Evaluation of Australian RDX in PBXN-109 - Defence Science and ...

REGULATED RELEASEEvaluation of Australian RDX in PBXN-109Ian J. Lochert, Richard M. Dexter and Brian L. HamshereWeapons Systems DivisionSystems Sciences LaboratoryDSTO-TN-0440ABSTRACTPBXN-109 is the explosive fill for a number of munitions including the Penguin ASM warheadwhich is being filled by ADI Limited as part of project SEA 1414. In support of this project anexamination of the replacement of the energetic material (RDX) with indigenous RDX wasundertaken. This work included performance and hazard assessment, with a focus onpotential improvements in Insensitive Munition (IM) properties through reduction in shocksensitivity of the PBX fill.RELEASE LIMITATIONDowngraded to Public Release June 2003Distribution additional to the initial list is limited to Australian Department of Defence and DefenceForce personnel and employees of ADI Limited. Others inquiring must be referred to Chief, WeaponsSystems Division, DSTO.REGULATED RELEASE

Published bySystems Sciences LaboratoryPO Box 1500Edinburgh South Australia 5111 AustraliaTelephone: (08) 8259 5555Fax: (08) 8259 6567© Commonwealth of Australia 2002AR-012-364August 2002Conditions of Release and DisposalThis document is the property of the Australian Government; theinformation it contains is released for defence purposes only and must not bedisseminated beyond the stated distribution without prior approval.The document and the information it contains must be handled inaccordance with security regulations applying in the country of lodgement,downgrading instructions must be observed and delimitation is only withthe specific approval of the Releasing Authority as given in the SecondaryDistribution statement.This information may be subject to privately owned rights.The officer in possession of this document is responsible for its safe custody.When no longer required DSTO Reports should be returned to the DSTOLibrary, (Reports Section), Edinburgh SA.

REGULATED RELEASEEvaluation of Australian RDX in PBXN-109Executive Summary (U)PBXN-109 is the explosive fill for a number of munitions including BLU-109A/B 2000lb penetrator bombs, Penguin anti-ship missiles, some joint standoff weapons andTomahawk Block IV. ADI Limited fills the Penguin ASM warhead with PBXN-109under contract for Kongsberg Defence & Aerospace (KDA) as part of Project Sea 1414(ANZAC Ship Helicopter Missile Project). This is the first time an in-service munitionhas been filled with a polymer bonded explosive (PBX) in Australia, albeit entirely withimported ingredients.In support of the introduction of the Penguin ASM and local production of thewarhead, DSTO was tasked to examine the high explosive fill PBXN-109. One aspect ofthis work was to examine the replacement of the imported energetic material (RDX)with indigenous RDX with the primary focus on potential improvements in InsensitiveMunition (IM) properties through reduction in shock sensitivity.Ordnance filled with PBXN-109 will typically pass most IM tests, the major exceptionto this being the failure to pass sympathetic reaction tests. The shock sensitivity of theexplosive fill is a major determining factor in the ability of a munition to survive thedetonation of a neighbouring round (sympathetic reaction). PBXN-109 filled withindigenous RDX was demonstrated to have equivalent performance to the qualifiedordnance yet to be significantly less shock sensitive. Whilst this advantage is yet to beproven in ordnance sized items, any reduction in shock sensitivity of the PBX fillshould result in improvements in sympathetic reaction scenarios and potentially leadto PBXN-109 filled munitions obtaining full IM compliance.REGULATED RELEASE

Contents1. INTRODUCTION................................................................................................................ 12. INGREDIENTS AND FORMULATION......................................................................... 12.1 Formulation ................................................................................................................ 12.1.1 RDX Comparison .......................................................................................... 22.1.2 Aluminium Comparison.............................................................................. 42.2 Charge Preparation ................................................................................................... 53. RESULTS ........................................................................................................................63.1 End of Mix Viscosity ................................................................................................ 63.2 Mechanical Properties.............................................................................................. 73.3 Sensitiveness Testing ............................................................................................... 73.4 Shock Sensitivity....................................................................................................... 83.5 Detonation Parameters........................................................................................... 103.5.1 Velocity of Detonation ............................................................................... 103.5.2 Relative Detonation Pressure .................................................................... 113.5.3 Critical Diameter......................................................................................... 114. DISCUSSION AND RECOMMENDATIONS ............................................................ 125. ACKNOWLEDGEMENTS............................................................................................... 136. REFERENCES ..................................................................................................................... 14

