DTIC ADA420337: Extrapolation of Explosive Formulations Based on Wax Binder Systems to High Performance

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by  Defense Technical Information Center

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‘AD-B403 002

Technical Report ARWEC-TR-03012

EXTRAPOLATION OF EXPLOSIVE FORMULATIONS BASED ON WAX
BINDER SYSTEMS TO HIGH PERFORMANCE

B. Fishburn
. Capellos
8. Singh
RHo
W. Balas
D. Sec Ik

January 2004

|

ARMAMENT RESEARCH, DEVELOPMENT AND
ENGINEERING CENTER:

‘Armaments Engineering and Technology Cenler

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‘OMB he aortas

7. REPORT DATE TOO ENESVYV ZREFOAT TPE “CBATES COVEREE (Ham Jn)
January 2008” | Final
4m ang SUNT Ge, CONTRACT NOMEER

EXTRAPOLATION OF EXPLOSIVE FORMULATIONS BASED | #8 GRANT UNBER
(ON WAX BINDER SYSTEMS TO HIGH PERFORMAN

JOGRAM ELEMENT MUR —

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8 Fishbum, ©. Capeles, 8. Singh, R, Ho, W. Béla! and {se thi iss
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"ANS ADDRESEIES PELCDIeaING ORGAN 7ATIOH

7 PERFORHING ORGANIZATION WANE
ic RE2SRT NUMOER

ARDEC, i
Energstics & Warheads [AUSHL-AAR-AEE WV) i
Picatinny, New Jersey 07806-5000

3 SPONSORINGIONITORING AGENCY HAHETS] ANU AUDRESSIES) Ti, Sonne
ARDEC, EM
“Technical Research Center (AMSRO-AAR-EMK) TT SPOHSORNICHTORS REPORT
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a ‘Techrical Report ARWEC-TR-03012
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‘Approved for public release; distribution is unlimited
48, SUPPLEMENIARY NOTES: J

14, ABSTRACT

Explosive formulations using wax hinders with 83 to 86% ROX have damonetrated axcellart resistance to
bullets and fragments when loaded into heavy corfinements. However, these lack the cetonation prassure to
replace Comp in fragmenting warheads. This work axaminas use af waxes of high density to boost
parfarmance,-yet keep faty high wax content consistent with lower sensiiviy. Teoratical calculalone of
performance detail what is possibfo, un ta very high parcoamance. Laborslory efforts (e make small quantities
of theoretically cecirable formulations are destrized

TS SURECT TER — ———eee
Explosive formulations, Wax bindars, Cilorowax binder, Flusrowax binder. Insensitive explosives, High power

explosives
[3S SECURITV CLASSIFICATION OF [17 Tinea or | a. wunene [Tea HAVE OF RESPONSE PERSON]
NisTRNCT OF B. Fishhurn, etal
[3 REPORT] RBETRAS] e THIS PRE PAGES | tb, TELEPAONE nUMbEte kia tae]
u vu ue} sar 20 | cacy (73) 724-4590

‘Siandard Fem POR [Rew BF)
CONTENTS

Infreduetion

Analysis

Chlorowax and Fluorowax

Formulation Elforts

Combining Acproaches te Obtain Reduced Sensitivity

Conclusions

Relerences

Distribution List

0

"

FIGURES
Detonation preasure versus amount af energetic

‘Availabe onergy output varsus amount of energetic

Effect of wax daneily an detonation pressure

fact of wax danely an avaiable energy

Release iseriropes

Energy ilerenee onthe two release isentropes

Compare ratatsted energy with undemnater energy measurement
Detonation pressure versus amount of energetic

Energy output versus amount of energetic.

Detonation pressure versus amount of energetic

Energy output versus amount of energetic,

Page

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INTRODUCTION

Recent efforts to replace TNT in Amny bursting charges had led fo development af an
RON/pleslictzed wax formtltion that can be mell cast into werheads, This materiet has
Undergona certain Insant va muntlons (Ij Yesting inthe M107 projectile. displayed one
especially interesting property, ithaad gcod resistance to bullet or fragment thraats: ft tested
superior even to an insens'ive plastic bondled explosive [PBX {of about same sods loading in
this regard, Actually, this result is not so surpris ng. ag this general property of wax binders was
sown more than 807s aga (ref. 1}. A forunuation using 14%6 wate had passed the most vinlenl
bullet impact test boing run atthe ime (crea, 1942}. Also fram referance 4, iT was shown lena,
ago that in nominally 6640 cyctotols, the bullet impact resistance increases withthe fracion of
decansitizing wax added and there is elgnifivant change [rom the T¥e in conventional Camp 8 to
3.8%, The motivation to furhe- investigate wax binders 's‘@ keap this IM property arid main
the inherent cost advantages of a me't cast formulation while boosting the performance,

