Post on 06-Jan-2016
description
FORMATION OF ALUMINUM NANOPOWDERS AND THEIR APPLICATION IN
NANOENERGETIC MATERIALS
Dr. Jan A. Puszynski
Chemistry and Chemical Engineering Department
South Dakota School of Mines & Technology
Rapid City, SD 57701
Tel: 605/394-5268 Fax: 605/394-5266
E-mail: Jan.Puszynski@sdsmt.edu
Effect of Operating Pressure onReactive Aluminum Content and Surface Area
20
40
60
80
100
0 4 8 12 16
Pressure (Torr)
Aluminum (%) Surface Area (sq. m/g)
PARAMETRIC STUDIES: FORMATION OF ALUMINUM NANOPOWDERS
100 nm
1.5 nm
0
500
1000
1500
2000
2500
3000
3500
4000
4500
15 20 25 30 35 40 45 50 55 60 65 70 75
Two-theta (degree)
Intensity (cps)
Mathematical Modeling of Aerosol Dynamics
Stages in Particle Formation
Stage1 (T1)
Stage2 (T2)
Stagen-1
(Tn-1)
Stagen (Tn)
Modeling the Aerosol Dynamics• The rate of change of various moments of the aerosol size distribution for the n th cell can be written by :
First Moment, M1
Aerosol Surface Area, A
Aerosol Number Density, N
1
3/1
111*
1 ])1([−
+−+=n
MNBSdIkM τ
1−+= nNIN τ
1111* ])1(2[
3/2
−+−+= nAMSBsIkA τπ
Modeling the Aerosol Dynamics• d1 , s1 , v1 are the monomer diameter, surface area and
volume respectively.
• The saturation ratio S is given by:
• The nucleation rate I is given by:
sc
cS 1=
))2
ln(exp()9
2()
2( *2/12/122/1
11
2 SkS
m
TkscI bs −∑=
ππ
Schematic Representation of Cascade Flow Model
Individualaerosol cells
withconstant
temperature
MoltenAluminumin the boat
Inert gasdistributor
Modeling the Aerosol Dynamics
In the case of several CSTAGs (Continuous Stirred Tank Aerosol Generator) in series, the governing mass balance equation is given by:
( )0
2
1
1
111 =⎟⎟
⎠
⎞⎜⎜⎝
⎛ −+−− ∗
−− Vv
ABSIkCFCF nnnn
2-D Temperature Profiles in the Al Nano-Powder Generator (PHe=5Tr)
2-D Temperature Profiles in the Al Nano-Powder Generator (PAr=5Tr)
Axial Temperature Profiles in the Generator for Helium and Argon
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Position in the generator (axis) in m
Temperature, K
Helium
Argon
Median Particle Diameter vs. Inert Gas Pressure
0
20
40
60
80
100
120
140
160
180
0 2 4 6 8 10 12 14 16
Inert Gas Pressure (Torr)
Median Particle Diameter (nm)
Helium
Argon
Linear (Helium)
Linear (Argon)
0
10
20
30
40
50
60
0 2 4 6 8 10 12 14 16
Inert gas pressure (Torr)
Surface area ( m
2/g )
Helium
Argon
Characterization of uncoated and coated aluminum nanopowders.
