P. A. Urtiew. C M. Tamer. R. L. Simpson

Transcription

1 1 UCRGJC Shock nitition of,4-dinitroimidzole (,4-DN) P. A. Urtiew C M. Tmer R. L. Simpson This pper ws prepred for submittlto the 1995 Americn Physicl Society Topicl Conference Shock Compression of Condensed Mtter Settle, Wshington August 1348,1995 July 19,1995 Thisis preprintofpperintended forpublictioninjoumlorpmeedings. Since chnges my be mde before publiction, this preprint is mde vilble with the understnding tht it will not be cited or reproduced without the permission of the uthor.

2 . DSCLAMER This document ws prepred s n ccount of work sponsored by n gency of the United Sttes Government. Neither the United Sttes Government nor the University of Cliforni nor ny of their employees, mkes ny wrrnty, express or implied, or ssumes ny legl libility or responsibility for the ccurcy, completeness, or usefulnessof ny informtion, pprtus, product, or process disclosed, or represents tht its use would not Mringe privtely owned rights. Reference herein to ny spedfic commercil product, process, or service by trde nme, trdemrk, mnufcturer, or otherwise, does not necessrily constitute or imply its endorsement, recommendtion, or fvoring by the United Sttes Government or the University of Cliforni. The views nd opinions of uthors expressed herein do not necessrily stte or reflect those of the United Sttes Government or the University of Womi, nd shll not be used for dvertising or product endorsementpurposes.

3 DSCLAMER Portions of this document my be illegible in electronic imge products. mges re produced from the best vilble originl document.

4 SHOCK NTATON OF,4-DNTROMDAZOLE (,4-DN) P. A. Urtiew, C. M. Trver nd R. L. Simpson Lwrence Livennore Ntionl Lbortory, P.O. Box 808, L-8, Livermore, CA The shock sensitivity of the pressed solid explosive,4-dinitroimidzole (,4-DN) ws determined using the embedded mngnin pressure guge technique. At n initil shock pressure of GP, severl microseconds were required before ny exothermic rection ws observed. At 4 GP,,4DN rected more rpidly but did not trnsition to detontion t the 1 mm deep guge position. At 6 GP, detontion occurred in less thn 6 mm of shock propgtion. Thus,,4-DN is more shock sensitive thn TATB-bsed explosives but is considerbly less shock sensitive thn HMX-bsed explosives. An gnition nd Growth rective flow model for,4-dn bsed on these guge records showed tht,4-dn exhibits shock initition chrcteristics similr to TATB but rects fster. The chemicl structure of,4-dn suggests tht it my exhibit therml decomposition rections similr to nitrogunine nd explosives with similr ring structures, such s ANTA nd NTO. NTRODUCTON The five membered ring explosive,4dinitroimidzole (,4-DN) ws first synthesized by Lncini et l. (1) by nitrting -nitroimidzole. t ws lter obtined by the therml rerrngement of 1,PDN (). Currently,4-DN is being mde from 4-nitroimidzole, which is commercilly vilble (3). This llows,4-dn to be produced in lrge quntities in cost effective mnner. The gol of the synthesis project is to produce reltively inexpensive explosive tht hs higher energy density thn TATB nd TNT, yet is still insensitive. The smll scle sfety properties, therml explosion behvior, nd detontion velocity versus chrge density of,4-dn were reported by Jysuriy et l. (3). n this pper, the shock sensitivity of,4-dn ws mesured t three shock pressures using embedded mngnin guge techniques (4) nd clculted using the gnition nd Growth rective flow model (5) for shock initition nd detontion in the DYNAD hydrodynmiccode (6). EXPERMENTAL The experimentl geometry is shown in Fig. 1. A 1.7 mm thick, 60 mm dimeter Lexn flyer plte impcted trget consisting of 6 mm thick, 90 mm dimeter Teflon buffer plte nd 5 mm thick, 50.8 mm dimeter.4-dn chrge. The,4-DN chrge ws held in plce by 3 mm thick Lexn ring. Six 0.3 mm thick Teflon-insulted mngnin guges were plced in pirs long the center line of the,4dn chrge t distnces of 0,6,nd 1 mm. Three experiments were fired in the 100 mm powder gun with Lexn flyer velocities of m d p s, mm/ps nd.73 m d p s, producing initil shock pressures of pproximtely GP, 4 GP nd 6 GP, respectively. The mesured chnges in resistnce of the mngnin guge elements were converted to Lexn Flyer Plte Lexn Buffer Plte Lexn,4-DN Ring xx L n g n i n Guges FGURE 1. Experimentl geometry for the shock

