Evaluation of Nano‐Co₃O₄ in HTPB‐Based Composite Propellant Formulations

Abstract

[a] 1IntroductionComposite propellants are composed of an elastomeric polymeric binder,i nw hich solid particles, such as oxidizer, fuel, and additivesa re incorporated.R ockets and missiles are propelled by composite propellants.T hey basically contain an oxidizer,m ainly ammonium perchlorate (AP), ab inder such as hydroxyl terminated polybutadiene (HTPB), and am etallic fuel like aluminum powder along with certain process aids as well as ballistic modifiers [1]. The burning rate of composite propellants is considered to be one of the most important properties governing the ballistic performance of solid rocket motors,w hich in turn dependsm ostly on particle characteristics of oxidizers, burning rate catalystsa nd metallic fuel [2].T oa chieve the desired burning rate of composite propellant formulations, the amount of oxidizer,p article size of oxidizer,a nd burning rate modifiers are used as variables. AP is used in composite propellantf ormulationsa st he major ingredient (oxidizer) [3] in different size fractions to enhance the burning rate. However,f ine and superfine particle fractions of AP increase the burning rate as well as the propellant slurry viscosity thus casting of slurry becomes difficult [4].Therefore, to cope with suchp roblems, burning rate modifiersa re preferred. The burning rate modifiers are transition metal oxides (TMOs) or their complexes. The burning rate modifiers added in small quantities affect the burning rate by lowering the thermald ecomposition temperature of AP and binder [5].T he effect of transition metal oxides on thermal decomposition of ammonium perchlorate has been studieda nd reviewed in literature [5,6].M any researchersh ave studied in detail the effect of TMOss uch as Fe 2 O 3 ,C uO, Co 2 O 3 ,N iO, and Cr 2 O 3 over ballistic properties of propellant mainly on burning rate behavior and found substantial increase in burning rate [7,8] [16].A lso, the number of nanoscale catalyst, Abstract:D ifferentp ropellant compositions were prepared by incorporatingn ano-sizedc obalt oxide from 0.25 %t o 1% in HTPB/AP/Al-based composite propellant formulations with 86 %s olid loading. The effects on viscosity buildup, thermal, mechanical and ballistic properties were studied. The findings revealed that by increasing the percentage of nano-Co 3 O 4 in the composition,t he end of mix viscosity,t he modulus and the tensile strength increased, whereast he elongation decreased accordingly.T he thermal property data envisaged ar eduction in the decomposition temperature of ammonium perchlorate( AP) as well as formulations based on AP.T he ballistic property data revealed an enhanced burning rate from 6.11mms À1 (reference composition) to 8.99 mm s À1 at 6.86 MPa and am arginal increase in pressure exponent from 0.35 (reference composition) to 0.42 with 1% nano-cobalt oxide.

Thermal Property Enhancement of Paraffin-Wax-Based Hydroxyl-Terminated Polybutadiene Binder with a Novel NanoSiO2-Expanded Graphite-PW Ternary Form-Stable Phase Change Material

“…As is known, PW has been widely used as fuel and desensitizer in hybrid propulsion and polymer-bonded explosives (PBX), owing to the high burning rate, low cost, and superior desensitization effect. − In addition, hydroxyl-terminated polybutadiene (HTPB) was preferred to be fuel or binders since it could provide easy availability, desirable manufacture, and polymeric properties required by hybrid propulsion and PBX. − Sinha et al investigated the ablation rate and thermal and mechanical properties of HTPB blended with different percentages of paraffin. Nevertheless, there is much difference in molecular weight and polarity between HTPB and PW, resulting in weak compatibility between the two phases .…”

Chemical Modification of Hydroxyl-Terminated Polybutadiene and Its Application in Composite Propellants

“…HTPB propellant is a type of composite solid propellant with hydroxyl-terminated polybutadiene (HTPB) as a polymeric binder. Because of its technical maturity, low cost, and good combination property, it is widely applied to various strategic and tactical solid missiles. − At present, the propellant is developing toward high thrust and strong antioverload capability, which requires the solid propellant used to have both high energy density and good mechanical properties. , Meanwhile, in practice, some new booster rockets and cruise missile engines also need the propellant to have a lower burning rate to ensure long-term sustained and stable thrust. , …”

Preparation of Ta(Ph)‐Fe/AP Composite Microspheres by Ultrasonic Spray Drying and Characterization of Their Catalytic Properties

“…Ammonium perchlorate (AP) is an important energetic material and is commonly used as an oxidant for solid propellants . The thermal decomposition characteristics of AP have a very important influence on the combustion performance of the propellant because AP accounts for 60 %–90 % of the total mass of the solid propellant .…”