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Advances In Characterization Techniques

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Title: Advances In Characterization Techniques


1
Advances In Characterization Techniques
  • Dr. Krishna Gupta
  • Technical Director
  • Porous Materials, Inc., USA

2
Topics
  • Flow Porometry
  • Accuracy and Reproducibility
  • Technology for Characterization under Application
    Environment
  • Directional Porometry
  • Clamp-On Porometry
  • Flexibility to Accommodate Samples of Wide
    Variety of Shapes, Sizes and Porosity
  • Ease of Operation

3
Topics
  • Permeametry
  • Diffusion Gas Permeametry
  • High Flow Gas Permeametry
  • Microflow liquid permeametry
  • High flow liquid permeametry at high temperature
    high presure
  • Envelope surface area, average particle size
    average fiber diameter analysis
  • Water vapor transmission rate

4
Topics
  • Mercury Intrusion Porosimetry
  • Stainless steel sample chamber
  • Special design to minimize contact with mercury
  • Non-Mercury Intrusion Porosimetry
  • Sample chamber that permits mercury intrusion
    porosimeter to be used as non-mercury intrusion
    porosimeter
  • Water Intrusion Porosimeter

5
Topics
  • Gas Adsorption
  • Conclusions

6
Flow Porometry (Capillary Flow Porometry)
  • Accuracy and Reproducibility
  • Most important sources of random systematic
    errors identified
  • Design modified to minimized errors
  • Appropriate corrections incorporated

7
Flow Porometry(Capillary Flow Porometry)
  • Accuracy

8
Flow Porometry(Capillary Flow Porometry)
  • Repeatability
  • Bubble point repeated 32 times
  • Same operator
  • Same machine
  • Same wetting liquid
  • Same filter

9
Flow Porometry(Capillary Flow Porometry)
Filter Wetting Liquid Wetting Liquid
Filter Porewick Silwick
Sintered Stainless Steel 1.8 1.2
Battery Separator 0.2 1.5
Paper 1.7 1.1
10
Flow Porometry(Capillary Flow Porometry)
  • Errors due to the use of different machines

Machine Bubble point pore diameter, Mean Value, mm Standard deviation Deviation from average of all machines
1 18.35 0.53 -1.34
2 18.78 0.48 0.93
3 18.37 2.34 0.28
4 18.63 0.75 0.13
11
Flow Porometry(Capillary Flow Porometry)
  • Operator errors

Machine Average of mean, mm Difference between mean values by operators Difference between mean values by operators
Machine Average of mean, mm mm Percentages
1 18.38 0.058 0.32
2 18.77 0.005 0.03
3 18.77 0.222 1.19
4 18.73 0.213 1.14
12
Technology for Characterization under Simulated
Application Environment
  • Compressive Stress
  • Arrangement for testing sample under compressive
    stress

13
Technology for Characterization under Simulated
Application Environment
Compressive Stress
  • Features
  • Any compressive stress up to 1000 psi (700 kPa)
  • Sample size as large as 8 inches
  • Programmed to apply desired stress, perform test
    release stress

14
Technology for Characterization under Simulated
Application Environment
15
Technology for Characterization under Simulated
Application Environment
16
Technology for Characterization under Simulated
Application Environment
  • Cyclic stress
  • Stress cycles are applied on sample sandwiched
    between two porous plates and the sample is
    tested during a pause in the stress cycle

17
Technology for Characterization under Simulated
Application Environment
18
Technology for Characterization under Simulated
Application Environment
  • Features
  • Any desired stress between 15 and 3000 psi
  • Stress may be applied and released at fixed rates
  • Duration of cycle 10 s
  • Frequency adjustable by changing the duration of
    application of stress

19
Technology for Characterization under Simulated
Application Environment
Features
  • Programmed tointerrupt after specified number of
    cycles, wait for a predetermined length of time,
    measure characteristics and then continue
    stressing

20
Technology for Characterization under Simulated
Application Environment
Features
  • Sample can be tested any required number of times
    within a specified range
  • Fully automated

21
Technology for Characterization under Simulated
Application Environment
22
Technology for Characterization under Simulated
Application Environment
23
Technology for Characterization under Simulated
Application Environment
  • Aggressive environment