5 pressure histories nd compred to gnition nd Growth rective flow clcultions. REACTVE FLOW MODELNG The gnition nd Growth rective flow model (5) hs been incorported into severl hydrodynmic codes nd used to solve mny explosive nd propellnt sfety nd performnce problems (7). The model uses two Jones-Wilkins-Lee (JWL) equtions of stte, one for the unrected explosive nd nother one for the rection products, in the temperture dependent form: p = A e-r1 + B e-rv+ wcvt (1) where p is pressure in Megbrs, V is reltive volume, T is temperture, o is the Gruneisen coefficient, C, is the verge het cpcity, nd A, B, R1 nd R re constnts. The equtions of stte re fitted to the vilble shock Hugoniot dt. The rection rte lw is: df/dt = (l-f)b(p/po-l-)x + Gi(1-F)CFdpY OeFeFigmx OeF<FG 1mx + G( l-f)efgpz F~min<F<1 overtkes the leding shock front nd thus cuses detontion. The eqution of stte prmeters for,4- DN, Lexn, nd Teflon nd the gnition nd Growth rte lw prmeters used in the rective flow clcultions re listed in Tble 1. The mesured pressure histories nd those predicted by the gnition nd Growth model re compred in the next section. COMPARSON OF RESULTS () where F is the frction rected, t is time, p is the current density, po is the initil density, p is pressure in Megbrs, nd, G, G,, b, c, d, e, g, x, y, nd z re constnts. As explined in previous ppers (4), this three term rection rte lw models the three TABLE 1. Eqution of stte nd rection rte prmeters 1. gnition nd Growth Model Prmeters for.4-dn unrected JWL Product JWL po = 1.67 g/cm3 A=700 Mbr stges of rection generlly observed during shock initition of heterogeneous solid explosives. The first term ignites some of the solid explosive s it is compressed by shock or compression wve creting heted res (hot spots) s the voids in the mteril collpse. Generlly the mount of explosive ignited by strong shock wve is pproximtely equl to the originl void volume. The second term in Eq. () represents the reltively slow growth of rection from the hot spots into the surrounding solid in deflgrtion-type process. The third term in Eq. () describes the rpid trnsition to detontion observed when the growing hot spots begin to colesce nd trnsfer lrge mount of het to the remining unrected prticles, cusing them to rect very quickly nd to crete high pressure pulse which A=6.113 Mbr Figure compres the experimentl pressure histories (solid lines) with those predicted by the gnition nd Growth model (dshed lines) for the lowest pressure,4-dn experiment with Lexn flyer velocity of mm/ps, which imprts GP shock pressure into the.4-dn chrge. The 0 mm guges mesured very little growth of rection for the first 6 p fter impct, nd then the pressure Rection Rte Prmeters 1=.0et8 B= Mbr B.1065 Mbr =O.O R1=13.0 R1=4.40 b=0.667 x=15.0 R;?=l.30 R=1.0 0=0.9 0=0.3 G1=9.5 y=1.0 Cv=3.0e-5 Mbr/K CV=1.0e-5MbrlK c=0.667 Toz98'K EH.089 Mbr Sher Modulus=35Mbr d=0.333 Yield Strength=0 Mbr. Gruneisen Prmeters for nert Mterils p = pocp[l+(1-yd)p-/p] / [l-(sl-1)p-sp/(p+l)-s3p3/(~+l)]+(~~ + p)e where p=p/po-l nd E is therml energy po(g/cm3) Yo nert c(mm/ms) S1 s3 s T6A Lexn Teflon

6 10- Clcultion 161 / $e! v), e! Clcultion /-. 1 d 10 P e! 1, U 8 O+-J Omm 6mm 1mm J m. A Time-us FGURE. Pressure histories for,4-dn impcted t m d p by Lexn flyer plte FGURE 3. Pressure histories in.4-dn impcted t m d p s by Lexn flyer rose slowly to 3 GP over the next ps before the guges filed. The 6 mm deep guges recorded no pressure increse for the first 3 ps, followed by continuous growth to over 10 GP in the next 5 ps. The 1 mm deep guges recorded similr pressure histories. The gnition nd Growth model pressure histories exhibit similr continuous energy releses up to bout 8 to 9 GP, corresponding to pproximtely 50% rection. At this shock pressure, TATB-bsed explosives do not rect (8), nd HMXbsed explosives exhibit fster growth of rection behind the shock front thn does,4-dn (9). The experimentl nd clculted results for the highest Lexn flyer velocity experiment,.73 mm/ps, producing 6 GP shock re shown in Fig. 4. The 0 mm guges record rpid growth rection to 1 GP over ps. The 6 nd 1 mm guges record high pressures chrcteristic of detontion wve. The gnition nd Growth clcultions gree closely with the guge records nd predict tht detontion occurs just before the rective shock reches the 6 mm guge. At shock pressure of 6 GP, HMX-bsed explosives detonte in bout 4 mm, while TATB-bsed explosives do not pressure histories for.4-dn impcted by Lexn t mm/j.ls, creting 4 GP shock. At this shock mplitude, TATB-bsed explosives do not rect, while HMX-bsed explosives trnsition to detontion t run distnces of less thn 10 mm (O). The guge records in Fig. 3 clerly show tht,4dn is not close to detonting t the 1 mm guge position. Although the 0 mm guge records re not very good, the other 4 guges clerly show some shock front mplitude increse t the 6 nd 1 mm depths, followed by pressure growth to 11 GP over the next 3 ps t the 1 mm guges. The gnition nd Growth model clcultes these increses ccurtely by llowing bout 3% rection during shock compression (ignition) nd subsequent rection rte with p1 dependence. DN is much more rective thn TATB t 6 GP, but but not s rective s most explosive molecules..figure 3 shows the experimentl nd clculted decompose to ny significnt degree. Therefore,,4SUMMARY The shock sensitivity of,4-dn hs been determined using embedded mngnin pressure guges nd the gnition nd Growth rective flow model. ts shock initition chrcteristics hve been shown to be similr to TATB-bsed explosives in tht shock of sufficient strength to ignite few percent of the chrge then exhibits some mplitude growth s it propgtes through the chrge, followed by growth of rection tht cn be modeled with liner pressure dependence. The trnsition to detontion then occurs in the usul fshion when the growing pulse pulse overtkes the leding shock front. Since it rects

