Aluminum Powder Preparation for Additive Manufacturing Using Electrostatic Classification

This work aims to study the possibility of using an electrostatic drum-type separator to prepare a powder with a narrow size distribution curve for usage in additive manufacturing. The size distributions of the uncoated commercial aluminum powders ASP-30, ASP-22, and ASP-5 were analyzed. It was shown that the powders ASP-30 and ASP-22 have similar asymmetric distributions with a SPAN of 1.480 and 1.756, respectively. ASP-5 powder, in turn, has a narrow distribution with a SPAN of 0.869. ASP-30 powder was chosen for further experiment because, traditionally, separators are used to classify large-sized materials with particle size more than 100 μm. The optimal mode of electrostatic classification was proposed for the selected powder. Various classification methods, including centrifugal and electrostatic, were compared. The powders before and after classification were studied by XRD, SEM, TEM, and TG–DSC analyses. The obtained results showed that electrostatic classification does not lead to the formation of coatings on the processed powders. Electrostatic separation effectively narrows the particle size distribution, making it a suitable and valuable method to classify initial powders for additive manufacturing.

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Particle number size distributions in urban air before and after volatilisation

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4643-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 4643-4660 ◽

Cited By ~ 50

Author(s):

W. Birmili ◽

K. Heinke ◽

M. Pitz ◽

J. Matschullat ◽

A. Wiedensohler ◽

...

Keyword(s):

Particle Size ◽

Volatile Compounds ◽

Size Distribution ◽

Particle Number ◽

Volume Concentration ◽

Urban Atmosphere ◽

Anthropogenic Sources ◽

Particulate Emissions ◽

Size Distributions ◽

Before And After

Abstract. Aerosol particle number size distributions (size range 0.003–10 μm) in the urban atmosphere of Augsburg (Germany) were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass. Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C), allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9) suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could be determined as a function of particle size. The results indicated that particles >60 nm contain a significantly higher fraction of non-volatile compounds, most likely black carbon, than particles <60 nm. The results are relevant for future health-related studies in that they explore the size distribution and time-dependent behaviour of the refractory component of the urban aerosol over an extended time period.

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Particle number size distributions in urban air before and after volatilisation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-9171-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 9171-9220 ◽

Cited By ~ 1

Author(s):

W. Birmili ◽

K. Heinke ◽

M. Pitz ◽

J. Matschullat ◽

A. Wiedensohler ◽

...

Keyword(s):

Particle Size ◽

Volatile Compounds ◽

Size Distribution ◽

Particle Number ◽

Volume Fraction ◽

Anthropogenic Sources ◽

Particulate Emissions ◽

Average Particle ◽

Size Distributions ◽

Before And After

Abstract. Aerosol particle number size distributions (size range 0.003–10 μm) with and without using a thermodenuder are measured continuously in the city of Augsburg, Germany. Here, the data between 2004 and 2006 are examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration in Augsburg was found to be 12 200 cm−3, similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer, a consequence of more frequent inversion situations and particulate emissions in winter. The diurnal variation of the size distribution is shaped by a remarkable increase in the morning along with the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening increase in concentration could frequently be observed, suggesting a re-stratification of the urban atmosphere. The mixed layer height turned out to be the most influential meteorological parameter on particle size distribution. Its influence was greater than that of the geographical origin of the synoptic-scale air masses. By heating every second aerosol sample to 300°C in a thermodenuder, the volume fraction of non-volatile compounds in the urban aerosol was retrieved. The obtained results compared well with an independent measurement of the aerosol absorption coefficient (R2=0.9). The balance of particle number upstream and downstream of the thermodenuder suggests that all particles >12 nm contain a non-volatile core at 300°C. As an artefact of the volatility analysis, nucleation of particles smaller than 6 nm was observed in the cooling section of the thermodenuder. An average diameter ratio of particles before and after volatilisation was determined as a function of particle size. It indicated that particles >60 nm contain significantly higher fractions of non-volatile compounds, most likely soot, than particles <60 nm.