AbbreviationsADIALARPAOARXASMD critDOADSCEBWESDF of IHMXHTPBIMI-RDXIPDIJANNAFKDALSGTMRLNOLPBXPBXNPBXWRDXROSEMSNPET of ITMDTNTTPBVTSADI LimitedAs low as reasonably practicableAnti-oxidantAustralian research explosiveAnti-ship missileCritical diameterDioctyl adipateDifferential scanning calorimetryExploding bridge wireElectrostatic spark dischargeFigure of insensitivenessCyclotetramethylenetetranitramineHydroxyl terminated polybutadieneInsensitive munitionsInsensitive RDXIsophorone diisocyanateJoint Army Navy NASA Air ForceKongsberg Defence and AerospaceLarge scale gap testMaterials Research Laboratory (DSTO)Naval Ordnance LaboratoryPolymer bonded explosivePBX formulation qualified for in service use by the US NavyPBX experimental formulation developed by Naval Surface WarfareCenter White Oak (USA)CyclotrimethylenetrinitramineRoyal Ordnance PLC, Bridgewater UKScanning electron microscopySociété Nationale des Poudres et ExplosifsTemperature of ignitionTheoretical maximum density2,4,6-TrinitrotolueneTriphenyl bismuthVacuum thermal stability2

DSTO-TN-04401. IntroductionPBXN-109 (64% RDX, 20% aluminium, 16% binder) is the explosive fill for a number ofmunitions including BLU-109A/B 2000lb penetrator bombs, Penguin anti-ship missiles(ASM), some joint standoff weapons and Tomahawk Block IV. As part of Project Sea1414 (ANZAC Ship Helicopter Missile Project), ADI Limited is presently fillingwarheads for the Penguin anti-ship missile with PBXN-109, under contract forKongsberg Defence & Aerospace (KDA). This is the first time an in-service munitionhas been filled with a polymer bonded explosive (PBX) in Australia, albeit entirely withimported ingredients.In support of the introduction of the Penguin ASM and local production of thewarhead, DSTO was tasked to examine the high explosive fill PBXN-109. Results ofperformance and hazards testing, tensile testing, ageing studies and examination ofinsensitive munition (IM) properties are reported elsewhere. An examination of theuse of locally produced RDX in PBXN-109, with the primary focus on potentialimprovements in IM properties, is reported here. The PBXN-109 formulationcontaining Australian RDX was designated [1] ARX-2014/M1.Ordnance filled with PBXN-109 will typically pass most insensitive munition (IM)tests, the major exception to this being the failure to pass sympathetic reaction tests.The shock sensitivity of the explosive fill is a major determining factor in the ability ofa munition to survive the detonation of a neighbouring round (sympathetic reaction).The French company SNPE has recently been promoting [2] an insensitive grade ofRDX (I-RDX) which is reported to be intrinsically less sensitive to shock stimuli in castcuredPBXs. Some evidence from an earlier DSTO study [3] lead to the hypothesis thatRDX produced locally by ADI might also exhibit reduced sensitivity to shock stimuli incast-cured PBXs. Any reduction in shock sensitivity of the PBX fill should result inimprovements in sympathetic reaction scenarios and potentially lead to PBXN-109filled munitions obtaining full IM compliance.2.1 Formulation2. Ingredients and FormulationPBXN-109 and ARX-2014/M1 are nominally exactly the same formulation (Table 1);the differences are the specifications of the solids ingredients. Of particular interest isthe RDX † used – PBXN-109 contains 64% RDX comprised of at least 57% of Class 1Type II RDX and no more than 7% of Class 5 Type II RDX manufactured by Dyno† RDX Terminology: Class is a particle size descriptor, Class 1 is coarser than Class 5. Typerefers to the method of manufacture and the resultant levels of HMX in the RDX – Type Icontains no HMX and Type II contains 5 – 12% HMX.1

