NEEM MURI ARO Final Review of "A Unified Multiscale Approach for Nano Engineered Energetic Materials,” Heat Center, Aberdeen, Maryland,

15 March 2010

Combustion Analysis of Nanoenergetic Materials

Richard Yetter, Jongguen Lee, Mike Weismiller, Justin Sabourin, Steven Dean, and Bruce Yang The Pennsylvania State UniversityThe Pennsylvania State University

Tim Foley, Blaine Asay(L Al N ti l L b t )(Los Alamos National Laboratory)Steven F. Son (Purdue University)Tim Eden, Orlando Cabarcos, Dave Allara (Penn State)

NEEM MURI Research Areas

• Flame spread across thin fuel films of nano metallic particles. • Combustion of nAl with O2/Ar mixtures – unified theory developed.• Combustion of nAl with CO CO N O and N• Combustion of nAl with CO2, CO, N2O, and N2.

• Combustion of nano metallic particles and flame propagation through quasi-homogeneous mixtures of nano metallic particles and liquid and gaseous oxidizers.gaseous oxidizers.

• Combustion of nAl/liquid H2O• Combustion of nAl/H2O/H2O2• Combustion of nAl/CH3NO23 2• Combustion of nB/CH3NO2

• Combustion of nano metallic particles and flame propagation through quasi-homogeneous mixtures of nano metallic particles and solid oxidizers.

• Combustion of nano Al/MoO3 thermites – stoichiometry and channel size.

• Combustion of nano Al/CuO thermites –fuel particle size, density, and dil tion effectsdilution effects.

• Combustion of nB in Al/CuO thermites.• Self-assembly of ordered microspheres of a nanoscale thermite.

NEEM MURI Research Areas

• Liquid propellants with nanostructured additives and nano aluminum gelled propellantsand nano aluminum gelled propellants.

• Temperature, pressure, and oxidizer particle effects on nanothermiteson nanothermites.

• Nano intermetallic powder systems.

NEEM MURI Self-Assembled Nanoscale Thermite Microspheres

Opal gem: organized nanoparticle self assemblySanders, J. V., Murray, M. J., Nature v275, 1978.

Structure of the Abalone Shell (A reactive material structure?)A. Lin and A. Meyers, Mat. Sci. Eng. A 390, 27-41, 2005.

inorganic layers: (inter-metallic fuel layers?)Laboratory assembled nAu & nAg composites o ga c aye s ( te eta c ue aye s )

organic layers: (energetic binder layers?)

Laboratory assembled nAu & nAg compositesKalsin et al., Science, v312, 2006

•Create Self‐Assembled Monolayer (SAM) on surface of particles•Monolayers contain a functionalized group at tail end (either + or 

nAl‐TMA(trimethyl(11‐mercaptoundecyl)

– charged)•When mixed in a diluted and elevated temperature they form energetic macroscale structures with nanoscale constituents

Malchi, J., Foley,T., Yetter, R.A., Reactive Composite

nAl (38nm)

ammonium chloride) ACS APPLIED MATERIALS & INTERFACES, 2009

p

~4 μm

nCuO(33nm)

nCuO‐MUA(11‐mercaptoundecanoic acid )

NEEM MURI Nanostructured Additives for Enhanced Propellant Combustion

GrapheneAluminum monohydroxide Silica

3

3.5

/s

Pchamber

=

5.24 +/- 0.05 MPa

Neat NM; 5.23 MPa, rb = 1.2 mm/s

2.5

FGSAl

2O

3 Plus

Porous SiO2

ning

Rat

e, m

m/NM + 0.5% (mass)

AlOOH; 5.16 MPa, rb = 1.6 mm/s

NM + 0 39% (mass)

1.5

2Li

near

Bur

t NM 1 20 /

NM + 0.39% (mass) SiO2 gel; 5.25 MPa, rb = 1.9 mm/s

10 0.1 0.2 0.3 0.4 0.5 0.6

Concentration, volume %

rb, neat NM ~ 1.20 mm/s

2 s steps, under Argon

NM + 0.3% (mass) FGS22; 5.16 MPa, rb = 2.2 mm/s

NEEM MURI Combustion of Nano Aluminum Gelled Propellants

NEEM MURI Propagation Mechanisms of Nanothermite Reactions

P Pressure Gradient drives gases forwardP Pressure Gradient drives gases forwardConvection wave