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Factors Influencing the Particle Size Distribution in an Abrasive Waterjet

Journal of Engineering for Industry ◽

10.1115/1.2899714 ◽

1991 ◽

Vol 113 (4) ◽

pp. 402-411 ◽

Cited By ~ 13

Author(s):

T. J. Labus ◽

K. F. Neusen ◽

D. G. Alberts ◽

T. J. Gores

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Cutting Speed ◽

Target Material ◽

Abrasive Waterjet ◽

Sieve Analysis ◽

Size Distributions ◽

Mixing Process ◽

Jet Mixing

A basic investigation of the factors which influence the abrasive jet mixing process was conducted. Particle size analysis was performed on abrasive samples for the “as-received” condition, at the exit of the mixing tube, and after cutting a target material. Grit size distributions were obtained through sieve analysis for both water and air collectors. Two different mixing chamber geometries were evaluated, as well as the effects of pressure, abrasive feed rate, cutting speed, and target material properties on particle size distributions. An analysis of the particle size distribution shows that the main particle breakdown is from 180 microns directly to 63 microns or less, for a nominal 80 grit garnet. This selective breakdown occurs during the cutting process, but not during the mixing process.

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Melting and Oxidation of Nanometer Size Aluminum Powders

MRS Proceedings ◽

10.1557/proc-0896-h04-06 ◽

2005 ◽

Vol 896 ◽

Author(s):

Mikhaylo A Trunov ◽

Swati Umbrakar ◽

Mirko Schoenitz ◽

Joseph T Mang ◽

Edward L Dreizin

Keyword(s):

Particle Size ◽

Oxidation Behavior ◽

Melting Behavior ◽

Size Distributions ◽

Particle Size Distributions ◽

Scanning Calorimetry ◽

Aluminum Powders ◽

Melting Temperatures ◽

X Ray Scattering ◽

Powder Samples

AbstractRecently, nanometer-sized aluminum powders became available commercially and their use as potential additives to propellants, explosives, and pyrotechnics has attracted significant interest. It has been suggested that very low melting temperatures are expected for nano-sized aluminum powders and that such low melting temperatures could accelerate oxidation and trigger ignition much earlier than for regular, micron-sized aluminum powders. The objective of this work was to investigate experimentally the melting and oxidation behavior of nano-sized aluminum powders. Powder samples with three different nominal sizes of 44, 80, and 121 nm were provided by Nanotechnologies Inc. The particle size distributions were measured using small angle x-ray scattering. Melting was studied by differential scanning calorimetry where the powders were heated from room temperature to 750 °C in argon environment. Thermogravimetric analysis was used to measure the mass increase indicative of oxidation while the powders were heated in an oxygen-argon gas mixture. The measured melting curves were compared to those computed using the experimental particle size distributions and thermodynamic models describing the melting temperature and enthalpy as functions of the particle size. The melting behavior predicted by different models correlated with the experimental observations only qualitatively. Characteristic step-wise oxidation was observed for all studied nanopowders. The observed oxidation behavior was well interpreted considering the recently established kinetics of oxidation of micron-sized aluminum powders. No correlation was found between the melting and oxidation of aluminum nanopowders.

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Methodology for determining rom size distribution

Rem Revista Escola de Minas ◽

10.1590/0370-44672014670184 ◽

2014 ◽

Vol 67 (4) ◽

pp. 405-412

Author(s):

Christiane Ribeiro da Silva ◽

Vládia C. G. de Souza ◽

Jair C. Koppe

Keyword(s):

Size Distribution ◽

Distribution Curve ◽

Size Distributions ◽

Sampling Protocol ◽

Product Size ◽

Operational Conditions ◽

Specific Protocol ◽

Open Side ◽

Ore Dressing

A methodology to determine the size distribution curve of the ROM was developed in a Brazilian iron ore mine. The size of the larger fragments was determined taking photographs and setting the scale of the images to analyze their dimensions (length of their edges and areas). This was implemented according to a specific protocol of sampling that involves split and homogenization stages in situ of a considerable quantity of ore (about 259 metric tonnes). During the sampling process, larger fragments were separated and smaller size material was screened. The methodology was developed initially in order to preview the performance of a primary gyratory crusher that is fed directly from trucks. Operational conditions of the equipment such as closed and open-side settings could be adjusted previously, obtaining different product size distributions. Variability of size of the fragments affects subsequent stages of crushing and can increase circulating load in the circuit. This leads to a decrease of productivity or recovery of the ore dressing. The results showed insignificant errors of accuracy and reproducibility of the sampling protocol when applied to friable itabirite rocks.

