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This presentation is archived with the original webinar video in the Download Center at www.horiba.com/us/particle.
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© 2010 HORIBA, Ltd. All rights reserved.
Particle Characterization of Abrasives
Mark [email protected]
© 2010 HORIBA, Ltd. All rights reserved.
Factors Affecting Abrasion Mechanics
Difference in hardness between the two substances: a much harder abrasive will cut faster and deeper
Grain size (grit size): larger grains will cut faster as they also cut deeper
Grain shape: sharp corners help Adhesion between grains, between grains
and backing, between grains and matrix: determines how quickly grains are lost from the abrasive and how soon fresh grains, if present, are exposed
© 2010 HORIBA, Ltd. All rights reserved.
Factors Affecting Abrasion Mechanics
Contact force: more force causes faster abrasion Loading: worn abrasive & cast off work material
fill spaces between abrasive grains, reducing cutting efficiency while increasing friction
Use of lubricant/coolant/metalworking fluid: Can carry away swarf (preventing loading), transport heat (may affect physical properties of the workpiece or the abrasive), decrease friction (with the substrate or matrix), suspend worn work material and abrasives allowing for a finer finish, conduct stress to the workpiece.
© 2010 HORIBA, Ltd. All rights reserved.
Macro vs. Microgrits
Macrogrits:Greater than ~ 60 µmTraditional size test is
sievingMicrogrits:Less than ~ 60 µmTraditional testing is
sedimentometer
2 mm
40 µm
© 2010 HORIBA, Ltd. All rights reserved.
Macrogrits
© 2010 HORIBA, Ltd. All rights reserved.
Microgrits
© 2010 HORIBA, Ltd. All rights reserved.
ISO 6344Macrogrits P12 to P220
© 2010 HORIBA, Ltd. All rights reserved.
Sieve Analysis
InexpensiveTime consumingAlternative: Dynamic
Image Analysis by CAMSIZERHigher throughputComplete distributionShape informationParticle images
Size and shape from 30 µm – 30 mm
© 2010 HORIBA, Ltd. All rights reserved.
Dynamic Image AnalysisBy choosing proper size parameter, Xc min, results can match historic sieve Data. Also generates shape data provenTo correlate with abrasive performance.
© 2010 HORIBA, Ltd. All rights reserved.
Sand: Round vs. “Edgy” by CAMSIZER
Similar in size.Shape difference seenin b/l and sphericity.Edgy would makebetter abrasive.
Sphericity
Breadth/length (b/l)
© 2010 HORIBA, Ltd. All rights reserved.
ISO 6344Microgrits P240 to P1200
© 2010 HORIBA, Ltd. All rights reserved.
ISO 6344
Microgrits P1500 to P2500
© 2010 HORIBA, Ltd. All rights reserved.
Sedimentometer
Sample is pre-wet, then placed in settling medium at top of tube, time is recorded
Time is recorded when the first material reaches the collecting tube
Times are recorded as sample reaches various graduations in settling tube
Example: If the 2mm height was reached in 4 minutes, that means 8% of the material is 39.8 microns and coarser
Still in use, but being replaced by newer technology (laser diffraction)
© 2010 HORIBA, Ltd. All rights reserved.
Laser Diffraction
Powders (in air) and suspensions
30 nm – 3000 µm Quick, easy,
reproducible Highly automated Most popular particle
sizing technique LA-950 highest
performance available but workhorse dependability
Dry powder feeder
© 2010 HORIBA, Ltd. All rights reserved.
Laser Diffraction DataDiamond Abrasives
Silicon Carbide
slurry
© 2010 HORIBA, Ltd. All rights reserved.
Chemical Mechanical Polishing (CMP)
Smooth (planarize) silicon wafer surface with combination of chemical & mechanical forces
Uses abrasive & corrosive colloidal slurry, polishing pad, and retainer ring
CMP slurry contains small abrasive particles
Large particles in slurry cause scratches (defects)
Want to know mean size + presence of larger particles
© 2010 HORIBA, Ltd. All rights reserved.
Particle Sizing Techniques
Technique Nano-Particle Measurement
Oversize Measurement Analysis Speed Dilution Required?
Laser Diffraction Very good Excellent Excellent Yes
Dynamic Light Scattering Excellent Very poor Very good Yes
Acoustic Spectroscopy Very good Excellent Good No
Light Obscuration Very good Good Poor Yes
Disc Centrifuge Very good Excellent Very poor Yes
Microscopy (SEM, TEM) Excellent Very poor
(statistics) Very poor No
© 2010 HORIBA, Ltd. All rights reserved.
Laser Diffraction Data
Ludox colloidal slurry (31 nm)
Geltech silica (1.65 µm)
0.05 wt % Geltech in Ludox
© 2010 HORIBA, Ltd. All rights reserved.
Acoustics: DT-1201 Experiment
0
1
2
3
4
5
6
7
8
9
Atte
n uat
ion
[dB
/cm
/MH
z]
10 0 10 1 10 2
Frequency [MHz]
diameter 1 microndiameter 0.5 micron
Attenuation [dB/cm/MHz]
out
in
II
cmLMHzflog
][][10
© 2010 HORIBA, Ltd. All rights reserved.
Acoustics: DT-1201 Experiment
Materials: Ludox colloidal silica, Geltech silica, commercially available CMP slurries
Spike SS25 CMP slurry with Geltech silica Note: all measurements made with no dilution,
major benefit of acoustics
© 2010 HORIBA, Ltd. All rights reserved.
Acoustics: DT-1201 Experiment
Attenuation spectra for single component silica slurries
Corresponding particle size distributions
© 2010 HORIBA, Ltd. All rights reserved.
Acoustics: DT-1201 Experiment
Particle size distributions of silica Cabot SS25, diluted down to 12 wt %, with various additions of silica Geltech 0.5
© 2010 HORIBA, Ltd. All rights reserved.
Image Analysis Experiment
Samples: small, medium, large abrasive particles
Measure size & shape using static image analysis (PSA300)
Prepare sample using Sampler Disperser
Calculate size, shape, custom calculation to define angularity
© 2010 HORIBA, Ltd. All rights reserved.
Image Analysis Experiment
Small abrasive, high angularity (left), low angularity (right)
Medium abrasive, high angularity (left), low angularity (right)
Large abrasive, high angularity (left), low angularity (right)
© 2010 HORIBA, Ltd. All rights reserved.
Shape Parameters
© 2010 HORIBA, Ltd. All rights reserved.
Spike Parameter*
* Stachowiak, W., Image Analysis of Abrasive Grits, Tribology and Interface Engineering, Vol 44
© 2010 HORIBA, Ltd. All rights reserved.
PSA300 Calculation
Find sharp edges at the tips of the particlesCount number of tips (child count)Number of tips alone not sufficient, long
particles w/2 tips not as good as hexagon w/6 tipsDefine angularity roundness as child count
x roundnessThus triangle w/3 points less angular than
octagon of 4 sharp edges & 4 rounded edges
© 2010 HORIBA, Ltd. All rights reserved.
PSA300 Calculation
© 2010 HORIBA, Ltd. All rights reserved.
PSA300 Calculation
© 2010 HORIBA, Ltd. All rights reserved.
PSA300 Calculation
© 2010 HORIBA, Ltd. All rights reserved.
Image Analysis Results
© 2010 HORIBA, Ltd. All rights reserved.
Conclusions
For particle size analysisLaser diffraction offers many benefits over
sedimentometerCAMSIZER offers many advantages over sievesDT-1201 for undiluted size and zeta potential
For particle size and shapeCAMSIZER for 30 µm – 30 mmPSA300 for 0.5 µm – 2000 µm
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