When ignited in a burn-tube, ‘fast’ nanothermites (Al/C O Al/M O

Pressure gradient drives reaction forward

(Al/CuO, Al/MoO3, Al/Bi2O3) react through a convective mechanism

Convective burning is

Heat Conduction

Convective burning is driven by the creation of a large pressure gradient in the porous mixture, and not by a temperature

Hot gases penetrate the granular mixtureFlame Zone

Temp= Tf

Porous Reactants

and not by a temperature gradient

Pressure Transducers

Fiber Optic Cables

Conduction waveTemperature gradient drives reaction forward

Conduction wave Temperature gradient drives reaction forward

ThT0Powder –FilledTube

NEEM MURI Effect of Pressure on the Propagation Rate in a Al/CuO Nanothermite

/s)

nt V

eloc

ity

atin

g

ting

nt V

eloc

ity

m/s

m/s /s

Nano-aluminum from Novacentrix (avg. dp=38nm)Nano CuO from Sigma-Aldrich (avg. dp=33nm)Studies conducted in an optical strand burner (V=23 liters)

ff ( )

Vf (

m/

As pressure is increased, several different modes of propagation are observed P t hi h ti d h d d

Fast

Con

stan

Acc

eler

a

Osc

illa

Slo

w C

onst

an

100’

s

~1 k

m

~1 mPressurized with 3 different gases (Ar, He, or N2)

Pressure (MPa)Pressure at which propagation mode changes depends on pressurizing gas; He has a high thermal conductivity

1000 1000 10002 32 3 3+ → +Al CuO Al O Cu

100

1000

] 100

1000

] 100

1000

s]

Ar He N2

10

Vf [m

/s]

atin

g

erat

ing 10

V f[m

/s]

llatin

g 10Vf[m

/s

llatin

gel

erat

ing

10 5 10 15

Pa

[MPa]

Osc

ill

Acc

ele

10 5 10 15

Pa[MPa]

Osc

il

10 5 10 15P

a[MPa]

Osc

iA

cce

NEEM MURI Temperature Measurements forunderstanding Gas Generation

Previous work: gas fraction at equilibriumDrawbacks:• No intermediate gases (not present at equilibrium)

nAl/MoO3 30

• Many of the equilibrium gases will not be realized until very high temperatures (ex. Cu: BP of 2835K)

nAl/CuO in burn tube at

10

20

essu

re [M

Pa] 1atm in air

nAl/MoO3 0

10

0 0.0005 0.001

Pre

Time [s]

The measured over-pressures (in excess of 10 [MPa]) can only be explained by gas generation

1 PTRPN

P gen ⎟⎟⎞

⎜⎜⎛

+=Δ

Time [s]

121int

PTRTRV

P −⎟⎟⎠

⎜⎜⎝

+=Δ

Heating of interstitial gasGeneration of

gaseous species

NEEM MURI Optical Temperature Measurements

Time integrated temperature measurement set-up

Temporally resolved temperature measurements via streak camera

Pile of energetic themite to be sampled

Optical fiber

Spark igniter

Image Processor

High Speed Camera

CL+

-

Spark igniter

SignalGenerator

CCD Camera

Spark Igniter

Thermite-FilledBurn TubeGenerator

External Trigger

StreakCamera

(C7700-01)

Output Optics

SignalGenerator

Ocean Optics HR2000 Spectrometer

Data Acquisition Computer

Spectrograph

Input Optics

Optical fiber Coupling lens

pp

NEEM MURI Optical Pyrometry requires consideration of Material Spectral Emissivity

Simplest Solution:

In general: ( )T,λεε =

.const=ε Two-color pyrometryMore Accurate Solution:

Assume emissivity has a known relationship with λ ( ε ~ λn )

Planck’s Law

( ) ( )⎥⎦⎤

⎢⎣⎡ −

⋅=1

,,25

1

TC

e

CTTEλλ

λελ

( )λε 3C=18

667 5001000λ [nm]

λ 2 d t l id d( ) λλε =

Curve Fitting Equation [used by Ng et al Review of Scientific Instruments (2001)] 14

16

Z

y = 6.06961E-06x + 5.0513T = 2370 K

ε~λ-2 and ε =const, also considered

( ) ( )3261 , CLnTCTECLnZ −⋅

=⎟⎠⎞

⎜⎝⎛ ⋅=

λλ

λ 121E+6 1.5E+6 2E+61/λ [m-1]

NEEM MURI Temperature Measurements Suggest that the Final Products are not Gasified