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Determination of atmospheric aerosol particle size distribution and visibility using a mobile laboratory

Canadian Journal of Physics ◽

10.1139/p82-150 ◽

1982 ◽

Vol 60 (8) ◽

pp. 1101-1107

Author(s):

C. V. Mathai ◽

A. W. Harrison

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Atmospheric Aerosols ◽

Suspended Particle ◽

Aerosol Size Distribution ◽

Size Distributions ◽

Mobile Laboratory ◽

Mean Values ◽

The City

As part of an ongoing general research program on the effects of atmospheric aerosols on visibility and its dependence on aerosol size distributions in Calgary, this paper presents the results of a comparative study of particle size distribution and visibility in residential (NW) and industrial (SE) sections of the city using a mobile laboratory. The study was conducted in the period October–December, 1979. An active scattering aerosol spectrometer measured the size distributions and the corresponding visibilities were deduced from scattering coefficients measured with an integrating nephelometer.The results of this transit study show significantly higher suspended particle concentrations and reduced visibilities in the SE than in the NW. The mean values of the visibilities are 44 and 97 km for the SE and the NW respectively. The exponent of R (particle radius) in the power law aerosol size distribution has a mean value of −3.36 ± 0.24 in the SE compared with the corresponding value of −3.89 ± 0.39 for the NW. These results arc in good agreement with the observations of Alberta Environment; however, they are in contradiction with a recent report published by the City of Calgary.

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The moment ratios of particle size distributions in some simple growth models

Journal of Applied Probability ◽

10.2307/3213205 ◽

1980 ◽

Vol 17 (4) ◽

pp. 956-967 ◽

Cited By ~ 1

Author(s):

H. L. MacGillivray

Keyword(s):

Particle Size ◽

Size Distribution ◽

Growth Model ◽

Hazard Rate ◽

Growth Models ◽

Size Distributions ◽

Particle Size Distributions ◽

Initial Size ◽

The Moment ◽

Simple Growth

Important parameters of particle size distributions in dispersed systems in engineering and related fields are ratios of moments and inverse powers of these ratios, known as mean sizes. The variation in these parameters is examined for the simplest growth model in which the size distribution is translated, and the results for this process considered in relation to the problems of models of other growth processes. For initial size distributions with monotone hazard rate, the results are particularly significant, and the properties of the normalised moments of other distributions are also considered.

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Arctic marine secondary organic aerosol contributes significantly to summertime particle size distributions in the Canadian Arctic Archipelago

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-2787-2019 ◽

2019 ◽

Vol 19 (5) ◽

pp. 2787-2812 ◽

Cited By ~ 9

Author(s):

Betty Croft ◽

Randall V. Martin ◽

W. Richard Leaitch ◽

Julia Burkart ◽

Rachel Y.-W. Chang ◽

...

Keyword(s):

