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Issues and Insights Regarding Particle Size Analysis
Transcript of Issues and Insights Regarding Particle Size Analysis
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Issues and Insights Regarding
Particle Size Analysis
Moderator
Melissa Gorris
Sales and Marketing Manager
Additive Manufacturing Team Lead
Host
Dave van der Wiel, Ph.D.
Director of Technology Development
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What we’ll talk about today…
Not a review of all the ways particle size can be measured
One method isn’t necessary better than another
Size range often limits potential techniques
Introduction to the most common measurement techniques
Degree of sample separation during measurement
Emphasis on basis of measurements
Testing standards
Factors that impact all technique
Sampling, agglomeration, dispersion
Particle shape assumptions
Measurement basis & data representation
Measurement calibrations & verification
Measurement comparisons
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NSL Analytical Services
NSL provides independent laboratory testing services to a diverse array of
customers where testing speed, accuracy and consistency are mission
critical to operations.
Our teams of chemists, engineers and metallurgists provide
scientific expertise in materials testing with a focus on metals,
polymers and technical ceramics used in critical end markets
such as aerospace, oil & gas, energy, chemicals and metallurgy.
Chemical Analysis Thermal Analysis Physical Properties
Microscopy &
Metallography
Particle
CharacterizationMechanical Testing
Metallurgical /
Failure AnalysisConsulting
Regulatory
Compliance
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Dynamic Light Scattering
Laser Diffraction
Acoustic Attenuation
Sedimentation/Centrifugation
Flow Field Fractionation
Sieve Analysis
Light Obscuration
Electro-Sensing Zone
Dynamic Image Analysis
Static Optical Imaging
Electron Microscopy
0.01 0.1 1 10 100 1000
microns
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Particle Size Analysis Methods
Counting Methods Separation Methods Ensemble Methods
Particles are analyzed
individually Rely on the segregation
of particles
All particles are
analyzed simultaneouslyImaging Non-Imaging
Basis of Data
Representation
Weighting
Number NumberMass/Density
or VolumeIntensity or Volume
Methods
Image Analysis
Microscopy
Electro-Sensing Zone
Optical Counting (TOT)
Light Obscuration (TOF)
Sieve Analysis
Sedimentation
Fractionation
Laser Diffraction
Dynamic Light Scattering
Air Permeability
Acoustic
Categorized by degree of separation
Method selection should align with how the results will be used
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Dynamic Light Scattering
Laser Diffraction
Acoustic Attenuation
Sedimentation/Centrifugation
Flow Field Fractionation
Sieve Analysis
Light Obscuration
Electro-Sensing Zone
Dynamic Image Analysis
Static Optical Imaging
Electron Microscopy
0.01 0.1 1 10 100 1000
Measurement Techniques
Counting
Separation
Ensemble
microns
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Basis of Measurement vs. Data Representation
Counting Methods Separation Methods Ensemble Methods
Particles are analyzed
individually Rely on the segregation
of particles
All particles are
analyzed simultaneouslyImaging Non-Imaging
Basis of Data
Representation
Weighting
Number NumberMass/Density
or VolumeIntensity or Volume
Basis of
MeasurementArea Volume or Intensity Area, Density Intensity or Volume
Methods
Image Analysis
Microscopy
Electro-Sensing Zone
Optical Counting (TOT)
Light Obscuration (TOF)
Sieve Analysis
Sedimentation
Fractionation
Laser Diffraction
Dynamic Light Scattering
Air Permeability
Acoustic
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Basis of Measurement vs. Data Representation
2D Imaging Sieve Analysis
AREA 3AREA 2
AREA 1
SOFTWARE
COUNTING
MESH
OPENING
AREA
MASS OF
PASSING
FRACTION
MASS OF
RETAINED
FRACTION
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Testing Standards
Counting Methods Separation Methods Ensemble Methods
Particles are analyzed