DETERMINATION OF REACTIVE ALUMINUM CONTENT
• Thermogravimetric method (TGA)
• Volumetric method (VM)
• Bomb calorimetry method (BCM)
TGA of Aluminum Nanopowders
95
100
105
110
115
120
Weight (%)
0 200 400 600 800
Temperature (°C)
Sample: al nano m040001Size: 8.3950 mgMethod: RampComment: m040001 at 20 c p min in O2 100ml/m on nov 26
DSC-TGAFile: C:...\Al_m040001_20cpm_100mlpm_ox.001Operator: somRun Date: 27-Nov-02 11:13Instrument: SDT Q600 V3.4 Build 41
Universal V3.5B TA Instruments
20.22 wt % of reactive aluminum
80
100
120
140
160
Weight (%)
0 200 400 600 800 1000 1200 1400 1600
Temperature (°C)
Sample: Al Nano 1030001Size: 2.3620 mgMethod: RampComment: Al Nano 1030001 NSWC/IH Argon and Air atmosphere
DSC-TGAFile: Al+Al2O3_1030001_al1450_100mlpm_argon...Operator: SomRun Date: 18-Jan-03 11:07Instrument: SDT Q600 V3.4 Build 41
Universal V3.5B TA Instruments
67.78 wt % of reactive aluminum
0
500
1000
1500
2000
2500
3000
3500
4000
4500
15 25 35 45 55 65 75
two theta (degree)
Intensity (cps)
aluminum
alon
alumina
Comparison of TGA, Volumetric, and Bomb Calorimetry Methods
Aluminum Average Particle
Size
TGA Method
wt%
Volumetric Method
wt%
Bomb Calorimetry
wt%
50 nm 69.0 68.0 69.4
80 nm 75.1 79.8 79.5
2 m 91.2 99.5 99.3
Surface Functionalization of Al Nanopowders And Their Reactivity with Moisture
and Liquid Water
• Mixing• Processing • Long-term stability
0
10
20
30
40
50
60
70
80
0 200 400 600 800 1000 1200 1400
Time of Exposure (hours)
Weight % Reactive Aluminum
97 % RH84 % RH75 % RH43 % RH
Effect of Moisture on Aluminum Nanopowders
0
20
40
60
80
100
0 50 100 150 200 250 300 350 400
Time of Exposure (hours)
Weight % Reactive Aluminum
Uncoated5.0% Z61245.0% oleic acid
Effect of Moisture (97% RH) on Coated and Uncoated Aluminum Nanopowders
0
20
40
60
80
0 100 200 300 400 500 600 700
Time of Exposure (hours)
Weight % Reactive Aluminum
1.0 % oleic acid3.0 % oleic acid5.0 % oleic acidUncoated
0
20
40
60
80
0 10 20 30 40 50Time (hours)
Percent Reactive Al
Uncoated 40 CUncoated 30 CUncoated 20 CCoated 40 C
Ageing of Aluminum Nanopowders in Liquid Water
Ageing of Aluminum Nanopowders97% RH and 40oC
Aged 0 hrs, 74 wt% reactive Al Aged 40 hrs, 59 wt% reactive Al
Ageing of Aluminum Nanopowders
Aged 60 hrs (97% RH), 17 wt% reactive Al Aged 80 hrs (97% RH), 0 wt% reactive Al
Aluminum Nanopowder Coated with 4 wt%of Silane
DISPERSION AND MIXING OF
NANO-POWDERS
Sedimentation of AluminumNano-powder in Hexane
Time: 30 sec Time: 50 sec
Without dispersant
Time: 5 min Time: 30 min
J
With dispersant (2 wt% sodium dioctyl sulfosuccinate, SDS)
Characterization of Mixing Quality of Binary Nano-powders (high resolution)
Wet Mixing of Al(red) / TiO2(blue) System (with SDS dispersant):SE/Cameo Image 50,000XSE/BSE/Element Mapping 50,000XSE/Element Line Scan 50,000X
Al-TiO2-mixture prepared in absolute ethanol with sodium dioctyl
sulfosuccinate as surfactant. Sample after three line scans of 10 m at 10000 X.
Dry mixingWet mixing hexane
Wet mixing ethanol(w/disp.)
Wet mixing hexane (w /disp.)
Mixing Index AK,L for different samples
0.945 0.950 0.955 0.536
Mixing Index for the Mixtures of Nanosized PowdersMixing Index for the Mixtures of Nanosized Powders
INVESTIGATION OF COMBUSTION CHARACTERISTICS IN SYSTEMS
CONTAINING ALUMINUM AND METALOXIDES NANOPOWDERS
REACTION Tad [K] [kg/m3]
2Al + MoO3 3,253 4.50
2Al + 3MnO2 2,918 4.01
10Al + 3I2O5 >3,253 4.12
2Al + 3CuO 2,843 5.10
2Al + WO3 3,705 5.45
2Al + Fe2O3 3,100 4.23
2Al + Bi2O3 3,325 5.70
Adiabatic Temperature of EnergeticReacting Systems
Computer
Oscilloscope
High Speed Camera(Photron Ltd.)16,000 fps1/128,000 ShutterSpeed
Piezo ElectricIgniter
Stand
OpticalFibers Photo
Detectors
PerforatedBaffles
ReactantMixture
Oscilloscope
Schematics of the Burn Test Equipment
Reacting System: Nanosize Al (40 nm) and Nanosize Fe2O3 (Nanophase Technologies, Corp.)
