RDX BASED HIGH-ENERGY TEGDN/NG PROPELLANT FOR TANK GUNS

摘要

TEGDN/NG propellant is a commonly used propellant for various weapon systems. It is well known for its high energy and good mechanical properties at low temperatures due to the effect of TEGDN. A number of compositions based on RDX, NC, NG ,TEGDN and combinations thereof were formulated and studied with the aim to select the suitable composition for advanced tank guns in respect of energy, ballistic performances and mechanical properties. Theoretical thermochemical properties of the compositions were computed using the REAL software and a 'THERM' programme, and a composition with a relative higher thermal performance was selected as a standard composition of TEGDN/NG propellant. An experimental investigation focused on the effect of 7.6μm RDX content (from 10% to 40%) on the ballistic performances and mechanical properties was carried out for assessing the suitability for application. The ballistic performances were evaluated on the basis of closed vessel tests at 0.20 g/cm~3 loading density at 20 °C and -40 °C, and bomb calorimeter was used to measure the explosion heat. Testing using universal material testing machine was conducted to study the impact strength of the compositions at 20°C and -40 °C, and the fracture surface was characterized using scanning electron microscope. Results obtained indicate that the incorporation of 5 percent RDX resulted in the enhancement of force constant by about 13 J/g and explosion heat around 45 K. The force constants of compositions containing RDX (mass fraction ＞25%) were larger than 1204 J/g (theoretical) and the explosion heat larger than 4740 J/g. The impact strength decreased with the increasing RDX content and that of the composition containing 25% RDX is 8.49 kJ/m~2 at -40°C. The average burning rate at 20°C increased with the increasing RDX content, while the pressure exponent increased from 0.95488 till to 1.0078 (25%RDX) and then decreased to the bottom 0.99245, and the linear rate of burning coefficient played on the contrary. The combustion performance at -40 °C was steady and had the same tendency compared to that at 20°C.