1 AbelTest ThistestonchemicalstabilitywasproposedbyAbelin1875.Thetest parameterdeterminedisthetimeafterwhichamoistpotassiumiodide starchpaperturnsvioletorbluewhenexposedtogasesevolvedbyone gramoftheexplosiveat82.2°C(180°F). In commercial nitroglycerine explosives, for example, this coloration onlydevelopsafter10minor more.Inamore sensitivevariantofthe method,Zinciodide–starchpaperisemployed. TheAbeltestisstillusedinqualitycontrolofcommercialnitrocellulose, butiscurrentlynolongeremployedinstabilitytestingofpropellants. Acceptor1) Empfängerladung;chargeréceptrice Achargeofexplosivesorblastingagentreceivinganimpulsefroman exploding→Donorcharge. Acremite ThisisthenamegivenbytheUSinventorAcretohismixtureofabout 94%ammoniumnitratewith6%fueloil.Thismixturewasatfirstpre- paredinaprimitivemannerbytheusersthemselvestoobtainavery cheapexplosiveforopenpitminingunderdryconditions.Like→ANFO, thematerialhaswidelydisplacedconventionalcartridgedexplosives. Actuator Mechanicaldeviceoperatedbyasolidpropellant. Adiabatic Processesorphenomenaassumedtooccurinaclosedsystemwithout energyexchangewiththesurroundings. adiabaticflametemperature The temperature obtained by thermodynamics calculations for the productsofcombustionofenergeticmaterialsneglectingenergyloss tothesurroundings. 1) Textquotedfromglossary. Explosives,7.Edition,RudolfMeyer,JosefKöhler,andAxelHomburg. ©2015WILEY-VCHVerlagGmbH&Co.KGaA.Published2015byWILEY-VCHVerlagGmbH&Co.KGaA. AdobeCharge 2 isobaricadiabaticflametemperature Adiabaticflame temperatureattained underconstant pressure condi- tions. isochoricadiabaticflametemperature Adiabatic flame temperature attained under constant volume condi- tions. adiabatictemperature Thetemperatureattainedbyasystemundergoingavolumeorpressure changeinwhichnoheatentersorleavesthesystem. AdobeCharge Auflegerladung;pétardage Synonymouswith→MudCap ADR Abbreviation for “Accord Européen Relatif au Transport des March- andisesDangereusesparRoute”(EuropeanAgreementConcerningthe internationalCarriageofDangerousGoodsbyRoad).Itisbasedonthe RecommendationsontheTransportofDangerousGoodsModelRegu- lations(UnitedNations). Aerozin Aliquidfuelforrocketenginesthatiscomposedof50%anhydroushy- drazineand50%asym-dimethylhydrazine. AGARD Abbreviation for the NATO Advisory Group for Aeronautical Research andDevelopment. Airbag Gasgenerator Thebasicideaoftheairbagasapassiverestraintsysteminamotorve- hiclewasalreadypatentedforthefirsttimein1951inGermany.How- ever,ittook nearly20 years before developmentbegan on two basic types–pyrotechnicandhybridgasgenerators.Bothtypesaremanufac- turednearlyexclusivelyinseriesproductionandwereincludedincars 3 Airbag Figure1 Sectionaldiagramofapyrotechnicalgasgeneratorforairbags. startingin1975.Mainstreamapplicationsofairbagrestraintsystemsin almosteverycarstartedin1990. Nowadays four main types of gas generating principles are used for airbag inflators in cars. Pyrotechnic gas generators inflate the bag by gaseouscombustionproductsofpyrotechniccompositions.Hybridgas generatorsarebasedonacombinationofpressurizedgasandpyrotech- nic(heating) charge todeliverthe gas. Both typesare widelyusedin driver, passenger, side and curtain airbag applications. So-called cold gasgeneratorsutilizepressurizedheliumforbaginflationandareusu- allyusedforkneeandsideairbagsystems.Thelatestdevelopmentin gas generating principles uses a combustible mixture of pressurized hydrogen,oxygenandinertgasbeingappliedfordriverandpassenger applications.Hybridandpyrotechnicgasgeneratorsarethemostcom- montypesusedandaredescribedindetailbelow.Theirconstructionis