High temperature stable detonators

— LA-10172-MS j — - : CIC-14 REPORT COLLECTION ~EpRoD”cT,oN co3 ““q Q@*===+%=@ , COPY - “ — “, ,— : , - - , ,,-,, :, , ., , -— — - ., .T-—— ——, , -.- ,, - , : , - < .,,, A , -, , -, , , , , ”.- - — ~ — ., - ,., ,,, !, - — — - - - , ,, - -.- — ., -.-—,.- , , —.—=— “ —, , - , - L , - High-Temperature=Sttible 3.,., , - .— -— — —.Detonators , 1- .- - —— - —— - —— - -: ,- , , , :’ i f - - ;W,; :’ -, E!E$” n Los ‘.,!- : -, - ,, “,,, — :_ —— — ,’ ,— ! annm LosAlamosNationalLaboratory LosAlamos,NewMexico87545 , , AffiitivC ASS Action/Eqrsd @fsOtity EsSSPIO)%X DISCLAIMER Thisreport waspreparedas an account of work sponsoredby an agencyof the UnitedStales (ksvemment Neither the United States Governmentnor any agencythereof, nor asryof their employees,makesJny warranty, expressor implied,or assumesany legalliabilityor responsibilityfor the accuracy.complctcrtcss or usefulnessof any information,apparatus,product, or processdiaclo=d, or representsthat its use would not Infringeprivatelyowned rights Reference hereinto any specificcornrrrerciafproduct proce= or sertice by trade name, trademark,marrufactuser,or otherwise,does not nec-y constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof views and opiniona of authors expressed herein not necessarily state or reflect those States Governmentor any agencythereof rrfthe LIniled llrc LA-10172-MS UC-45 Issued: October 1984 High-Temperature-Stable Detonators Robert H Dinegar —— E– b — -=— y - —s= - “- G — — - - , — - ,- *A 2: - — : ! — J- —- ~~~~1~~~~ LosAlamosNationalLaboratory LosAlamos,NewMexi 87545 HIGH-TEMPERATURE-STABLE DETONATORS by RobertH Dinegar ABSTRACT Current experimentsin the area of high-temperaturestable detonators involve using HMX, KP, HNS, and PYX explosives The test.devicesemployboth hot-wireflyingplate and slappermodes of operation Hot-wiredetonators using HMX as the donor explosive,with HMX, KP, and HNS as the intermediateacceptormaterialand HNS as the booster pellet,were successfullyfired at temperaturesas high as 225°C Very limitedsuccesswasachieved usingPYX explosive in a few experiments The program of investigation also calls for the developmentof a high-temperature-stable hot-wiredevice functioningin the DDT mode of operation PYX explosive-a truly high-temperature-stable explosive-has been initiated to detonationby low-energyslapper foils - I INTRODUCTION The developmentof a detonatorthat will withstandelevatedtemperatures is governedby both the temperatureregimedesiredand whetherthe explosives that are stable at those temperaturescan be initiatedto detonation In addition,it must also be determinedthatpracticaland realizableamountsof energywill sufficefor the properfunctioningof the system Two methodsof explosiveinitiationare consideredin this report,i.e., hot-wire and slapper-foil In the first, a small wire in contactwith an explosiveis heatedby the passageof currentof the orderof A The explosive (donor)is ignited,and the gases that are producedrupturea metallic disc The flyingplate formedstrikesa secondexplosive(acceptor)that is initiatedto detonation In the second,the slappersystem,the rapidpassage of an electriccurrentthrougha foil vaporizesit The resultantexpansion process drives materialcoveringthe foil into an explosive,which is initiated to detonation A fractionof J of energy is sufficientfor proper functioning 11 EXPERIMENTALDETAILS A Hot-WireDetonators The test device is shown in I?ig.1 It functionsin the flying-plate mode of operation Two parallelNichromeV bridgewires,0.05 mm in diameter and 2.5 mm long, are resistance-welded to FeNi alloyelectrodesembeddedin a compressed-glass header The explosivechargeholderis made of Teflonand is 4.4 mm in diameterand mm long A chargemass of 100 mg gives a loading densityof 1.6 g/cm3 waster / — ““’S-=-.IVNM \ Explosive Acceptor Explosive ,., -.:, ~L:;::[p’o’e Al Disk Becomes > ‘Flying