7 ExDeriment This work ws performed under the uspices of the U.S. Dept. of Energy by Lwrence Livermore Ntionl Lbortory under contrct No. W ENG REFERENCES 1. Lncini, G. C., Mggi, N., nd Sensi, P.. Furmco (puvi), Ed. Sci.. 18, (1963) Shrnin, G. P., Fsskhov, R. Kh.. nd Orlov. P. P., USSR Ptient (1975). 3. Jysuriy, K., Dmurpu. R.. Simpson. R. L., Coon. C. L., nd Colburn. M. D.. ".4-Dinitroimidzole: A Prcticl nsensitive High Explosive," Lwrence Livermore Ntionl Lbortory Report UCRL-JC-D Mrch Urtiew, P. A., Erickson, L. M., Hyes, B., nd Prker, N. L., Combustion, &pf05ionmd Shock Wves, (1986) Time-us FGURE 4. Pressure histories for,4-dn impcted t.73 m d p s by Lexn flyer reltively slowly t nd 4 GP shock pressures,,4-dn is definitely less shock sensitive thn HMX. Since it rects slowly t nd 4 GP nd detontes within 6 mm t 6 GP,,4-DN is more shock sensitive thn TATB. However, since most hzrd scenrios involve shock pressures well below 6 GP,,4-DN my be shock insensitive enough for mny pplictions. Willims et l. (1 1) hve studied the therml decomposition of severl explosives with ring structures similr to tht of,4-dn, such s 3-nitro1,,4-trizol-5-one (NTO) nd 3-mino-S-nitro-l,,4trizole (ANTA), nd found tht these compounds prtilly decompose forming polymer-like residue clled melon. Thus,4-DN should decompose in similr mnner. Since t lest one of these compounds, nitrogunidine, exhibits Group explosive behvior (1),,4-DN my lso fll into this ctegory. ACKNOWLEDGEMENTS The uthors would like to thnk Dr. K. Jysuriy nd Dr. R. Dmurpu of the Army Reserch nd Development Center for furnishing the,4-dn used in this study. The uthors lso would like to thnk Frnk Grci for firing the 100 mm gun shots nd Leon Meegn for ssembling the embedded guge meets. Y Y Y 5. Trver. C. M.. Hllquist, J. 0.. nd Erickson, L. M.. in Eighth Symposium (nterntionl) on Detontion, Nvl Surfce Wepons Center NSWC Albuquerque. NM, pp Whirley, R. G., Engelmnn. B. E., nd Hllquist, J. 0.. "DYNAD User Mnul," Lwrence Livermore Ntionl Lbortory Report UCRL-MA April Trver, C. M.. Urtiew, P. A., Chidester. S. K.. nd Green, L. G., Propellnts. Explosives, Pyrotechnics 18, (1993). 8. Trver, C. M., Propellnts. Explosives, Pyrotechnics 15, 1314 (1990). 9. Lee, E. L. nd Trver, C. M.,Phys. Fluids 3, (1980). 10. D o b m B. M. nd Crwford, P. C., "LLNL Explosives Hndbook," Lwrence Livemore Ntionl Lbortory Repon UCRL-5997, Jnury Willims, G. K., Plopolli S. E.nd Brill, T. B., Combustion md Flme 98, (1994). 1. Price. D., Clirmont, A. R., nd Erkmn. J. 0..Combustion md Flme 17, (1971). '