obtaining powders, such as electroerosive dispersion. (Materials and methods) Authors have studied literary sources, works of prominent scientists and specialists on the subject of research. (Results and discussion) The article presents the main methods of powder production: mechanical and physical-chemical, as well as a relatively new method of electroerosive dispersion. More productive methods of obtaining powders are being introduced into production, in which considerable attention is paid to methods of cleaning powders from oxygen and carbon, controlling the shape of particles and their sizes. (Conclusions) Analysis of existing methods for obtaining powder materials has shown that they do not fully meet the requirements for quality composition of new technological solutions, in particular, additive technologies. The development of fundamentally new methods for obtaining powders, such as electroerosive dispersion, is a promising direction that makes it possible to obtain powders from almost all conductive materials, adjusting the size and shape of granules.

scholarly journals Effect of Metal Powder Characteristics on Structural Defects of Graphene Nanosheets in Metal Composite Powders Dispersed by Ball Milling

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 260
Author(s):  
Qi Yan ◽  
Biao Chen ◽  
Xinyi Zhou ◽  
Katsuyoshi Kondoh ◽  
Jinshan Li
Keyword(s):  
Particle Size ◽  
Ball Milling ◽  
Metal Powder ◽  
Graphene Nanosheets ◽  
High Energy ◽  
Structural Defects ◽  
Metal Composite ◽  
Metal Powders ◽  
Composite Powders ◽  
Powder Characteristics

Ball milling (BM) is the prime method to disperse graphene into metal powders; however, it inevitably introduces structural defects to graphene. The balance between dispersion quality and structural damage of graphene during BM is a significant issue for fabricating graphene/metal composite powders. In this study two metal powder characteristics, namely type and size, were investigated to understand the effect of the BM process on graphene structure in graphene/metal composite powders. Graphene nanosheets (GNSs) were added into commercial Ti-6Al-4V and pure Al powders with different diameters by three kinds of BM processes with distinct energy levels. According to the microstructure and Raman spectra, the results suggested that metal particle size had a minor influence in low-energy BM, while it played an important role in high-energy BM (HEBM). The structural defects of GNS crystals increase with increasing BM energy. However, increasing energy in BM has limited damage as the discrepancy in particle size is quite large. Furthermore, Al powders with lower hardness tend to deform with lower BM effect, which will cause less damage to GNSs compared to that in the harder Ti powder. Those findings may have implications for the development of high-performance metal matrix composites reinforced with nanocarbon materials.

Evaluation of Low-Dose Gentamicin Once Daily Dosing Regimen at A General Hospital in Malaysia

2018 ◽  
Vol 9 (01) ◽  
Author(s):  
Ab Rahman A F ◽  
Md Sahak N. ◽  
Ali A. M.
Keyword(s):  
Medical Records ◽  
Public Hospital ◽  
Low Dose ◽  
Dosing Regimen ◽  
Once Daily ◽  
Neutropenic Sepsis ◽  
Wide Acceptance ◽  
The Mean ◽  
Initiation Of Therapy ◽  
Almost All

Objective: Once daily dosing (ODD) aminoglycoside is gaining wide acceptance as an alternative way of dosing. In our setting it is the regimen of choice whenever gentamicin is indicated. The objective of this study was to evaluate the practice of gentamicin ODD in a public hospital in Malaysia. Methods: We conducted a retrospective review of medical records of patients on gentamicin ODD who were admitted to Hospital Melaka during January 2002 until March 2010. All adult patients who were on ODD gentamicin with various level of renal function were included in the study. Patients on gentamicin less than 72 hours and pregnant women were excluded. Results: From 110 patients, 75 (68.2%) were male and 35 (31.8%) were female. Indications for ODD gentamicin included pneumonia, 34 (31.0%) neutropenic sepsis, 27 (24.5%) and sepsis, 11 (10.0%). The mean dose and duration of gentamicin was 3.2 mg/kg/day and 7 days, respectively. Almost all patients were on gentamicin combined with other antibiotics. Clinical cure based on fever resolution was found in 89.1% of patients treated with ODD. Resolution of fever took an average of 48 hours after initiation of therapy. The evaluation for bacteriologic cure could not be performed because of insufficient data on culture and sensitivity. Out of 38 patients with analyzable serum creatinine data, four patients might have developed nephrotoxicity. Conclusion: In our setting, lower dosages of ODD gentamicin when used in combination with other antibiotics seemed to be effective and safe in treating most gram negative infections.

Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Kranti Singh ◽  
Surajpal Verma ◽  
Shyam Prasad ◽  
Indu Bala
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Drug Loading ◽  
In Vitro Release ◽  
Formulation Development ◽  
Ciprofloxacin Hydrochloride ◽  
Potential Value ◽  
The Mean ◽  
In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

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