DSTO-TN-0440Nobel (Norway) whilst ARX-2014/M1 contains 59% Class 1 Type I RDX from ADI and5% Class 5 Type I RDX from Royal Ordnance (Bridgewater UK). Locally producedaluminium powder (Comalco CAP45A) was selected in preference to X-81 aluminiumfor reasons of availability and cost. All ingredients for the PBXN-109 are consistentwith the military specification MIL-E-82886(OS) [4]. The RDX and aluminium used inARX-2014/M1 approximate the requirements of this specification but are notmanufactured to comply with it.Table 1. PBXN-109 and ARX-2014/M1 FormulationsPBXN-109ARX-2014/M1Ingredient Grade/Source Nominal wt % 1 Grade/Source Nominal wt % 1RDX (class 1) Type II, Dyno Nobel 2 ≥ 57 3 Type I, ADI 4 59RDX (class 5) Type II, Dyno Nobel 2 ≤ 7 3 Type I, RO 5 5Aluminium X-81 20 CAP45A 20HTPB (R-45HT) R-45HT 7.346 6 R-45HT 7.346 6IPDI 0.9465 6 0.9465 6Dioctyl adipate 7.346 7.346Dantocol DHE 0.26 6 0.26 6Anti-oxidant Lowinox 2246 0.10 Lowinox 2246 0.10Triphenyl Bismuth 0.02 0.021as per MIL-E-82886(OS)2lot no. NS 198H001-0013total RDX = 64%4 grade A RDX, lot no. R6345lot no. 1659, batch AM5R2406quantities are based on an NCO/OH ratio of 1.0 and depend on equivalent weights2.1.1 RDX ComparisonExamination of the three RDX variants by scanning electron microscopy (figs. 1 – 5)showed some distinct differences. The RDX from CXM-7 † is a blend of the Class 1 andClass 5 particle sizes, the Class 1 in particular was observed to possess quite angularmorphology, consistent with a milling process. The type I RDX grades are both morerounded as expected for recrystallised RDX grades. Pure RDX was obtained fromCXM-7 by repeated washings with solvent to remove the plasticiser followed bydrying at elevated temperature.† CXM-7 is RDX coated with the plasticiser dioctyl adipate according to the specification WS26702, Material Specification for Explosive Material, Coated, CXM-7.2

DSTO-TN-0440Figures 1 & 2. SEM Images of Dyno Nobel Type II RDX from CXM-7Figure 3 & 4. SEM Images of ADI Type I Grade A RDXFigure 5. SEM Image of Royal Ordnance Type I Class 5 RDXSmall scale sensitiveness [5] and vacuum thermal stability (VTS) testing was carriedout in the DSTO laboratories and the results are reported in Table 2. All of the3

DSTO-TN-0440sensitiveness testing results for the different types of RDX are considered to beessentially identical and consistent with results typically expected for RDX.Table 2. Sensitiveness Testing and Vacuum Stability Results for RDX SamplesRDXType II 1 Type I Class 1 Type I Class 5 Standard (Grade F)Source Dyno ADI RORotter Impact (F of I) 2 80 (NR) 3 90 (12.3) 90 (11.6) 80 (11.9)BAM Friction (N) 108 80 108 108T of I (ºC) 213 228 219 213ESD – ignition (J) 4.5 4.5 4.5 4.5ESD – no ignition (J) 0.45 0.45 0.45 0.45VTS (mL/g) 0.03 0.16 0.12 0.031 from CXM-7, blend of class 1 and class 5 RDX.2 evolved gas volumes (mL) shown in parentheses.3 not recorded.2.1.2 Aluminium ComparisonThe aluminium powder in the PBXN-109 formulation was described as ATA X-81aluminium powder and certification was provided by the supplier indicating that itcomplies with MIL-A-23950A (amendment 1), Type IV specifications. CAP45Aaluminium powder, supplied by Comalco Aluminium Powders (now EckartAustralia), was used in ARX-2014/M1.Particle size of the two aluminium grades was comparable at 16 microns for X-81 † and17 microns for CAP45A [6] however it should be noted that different techniques wereused to determine these values.The scanning electron microscopy (SEM) analysis of the aluminium powders shows(figs. 6 - 9) that X-81 is mostly spherical in nature compared with CAP45A, which isrounded but less regular in shape. The SEM study supports the particle size analysis.† The particle size date for X-81 aluminium powder was provided by the supplier anddetermined according to ASTM-B3304

DSTO-TN-0440Figures 6 & 7. SEM images of X-81 Aluminium PowderFigures 8 & 9. SEM Images of CAP45A Aluminium Powder2.2 Charge PreparationThe PBXs were prepared in a vertical planetary action mixer according to theprogramme shown below. Charges were cast under vacuum with vibration and curedat 60ºC for 7 days.5