• Combustion Front Velocity: 30 m/s
• Recording Speed: 8000 frames/sec
• Playback Rate: 30 frames/sec
st= 0.1
t= 200
t= 600
t= 800
t= 100
t= 300
t= 500
Reacting System: Nanosize Al (50 nm NSWC/IH) and Micronsize MoO3 (Climax Molybdenum Company)
With Perforated Baffles
t= 0.1
t= 100
t= 170
t= 200
t= 50
t= 150
t= 160
s
0
200
400
600
800
0 2 4 6 8 10 12
Weight % Coating
Propagation Velocity (m/s)
oleic acid
Silane 1-6341
Poly. (oleicacid)Linear (Silane1-6341)
Effect of Coating on Combustion Front VelocityUnder Unconfined Conditions
Wt% of Coating Wt% of Coating
0
50
100
150
200
250
0 2 4 6 8 10 12
Weight % Silane Coating
Ignition Delay (us)
Z6124Oleic acid
Wt% of Coating
Effect of Coating on Ignition Delay Time
Effect of Average Particle Size of Aluminum on Burn Rate in Al-CuO System
0
200
400
600
20 40 60 80 100 120
Aluminum Average Particle Size (nm)
Propagation Velocity (m/s)
Average Particle
Size (nm)
Ignition
Delay (ms)50 8980 84100 88
Gas Tank
Pressure ReliefValve
Vacuum Pump
Pressure Vessel
PressureTransducer
Sensor SignalConditioner
PiezoelectricIgniter
Oscilloscope
Oscilloscope
Schematics of the pressure vessel equipment
Equipment for Burn test of Aluminum under confined conditions
CAMERA
REACTOR
AUTOTRANSFORMER
VACUUM PUMP
VENT
GAS INLET
DATA ACQUISITION SYSTEM
PRESSURE GAUGE
THERMOCOUPLE WIRES
SAFETY
VALVE
FLANGE 1 FLANGE 2
ReactorReactor Alumin Boat
LEADS FROMTHERMOCOUPLE TODATA AQUISITION
MOLYBDENUM
IGNITION WIRE
Aluminum loose powder
Pressure Vessel Experimental Set-up
0
10
20
30
40
50
60
70
80
90
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01
Time [s]
Pressure [psi]
Pressure Responses in Al (uncoated)-CuO System
IDT
Pmax
Wt% of Coating Wt% of Coating
0
50
100
150
200
250
0 2 4 6 8 10 12
Weight % Silane Coating
Ignition Delay (us)
Z6124Oleic acid
Wt% of Coating
Effect of Coating on Ignition Delay Time
0
20
40
60
80
100
120
0 0.005 0.01 0.015 0.02
Time [s]
Pressure [psig]
30 psig Ar
15 psig Ar
0 psig Ar
0
20
40
60
80
100
120
0 0.005 0.01 0.015 0.02
Time [s]
Pressure [psig]
30 psig Ar
15 psig Ar
0 psig Ar
20
40
60
80
100
0.01 0.02
Time [s]
Pressure [psig]
Al/MoO 3
Al/Bi 2O3
Al/CuO
0
20
40
60
80
100
0.01 0.02
Time [s]
Pressure [psig]
Al/MoO 3
Al/Bi 2O3
Al/CuO
0
New experimental technique:
Recoil force measurement during unconfined burn of a nanoenergetic
mixture.
Load cell (force transducer) : Entran Devices, Inc.
Linear range: 0 – 1000 NSensitivity : ~200 mV/1000 N
Average recoil force during combustion of the MICs
0 2 4 6 8 10 120
50
100
150
200
250
300
350
400
Al-MoO3
Al-Bi2O
3
Al-CuO
recoil force [N]
mass of the MIC [mg]