2500

3000

3500

[K]

erature

re t oint 

t 

2 32 3 3+ → +Al CuO Al O CuBurn Tube Propagation Rate ~ 1 km/s um BPure

(K)

Al/CuO

0

500

1000

1500

2000

Al/CuO

Tem

pera

ture

Equilib

rum Tem

pe

Measured Tempe

ratur

Cu boilin

g Po

in

Al 2O3 bo

iling

 p

Al b

oilin

g po

intp g

Combustion Temperature ~ 2350±150 K

Equ

ilibr

i

Mea

sure

d

Cu

BP

Al2O

3B

Al B

P

Tem

pera

tu

2500

3000

3500

4000

4500

5000

erat

ure

[K]

m 

ure

oilin

g Po

int

int 

nt 

3 2 32 + → +Al MoO Al O MoAl/CuO

Burn Tube Propagation Rate ~ 1 km/sCombustion Temperature ~ 2150±150 K ium o B

P

BPerat

ure

(K)

Al/MoO3

0

500

1000

1500

2000

Al/MoO3

Tem

pe

Equilib

rum

Tempe

ratu

Mea

sured 

Tempe

rature

Mo bo

Al 2O

3 

boiling

 poi

Al

 boilin

g po

i n

35002 3 2 32 2+ → +Al Fe O Al O Fe

p

Equi

libri

Mea

s. Mo

Al2O

3B

Al B

P

Tem

pe

Al/F O

1500

2000

2500

3000

3500

pera

ture

[K]

rum 

ature

ling Po

int

boiling

 point 

ing po

int 

2 3 2 32 2+ → +Al Fe O Al O FeBurn Tube Propagation Rate ~ 0.1 m/sCombustion Temperature ~ 1700±150 K

rium

e B

P

O3

BP

BPpera

ture

(K)

Al/Fe2O3

0

500

1000

1500

Al/Fe2O3

Tem

p

Equilib

rTempe

ra

Measured 

Tempe

rature

Fe boil

Al 2O3 

Al boil

Equ

ilibr

Mea

s. Fe

Al2

Al B

Tem

p

NEEM MURI Metal Oxides Vaporize or Decompose at Low Temperatures

2 212 → +CuO Cu O O

Compound Tmp(K)

Tbp(K)

Tvol(K)

Al 1687 3013 n/a 2 22 2→ +CuO Cu O O

2 3 3 4 213 22

→ +Fe O Fe O O

Al 1687 3013 n/aAl2O3 2345 3253 n/aCuO 1500 decomposes 1400

14 8000 14 1 104

2Fe2O3 1855 decomposes 1750MoO3 1075 1428 n/a

8

10

12

5000

6000

7000

n [m

ol/k

g]

V

Volume

Cu

O

Cu2O (l)

8

10

12

6000

8000

n [m

ol/k

g]

V [Fe2O

3 (s)

FeO (l)

4

6

8

2000

3000

4000

Con

cent

ratio

n [cm3/g]

OCu2O (s)

O2 4

6

8

2000

4000

Con

cent

ratio

n

[cm3/g]

2 3

O

Fe3O

4 (s) O

2

Volume

0

2

0

1000

0 1000 2000 3000 4000 5000

C

Temperature [K]

Cu2 CuO

0

2

00 1000 2000 3000

C

Temperature [K]

O2

NEEM MURI Temperature continues to Rise after Luminous Front Passes

Wave speed ~ 800 m/s

800m/s x 50μs = 40 mm

T still increasing,

Energy being released

1.2 4000const.1/lambda1/lambda^2

800m/s x 50μs 40 mm

~80

mm

Energy being released

Al/CuO

0.8

1 3500

1/lambda^2

nits

] Tem

t0 +14μs +28μs +42μs +56μs

Al/CuO

0.6

2500

3000

nsity

[arb

. un mperature [K

50μs

time

pix

Un-reactedtime

0.2

0.4

2000

Inte

n K]xels

0 1500600 650 700 750 800 850 900

Time from Trigger [micro sec]wavelength

pixels

wavelength

NEEM MURI Effects of Oxidizer vs Fuel Particle Size

Energetic Mass

Aluminum: nanoparticles (38nm) from Technanogy, micron-particles (2μm) from ValimetCopper-Oxide: nanoparticles (33nm) and micron particles (3μm) from Sigma Aldrich

Linear Burning Rate [m/s]

Mass Burning Rate [kg/s]

Burning Rate [kg/s]