DSTO-TN-0440Table 3. PBX Mixing ProgrammeIngredients/Action Mix time (no vacuum) Mix time (vacuum)HTPB, DOA, Dantocol, TPB, AO 2 28Aluminium 2 13RDX (50%) 2 13RDX (25%) 2 13RDX (25%) 2 13Scrape DownMix 0 60IPDI 1 4Scrape DownMix 0 15The only processing difference between PBXN-109 and ARX-2014/M1 is the form inwhich the RDX exists prior to incorporation. PBXN-109 uses a pre-blend called CXM-7,which is composed of the combined class 1 and class 5 RDX grades along with(nominally) 4.75% plasticiser. This is done primarily for safety reasons – the CXM-7 isless sensitive than dry RDX and is safer to transport and process. When processingARX-2014/M1 all of the plasticiser was added at the start of the mix and the dry RDXgrades were added later. This technique is possible on a research scale however it isinappropriate on a production scale.3.1 End of Mix Viscosity3. ResultsThe nature of the PBX slurries at the end of the mix cycle (high solids loading, highviscosity) was such that the viscometer with cup and rotor attachment was unable tomeasure the viscosities. Observations during handling and casting indicated that theviscosity of ARX-2014/M1 was lower than PBXN-109. This is most likely due to themore rounded nature of the RDX particles in ARX-2014/M1, along with minorvariations in particle size distribution. An example of this can be seen whencomparing the viscosity of two PBXN-109 formulations using CXM-7 with differentforms of RDX [7]. It was also noted that further reductions in the viscosity of ARX-2014 formulations were obtained when the percentage of Class 5 RDX was increased.Improvements in viscosity have the potential to improve charge quality.6

DSTO-TN-04403.2 Mechanical PropertiesUniaxial tensile testing of the cured PBXs was performed on an Instron 5500R1185Universal Test Instrument. Load was applied at a constant strain rate of 50mm/min tothe JANNAF [8] stamped test specimens until rupture.Table 4. Uniaxial Tensile Test ResultsFormulationBatchStress at Max. Load(MPa)% Strain at Max.LoadYoung’s Modulus(MPa)PBXN-109 EG119 0.65 13.9 8.31PBXN-109 EG144 0.61 10.7 8.67PBXN-109 1 EG205 0.70 11.3 9.48ARX-2014/M1 EG163 0.68 20.0 7.39ARX-2014/M1 EG222 0.72 23.4 6.11ARX-2014/M1 2 EG221 0.71 22.7 6.131 dry RDX (CXM-7 with DOA removed) was used for this batch2 RDX lot no. 11852 (Mulwala)The data in table 4 represents tensile testing of three different batches of PBX for eachformulation. There is a significant difference in the strain at maximum load for the twoformulations with consequent change in Young’s Modulus. Factors that may haveinfluenced the tensile test results include particle size distribution, particle shape andplasticiser content. During related work with PBXN-109 † , plasticiser content wassuspected as being a major factor in batch to batch variation in tensile test results,particularly strain and modulus. The comparison between EG205 and EG222 (orEG163) however effectively eliminates variations in plasticiser levels being acontributing factor to the differences between PBXN-109 and ARX-2014/M1 as bothbatches were made from dry RDX with identical amounts of plasticiser added in liquidform. This leads to the assumption that some property of either the RDX or thealuminium powder, or a combination of the two, is the cause of differences inmechanical properties between the two formulations. One factor for consideration isthe angular nature of the RDX particles in the standard PBXN-109. These are likely toact as stress concentrators, causing a reduction in strain at maximum load. A muchmore extensive investigation than that allowed by the scope of this project would berequired to reach more specific conclusions.3.3 Sensitiveness TestingSensitiveness testing was performed for the PBXN-109 formulations with the resultsreported in Table 5. Results from multiple batches are reported as a data range and† Yet to be published.7

DSTO-TN-0440reflect batch variation. Overall the sensitiveness properties of each formulation areessentially identical, the variations in results between formulations are consideredinsignificant.Table 5. Sensitiveness Testing and Vacuum Stability Results, PBXN-109 Type FormulationsPBXN-109ARX-2014/M1Rotter Impact (F of I) 1 140 – 180 (3.3) 130 – 150 (4.3)BAM Friction (N) 252 - >360 288 - 324T of I (ºC) 221 222ESD – ignition (J) - 4.5ESD – no ignition (J) 4.5 0.45VTS (mL/g) 0.03 0.051evolved gas volumes (mL) shown in parentheses3.4 Shock SensitivityThe shock sensitivities of the two formulations were determined using the MRL LargeScale Gap Test (LSGT) [9]. The results are recorded in Table 6.Table 6. LSGT Results, PBXN-109 Type Formulations50% point PBXN-109 ARX-2014/M1Number of Cards 196 109Pressure (GPa) 2.35 5.02ARX-2014/M1 is significantly less sensitive to shock stimuli than PBXN-109. Similarresults have been observed [3] for another PBX containing Australian RDX, namelyPBXW-115(Aust), when compared with PBXW-115 produced in the USA (Table 7).Bocksteiner et al. [3] have discussed in some detail possible explanations for differencesin shock sensitivity for nominally identical formulations, including RDX particle sizedistribution and morphology, defect levels in the RDX and the presence of cocrystallisedHMX in the US Type II RDX. No conclusive evidence was presented tosupport any of these possibilities.Table 7. LSGT Results, PBXW-115 Formulations50% point PBXW-115 (US) PBXW-115 (Aust)Number of Cards 130 86Pressure (GPa) 4.7 6.3The most obvious difference between Australian produced RDX (Type I) and theoverseas sourced RDX (Type II), in both the PBXW-115 and PBXN-109 cases, is the8