shownschematicallyinFigures1and2. Inthehybridsystemthepre-pressurizedgas(nitrogen,argon/helium) is stored in pressure containers fitted with a burst disc. Opening this membrane by pyrotechnic means allows the gas to flow out intothe airbag.Thecoolingoftheexpandinggasiscompensatedorevenover- compensatedbythepyrotechniccharge.Sincethetotalamountofpy- rotechnicmixtureissmallinquantitativeterms,thecompulsorythresh- oldvaluesofthetoxicimpuritiescontainedintheworkinggascanbe adheredtorelativelyeasily.Thisfact,inadditiontotheidealtempera- tureoftheworkinggas,isthemainadvantageofhybridgasgenerators. Airbag 4 Figure2 Sectionaldiagramofahybridgasgeneratorforairbags. Thedisadvantagesarethelargerweightcomparedtopyrotechnicgas generators,themorecomplexproductiontechnologyneededandthe subjectiontopressurevesselregulation. Theuniquefeatureofalmostallpyrotechnicalgasgeneratorsisthecon- centricassemblyofthreedifferentchamberswithdesignscorrespond- ing to their pressure conditions and functions. The innermost cham- ber containsthe booster unitconsisting of aplug,squiband booster charge. An auto ignition charge is usually integrated in the booster setup,whosetaskistoignitethepyrotechnicmixturewithoutelectric current in case of high temperatures,e.g. in case of fire. Duringstan- dardelectricalignitionthethinresistancewireoftheigniterisheated andtheignitiontrainstarted.Theboosterchargeusuallyusedinearlier times was boron/potassium nitrate. Nowadays pyrotechnic formula- tionswithgoodignitionpropertiesareusedinpelletizedgraindesign contributingnoticeablytotheoverallgasyieldofthegenerator.Thehot gases and particles generatedby this charge enterthe concentrically arrangedcombustionchamberandignitethepyrotechnicmaincharge. Bothchambersaredesignedforhighpressuresupto60MPa.Thepy- rotechnicmainchargeconsistsgenerallyofcompressedpelletswhich 5 Airbag Table1 EffluentgaslimitsaccordingUSCAR-24regulation. EffluentGas VehicleLevelLimit Driver-SideLimit (ppm) (ppm) Chlorine(Cl ) 1 0.25 2 Carbonmonoxide(CO) 461 115 Carbondioxide(CO ) 30000 7500 2 Phosgene(COCl ) 0.33 0.08 2 Nitricoxide(NO) 75 18.75 Nitrogendioxide(NO ) 5 1.25 2 Ammonia(NH ) 35 9 3 Hydrogenchloride(HCl) 5 1.25 Sulphurdioxide(SO ) 5 1.25 2 Hydrogensulfide(H S) 15 3.75 2 Benzene(C H ) 22.5 5.63 6 6 Hydrogencyanide(HCN) 4.7 1.18 Formaldehyde(HCHO) 1 0.25 generatetheworkinggasandslagresiduesbyacombustionprocess. Theproductsleavethecombustionchamberthroughnozzlesanden- terthe lowpressure regionofthe filtercompartment,where theslag isremovedfromthegasflow.Thefiltercompartmentisequippedwith varioussteelfiltersanddeflectorplates.Thegasthenflowsthroughthe filtercompartmentnozzlesintothebag. Thebasictaskofeachgasgeneratoristoprovidesufficientnontoxicgas (seeTable1)withintherequiredtimeframeof11–30mstoinflatethe airbagtothespecifiedpressure.Thefirstpyrotechnicmixtureusedin airbaggasgeneratorswasbasedonsodiumazide.Duringcombustion, sodiumazidereactswithoxidizingagents,whichbondchemicallythe elementalsodiumasthenitrogenisreleased.Establishedoxidizerswere alkaliandalkalineearthnitrates,metaloxides(e.g.CuO,Fe O ),metal 2 3 sulfides(MoS ) and sulfur.If necessaryslag forming agents(e.g. SiO , 2 2 aluminosilicates)were also added.Advancesinenvironmental aware- nessledconsequentlytothereplacementofsodiumazide,thoughpure nitrogenasaworkinggaswasgeneratedbythiscomposition.Another factortothedetrimentofsodiumazidewastherelativelowspecificgas yieldandtheunsolveddisposalprocedureforthistypeofpyrotechnic mixture. With regard to azide-free gas