‘New ROXs being considered for use in United States rmuntions generally have better
perticls shapes than previously availabe. In particular, particles are more round. with smoother
Surfaces than was typical. che formulater has raparted sigrlficantly lower viseasity, bath In
reliable bniders and in cast cure mixtures, when using new parties as opposed to tradtionai
particles (fs. 2 and 9). Fo exaunple, ference 1 ques Inal cer 20% wax was necessary For
Satisfactory pouring. Tho new RDXs in clase | anc class V mixturcs pour vory wall at 17% wax
and have been casi even at 14%. In contrast at 17%, the previous RDX using class | and V as
bbafora, makes 2 mivture to thick la cast (atleast very wel)- ‘These properties suggest to by to
‘combine highe> solids loadings of new ROX types with exploration of other waxes 1o atlempt to
sake an explosive that has performance of Comp B, while retaining te bullet and fragrnent
resistance characteristics of wax based formulations. Wa dafire ‘peelormance of Comp B" as a
formulation with identical detonation pressure {s0 should have sinlar fragmentation ability) and
cequivalont cylinder enaray {so should hava sara velocly on the Iraqments), at leest out to
‘seven volume expansions of the detoration products. Such a formulation would holp in
developing IMs, 98 bullet and fragment impact are an important threat to Army systems.

ANALYSIS

‘Thermachemical code calculations (Cheetah code, ref. 4) were used te identity the
performance potential possible fram this appreach, It was obvicus that us: uying ta increase
the golds loed inthe hycrocaebon wax binder system, as currently developed, has limits
Figures 1 and 2 show, thaorafcaly, vinat ls possible,
Figure 1

Figure 2
Aveilable energy aulpul versus amount of ane-gatic

2
Figure 1 shows detonation preseura versus atnoun of energetic inthe torulation, All
calculations essume 98% theoretical maximurn density (TMD) Itis expactad that ty stnallor
the amauni of energetic, the more insensiive the formulation, so generally, formulations at
smailer parcent would have better IM polenta, Note: the loal of all energetic materials inthe
ormulatior is plo:ted, so. for example, Comp B is plotted at 90% avergetie constituents and
PAX2A js plotied at 94%. The lower curve (dots) is based on adding more ROX to the wax, and
the upper curve (eal) agsumes HMIX. To match Comp B in pressure “equires about 91.5%
RDX oF 87% HMIX. Figuro 2 plats sneray los” feo the prods by the time they expend to
shoul tree tines ‘heir ofginal volume versus amount of energetic. The anavay scale Is the
work dane by the expanding oroducts per unit of original volume divided by the equivalent
hummber for tha Camp 8 raferanca. When this relic is pllled versus volume, the relationship
betuten different explosives tonds te plateau 2y the ume three valume expansion is reached:
the cures are fairly fal as expansion continues, Thus, comparison is dane at that volume
‘whore Comp Breaches approxamately three volume expansions, In igure 2, materials ara
boeing compared atthe sare actual volume. Figure 2 shews abaul 97% ROX or 85% HMR is
required to match Comp B, more ar-less in agreameat with the prossure requirement

Although no: impossible, thasa ara haawy solid loadings. Ninety-two percent RDX by
‘weight in this forulation translates into 85.7% by volume: meaning 14.3% of tha volume would
be binder. An estimate for sha empty volurae betaen the REX grains in a mixture of three parts
class | to ore part class V (about the best packing fraction) is 18.5%. So thera would not he
‘enough binder Io fat the partes spar, To approseh 14.3% requires a fimodal RDX particle,
size cstribution such as 6,75/2.2311 of class A/classVi4 um that may be abla to reach the low
143% value. Now that bulk quantities of 4 urn material have become available, it may Be
possible fo make such a formulation, Gut, at bee, i represents working atthe imi.

There ate other approaches to avoid the need for rimodat partite dstrbutions. The
Iypieal approach te inczease fomulation performance isto pack mare energy par valume Into
the formulation. Tis usually has the disadventage of increasing the seneitiy ofthe formula
tion at the same tine. On the one hand, if one just nacks In mora sallds and presses to density,
tha provious avallabla volume cansiderstion show that many particles must be brokan up or
distorted in order to achieve the density. The pore saacw has to bs filed in. On tie ler hand,
ifthe binder Is made energetic, then it may loose some of ine ability to absorb oxtoinally applad
energy without starting to react