DSTO-TN-0440presence of the more sensitive HMX in the Type II RDX. Additional LSGT experimentshave been carried out in this and other work (yet to be published) to investigate thisdifference. Two additional PBXN-109 formulations were produced, one contained anRDX supplied by DYNO Nobel that was recrystallised to improve particle shape. Therecrystallisation also reduced the co-crystallised HMX content to < 0.5%. HMX wasthen blended into the RDX to make it nominally equivalent to Type II RDX. Theformulation produced from this RDX is referred to as PBXN-109/M1 [7]. Forcomparison, ARX-2014/M1 was modified by replacing 5% of the Grade A RDX withHMX (referred to as ARX-2014/M3).Table 8. LSGT Results, Standard and Modified PBXN-109 Type FormulationsPBXN-109 PBXN-109/M1 ARX-2014/M1 ARX-2014/M3HMX Co-crystallised Blended (~ 5%) Nil Blended (5%)50% Point (cards) 196 196 109 11750% Point (GPa) 2.35 2.35 5.02 4.68As can be seen from the results in Table 8, the presence of 5% blended HMX in PBXN-109/M1 has not changed the shock sensitivity compared with standard PBXN-109(table 6) and the 5% blended HMX in ARX-2014/M3 has not significantly affected thisformulation. More conclusive results come from a related study (yet to be published)where, in a generic PBX formulation, comparison of the shock sensitivity is madebetween two batches of ADI Type I Grade A RDX, ADI Type I Grade B † RDX and DynoNobel Type II RDX. The two formulations containing ADI Grade A RDX have a LSGT50% point of approximately 4.6 GPa, compared with 2.9 GPa for the Type I Grade Band Type II RDX. These results clearly support the statement that the observedreduction in shock sensitivity for PBX formulations containing ADI Grade A RDX isnot simply because it is free of HMX (ie Type I).Similar outcomes have been reported by the French company SNPE, which hasrecently been promoting a grade of RDX they claim is intrinsically less sensitive toshock stimuli in cast-cured PBXs. A timely publication [2] reports the LSGT results forPBXN-109 using standard RDX (MI-RDX) and their insensitive RDX (I-RDX). Areduction in shock sensitivity for the PBXN-109 (I-RDX) similar to that for ADI GradeA RDX is observed. Whilst Bouma et al. [10] have stated that the shock sensitivity ofPBXs containing RDX is related to internal defects in the RDX, SNPE [2] claim that I-RDX does not differ from regular grades in terms of internal defects. Table 9summarises the shock sensitivity results and clearly demonstrates the similaritiesbetween ADI Grade A RDX and SNPE I-RDX in PBXN-109 formulations.† Grade B = boiled and milled.9

DSTO-TN-0440Table 9. Summary of LSGT Results for PBXN-109 Type FormulationsRDX typeARX-2014/M1Type I (A)ARX-2014/M3Type I (A) +5% HMXPBXN-109Type IIPBXN-109/M1Recryst. +5% HMXPBXN-109MI-RDXPBXN-109I-RDXRDX source ADI 1 ADI 1 DYNO DYNO SNPE SNPEPBXManufacture50% point(cards)DSTO DSTO DSTO DSTO SNPE SNPE109 117 196 196 200 13050% point (GPa) 5.02 4.68 2.35 2.35 2-3 5-6Reference This work This work This work [7] [2] [2]15% type I class 5 from Royal Ordnance.In examining the complete set of results it must be remembered that all data wereobtained from gap tests based on the NOL LSGT and minor differences in techniqueare known to exist.3.5 Detonation ParametersAll detonation experiments were performed on unconfined charges boosted with 50:50pentolite cylinders (length/diameter = 1) and initiated with Risi RP-501 EBWdetonators. Density of the PBX charges was 1.65 ± 0.01 g.cm -3 .3.5.1 Velocity of DetonationThe velocity of detonation for unconfined charges was determined at two diameters(50 and 82 mm) by either digital streak photography or time-of-arrival piezoelectricpins spaced at 20.0 mm intervals along the length of the charge.Table 10. Velocity of Detonation DataFormulation Diameter (mm) Technique VoD (m/s) 1PBXN-109 50 Digital streak imaging 7678PBXN-109 82 Digital streak imaging 7567PBXN-109 82 Piezoelectric pins 7617 2ARX-2014/M1 20 3 Digital streak imaging 6209ARX-2014/M1 50 Piezoelectric pins 7599ARX-2014/M1 82 Piezoelectric pins 76071average from three firings2one firing only3 for critical diameter determination10