Particle Size ◽

Size Distribution ◽

Secondary Organic Aerosol ◽

Canadian Arctic ◽

Particle Growth ◽

Organic Aerosol ◽

The Arctic ◽

Canadian Arctic Archipelago ◽

Size Distributions ◽

Fractional Error

Abstract. Summertime Arctic aerosol size distributions are strongly controlled by natural regional emissions. Within this context, we use a chemical transport model with size-resolved aerosol microphysics (GEOS-Chem-TOMAS) to interpret measurements of aerosol size distributions from the Canadian Arctic Archipelago during the summer of 2016, as part of the “NETwork on Climate and Aerosols: Addressing key uncertainties in Remote Canadian Environments” (NETCARE) project. Our simulations suggest that condensation of secondary organic aerosol (SOA) from precursor vapors emitted in the Arctic and near Arctic marine (ice-free seawater) regions plays a key role in particle growth events that shape the aerosol size distributions observed at Alert (82.5∘ N, 62.3∘ W), Eureka (80.1∘ N, 86.4∘ W), and along a NETCARE ship track within the Archipelago. We refer to this SOA as Arctic marine SOA (AMSOA) to reflect the Arctic marine-based and likely biogenic sources for the precursors of the condensing organic vapors. AMSOA from a simulated flux (500 µgm-2day-1, north of 50∘ N) of precursor vapors (with an assumed yield of unity) reduces the summertime particle size distribution model–observation mean fractional error 2- to 4-fold, relative to a simulation without this AMSOA. Particle growth due to the condensable organic vapor flux contributes strongly (30 %–50 %) to the simulated summertime-mean number of particles with diameters larger than 20 nm in the study region. This growth couples with ternary particle nucleation (sulfuric acid, ammonia, and water vapor) and biogenic sulfate condensation to account for more than 90 % of this simulated particle number, which represents a strong biogenic influence. The simulated fit to summertime size-distribution observations is further improved at Eureka and for the ship track by scaling up the nucleation rate by a factor of 100 to account for other particle precursors such as gas-phase iodine and/or amines and/or fragmenting primary particles that could be missing from our simulations. Additionally, the fits to the observed size distributions and total aerosol number concentrations for particles larger than 4 nm improve with the assumption that the AMSOA contains semi-volatile species: the model–observation mean fractional error is reduced 2- to 3-fold for the Alert and ship track size distributions. AMSOA accounts for about half of the simulated particle surface area and volume distributions in the summertime Canadian Arctic Archipelago, with climate-relevant simulated summertime pan-Arctic-mean top-of-the-atmosphere aerosol direct (−0.04 W m−2) and cloud-albedo indirect (−0.4 W m−2) radiative effects, which due to uncertainties are viewed as an order of magnitude estimate. Future work should focus on further understanding summertime Arctic sources of AMSOA.

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Spatial and Seasonal Variations of PM Concentration and Size Distribution in Manure-Belt Poultry Layer Houses

Transactions of the ASABE ◽

10.13031/trans.12950 ◽

2019 ◽

Vol 62 (2) ◽

pp. 415-427 ◽

Cited By ~ 1

Author(s):

Reyna M. Knight ◽

Xinjie Tong ◽

Zhenyu Liu ◽

Sewoon Hong ◽

Lingying Zhao

Keyword(s):

Particle Size ◽

Particulate Matter ◽

Size Distribution ◽

Seasonal Variations ◽

Size Distributions ◽

Particle Size Distributions ◽

Potential Health ◽

Significant Difference ◽

Autumn And Winter ◽

Mass Concentrations

Abstract. Poultry layer houses are a significant source of particulate matter (PM) emissions, which potentially affect worker and animal health. Particulate matter characteristics, such as concentration and size distribution inside layer houses, are critical information for assessment of the potential health risks and development of effective PM mitigation technologies. However, this information and its spatial and seasonal variations are lacking for typical layer facilities. In this study, two TSI DustTrak monitors (DRX 8533) and an Aerodynamic Particle Sizer (APS 3321) were used to measure PM mass concentrations and number-weighted particle size distributions in two typical manure-belt poultry layer houses in Ohio in three seasons: summer, autumn, and winter. Bimodal particle size distributions were consistently observed. The average count median diameters (mean ±SD) were 1.68 ±0.25, 2.16 ±0.31, and 1.87 ±0.07 µm in summer, autumn, and winter, respectively. The average geometric standard deviations of particle size were 2.16 ±0.23, 2.16 ±0.18, and 1.74 ±0.17 in the three seasons, respectively. The average mass concentrations were 67.4 ±54.9, 289.9 ±216.2, and 428.1 ±269.9 µg m-3 for PM2.5; 73.6 ±59.5, 314.6 ±228.9, and 480.8 ±306.5 µg m-3 for PM4; and 118.8 ±99.6, 532.5 ±353.0, and 686.2 ±417.7 µg m-3 for PM10 in the three seasons, respectively. Both statistically significant (p < 0.05) and practically significant (difference of means >20% of smaller value) seasonal variations were observed. Spatial variations were only practically significant for autumn mass concentrations, likely due to external dust infiltration from nearby agricultural activities. The OSHA-mandated permissible exposure limit for respirable PM was not exceeded in any season. Keywords: Air quality, Particulate matter, Poultry housing, Seasonal variation, Spatial variation.

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