EXPLOSIVE WELDING USING THE EMULSION EXPLOSIVES Victor V. Silvestrov A.V. Plastinin, S.I. Rafeichik, M.A. Gulevitch, and V.V. Pai E-mail: silver@hydro.nsc.ru D = 1.9 km/sec Lavrentyev Institute of Hydrodynamics Siberian Branch of Russian Academy of Sciences Novosibirsk, Russia X International Symposium on Explosive Production of New Materials: Science, Technology, Business, and Innovations (EPNM-2010) June 7 – 11, 2010, Bechichi, Montenegro

Goals The decrease of the velocity of detonation (VOD) to 2‒3.5 km/sec for the emulsion explosives The application of the compositions for explosive welding of metals

Outline Emulsion Explosives with detonation velocity 2-3.5 km/sec and high detonation ability VOD vs charge diameter. Detonation limits Shell-life. Effect of casing Particle velocity – time profile, detonation pressure Throwing ability of low VOD emulsion explosives Examples of explosive welding applications Cladding of metals by foils with thickness up to 100 microns (without buffer layer) Explosive welding of small diameter tube with tubeplate model (the thermal welding to pressurize the tube/tubeplate connection is not needed)

History of low VOD emulsion explosives Yoshida, M., Iida, M., et al., 8th Symp. Intern. on Detonation, 1985: dcr < 6 mm, Δcr < 1 mm in wedge test for handmade emulsion explosives Matsuzawa, T., Murakado, T., et al., “Method for explosive cladding” US Patent 4844321, 04.07.1989: D = 2-5 km/sec, but the details and detonation limits were not discussed Petel, O.E., Mack, D., et al., 13th Symp. Intern. on Detonation, 2006: D ≥ 3 km/sec, dcr ≈ 13 mm, Δcr = 3.3 mm in PMMA casing for commercial explosives There are only the scanty information for the low detonation velocity emulsion explosives

Main Ideas Use of fine emulsion matrix to increase of detonation ability of explosives Introduction of large amount of light hollow glass microballoons (GMB) into the emulsion matrix to decrease the explosive density and the detonation velocity

Compositions Components, wt. % EmExp–8 EmExp–50 Ammonium Nitrate 67 Sodium Nitrate 14 Water 12 Paraffin, solid 3 Industrial Oil 2 Sorbitan monooleate Sensitizer (GMB), μ 8 50 Explosive Density, g/cc 1.0 0.5 Maximal VOD, km/sec 4.76 2.1 Minimal VOD, km/sec 2.67 1.8 Critical diameter / thickness, mm 4.8 / 2 13 / 12 μ = GMB weight / Emulsion matrix weight

Fine Emulsion Optical picture High detonation ability Between marks 12 μm The size of oxidizer droplets is lower 1-2 μm Non-Newtonian elastoplastic fluid, Apparent viscosity 30–40 kP at 60°C High detonation ability

Domestic Glass Microballoons 1 – optical analysis, 3 – 3M Belgium, 2 – sieve analysis d, μm 58 μm ρ00 = 0.15 g/cc Trade mark MS-V

Synchrotron Radiation-Aided Tomography Like as “Honeycombs of wild bees” 3D structure 1 mm A small morsel of emulsion explosive at μ = 8 % According to Pruell Ed.R., Ten K.A. (2009, LIH)

«Explosive Welding» area Effect of GMB quantity Ø 30 mm US Patent 0.75  0.5 g/cc Ø 20 mm Our data «Explosive Welding» area μ = 20  50 wt.% GMB, D = 2  3.5 km/sec

Steady-State Detonation 8 % 50 % 20 % μ is increasing GMB, wt. %: 1 – 8 2 – 20 3 – 25 4 – 35 5 – 50 6 – 50 in casing Weak dependence of detonation velocity on charge diameter at μ ≥ 20 % Only one explosive component is ammonium nitrate → high safety of blasting

Detonation Limits dcr dcr/Dcr 1 – Di 2 – Dcr 3 – Dcr 4 – dcr

dcr. w/o case/ dcr. metal case≈ 7-8 as for individual HE’s Effect of Casing D, km/sec μ = 50 % 12.4 mm 1.7 mm Thin PE case, 12.4 mm PTFE, 6.2 mm Duralumin, 1.7 mm Steel, 1.5 mm for emulsion matrix Sound velocity L/d = 12 – 30 Cylindrical charge diameter, mm dcr. w/o case/ dcr. metal case≈ 7-8 as for individual HE’s

Shell-Life of low VOD emulsions industrial oil () and solid paraffin (▲) Shell-life is larger than one month 16 mm