individually Rely on the segregation
of particles
All particles are
analyzed simultaneouslyImaging Non-Imaging
Image Analysis Sensing Zone
Sieve Analysis Light Scattering
ISO 3310
ASTM D4513
ASTM D5861
ISO 13320
ISO 22412
ASTM C1070
ASTM D4464
UOP856
ISO 13322
ASTM D8090
ISO 13319
ASTM C690
Sedimentation Air Permeability Acoustic
ISO 13317
ISO 13318
ASTM B761
ASTM C958
ASTM C1182
ASTM C1730
ASTM E2980
ASTM C721
ISO 20998
Excluding standards specific to metallic powders
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Testing Standards - Metallic Powders
Counting Methods Separation Methods Ensemble Methods
Particles are analyzed
individually Rely on the segregation
of particles
All particles are
analyzed simultaneouslyImaging Non-Imaging
Image Analysis Zone Sensing
Sieve Analysis Light Scattering
ISO 4497
ASTM B214
MPIF 05
ISO 13320 ASTM B822
ISO 13322 ISO 13319 Sedimentation Air Permeability Acoustic
ISO 13317 ASTM B761ASTM B330
MPIF 32
Standards encompassing metallic powders
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Additional Particle Information
Counting Methods Separation Methods Ensemble Methods
Particles are analyzed
individually Rely on the segregation
of particles
All particles are
analyzed simultaneouslyImaging Non-Imaging
Method Image Analysis Electro-Sensing Zone Sieve Analysis Laser Diffraction
Add’n Data Morphology Concentration Homogeneity Isometry
Method Microscopy
Sedimentation
Fractionation
Dynamic Light Scattering
Air Permeability
Acoustic
Add’n DataElemental
distributionDensity Diffusion Coefficients
Several techniques may measure more than just particle size
Most techniques can model other information like shape factors
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Contributors to Particle Size Measurement Results
Representative SamplingParent sample
Test portions (method specific)
Particle Agglomeration De-agglomeration must not breakup primary particles
Sample DispersionWet or dry
Uniformity
Method Suitability (incl. assumptions)
Test sample size
Particle shape – sphericity
Distribution, uniformity
Method ParametersIndex of refraction
Shape & distribution models
Data Analysis & Representation Correlation Values & Graphs
Results Analysis & Comparisons Direct results vs. converted data
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Sampling, Agglomeration
& Dispersion
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Representative Sampling
Parent Samples• ASTM B215 – Sampling metal powders
• ISO 14488 – Sampling for the determination of particulate properties
• Microrifflers require about >10 cm3 to function properly
• >12 g for aluminum powder or >45 g for Inconel powder
Test Samples – example quantities for metal powders:• Sieve Analysis: <100 g (ASTM B214)
• Laser Diffraction: <5 g (2% to 10% obscuration)
• Microscopy: <0.1 g
• Representative analysis vs. sample size
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Particle Agglomeration
Agglomerates vs. primary particles• Goal is to reduce apparent particle size without affecting primary particle size
or shape
• A shift from a monomodal to multi-modal size distribution may indicates
fracturing of primary particles
De-agglomeration• Stirring and sonication
• Minimum sonication time and power (ASTM B821)
• Dispersion (next slide)
• Re-testing to check for changes in size distribution after repeated analyses
• ISO/TR 13097 – Dispersion stability
• Common issue when sieving (shaking, use of brushes, etc.) or air-dispersing
(impact forces)
Chakrabarty et.al., Atmos. Chem. Phys. 16, 3033 (2016)
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Sample Dispersion
ASTM B821 – Liquid dispersion of metal powders and related compounds for particle size analysis• To be used for X-Ray Sedimentation (ASTM B761) and Laser Diffraction (ASTM B822)
• Carrier liquid, surfactant, ultrasonication
• Provides specific recommendations for steel, nickel, copper and several other materials
• Section 7.1.4 requires sample inspection for dispersion
ISO 13320 – Particle size analysis – laser diffraction• Wet procedures - Recirculation, small volume cells, etc.