Avg. mass per run [g] % mass Al2O3

Nano Al/ Nano CuO 977 3.79 3.14 0.31 17.1Micron Al/Nano CuO 658 4.77 4.72 0.58 1.0

micron Al - micron CuO

nm Al micron CuO

Nano Al/Micron CuO 197 1.31 1.08 0.53 17.1Micron Al/Micron CuO 182 2.02 2.00 0.89 1.0

micron Al / micron CuO nm Al - micron CuO

micron Al - nm CuO

nm Al-nm CuO

Linear propagation rate was more

dependant on the CuO particles size

micron Al / micron CuO

nm Al / micron CuO

micron Al / nm CuOnm Al nm CuO

22 212 OOCuCuO +→

micron Al / nm CuO

nm Al / nm CuO

0 200 400 600 800 1000Linear Burn Rate [m/s]

Evidence that the oxide decomposition drives convective burning Linear Burning rate [m/s]

NEEM MURI Al/MoO3 System has Similar Trend

Linear Burning Rate [m/s]

Mass Burning Rate [kg/s]

Energetic Mass Burning Rate

[kg/s]Avg. mass per

run [g] % mass Al2O3

Oxide Shell Thickness

(nm)Nano Al/ Nano MoO3 678 1.95 1.43 0.23 26.4 6.213Micron Al/Nano MoO3 362 1.54 1.51 0.34 1.7 22.26Nano Al/Micron MoO3 151 0.45 0.33 0.24 26.4 6.21

Micron Al/Micron MoO3 47 0.52 0.51 0.89 1.7 22.26

micron Al - micron MoO3

nm Al - micron MoO3

micron Al - nm MoO3

MoO3 vaporizes at relatively low temperatures

micron Al / micron MoO3

nm Al / micron MoO3 micron Al nm MoO3

nm Al - nm MoO3

temperatures. Reducing the size of

these particles promotes convective

burning

micron Al / nm MoO3

nm Al / nm MoO3

0 200 400 600 800 1000Li B R t [ / ]

burning nm Al / nm MoO3

Linear Burn Rate [m/s]Linear Burning rate [m/s]

reducing the oxidizer particle size has greater impact on increasing propagation rate

NEEM MURI Pressure Profiles for Mixtures of Al/CuO and Al/MoO3 with different Powder Sizes

20

30

MPa

]

20

30M

Pa]

1.82 [MPa/μs] 0.50 [MPa/μs] nano-Al / micro-CuOmicro-Al / nano-CuO

10

20

ress

ure

[M

10

20

ress

ure

[M

[ μ ]

00 0.0005 0.001

Pr

Time [s]

00 0.0005 0.001

Pr

Time [s] 1515[ ][ ]

10

15

MPa

]10

15

MPa

] micro-Al /nano-MoO3 nano-Al / micro-MoO30.44 [MPa/μs] 0.20 [MPa/μs]

5

ress

ure

[M

5

ress

ure

[M

00 0.00075 0.0015

Pr

Time [s]

00 0.00075 0.0015

Pr

Time [s]

NEEM MURI nNi-nAl Burning Rates

• Al + Ni → AlNi -1.38 kJ/g• Taf = 1912 K• Vertical glass tubes 2” in length

Material Manufact. Size (nm)

Morphology Purity (%)

Vertical glass tubes 2 in length • Ignited with Nichrome wire• Flame propagation measured with

Phantom 7.3

AlNi

Novacentrix 80 Spherical 80

Alfa Aesar 5-20 Spherical 99.9

Heat treatment performed on nm Ni powder in oven

at 250 °C

StoichiometryCombination

Molar RatioAl : Ni

Mass Percentage (%)Al : Ni

1 1 : 1 29.2 : 90.82 1 : 0.56 36 : 643 1 : 1.38 20 : 80

1.8

2

3

3.5nNi-nAl Burning Rates

Burning Rates after Heat Treatment

29% Al

1.2

1.4

1.6

2

2.5

3

0.8

1

15 20 25 30 35 40% Al

1.5

2

0 5 10 15 20Heat Treatment Duration (min)

NEEM MURI Our work has led to the following conclusions…

• Further evidence showing that the fast propagation rates in nanothermites are induced by the convective burning mechanism

• Increasing ambient pressure leads to decreased gas generation and a change in the propagation mechanismg g p p g

• Gas generation is due to decomposition of oxide particles

• Temperature rise takes place over a thick region• Temperature rise takes place over a thick region– Reaction relies on pressure, not temperature,

gradient to drive propagation– Need only heat mixture to point of gas generation to

propagate• Reducing the size of oxidizer particles seems toReducing the size of oxidizer particles seems to

increase rate of gas generation and promote convective burning

NEEM MURI Summary - continued

• Electrostatic self-assembly of nanoscale thermites into microspheres show improved mixing overinto microspheres show improved mixing over sonication.

