1. PAU Cartridge Compatibility Study
16 May 2018
Presented by: Dr. Gina M. Canfield
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

2. Introduction
Pyrotechnic and Arming Unit (PAU) Cartridge – functions store/release in U.S. weapons systems
PAU Cartridge
BKNO3 Powder
Metal Disk
HES propellant grains containing AP or HMX
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

3. Introduction
Chemical & Materials Analysis Branch (R14) at NSWC IHEODTD received 4 PAU Cartridges: 3A, 3B, 3C, and 3D for a component compatibility study
Gas cylinders of previously collected cartridge headspace gases were also received by the lab for analysis
Gas Chromatography (GC)
Cartridges were opened – individual components removed, cartridge admixtures prepared for analysis*
Differential Scanning Calorimetry (DSC)
Accelerating Rate Calorimetry (ARC)
Powder X-ray Diffraction (PXRD)
*at various stages of sample age
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

4. Experimental GC Analysis – 4 as-received gas cylinders sampled 3 ways:
Sampling port (septum) fitted onto cylinder, syringe used to withdraw 10 mL gas, injected into Agilent headspace vial to be run on GC
Same as above but syringe injected directly onto GC
Argon gas used to flush cartridge sample into a headspace vial to be run on GC
Cartridge Admixture Prep
Graphite coating removed from all types of HES grains
Bits from three types of HES grains (from each cartridge) were shaved off
Shaved bits along with BKNO3 powder were combined (1:1:1:1) and ground together in mortar/pestle
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

5. Experimental DSC ARC PXRD
Individual components (BKNO3, 3 HES grain types) and all cartridge admixtures tested
TA Instruments model DSC 2910 at 5 °C/min under a 50 mL/min N2 purge in hermetic sealed Al pans
ARC
Only cartridge admixtures tested
CSI ARC with TIAX/Netzsch control cabinet under a HWS testing profile from °C at 3 °C/min in 3 °C steps
PXRD
Only cartridge admixtures 3B, 3C, 3D tested
Bruker D8 Discover with Cu Kα source at 50 kV/1000 µA and Vantac 2D Area detector
Samples scanned from 20-65° 2-theta, 15° increments, 4 frames, 30 min scan
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

6. GC Analysis GC conducted on cartridge headspace gases
None of the samples tested showed any new measurable peaks compared to Argon blank
GC scan of an Argon blank and a representative cartridge, respectively
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

7. DSC Analysis
DSC conducted on individual components from each cartridge:
BKNO3 as expected, cartridges overlap well
HES #1 (HMX) as expected
HES #2 (HMX) cartridge 3A slightly different
HES #3 (AP) cartridges 3A/B different from 3C/D
HES #2 (HMX) (3A, 3B, 3C, 3D)
HES #3 (AP) (3A, 3B, 3C, 3D)
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

8. DSC Analysis DSC conducted on cartridge admixtures 3A, 3B, 3C, 3D new
Small thermal event ~240 °C before AP crystalline shift
Cartridge components appear compatible
PAU Cartridge Admixtures 3A, 3B, 3C, 3D (new)
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

9. ARC Analysis
ARC conducted on cartridge admixtures 3A (new/aged), 3B, 3C, 3D
HWS profile showing Temp/Press vs. Time
Cartridge admixture 3A new has only one exotherm
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

10. ARC Analysis
Summary of exotherm data for cartridge admixtures 3A (new/aged), 3B, 3C, 3D
* denotes approximate values
Cartridge
Sample Age
Exotherm #1
Exotherm #2
Onset, °C
Peak, °C/min
Peak, °C
End, °C
3A new
new
---
208.6
0.1647
231.3
241.1
3A aged
aged
129*
175*
219.6
0.1228
224.4
227.6 3B
154.5
0.0276
156.2
158.4
216.3
0.4199
226.8
234.3 3C
135.0
0.0891
139.5
142.3
213.2
0.1955
224.1
231.2 3D
136.4
0.0658
140.2
142.7
218.4
0.2694
227.2
234.5
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

11. ARC Analysis
Exotherm data showing dT/dt vs. T for cartridge admixtures 3A (new/aged), 3B, 3C, 3D
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

12. DSC Analysis DSC conducted on cartridge admixtures 3A, 3B, 3C, 3D aged
Aged shows loss of thermal stability
Aged shows endotherm °C
PAU Cartridge Admixtures 3A, 3B, 3C, 3D (aged)
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

13. PXRD Analysis PXRD conducted on cartridge admixtures 3B, 3C, 3D
Sample scans overlay well
HMX and reaction products are identified
Overlaid PXRD scans from PAU Cartridge Admixtures 3B, 3C, 3D (aged)
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

14. Conclusions GC analysis inconclusive
DSC shows decreased thermal stability with age
ARC shows increased sample sensitivity with age
PXRD shows presence of reaction products
***Aged PAU Cartridge components lead to increased thermal sensitivity
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

15. Recommendations Repeat cartridge headspace gas collection / GC testing
Prepare new cartridge admixtures, re-test ARC / PXRD
Conduct humidity / temperature / time controlled study of BKNO3 / AP admixtures
***Reduce the risk of any physical contact between PAU Cartridge components, i.e. BKNO3 / AP
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.

16. Acknowledgements Jason Steffin – GC Analysis
Dr. Daniel Sorensen – DSC Analysis
Dr. Sean Maharrey – Data Consultant
Dr. Chad Stoltz – ONR (former R14 Branch Manager)
Todd Allen – NSWC IHEODTD CAD/PAD Branch
Travis Thom – NSWC IHEODTD CAD/PAD AF IPT Branch
CAD/PAD JPO – Project Supporter
DISTRIBUTION STATEMENT A (18-046). Approved for public release: distribution unlimited.