Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge

Boron-potassium nitrate (B-KNO3) (25/75) is a well-known pyrotechnic composition whichfinds application as energy-release system for small-calibre rockets and pyrogen igniters forlarger motors. The decomposition of the oxidiser in this composition is endothermic which canbe activated by the addition of high explosives, which decompose exothermically. This paperdescribes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristicsof B-KNO3 composition using thermogravimetry, differential scanning calorimetry, heat andpressure output measurements. Different compositions were prepared by varying the amount ofRDX/HMX from 10 per cent to 50 per cent. Thermal studies on the B-KNO3/high explosivemixtures reveal that these undergo two-stage decomposition. The first stage corresponds to thedecomposition of high explosive and the second stage corresponds to that of the reaction betweenB and KNO3. Kinetic parameters were calculated for both the stages of TG curves using Coats-Redfern and Mac Callum-Tanner methods. Ignition temperature of B-KNO3 decreases on theaddition of RDX/HMX while the onset of RDX or HMX decomposition is not significantly affectedby B-KNO3. The pressure output of B-KNO3 increases on adding RDX/HMX. The heat outputof B-KNO3 is not much affected by the addition of RDX or HMX, even though the heat ofexplosion of RDX and HMX are low. This is due to the reaction between the combustion productsof RDX/HMX and reaction products of B-KNO3 to form more exothermic products like B2O3,releasing extra heat. The flame temperature of the charge increases while the average molecularweight of the products of combustion decreases as the RDX/HMX content increases. Thus, thecharge, on addition of RDX or HMX, produces higher pressure output, maintaining the heatoutput at comparable levels

Detonator using Nickel Hydrazine Nitrate as Primary Explosive

Nickel hydrazine nitrate is an energetic coordination compound having explosiveproperties in between that of primary and secondary. This compound was used to develop a newtype of detonator by replacing the sensitive primary explosive, lead azide in conventionaldetonators and keeping RDX (cyclotrimethylenetrinitramine) as the output secondary explosive.The detonator consists of three regions, viz., initiation, deflagration-to-detonation transition(DDT), and output. The initiation and the electrical rating of 1A/1W no-fire were achieved usinga suitable squib. The DDT and the output were taken care of, by pressing requisite quantitiesof Nickel hydrazine nitrate and RDX, respectively at required densities in a stainless steel stemchannel. The detonator assembly involves crimping the squib and the stem channel in a stainlesssteel housing and applying a suitable resin at the crimped-end for leak tightness. The outputwas assessed from the dent depth on aluminium plate, volume expansion on lead block, and byachieving veloctiy of detonation of 8200 m/s in mild detonating cords, containing 0.95 g/m ofRDX, which indicates full-order detonation. The detonators were tested at system level andfound to perform satisfactorily