• Nano functionalized colloids of metal oxides and• Nano functionalized colloids of metal oxides and graphene demonstrated to affect pressure exponent and burning rate. Nano aluminum affects p gburning rate.

NEEM MURI 2008-2009 Publications“Combustion and conversion efficiency of nanoaluminum-water mixtures,” Risha, GA; Sabourin, JL; Yang, V; Son, SF;

Tappan, BC, COMBUSTION SCIENCE AND TECHNOLOGY, 12, 2127-2142, 2008. “Combustion characteristics of nanoaluminum, liquid water, and hydrogen peroxide mixtures,” Sabourin, JL; Risha, GA; Yetter,

RA; Son, SF; Tappan, BC,COMBUSTION AND FLAME, 154, 3, 587-600, 2008. “The effect of added Al2O3 on the propagation behavior of an Al/CuO nanoscale thermite ” Malchi JY; Yetter RA; Foley TJ;The effect of added Al2O3 on the propagation behavior of an Al/CuO nanoscale thermite, Malchi, JY; Yetter, RA; Foley, TJ;

Son, SF, COMBUSTION SCIENCE AND TECHNOLOGY, 180, 7, 1278-1294, 2008. “Functionalized Graphene Sheet Colloids for Enhanced Fuel/Propellant Combustion,” Sabourin, JL; Dabbs, DM; Yetter, RA;

Dryer, FL; Aksay, IA, ACS NANO, 3, 13, 3945-3954, 2009.“Electrostatically Self-Assembled Nanocomposite Reactive Microspheres,” Malchi, JY; Foley, TJ; Yetter, RA, ACS APPLIED

MATERIALS & INTERFACES 1 11 2420-2423 2009MATERIALS & INTERFACES, 1, 11, 2420-2423, 2009. “Effect of Nano-Aluminum and Fumed Silica Particles on Deflagration and Detonation of Nitromethane,” Sabourin, JL; Yetter,

RA; Asay, BW; Loyd, JM; Sanders, VE; Risha, GA; Son, SF,” PROPELLANTS EXPLOSIVES PYROTECHNICS, 34, 5, 385-393, 2009.

“Metal particle combustion and nanotechnology,” Yetter, RA; Risha, GA; Son, SF, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 32, 1819-1838, 2009.INSTITUTE, 32, 1819 1838, 2009.

“Dependence of flame propagation on pressure and pressurizing gas for an Al/CuO nanoscale thermite,” Weismiller, MR; Malchi, JY; Yetter, RA; Foley, TJ, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 32, 1895-1903, 2009.

“The effect of stoichiometry on the combustion behavior of a nanoscale Al/MoO3 thermite,” Dutro, GM; Yetter, RA; Risha, GA; Son, SF, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 32, 1921-1928, 2009.

“Realizing microgravity flame spread characteristics at 1 g over a bed of nano-aluminum powder,” Malchi, JY; Prosser, J;Realizing microgravity flame spread characteristics at 1 g over a bed of nano aluminum powder, Malchi, JY; Prosser, J; Yetter, RA; Son, SF, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 32, 2437-2444, 2009.

“Effect of particle size on combustion of aluminum particle dust in air,” Huang, Y; Risha, GA; Yang, V; Yetter, RA, COMBUSTION AND FLAME, 156, 1, 5-13, 2009.

“Exploring the Effects of High Surface Area Metal Oxide Particles on Liquid Nitromethane Combustion,” Sabourin, JL; Yetter, RA; Parimi, S, JOURNAL OF PROPULSION AND POWER, submitted DECEMBER 2009.

“Oxidizer and Fuel Particle Size Dependence on Propagation Rates of Thermite Reactions,” Weismiller, MR; Lee, JG; Yetter, RA, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 33, submitted DECEMBER 2009.

“Multiwavelength Spectroscopic Temperature Measurements of Thermite Reactions,” Weismiller, MR; Lee, JG; Yetter, RA, PROCEEDINGS OF THE COMBUSTION INSTITUTE, 33, submitted DECEMBER 2009.