24
Technology for Characterization under Simulated
Application Environment
  • Directional Porometry
  • In this technique, Gas is allowed to displace
    liquid in pores in the specified direction

25
Technology for Characterization under Simulated
Application Environment
26
Technology for Characterization under Simulated
Application Environment
27
Technology for Characterization under Simulated
Application Environment
Material Bubble point, mm Mean flow pore diameter, mm
Fuel cell component
z-direction 14.1 1.92
x-direction 14.6 1.04
y-direction 7.60 0.57
Printer Paper
z-direction 12.4 4.20
x-y plane 1.11 0.09
Transmission fluid filter felt
z-direction 80.4 ?
x-y plane 43.3 ?
Liquid filter
z-direction 34.5 ?
x-y plane 15.3 ?
28
Clamp-On Porometry
  • Sample chamber clamps on any desired location of
    sample (No need to cut sample damage the
    material)

29
Clamp-On Porometry
  • Advantages
  • Very fast
  • No damage to the bulk material
  • Test may be performed on any location in the bulk
    material

30
Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
Shapes
  • Sheets
  • Hollow Fibers
  • Plates
  • Pen tips
  • Discs
  • Cartridges
  • Rods
  • Diapers
  • Tubes
  • Odd shapes
  • Powders
  • Nanofibers

31
Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
  • Size
  • Micron size biomedical devices
  • 8 inch wafers
  • Two feet cartridges
  • Entire diaper

32
Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
  • Materials
  • Ceramics
  • Nonwovens
  • Metals
  • Composites
  • Textiles
  • Gels
  • Sponges
  • Hydrogels

33
Ease of Operation
  • Fully automated
  • Test execution
  • Data storage
  • Data Reduction
  • User friendly interface
  • Menu driven windows based software

34
Ease of Operation
  • Graphical display of real time test status and
    results of test in progress
  • Many user specified formats for plotting
    display of results
  • Minimal operator involvement

35
Advanced Permeametry
  • Capability
  • A wide variety of gases, liquids strong
    chemicals
  • Different directions x, y and z directions, x-y
    plane
  • At elevated temperatures, high pressure under
    stress
  • Very low or very high permeability

36
Diffusion Gas Permeametry
37
Diffusion Gas Permeameter
38
Diffusion Gas Permeametry
  • (dVs/dt) (TsVo/Tps)(dp/dt)
  • Vs gas flow in volume of gas at STP
  • Vo volume of chamber on the outlet side
  • Flow rate lt 0.75x10-4 cm3/s

39
High Flow Gas Permeametry
  • Uses actual component Diaper, Cartridges, etc.
  • Can measure flow rates as high as 105 cm3/s
  • Can test large size components

40
High Flow Gas Permeametry
41
Microflow Liquid Permeametry
  • Measures very low liquid permeability in materials
  • Ceramic discs
  • Membranes
  • Potatoes
  • Other vegetables fruit
  • Uses a microbalance to measure small weights of
    displaced liquid, 10-4 cm3/s

42
High Flow Liquid Permeametry at High Temperatures
and High Pressures
  • Measures high permeability of application fluids
    at high temperature through actual parts under
    compressive stress

43
High Flow Liquid Permeametry at High Temperatures
and High Pressures
44
High Flow Liquid Permeametry at High Temperatures
and High Pressures
  • Capability
  • Temperature 100?C
  • Compressive stress on sample 300 psi
  • Liquid Oil
  • Flow rate 2 L/min

45
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
46
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Envelope Surface Area
  • Computes surface area from flow rate using Kozeny
    and Carman relation

47
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
Envelope Surface Area
  • Fl/pA P3/K(1-P)2S2mZP2p/(1-P)S(2ppr)1/2