A different approach isto improve the charge density to get the desired detonation
presse ane rylnder energy. The idea isto improve the efficiency of using the enaray In the
cxplosive formulation rather than increasing the total energy. inullvely, this approach should
lend itself towards less senstive, high performance formulations, as a larger amaunt of inert
binder can be maintained in the formulation. The concept is demonstrated using thermio-
chemical celculatons as follows. Figure 3 shows tha sama RDX farrnulstion considered in
figures 1 and 2 along with two hypethelical RDX formulations, where the wax used inthe binder
systom is assumed ta be mote dense, The reason for picking these partcular density valbes
will become azparent ater. Figure 4 shows the corresponding avallabie energy ploted as
before. The celculation was done using twe diferent equatiors of state in Cheetah (BIS and
.JCZS)'o show the trends are similar althougi values do change.
‘Thora are grounds to salsct the Cheetah BKWS cver the Cheetah JZC8 caleulalons, it
happens that one deta point for prassura is avelleble as indicated forthe veal wax bindor
‘system, but at slghtly larger percent TMD than 98%, “his paint i fan witness plate dart, 36
‘should nol be taken as an ndependent pressure measurement, Basicaly, the dent ranks an
Unknown pressure vis a-vis cents from re‘erence explosives, As seen ia figure 3, he JCZS.
ccaleuations would lake the 83% RDX materia! to abaut tre TNT pressure, implying its dent
should bs the same. However. the reparted pressure value implies the den must be about
halfway between TNT and Comp B. Right whera tha BKWS caleulations incioal it shouk’ be.
A simiarsitelion occurs whan considering exp Cheetah calculations views-vs SWS, We
‘conclude tha BKWS js better al calculating pressure, Itis demonstrably much betir than the
‘others at calculating the correct detonation volaaly,

Figtre 3
Effect of wax density on detonation pressure

‘The measure of explosive ouput in tha laborstory isthe eyl ndar test from which Gumey
‘energies are obtained. Wher Ihe square of the ratio o” measurec Gurney energy lo measured
Comp B Gumey energy is plotied against We ratio of calouatd anergy output to Comp B
‘calculated eneray output, bot at the respective whines correspanding ta the 18mm.
‘axpansion ofthe cylinder test, the BKWS calculation is about the seme as exp6 or JCZS
‘saloulafions in corelating test data. For all ree equations of state, points representing LX-14,
Comp A3, PAXIG4, and TNT are close fo the 44 deg line; indicating af calculations property
fank the oytnder test results, Yet again, BKWS is slabnly superiar, but diferancas ate minor.
Beca.tsa BKWS Cheetah calaulations seem to give good results, the BKW/S equation of site
vill be used for the ramainder ofthis papar.
Figure 4
Effect of wax density on available energy

cseeme that remarkable inprovements can be expected just from adjusting binder
donalty. Adopting lis BKWS ca'cutalins, wih the 1.60 gery wax 2° only 74% ROX Is
required to obtain Comp © detcnation pressure, although 84% is naedad to gna the requed
avallabl2 energy. Bil, even 84% i¢@ hig reliel Im the situation of Rgures 1 and 2. AtG4% by
‘weight, RDX only constitutes 80.69% af the volume and fhe 19.22% valuma occupiad by bindae
an aanily [ial a class Wetess V mixlure aperl. The (otal spectic energy from detonation in the
twa 84% formulations, one with wax at 0.853 glom" and the othr with wax sl 1.60 glam’, isthe
same (1540.57 cally at the end of the release isestrope!. but of course, itis ciferent on a pat
volume basis. Tha detonation energy for wax 2 @ 84% (when the products have heen returned
te STP) at 1840.57 oalig is almost the same as Comp & (1544.26 calig). Gut the bast energy is
different. Energy at tha and ofthe release Isentrape forthe wax 2 version is 1202.7 calg and
for Comp Bis 1877.87 calg, ala minor difference. A significant diferenca is that the wax 2
formulation fas higher delonalion pressure than Gornp B

“Tha elect of densiy in improving selanalion pressure seems obvious. There is ore
shan 8% mere males of gas par unit volume created in the detonation wih wax 2. The eFect on
‘expansion energy depends on where iis measured. Figure 5 shows the release isentropes.
Figure 5
Release isentropes

‘Thare ate large dfterences in anergy yield at emall volume expansions. Figure 6 picts the
increase in energy par gram nf 82% ROXIwar 2 over the 83% ROXIway 1 based cn figure 5
‘The diference in energyigram is 19.4% al three volume expansions and stil 8.6% al seven
volume expansions (the usual cutoff exparsinn for determining fragment kinetic energy). That
's, over the useful range, about 10% more ereray par gram (or ~22% mara par ial cubic
centimeter) is outpuiled by the wax 2 systein over the wax 1 system, Tris advantage goss
vay as the products expend out to atmospheric pressure. When P=1 atmosphere, tre
ifferance in energy per gram has rscured to only 1.8%. Which means itis a small advantege
{o reise the wax density if he oniy intent ts fo produce blast without fragments. The advantage
‘ames in preducing ard launching fragments.

Figure 6
Energy aifa-ence on the two release ‘sentropes,

6