Title: Advances In Characterization Techniques
1Advances In Characterization Techniques
- Dr. Krishna Gupta
- Technical Director
- Porous Materials, Inc., USA
2Topics
- 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
3Topics
- 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
4Topics
- 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
5Topics
6Flow Porometry (Capillary Flow Porometry)
- Accuracy and Reproducibility
- Most important sources of random systematic
errors identified
- Design modified to minimized errors
- Appropriate corrections incorporated
7Flow Porometry(Capillary Flow Porometry)
8Flow Porometry(Capillary Flow Porometry)
- Repeatability
- Bubble point repeated 32 times
- Same operator
- Same machine
- Same wetting liquid
- Same filter
9Flow 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
10Flow 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
11Flow Porometry(Capillary Flow Porometry)
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
12Technology for Characterization under Simulated
Application Environment
- Compressive Stress
- Arrangement for testing sample under compressive
stress
13Technology 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
14Technology for Characterization under Simulated
Application Environment
15Technology for Characterization under Simulated
Application Environment
16Technology 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
17Technology for Characterization under Simulated
Application Environment
18Technology 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
19Technology 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
20Technology for Characterization under Simulated
Application Environment
Features
- Sample can be tested any required number of times
within a specified range
21Technology for Characterization under Simulated
Application Environment
22Technology for Characterization under Simulated
Application Environment
23Technology for Characterization under Simulated
Application Environment
24Technology for Characterization under Simulated
Application Environment
- In this technique, Gas is allowed to displace
liquid in pores in the specified direction
25Technology for Characterization under Simulated
Application Environment
26Technology for Characterization under Simulated
Application Environment
27Technology 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 ?
28Clamp-On Porometry
- Sample chamber clamps on any desired location of
sample (No need to cut sample damage the
material)
29Clamp-On Porometry
- No damage to the bulk material
- Test may be performed on any location in the bulk
material
30Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
Shapes
31Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
- Size
- Micron size biomedical devices
- 8 inch wafers
- Two feet cartridges
- Entire diaper
32Flexibility to Accommodate a Wide Variety of
Sample Shape, Size and Porosity
33Ease of Operation
- Fully automated
- Test execution
- Data storage
- Data Reduction
- User friendly interface
- Menu driven windows based software
34Ease 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
35Advanced 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
36Diffusion Gas Permeametry
37Diffusion Gas Permeameter
38Diffusion 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
39High Flow Gas Permeametry
- Uses actual component Diaper, Cartridges, etc.
- Can measure flow rates as high as 105 cm3/s
- Can test large size components
40High Flow Gas Permeametry
41Microflow 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
42High Flow Liquid Permeametry at High Temperatures
and High Pressures
- Measures high permeability of application fluids
at high temperature through actual parts under
compressive stress
43High Flow Liquid Permeametry at High Temperatures
and High Pressures
44High 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
45Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
46Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
- Envelope Surface Area
- Computes surface area from flow rate using Kozeny
and Carman relation
47Envelope 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
48Envelope 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
49Envelope 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
50Envelope 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
51Envelope 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
52Envelope Surface Area, Average Particle Size
Average Fiber Diameter Measurement
53Envelope 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
54Water Vapor Transmission
- Transmission under pressure gradient
55Water Vapor Transmission
- Transmission under pressure gradient
56Water Vapor Transmission
- Transmission under concentration gradient
57Water Vapor Transmission
- Transmission under concentration gradient
58Mercury Intrusion Porosimetry
- Stainless Steel Sample Chamber
59Mercury Intrusion Porosimetry
- Special design to minimize contact with mercury
60Mercury 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
61Mercury Intrusion Porosimetry
- Automatic refilling of penetrometer by mercury
- Automatic drainage of mercury
- In-situ pretreatment of the sample
- Fully automated operation
62Non-Mercury Intrusion Prosimetry
- Sample Chamber That permits Mercury Intrusion
Porosimeter to be used as a Non-Mercury Intrusion
Porosimeter
63Water Intrusion Porosimeter (Aquapore)
- Uses absolutely no mercury
- Water used as intrusion liquid
- Can test hydrophobic materials
- Can detect hydrophobic pores in a mixture
64Water Intrusion Porosimeter (Aquapore)
65Gas 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
66Conclusions
- 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
67Conclusions
- Results have been presented to show the
improvements in accuracy and repeatability of
results and ease of operation of the test.
68Conclusions
- Measurement of characteristics under application
environments involving
- compressive stress
- cyclic compression
- aggressive conditions
- elevated temperatures
- high pressures
- have been illustrated with examples
69Thank You