mixtures, there have been numerous patents and initial applications since the early 1990s. These new gas mixtures generate more gas per gram (gas yields from gas mixtures AirBlast 6 containing NaN : 0.30–0.35l/g) and thus enable smaller and to some 3 extentamorelightweightconstructionofthegasgenerators. Theycanbeclassifiedintotwocategories: 1. High-nitrogen organic compounds(C, H,O, N)are combined with inorganicoxidizers: The fuels are, for example, 5-aminotetrazole, azodicarbonamide, →Guanidinenitrate,→Nitroguanidine,dicyandiamide,→Triamino- guanidinenitrateandsimilarcompounds,aswellassaltsof,forex- ample, 5-nitrobarbituric acid, urea derivativesand also nitramines andsimilarcompounds.Theoxidizersare,forexample,alkalioral- kaline earth nitrates, →Ammoniumnitrate, alkali or alkaline earth perchloratesandmetaloxides. Gasyieldofthesemixtures:0.50–0.65l/g. 2. High-oxygen,nitrogen-freeorganiccompounds(C,H,O)areblended with inorganic oxidizers.The fuelsused are, for example,tri or di- carboxylicacids(e.g.citricacid,tartaricacid,fumaricacid)orsimilar compounds.Theoxidizersusedareespeciallyperchloratesandchlo- rateswithadditionalassistancefrommetaloxides.Thisenablesany formationofNOxtobeexcluded.Gasyieldofthemixture:0.5–0.6l/g. Thegasgeneratorformulationsareusuallymanufacturedbygrinding andblendingtherawmaterials,whichafterapre-compactingstepare pressedintopelletsordisksonrotarytablepresses.Somegasgenera- torformulationsusingplastic(reactive)bindersaremanufacturedbyan extrusionprocess. AirBlast Druckwelle;ondedechoc Theairborneacousticorshockwavegeneratedbyanexplosion→De- tonation,→FuelAirExplosives,→ThermobaricExplosives. AirLoaders Blasgeräte;chargeurspneumatiques Airloadersserve tocharge prilled→ANFOblastingagentsintobore- holes.Ifthefree-runningprillscannotbechargedbypouring,e.g.hor- izontalboreholes,boreholeswithneglectableslopeorboreholeswith smalldiameters,theycanbeintroducedbyairloaders.Thisisdoneby loadingthechargeintoapressurizedvesselandapplyinganairpressure ofabout0.4MPa;avalveatthelowestpointofthemachine,whichcan becontrolledfromtheboreholetobefilled,leadstoalonghose;when thevalveisopened,astreamofaircontainingtheexplosivechargein suspensionissentthroughitintotheborehole.Otherportablemachines workontheinjectorprinciple. 7 AkarditeII AkarditeI diphenylurea;Diphenylharnstoff;diphénylurée colorlesscrystals(molecularweight:212.25g/mol) empiricalformula:C H N O energyofformation:13−11127.23kcal∕kg=−490.6kJ∕kg enthalpyofformation:−138.2kcal∕kg=−578.2kJ∕kg oxygenbalance:−233.7% nitrogencontent:13.21% density:1.276g∕cm3 Akardite I serves as a →Stabilizer for gunpowders, in particular for →Double-BasePropellants. Specifications meltingpoint: atleast183°C=361°F moisture: notmorethan0.2% ashes: notmorethan0.1% chlorides: notmorethan0.02% pHvalue: atleast5.0 acid,0.1NNaOH∕100g: notmorethan2.0cm3 AkarditeII methyldiphenylurea; Methyldiphenylharnstoff; N-méthyl-N′,N′-diphényl- urée colorlesscrystals empiricalformula:C H N O 14 14 2 molecularweight:226.3g/mol energyofformation:−90.5kcal∕kg=−378.5kJ∕kg enthalpyofformation:−112.7kcal∕kg=−471.5kJ∕kg oxygenbalance:−240.4% nitrogencontent:12.38% density:1.236g∕cm3 AkarditeIIisaneffective→Stabilizerfordouble-basegunpowders AkarditeIII 8 Specifications sameasforAkarditeI, exceptmeltingpoint atleast170−172°C=338−342°F AkarditeIII ethyldiphenylurea;Ethyldiphenylharnstoff;N-éthyl-N′,N′-diphénylurée colorlesscrystals empiricalformula:C H N O 15 16 2 molecularweight:240.3g/mol energyofformation:−128.5kcal∕kg=−537.7kJ∕kg enthalpyofformation:−151.9kcal∕kg=−635.5kJ∕kg