DSTO-TN-0440Due to problems with the calibration software for the digital camera the velocity ofdetonation results for PBXN-109 measured with this technique are not extremelyaccurate as is observed for the results at 50 mm diameter, which is unrealistically high.The best available results for comparison are those obtained for 82mm diametercharges with piezoelectric pins. The velocities of detonation for PBXN-109 and ARX-2014/M1 are essentially identical and comparable to literature values of 7602 and 7630m/s [11].3.5.2 Relative Detonation PressureRelative detonation pressure was determined at two diameters using the dent testtechnique [12, 13]. The unconfined charges were detonated on top of a stack of at leastthree 50 mm thick plates of 250 grade steel with Rockwell hardness B74-76. The dentdepths were compared to dents produced by TNT and/or Composition B charges ofthe same diameters.Table 11. Relative Detonation Pressure DataP CJ relative toFormulation Diameter Dent Depth (mm)TNT (GPa) Comp B (GPa)PBXN-109 50 7.78 20.1 19.4PBXN-109 82 14.28 18.3ARX-2014/M1 50 8.33 21.6 20.7ARX-2014/M1 82 14.27 18.3The differences in detonation pressure between the two formulations at 50 mmdiameter are considered to be insignificant. The detonation pressure of bothformulations is lower than the 23.7 GPa (at a density of 1.681 g.cm -3 ) reported in theliterature [11] however this difference is probably attributable to the differenttechniques rather than any absolute difference.3.5.3 Critical DiameterThe critical diameter of the two formulations was estimated by firing cylindricalcharges of various diameters. Success or failure of the charge to sustain a detonationwas determined from the digital streak image.11

DSTO-TN-0440Table 12. Critical Diameter DataFormulation RDX Type/Source D crit (mm)PBXN-109 Type II/Dyno < 10ARX-2014/M1 Type I/ADI (& RO) 15 < D crit < 20PBXN-109 MI-RDX/SNPE 7PBXN-109 I-RDX/SNPE 14PBXW-115(Aust) Type I/ADI 80PBXW-115(US) Type II/US 38The critical diameter for the standard PBXN-109 was determined to be below 10mm,which is consistent with the value of 7mm reported by SNPE [2] and in the literature[11]. ARX-2014/M1 has a higher D crit with stable detonation occurring for 20mm butnot for 15mm diameter charges. This significant increase is again comparable with theresults obtained for PBXN-109 produced with SNPE I-RDX [2]. A similar increase inD crit was observed when PBXW-115(Aust) was compared with PBXW-115(US) [3].4. Discussion and RecommendationsThe outcomes from this preliminary comparison between standard PBXN-109 andARX-2014/M1 can be summarised by the following statements:- The sensitiveness of the various RDX grades is essentially identical.- The sensitiveness of the two PBX formulations is comparable.- The performance of the two formulations is identical.- The shock sensitivity of ARX-2014/M1 is significantly improved comparedwith standard PBXN-109 and is consistent with results obtained with SNPE I-RDX.- The critical diameter of ARX-2014/M1 is increased compared with standardPBXN-109.The use of Australian produced RDX in PBXN-109 has no apparent disadvantages andone major advantage, namely the reduction in shock sensitivity of the explosive. Thisreduction in shock sensitivity should translate into improvements in response insympathetic reaction scenarios and thus has the potential to take PBXN-109 filledordnance, such as the Penguin ASM warhead, a step closer to IM compliance. Testswould need to be carried out to determine whether the reduction in shock sensitivitydoes translate to large ordnance items in in-service scenarios.Specifically in relation to the Penguin ASM warhead, the authors are unable to makeany definitive recommendations until the potential benefits of using insensitive RDXare demonstrated in such ordnance. If the benefits do translate from small scale testingto in-service ordnance it is not known whether the gains would be sufficient to allow12