• Annex B – Advice on dispersion liquids
• Liquid medium, surfactant, dispersant
• Annex C.2 – Liquid dispersion recommendations
• Dry procedures – Aerosolizing
• Annex C.1 – Gas dispersion recommendations
• Section 5.4.1 requires sample inspection for dispersion
ISO 14887 – Dispersing procedures for powders in liquids
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Particle Shape Effects
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Uniformity of dimensions
Isometric
dmaxdequiv x = d x = r
IsotropicAnisotropic
Similarity in dimensions
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Influence of Particle Shape
Isotropic shapes• Mathematical models may be able to do a good job of
correlating raw data to size data
Anisotropic shapes• Non-imaging techniques rely on various equivalency
models• Equivalent diffraction patterns
• Equivalent spherical area, volume, perimeter
• Equivalent dynamics
Such models may or may not provide valid correlations• Must be confirmed for a particle type, morphology
• A given model is not necessarily universal
oblate spheroid
prolate spheroid
sphere
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Anisotropic Particles
da = 30.8 m
dv = 30.2 mda = 31.4 m
dv = 30.4 m
da = 31.9 m
dv = 30.5 m
11 m
30 m
Isometric (area and volume equivalencies) measurements may be misleading
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Anisotropic Particles
da = 30.8 m
dv = 30.2 mda = 31.4 m
dv = 30.4 m
da = 31.9 m
dv = 30.5 m
11 m
da = 32.2 m
dv = 30.0 m26 × 40 m
da = 29.8 m
dv = 27.7 m24 × 37 m
30 m
Area and volume equivalencies may provide different size results
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Measurement Basis &
Representation
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Distribution Basis
Number
Area
Volume
0%
10%
20%
30%
40%
50%
60%
20 40 60
0%
10%
20%
30%
40%
50%
60%
20 40 60
0%
10%
20%
30%
40%
50%
60%
70%
20 40 60
mean 40 m
median 40 m
mode 40 m
mean 49 m
median 50 m
mode 60 m
mean 52 m
median 60 m
mode 60 m
20 m
40 m
60 m
m
m
m
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Multimodal Distributions
70 m
40 m
10 m
100 m
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Multimodal Distributions
Particle Diameter (m)
Laser
Diffraction
Image
Analysis
0%
5%
10%
15%
20%
25%
30%
35%
0 20 40 60 80 100 120
NumberVolume
Area Number Area Volume
mean 50 m 69 m 74 m
median (d50) 45 m 70 m 80 m
mode 40 m 70 m 70 m
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Converting Between Weighted Distributions
Applying different weightings to raw data Converting a weighted distribution
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Size Sensitivity in Weightings
Measurement or
Reporting BasisNumber Area Volume Intensity
Size sensitivity r0 r2 r3 r2 to r6
Counting
Techniques
Imaging Methods
Sieve Analysis
Laser Diffraction
Dynamic Light
Scattering
Acoustic
Attenuation
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Converting Between Weighted Distributions
HORIBA Guidebook to
Particle Size Analysis
horiba.com
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Converting Between Weighted Distributions
General advice is to don’t do it!• The results of conversions are often misleading or erroneous
Issues• Assumptions must be made to do conversions
• Particularly problematic for intensity-weighted distributions
• The resolution (signal-to-noise) of a given technique may not scale
well when converting to another basis
Do direct comparisons instead• Always note differences in basis
• Often such comparisons are insightful
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Data Representation - Bins
Sieve
Analysis
75 m 106 m 150 m
% Number
19% <75 m
45% 75-106 m
23% 106-150 m
13% >150 m
% Mass or Vol.
2% <75 m
18% 75-106 m
32% 106-150 m
48% >150 m
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Data Representation - Bins
% Number
19% <75 m 17% 45-75 m
45% 75-106 m 48% 75-106 m
23% 106-150 m 32% 106-150 m
13% >150 m 48% 150-180 m
% Mass or Volume
2% <75 m 2% 45-75 m
18% 75-106 m 22% 75-106 m
32% 106-150 m 39% 106-150 m
48% >150 m 38% 150-180 m
75 m 106 m 150 m 180 m45 m
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0%
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20%
30%
40%
50%
60%
70%
80%
90%
100%
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10%
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20%
25%
30%
0 20 40 60 80 100 120
Data Representation - Distributions
Graphical distributions• Size distribution and/or cumulative distribution
diameter (m)
Size
Fraction Cumulative
Fraction
%vol
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0%
10%
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30%
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0 20 40 60 80 100 120
Data Representation - Distributions
Graphical distributions• Size distribution and/or cumulative distribution
diameter (m)
Size
Fraction25% of particles by volume are ~40 m
or
~40 m particles make up about 25%vol)
%vol
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0%
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30%
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20%
25%
30%
0 20 40 60 80 100 120
Data Representation - Distributions