Plate” Steel 9EiiRi’rse: , Steel J - J’///i ~Ta Firing Unit Fig Flying-plateassembly The flying-platematerialis 6061-T6A1 The flyerdesignis called“Top Hat” because0.2 mm of an overall l.O-mm-thickshim fits snugglydown inside the flyer barrel forminga “Top Hat.” The flyer barrel has a diameterof 2.5 mm and is 7.0 mm in length The acceptorcharge holder has the same dimensions Both parts are made of 303 stainlesssteel and are screwedtogether The boosterpellet is confinedin a brass hexagonalring gluedonto the end of the acceptor charge An aluminumwitness block (usually2024 Dural)is gluedonto the metal ring that containsthe boostercharge HMX,’” KP,-~*HNS,~ and PYXl_~explosiveshave been investigated.The maximum temperatureat which we have done experimentsis 250°C The majorityof the testing in hot-wireassemblieswas done with HMX explosive KP and HNS were looked at in some detail; the daLa on PYX were sparsebecauseof its relativeinsensitivity.The specificsurface(S.)of the explosivesdiffered HMX used in the donor and the acceptorwas 8500 and 3450 cm2/g,respectively KP donorpowderwas 7600 cm2/gand the acceptorexplosive2350 cm2/g HNS was the fine-particlevariety (lINS-l) with the same S value of 13 000 cm2/g in both the donor and acceptor Large-particle PYX was wet-groundby porcelain balls to an S of about 30 000 cm2/g for this testing The donor explosiveswere all fired at 10 A or more This is far above the 1-A threshold-current value for HllX,KP, and HNS Since PYX explosive requiresa larger-diameter bridgewire(0.127mm vs 0.05 mm) for ignition,this currentvalue is only about twice the thresholdvalue B SlapperDetonators Figure2 shows the slapperdetonator Electricalenergyfrom an external source is depositedextremely rapidly in a metallic foil of the order of 0.01 mm thick There is a rapid productionof vaporizedmetal and plasma The high pressureaccelerateshigh-tensile-strength insulatingmaterialless than 0.1 mm thick placed againstthe bridge down a barrel a few tenths of a millimeterin length The impact of the rapidly moving materialupon an attachedhigh-densityexplosivepelletprovidesenoughenergyto initiatethe explosiveto detonation * l,3,5,7-tetranitro, 1,3,5,7-tetrazacyclooctane ~~-potassiumpicrate + 2,2’, 4,4’ , 6,6’ hexanitrostilbene ~~ 2,6-bis(picrylamino)-3,5-dinitropyridine !, : * Fig ‘ I Slapperdetonator III.EXPERIMENTALRESULTS A Hot-WireDetonators PYX At room temperature,+75, and +150°C, PYX decomposesjust enough to generatea usablepressurethat forms flyingplates from aluminum discs The flying plates have energiesgreat enough to dent both 6061-T6A1 and 2024 Dural witnessblocks The system is also sufficientlyenergeticto ignite PETN acceptor/boosterpellet combinationsto violent deflagration KP KP donors at elevated temperaturesof +75 and +lOO°C caused explosionsof larger-particle KP in the acceptorbarrelin 12/14shots,one of which detonated The success shows that the all-KP,flying-platedetonator will work, but whether the probabilityof an explosiondevelopinginto a detonationis high enough for practicaluse remainsto be seen Extrapolation of time/temperature data on KP indicatesa survivaltime at 300°Cof 30 minutes for all-KPdetonators HNs HNS is a very heat-stablematerial Its melting point is As a -3150C, and it has an excellentvacuum-thermalstabilitybehavior donor material,HNS decomposedupon hot-wireheatingto form a flyingplate but not with sufficientenergy to reactKNS or KP at 1.0 and 1.2 g/cm3 in the acceptorbarrel As an acceptormaterial, initiatedby a flyingplate driven by anotherexplosive,it performsmuch better HMx While not truly a high-temperature explosivein the same sense as KP, HNS, or PYX (certainly),HMX has a meltingpoint almost 250°C above room temperatureand a reasonablevacuum-thermal stabilityfor periodsof time of severalhours into the 200°C region It is certainlyworth seeingat how high a temperatureit will function(TableI) TABLE I HIGH-TEMPERATURE, HOT-WIREDETONATORPERFORMANCE AT ELEVATEDTEMPERATURES NUMBER DONOR 2 2 KP S.