oxygenbalance:−246.3% nitrogencontent:11.65% density:1.128g∕cm3 AkarditeIIIisaneffective→Stabilizerfordouble-basepropellants.Both AkarditeIIandIIIaregelatinizersaswellas→Stabilizers. Specifications sameasforAkarditeI, exceptmeltingpoint atleast89°C=192°F Alex Alexisan→aluminumpowderformedbyexplosionofelectricallyheated aluminumwiresininertatmosphereswithparticlesizesbetween50and 200nm.Duetoapassivationlayerofthicknessbetween2and4nm,a substantial numberof theparticlesare alreadyconvertedtoalumina, theformationofwhichshouldbeavoidedbyinsitucoating.Inaddition tothediffusioncontrolledoxidationatlowertemperatures,apartialoxi- dationoftheparticlescanoccurbyafastchemicallycontrolledreaction. Alexcanincreasetheburningrateofsolidcompositerocketpropellants uptoafactoroftwo.Anincreaseofdetonationvelocityisnotconfirmed butAlexmightimprove→airblastorfragmentvelocitiesofsomehigh explosives,andviscosityincreasesinformulationswithliquidbinders. Alginates Saltsofalginicacidwhicharecapableofbinding200–300timestheir ownvolumeofwater.Theyareaddedasswellingorgellingagentsto 9 Amatols explosivemixturesinordertoimprovetheirresistancetomoistureand to→Slurriestoincreaseviscosity. AllFire Mindestzündstrom;ampèrageminimed’amorcage Minimumcurrentthatmustbeappliedtoanignitercircuitforreliable ignitionoftheprimerchargewithoutregardtotimeofoperation. AluminumPowder Aluminiumpulver;poudred’aluminum Aluminumpowderisfrequentlyaddedtoexplosivesandpropellantsto improvetheirperformance.Theadditionofaluminumresultsinconsid- erablegaininheatofexplosionbecauseofthehighheatofformationof aluminia(1658kJ/mol,16260kJ/kg)leadingtohighertemperaturesof thefumes.Aluminumnotreactedinthedetonationfrontmightbeox- idizedbyatmosphericoxygentoinducepost-heatinginthefumezone andtoincreasethe→airblastoreventoinitiateadelayedsecondary explosion. Widely used mixtures of explosives with aluminum powder include →Ammonals,→DBX,→HBX-1,→Hexal,→Minex,→Minol,→Torpex, →Trialenes,→Tritonal andHexotonal. Inaddition,underwaterexplo- sivesoftencontainaluminumpowders. The performance effect produced by aluminumpowder is frequently utilizedin→Slurries,alsoin→CompositePropellants. Importantcharacteristicsofaluminumpowdersareshapeandgrainsize of the powder granules. Waxed and unwaxed qualitiesare marketed. Propellantformulationsoftenprescribesystematicallyvariedgrainsizes forobtainingoptimaldensities. Amatex Apourablemixtureoftrinitrotoluene,ammoniumnitrateandRDX. Amatols Pourablemixturesofammoniumnitrateandtrinitrotolueneofwidely varying compositions (40 : 60,50 : 50, 80 : 20). The composition 80 : 20maybeloadedintogrenades,forexample,usingascrewpress(ex- truder). Ammonals 10 Ammonals Compressibleorpourablemixturescontainingammoniumnitrateand aluminumpowder;thepourablemixturescontain→TNT AmmoniumAzide Ammoniumazid;azotured’ammonium NH N 4 3 colorlesscrystals molecularweight:60.1g/mol energyofformation:+499.0kcal∕kg=+2087.9kJ∕kg enthalpyofformation:+459.6kcal∕kg=+1922.8kJ∕kg oxygenbalance:−53.28% nitrogencontent:93.23% density:1.346g∕cm3 Ammoniumazideispreparedbyintroducingasolutionofammonium chlorideandsodiumazideintodimethylformamideat100°C.Thesol- ventisthendrawnoffinvacuum.Owingtoitshighvaporpressure,this compoundhasnotyetfoundanypracticalapplication. Vaporpressure: Pressure Temperature (mbar) (°C) (°F) 1.3 29.2 84.6 7 49.4 121.0 13 59.2 138.6 27 69.4 157.0 54 80.1 176.2 80 86.7 188.1 135 95.2 203.4 260 107.7 225.9 530 120.4 248.7 1010 133.8 272.8 AmmoniumChloride Ammoniumchlorid;chlorured’ammonium NH Cl 4 colorlesscrystals molecularweight:53.49g/mol