F gas flow rate in volume at average pressure,
p l thickness of sample per unit
time p pressure drop, (pi-po) p average
pressure, (pipo)/2, where pi is the inlet rb
bulk density of sample pressure and po is
the outlet pressure ra true density of
sample A cross-sectional area of sample m
viscosity of gas P porosity (pore volume/total
volume) 1-(rb/ra) p average pressure,
(pipo)/2, where pi is the r density of the
gas at inlet pressure and po is the
outlet pressure the average pressure, p S
through pore surface area per unit volume Z
a constant. It is shown to of solid in
the sample be (48/13p) K a constant
dependent on the geometry of the pores in the
media. It has a value close to 5 for random
pored media
48
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Comparison between BET and ESA Methods

Sample ID ESA surface area (m2/g) BET surface area (m2/g) ESA particle size (microns) BET particle size (microns)
Magnesium stearate A 11.13 12.16 0.43 0.39
Magnesium stearate B 6.97 7.13 0.69 0.67
Glass bubbles A 0.89 0.915 14.82 14.83
Glass bubbles B 1.76 1.91 22.25 20.53
49
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Average particle size
  • Computes from surface area assuming same size
    spherical shape of particles
  • d the average particle size
  • S specific surface area of the sample (total
    Surface area/mass)
  • r true density of the material

50
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Comparison between BET and ESA Methods

Sample ID ESA surface area (m2/g) BET surface area (m2/g) ESA particle size (microns) BET particle size (microns)
Magnesium stearate A 11.13 12.16 0.43 0.39
Magnesium stearate B 6.97 7.13 0.69 0.67
Glass bubbles A 0.89 0.915 14.82 14.83
Glass bubbles B 1.76 1.91 22.25 20.53
51
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Average fiber diameter
  • Computed from flow rate using Davies equation
  • (4?pAR2)/(mFl) 64 c1.5152c3

P ? 0.7-0.99 c packing density (ratio of volume
of fibers to volume of sample) (1-P) ?p
pressure gradient A cross-sectional area of
sample R average fiber radius m viscosity of
gas F gas flow rate average pressure L
thickness of sample
52
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
53
Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
  • Average fiber diameter can also be computed from
    the envelope surface area. Assuming the fibers to
    have the same radius and the same length

Df 4V/S 4/Sr Df average fiber
diameter V volume of fibers per unit mass S
envelope surface area of fibers per unit mass r
true density of fibers
54
Water Vapor Transmission
  • Transmission under pressure gradient

55
Water Vapor Transmission
  • Transmission under pressure gradient

56
Water Vapor Transmission
  • Transmission under concentration gradient

57
Water Vapor Transmission
  • Transmission under concentration gradient

58
Mercury Intrusion Porosimetry
  • Stainless Steel Sample Chamber

59
Mercury Intrusion Porosimetry
  • Special design to minimize contact with mercury

60
Mercury Intrusion Porosimetry
  • Separation of high-pressure section from
    low-pressure section
  • Sample chamber is evacuated and pressurized
    without transferring the chamber and contacting
    mercury
  • Automatic cleaning of the system by evacuation

61
Mercury Intrusion Porosimetry
  • Automatic refilling of penetrometer by mercury
  • Automatic drainage of mercury
  • In-situ pretreatment of the sample
  • Fully automated operation

62
Non-Mercury Intrusion Prosimetry
  • Sample Chamber That permits Mercury Intrusion
    Porosimeter to be used as a Non-Mercury Intrusion
    Porosimeter

63
Water Intrusion Porosimeter (Aquapore)
  • Uses absolutely no mercury
  • Water used as intrusion liquid
  • Can test hydrophobic materials
  • Can detect hydrophobic pores in a mixture

64
Water Intrusion Porosimeter (Aquapore)
65
Gas Adsorption
  • A new technique developed by PMI
  • Capable of very fast measurement (lt10 min) of
    single point and multi-point surface areas
  • The PMI QBET for fast surface area measurement

66
Conclusions
  • Recent advances made in the technology of
    measurement and novel methods of measurement of
    properties using porometry, permeametry,
    porosimetry and gas adsorption have been discussed

67
Conclusions
  • Results have been presented to show the
    improvements in accuracy and repeatability of
    results and ease of operation of the test.

68
Conclusions
  • Measurement of characteristics under application
    environments involving
  • compressive stress
  • cyclic compression
  • aggressive conditions
  • elevated temperatures
  • high pressures
  • have been illustrated with examples

69
Thank You
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