DSTO-TN-0440PBXN-109 filled Penguin ASM warheads to be rated IM. Any benefits would still be ofvalue in light of the ALARP risk reduction approach proposed for the upcoming IMpolicy and implementation plan. Cost benefit analysis of such gains is beyond thescope of this project.Issues that would need to be considered before using ADI Grade A RDX in PBXN-109(and other PBXs), in Penguin ASM or other applications, include:- ADI Grade A RDX is a Type I RDX however the US specification for PBXN-109(MIL-E-82886(OS)) requires Type II RDX to be used. Penguin ASM (and otherordnance) is currently qualified with PBXN-109 to this specification.- The particle size specification for Class 1 RDX according to DEF(AUST)5382B[14] is slightly different to that specified by MIL-DTL-398D [15] which is thecommonly used specification for RDX in the international community. It ispossible that Class 1 RDX produced by ADI does conform to the particle sizeregime in MIL-DTL-398D however it is not currently produced to meet thatspecification.- ADI currently only produce Grade A RDX in one particle size. For PBXformulations, including PBXN-109, two or more particle sizes (that complywith MIL-DTL-398D) are normally required.- It is inappropriate to handle dry RDX on an industrial scale and therefore theability to coat RDX with a plasticiser to desensitise it would be required.- Requalification issues would need to be considered, however, with small scaletesting demonstrating equivalent performance, reduction in shock sensitivityand no increase in other hazards, full requalification testing may not berequired.In conclusion, whilst the authors acknowledge that there is still significant work to becompleted, they recommend that insensitive grades of RDX be considered for use in allfuture cast-cured PBX filled ordnance.5. AcknowledgementsThe authors would like to acknowledge John Symes, Max Joyner and Bob Arbon fortheir assistance in the manufacture of the explosive charges. Instrumentation andfiring support was provided by staff from Terminal Effects Group and the Proof andExperimental Establishment Port Wakefield. Scientific and Engineering Servicesprovided excellent support in a range of areas.13

DSTO-TN-04406. References1. Cliff, M. D. and Dexter, R. M., (2000), Nomenclature and Cataloguing of ExperimentalExplosive Compositions, DSTO-TN-0284.2. Lecume, S.; Chabin, P. and Brunet, P., (2001), Two RDX Qualities for PBXN-109Formulation Sensitivity Comparison, 2001 Insensitive Munitions and Energetic MaterialsSymposium, Bordeaux.3. Bocksteiner, G.; Wolfson, M. G. and Whelan, D. J., (1994), The critical diameter,detonation velocity and shock sensitivity of Australian PBXW-115, DSTO-TR-0076.4. Military Specification MIL-E-82886(OS). Explosive, Plastic Bonded, Cast PBXN-109.5. RARDE, (1988), Sensitiveness Collaboration Committee Manual of Tests.6. Cliff, M. D.; Dexter, R. M. and Watt, D. S., (2000), The Effect of Ultrafine,Electroexploded Aluminium (Alex) on Detonation Velocity and Pressure, DSTO-TR-0999.7. Dexter, R. M.; Hamshere, B. L. and Lochert, I. J., (2002), Evaluation of An AlternativeGrade of CXM-7 For Use in PBXN-109, The Explosive Fill For the Penguin ASM Warhead,DSTO-TN-0441.8. CPIA, (1998), Uniaxial Tensile Tests at Constant Strain Rate, Publication 21.Supplement/Section 4.3.2,9. Wolfson, M. G., (1994), A Large Scale Gap Test at MRL for Measuring Shock Sensitivityof Explosive Fillings for Insensitive Munitions, MRL-TR-93-43.10. Bouma, R. H. B.; Hordijk, A. C. and van der Steen, A. C., (2001), Influence of RDXCrystal Quality and Size on the Sensitivity of RDX based PBXs, 2001 Insensitive Munitionsand Energetic Materials Symposium, Bordeaux.11. Hall, T. N. and Holden, J. R., (1988), Navy Explosives Handbook. Explosion Effects andProperties -- Part III. Properties of Explosives and Explosive Compositions, NSWC MP 88-116, NSWC Dahlgren.12. Smith, L. C., (1967), On Brisance, and a Plate-Denting Test for the Estimation ofDetonation Pressure, Explosivstoffe, 5, 106-110.13. Smith, L. C., (1967), On Brisance, and a Plate-Denting Test for the Estimation ofDetonation Pressure, Explosivstoffe, (6), 130-134.14. Australian Defence Department, (1996), Australian Defence StandardDef(Aust)5382B RDX: Specification.15. (1996), MIL-DTL-398D. Detail Specification, RDX (Cyclotrimethylenetrinitramine).14

