Nickel hydrazine nitrate

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Nickel hydrazine nitrate (NHN), (chemical formula: [Ni(N2H4)3](NO3)2) is an energetic material having explosive properties in between that of primary explosive and a secondary explosive.[1] It is a salt of a coordination compound of nickel.

Preparation[edit]

NHN can be synthesized by reacting nickel nitrate with a dilute aqueous solution of hydrazine at 65 C.[2] To help speed the drying of the product after filtration from the hot water, it can be rinsed with alcohol. The product is a fluffy powder (density=0.9 g/cm3). To increase its bulk density ( 1.2 g/cm3), dextrin can be added.[3]

Non-primary explosive detonator (NPED)[edit]

NHN needs minimal confinement to properly make the deflagration to detonation transition (DDT). Thin steel / aluminum tubing with dimensions 5/16" OD, 0.273" ID (a 0.020" wall thickness) is sufficient for NHN to make the DDT.[1] Properly made NHN will even detonate in a plastic tube with a sensitive secondary like powdered ETN to set off melt-cast materials such as ETN, PETN, or RDX. Using powdered ETN as a transition explosive completely eliminates the need to use a primary explosive in the detonator thus making an NHN based detonator a true NPED.

Safety[edit]

NHN straddles the line between primary and secondary. Because of this it is a relatively safe explosive to work with having much less sensitivity to shock and friction (16.0 N) than Lead Azide (0.1N) as shown in table 2.

Friction sensitivities of some traditional explosives (lead azide – 0.1N; lead trinitroresorcinate – 1.5 N; mercury fulminate (white) – 5,0 N; tetrazene – 8.0 N; PETN – 60 N; hexogen – 120 N; octogen – 120 N, show that NHN is not very sensitive, and is thereby not exceedingly hazardous in handling.[4]

Table 1. General and structural properties of Nickel hydrazine nitrate[1][edit]

Molecular formula Ni H12 N8 O6
Formula weight 278.69
Color Purple Violet
Crystal density (g/cm3) 2.1
Average particle size (μm) 13
Nickel content (%) 21.16 (21.06) a
Hydrazine content (%) 34.46 (34.45) a
Nitrate content (%) 44.47 (44.49) a
Nitrogen content in coordination sphere (%) 30.25 (30.14) a
FTIR peaks, (cm−1) 3238, 1630 (NH2); 1356,1321 (-NO3)
Moisture content (at 333 K for 10 min) (%) 0.34
Average mol wt of combustion products 27.35
Percent condensable Ni (l) 18
Oxygen-fuel ratio 0.8571
Oxygen balance % -5.74

a Values in brackets are theoretical

Table 2. Comparative properties of Nickel hydrazine nitrate and lead azide[1][edit]

Property Nickel hydrazine nitrate a Lead azide b
Density (g/cm3) 2.129 4.38
Oxygen balance (%) – 5.74 c – 5.50
Heat of combustion (kJ/kg) 5225 2635
Heat of formation (kJ/mol) – 449 469
Heat of explosion (kJ/kg) 4390 1610
Pressure output in closed vessel (100 mg in 48 cm3) (kg/cm2) 17.5 8.2 c
Onset of decomposition (K) 505.7 463
Peak of decomposition (K) 506.5 618
Friction sensitivity (kg f) 1.6 0.02
Impact sensitivity (cm, 400 g wt, 20 mg sample, 50% explosion) 21 b 10.5
ESD sensitivity (J) 0.02 b 0.003
Vol. of detonation gases (ml/g) 884 c 308
Detonation temperature (K) 2342 c 5600
Detonation pressure (GPa) 20.8 c (1.7 g/cm3) 16.1 (3.0 g/cm3)
Detonation velocity (m/s) 7000 b (1.7 g/cm3) 4630 (3.0 g/cm3)
RE Factor 1.05 b (1.7 g/cm3) .8 (3.0 g/cm3)

a Experimental value, b literature value, and c theoretical value

References[edit]

  1. ^ a b c d Hariharanath, B.; Chandrabhanu, K. S.; Rajendran, A. G.; Ravindran, M.; Kartha, C. B. (2006). "Detonator using Nickel Hydrazine Nitrate as Primary Explosive". Defence Science Journal. 56 (3): 383–9. doi:10.14429/dsj.56.1904.
  2. ^ Chhabra, J.S; Talawar, M.B; Makashir, P.S; Asthana, S.N; Singh, Haridwar (2003). "Synthesis, characterization and thermal studies of (Ni/Co) metal salts of hydrazine: Potential initiatory compounds". Journal of Hazardous Materials. 99 (3): 225–39. doi:10.1016/S0304-3894(02)00247-9. PMID 12758009.
  3. ^ "NOPR: Studies on nickel hydrazinium nitrate (NHN) and bis-(5-nitro-2H tetrazolato-N2)tetraamino cobalt(III) perchlorate (BNCP): Potential lead-free advanced primary explosives". Nopr.niscair.res.in. Retrieved 2017-03-31.
  4. ^ http://www.chemikinternational.com/pdf/2011/01_2011/chemik_2011_65_1_24-27.pdf