Graphical distributions• Size distribution and/or cumulative distribution
diameter (m)
d50
Cumulative
Fraction
d10 d90
%vol
of particlesdiameter
10% <28 m
50% <47 m
50% >47 m
90% <76 m
%vol
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0%
10%
20%
30%
40%
50%
60%
70%
80%
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100%
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15%
20%
25%
30%
0 20 40 60 80 100 120
Data Representation - Distributions
diameter (m)
MeanMode
d10 d90
Median
d50
Graphical distributions• Size distribution and/or cumulative distribution
Single values• Generally a bad idea
• Median (d50)
• Arithmetic vs. geometric mean
• Variance (2) or Span (d90-d10)/d50
Multiple values• Most common: d10, d50, d90
• Mean, median, mode
%vol
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Calibration & Verification
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Particle Size Reference Materials
Many suppliers
provide NIST
traceable particle
size reference
materials for
specific materials,
morphologies
and sizes
Weighting: Number Volume
d10 12.0 ± 1.9 nm 6.9 ± 2.7 nm
d50 18.5 ± 2.5 nm 12.6 ± 2.1 nm
d90 34.6 ± 4.8 nm 19.4 ± 2.2 nm
Exemplar RMs Size Range (m) Material
BAM-N001 0.012 to 0.035 Nano Ag
NIST RM 8988 0.1 to 0.5 TiO2
NIST SRM 1690 1 Polystyrene spheres
NIST SRM 1978 0.2 to 10 ZrO2 powder
NIST SRM 1021 2 to 12 Glass beads
BCR-067 2.4 to 32 Quartz
NIST SRM 1984 9 to 30 WC/Co needles
NIST SRM 1961 30 Polystyrene
NIST SRM 1985 18 to 55 WC/Co spheroids
BCR-069 14 to 90 Quartz particles
NIST SRM 1003c 20 to 50 Glass beads
NIST SRM 1982 25 to 80 Y-ZrO2 spheroids
NIST SRM 1004b 40 to 150 Glass beads
NIST SRM 1017b 100 to 400 Glass beads
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Proficiency Test Programs
ASTM AMPM - metal powders• Sieve Analysis ASTM B214 (equivalency to ISO 4497)
• Laser Diffraction ASTM B822 (equivalency to ISO 13320)
• Static Image Analysis ISO 13322-1
• Dynamic Image Analysis ISO 13322-2
BAM (Germany) - ceramics• Laser Diffraction ISO 13320
Swiss Institute for Interlaboratory Proficiency - ceramics• Laser Diffraction ISO 13320
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BAM Interlaboratory Comparison
https://rrr.bam.de/RRR/Navigation/EN/Proficiency-Testing/PARTICLE-SIZE/particle-size.html
Laboratories
Dia
mete
r
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Comparative Measurements
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Comparing Techniques - Glass Spheres
Comparison Using 50-75 m Glass Spheres• Eliminates effects due to non-spherical shape factors/models
The Particle Size Paradox, Micromeretics Application Note 177
d10 d50 d90 dmode
Sedimentation 41.0 61.6 89.1 63.1 Diameter directly from Stokes equation
Dynamic Imaging 45.1 61.7 75.9 67.1 Spheres provide well-defined shape factor
Laser Diffraction 45.0 66.9 85.0 71.1 Spherical, isotropic particles – no need for equivalency
ESZ 49.5 66.5 82.4 72.4
Variation 7% 4% 6% 5%
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Comparing Techniques - Coffee!
d10 d50 d90
Sieve Analysis* 128 418 714
Dynamic Imaging 168 559 875
Laser Diffraction 222 586 1200
Variation 22% 14% 22%
Retsch Technology Gmbh
dimension (mm)
• Sieve analysis corresponds with narrowest particle
dimension (width)
• As in previous example, laser provide larger sizes
than dynamic imaging
mass
area
volume
?
%vol
*requires interpolation between bins
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See also…
Considerations in Particle Sizing
• Lubrizol Technical Brief – https://lubrizolcdmo.com/technical-briefs/
Particle Size Characterization
• NIST Special Publication 960-1
ISO 9276 Representation of Results of Particle size Analysis• Part 1 Graphical representation
• Part 2 Calculation of average particle sizes/diameter and moments
• Part 3 Adjustment of an experimental curve to a reference model
• Part 4 Characterization of a classification process
• Part 5 Particle size analysis using logarithmic probability distributions
• Part 6 Descriptive and quantitative representation of particle shape and morphology
Particle Size Distribution Measurement from Millimeters to Nanometers and from Rods to Platelets
• P. Bowen, Journal of Dispersion Science & Technology 23(5), 631-662 (2002)
https://doi.org/10.1081/DIS-120015368
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Take Aways
It’s important to know the basis of measurement vs basis of reported
distributions for techniques under consideration
– One doesn’t necessarily need to fully understand the fundamentals of each
Suitability of a measurement technique depends on:
– Nature of the sample – homogeneity, shape
– What type of size information is desired
– How the size data will be used
Converting measurement distributions from one basis to another is a
minefield best avoided
– Comparing measurements with different basis may actually be informative
Any measurement must be carefully calibrated, verified and re-verified
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Let’s Talk Tech!
Dave van der Wiel
Director of Technology Development
216.428.5215
Optical Microscopy
Hosted By
Rebecca Stawovy
Dave Kovarik
NSL Analytical Services
Join Us For Our Next Tech Talk!
December 10, 2020 at 2pm EDT