DISTRIBUTION LISTEvaluation of Australian RDX in PBXN-109Ian J. Lochert, Richard M. Dexter and Brian L. HamshereDEFENCE ORGANISATIONAUSTRALIATask SponsorDirector Navy Aviation Project OfficeProject Manager SEA 1414. Navy Aviation Project Office (2 copies)S&T Program}Chief Defence ScientistFAS Science Policyshared copyAS Science Corporate ManagementDirector General Science Policy DevelopmentCounsellor Defence Science, London (Doc Data Sheet only)Counsellor Defence Science, Washington (Doc Data Sheet only)Scientific Adviser JointNavy Scientific AdviserScientific Adviser - Army (Doc Data Sheet and distribution list only)Air Force Scientific AdviserDirector TrialsSystems Sciences LaboratoryChief of Weapons Systems DivisionRLMWSRLLWSHead Explosives GroupAuthor(s):Dr Ian Lochert (2 copies)Richard Dexter (1 copy)Brian Hamshere (1 copy)Dr Matthew CliffDr Arthur ProvatasDr Jing Ping LuMr Matthew SmithMr Mark FransonMr Steve OdgersDSTO LibraryLibrary Edinburgh 2 copiesAustralian ArchivesCapability Systems StaffDirector General Maritime DevelopmentDirector General Aerospace Development (Doc Data Sheet only)

Knowledge StaffDirector General Command, Control, Communications and Computers (DGC4)(Doc Data Sheet only)NavySO (SCIENCE), COMAUSNAVSURFGRP, NSWdistribution list only)(Doc Data Sheet andArmySO (Science), Deployable Joint Force Headquarters (DJFHQ) (L), Enoggera QLD(Doc Data Sheet only)Intelligence ProgramDGSTA Defence Intelligence OrganisationManager, Information Centre, Defence Intelligence OrganisationDefence LibrariesLibrary Manager, DLS-CanberraLibrary Manager, DLS - Sydney West (Doc Data Sheet Only)DMOTSO-Navy, Ordnance Safety Group, Joint Logistics CommandOTHER ORGANISATIONSADI LimitedMr David Lang (2 copies)Mr Tim Miller (3 copies)Mr David CorkSPARES (5 copies)Total number of copies: 41

Page classification: UNCLASSIFIEDDEFENCE SCIENCE AND TECHNOLOGY ORGANISATIONDOCUMENT CONTROL DATA2. TITLEEvaluation of Australian RDX in PBXN-1091. PRIVACY MARKING/CAVEAT (OFDOCUMENT)Regulated Release3. SECURITY CLASSIFICATION (FOR UNCLASSIFIED REPORTSTHAT ARE LIMITED RELEASE USE (L) NEXT TO DOCUMENTCLASSIFICATION)DocumentTitleAbstract(U)(L)(U)(U)4. AUTHOR(S)Ian J. Lochert, Richard M. Dexter and Brian L. Hamshere5. CORPORATE AUTHORSystems Sciences LaboratoryPO Box 1500Edinburgh South Australia 5111 Australia6a. DSTO NUMBERDSTO-TN-04406b. AR NUMBERAR-012-3646c. TYPE OF REPORTTechnical Note7. DOCUMENT DATEAugust 20028. FILE NUMBERJ9505-23-95-19. TASK NUMBERNAV98/07813. DOWNGRADING/DELIMITING INSTRUCTIONS10. TASK SPONSORDNAPO11. NO. OF PAGES1314. RELEASE AUTHORITY12. NO. OFREFERENCES15Downgraded to Public Release June 2003To be reviewed three years after date of publicationChief, Weapons Systems Division15. SECONDARY RELEASE STATEMENT OF THIS DOCUMENTApproved for Public ReleaseDistribution additional to the initial list is limited to Australian Department of Defence and Defence Force personnel and employees of ADILimited. Others inquiring must be referred to Chief, Weapons Systems Division DSTO.OVERSEAS ENQUIRIES OUTSIDE STATED LIMITATIONS SHOULD BE REFERRED THROUGH DOCUMENT EXCHANGE, PO BOX 1500, EDINBURGH, SA 511116. DELIBERATE ANNOUNCEMENTNo LimitationAustralian Department of Defence and Defence Force personnel.17. CITATION IN OTHER DOCUMENTS Yes18. DEFTEST DESCRIPTORSPlastic Bonded Explosives, RDX, Sympathetic Detonation, Insensitive Munitions19. ABSTRACTPBXN-109 is the explosive fill for a number of munitions including the Penguin ASM warhead which isbeing filled by ADI Limited as part of project SEA 1414. In support of this project an examination of thereplacement of the energetic material (RDX) with indigenous RDX was undertaken. This work includedperformance and hazard assessment, with a focus on potential improvements in Insensitive Munition(IM) properties through reduction in shock sensitivity of the PBX fill.Page classification: UNCLASSIFIED