Particle velocity - time profiles Original free-contact electromagnetic method (Pai V.V. et al, 1998) was used 80 mm, 230 mm (L) GMB, wt. %: 1 – 8 2 – 20 3 – 35 4 – 50 Chemical spike predicted by ZND theory = YES except for curve (4)

Estimations of Detonation Parameters ρ0, g/cc UD, km/sec PD, GPa tR, μs aR, mm n 1.04 1.08 5.1 0.4 1.3 3.2 0.75 0.86 2.0 0.9 2.6 0.63 0.6 0.8 2.9 0.5 0.77 ‒ 1.5 U7[p.l; [;\=\\\\ Particle velocity, UD 0.6 ~ 1.1 km/sec Reaction zone width, aR ~ 1 mm Detonation pressure, PD 0.7 ~ 5.1 GPa Detonation product’s index, n 1.5 ~ 3.2 Reaction time, tR 0.4 ~ 0.8 μsec Detonation energy, Q 0.6 ~ 1.4 kJ/g Q = D2/(2(n2-1))

Acceleration of Plate by Sliding Detonation To study the throwing ability of emulsion explosives it was determinate the 2D X-Y profile of test copper plate (inclined resistive wire method) 1 – Nichrome wire 40 μm 2 – copper plate 1 mm 3 – plane layer of explosive 4 – pins 5 – detonation front

Comparisons of 2D Experimental and Computed Plate Profiles Experimental profiles P ~ ρn Hydrodynamic approximation 2D numerical calculations with n - target values n value Bend angle Plate velocity Solid curves – experiments, markers – 2D calculations

n - index of Detonation Products (a) 1 – cylindrical and 2 – flat charges (b) μ = 8 (3), 20 (4), 50 (5) wt. % For developed emulsion explosives n – index depends on the initial density and on the thickness of flat layer of explosives

Results of lateral acceleration The plate velocities are ranged from 0.5 up to 1.3 km/sec, and the bend angles from 10 to 27 degrees. These collision values are close to the necessary ones to explosive welding of metals.

Explosives Cladding by foils Clad layers: foils 100-300 μm – aluminum, titanium, stainless steel, bronze, nickel, copper, molybdenum Emulsion explosives: 2-3 or 6-12 mm (T), 50 mm (W), up to 300 mm (L) Base plate: copper, mild steel Bronze 0.29 mm/steel 10 mm, Expl = 3.4 mm After shot Without shock buffer layer between explosives and foil

Emulsion Explosives Cladding by Foils exp = 3 mm Al 0.2 mm / Copper exp = 2 mm 0.1 mm exp = 2.7 mm Cu 0.2 mm / Steel 0.2 mm 100  Ni 0.3 mm / Steel 1 mm exp = 3 mm exp = 12 mm Ti 100 μm / stainless steel Mo 200 μm / steel Cu 1 mm / steel  ≈ 150-200 m, a/ ≈ 0.1-0.2 VC = 2.0 – 3 km/sec, Δexp = 2 – 12 mm

Explosive Welding Tube to Collar pressing-out, r = 0.27 air gap welding, r = 0.32 Ø11 мм section of the connection zone wavy seam model of tubeplate is the mild steel sleeve stainless steel tube, Ø12.5/11 mm explosive cartridge: < 11 mm in diameter, D ≈ 3 km/s, 0.75 g/cc The thermal welding to pressurize the tube/sleeve connection is not needed

Results Emulsion explosives with a detonation velocity of 2–3.5 km/sec, detonation pressure of 0.7-2.0 GPa and high detonation ability are developed Emulsion explosive based on fine emulsion has a very small critical diameter if the charge is enclosed to strong casing Two applications of the low velocity detonation emulsion explosives for explosive welding are tested: cladding of metals by foils up to 0.1 mm in thick welding of small diameter tubes to a tube collar

Thank You for Attention Acknowledgments The work was supported by the RFBR (grant # 09-08-00164-a), by the Siberian Branch of RAS (project 2.10), and partially by the Grant of President of the Russian Federation (project NSh-5770.2010.1) Thank You for Attention

X-ray picture of detonating charge Cylindrical charge 20 mm in diameter, 0.5 g/cc, Detonation pressure 0.7-0.8 GPa D = 1.9 km/sec Detonation front tR < 0.5 μsec, aR < 1 mm Bend angle of casing (PE 0.7 mm + 30 μm Lead)  35 º

Optical Fiber Technique for VOD measuring at d<4 mm Pins L/d = 20 – 35 Detonation cord 3 fibers Contact / ion pins Optical fibers