=8500 cm2/g !1 II f! 1 It EXPLOSIVE ACCEPTOR t! !! S = 2350 cm2/g !t HNs-1 S = 13000 cm2/g s = 3450 !! cm2/g !! It t! BOOSTER CYLINDRICAL DENT VOLUME (cm3) PETN 0.69a ins-l HNs-1 HNs-1 o.39a o.47a o.3oto Km-l 0.32t0.01 +200 HNs-1 0.29 +225 HI/s-l o.44a +100” HNs-1 HNs-1 o.49a +150 +150 HNs-1 HNs-1 a6061-T6Alwitnessblock;all others2024 Dural 0.29t0.02 0.32t0.04 0.32t0.04 TEMPERATURE (’JC) + 74 +100 +150 +200 +200” +225 HMX donorswill initiateHMX, KP, and HNS-1 acceptorexplosivesto deto- nation by driving flying plates withoutmuch difficultyup to +150°C Followingare detailsof the resultsof all-HMXdevicesat highertemperatures a Temperature= 200”C Seven of ten detonatorsfunctionednormally The detonatedHNS-1 boosterpellet gave good witness-block dents One device failedto ignitedue to an open bridgewire.One donordid not shearthe flyer plate, and one threw the flyer only halfwaydown the barrel Althoughsome engineeringproblemsstill seem to exist, hot-wiredetonatorsusing HMX as donorand acceptor-barrel chargesappearusableat 200°C b Temperature= 225°C At this temperatureHMX is basicallyunstable Its auto-ignitiontime appears to be less than 30-45 minutes The solid decomposedpartially,and the pressurebuildupspontaneously burst the flyer plate that was recoveredat the end of the flyerbarrel The gasesevidently causedbridgewiresto come loose from their welds in severalcases The HMX of low density (-1.2g/cm3) in the acceptorbarrelsublimedcompletelyin two assemblies Severalothersshowedtypicalbrownish-colored partialdecomposition of the HMX One device fired spontaneouslyand gave a good (average) dent in the witnessblock Temperature= 250°C Six detonators“cookedoff” and explodedspontaneouslyat differenttimes of heating (less than 30 minutes) No evidence c of initiationto detonationwas observed B SlapperDetonators W Hemsingand I M Garcia (M-7)have foundthat PYX can be detonatedin slapper-typedetonatorsat fairlylow energylevels(~0.3-Jstoredenergy)at ambient temperature At high temperatures,the required energy should be significantlylower Therefore,in principle,a detonatorcapableof withstanding+300°C is at hand We are endeavoringto make a high-temperaturecapablefiringsystem that will avoid the complications associatedwith providingthe cryogenicprotec~ionneededby present-dayfiringsystemsin undergroundwork REFERENCE John F Baytos,“High-Temperature Vacuum ThermalStabilityTests of Explosives,”Los Alamos National Laboratoryreport LA-5829-MS(January 1975) - — — - , , - - ~, a .- - —.- - - , , - ., ,, - “ .; , - — - - Printed i!l the United States of Americ Available from National Technical Information Service US Dcpaflmcnt of Commerce S285 Port Royal Road Springfield,VA 22161 MicroIlchc (AOI) Page Range NTSS Prim Code Page Range N’IIS Prim Code Page Range NTIS Price Code 001.025 026.050 0s1.075 076.100 101- [25 126.150 A02 A03 A04 A05 A06 A07 151.17s 176.200 201-22s 226-250 2S1.275 276.300 A08 AW A1O AI1 A12 A13 301-32S 326.3S0 351-375 376430 401-425 426430 A14 A15 A16 A17 A18 A19 “Contact NT2S for a price quote, PWC Range 45[47s 476.500 501.525 526.550 551.575 576.600 1501.up” - NTIS Price Code A20 A21 A22 A23 A24 A25 A99 , - — Lmlw-nnlos ... LosAlamosNationalLaboratory LosAlamos,NewMexi 87545 HIGH- TEMPERATURE- STABLE DETONATORS by RobertH Dinegar ABSTRACT Current experimentsin the area of high- temperaturestable detonators involve using HMX, KP, HNS,... investigation also calls for the developmentof a high- temperature- stable hot-wiredevice functioningin the DDT mode of operation PYX explosive-a truly high- temperature- stable explosive-has been initiated to... High- Temperature- Stable Detonators Robert H Dinegar —— E– b — -=— y - —s= - “- G — — - - , — - ,- *A 2: - — : ! — J- —- ~~~~1~~~~ LosAlamosNationalLaboratory LosAlamos,NewMexi 87545 HIGH- TEMPERATURE- STABLE