Recent advances in catalytic combustion of AP-based composite solid propellants

Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(MOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of combustion catalysts in burning rate enhancement. Available information on different types of combustion nanocatalysts is also presented with critical comments.

Degradation of Disposal Hydroxyl-Terminated Polybutadiene Composite Solid Propellant

With the greatly increasing amount of discarded hydroxyl-terminated polybutadiene(HTPB)propellant year by year,it is of high significance to study the safe,efficient and environmental processing method of disposal HTPB propellant.In this paper,the decomposition agents are formulated for degrading the waste composite solid propellant.It is found that the following formulations of butanone 25%-55%,xylene 30%-75%,deionized water 40%-45%have effective influence on the degradation of the waste composite solid propellant.The proper degradation time is found to be about 7-8 h.With the help of infrared spectrum analysis,scanning electron microscope imaging,thermogravimetric analysis and solvent viscosity test,it was proved that after degradation reaction on the propellant sometimes,a large number of irregular fractures occurred in bulk resulting from effective degradation.The characterization of the propellant after degradation showed that the hardness of the propellant decreased,the viscosity increased,and a large number of holes and cracks appeared on the surface.The results showed that the formulated degradation agent and degradation condition perform good degradation effects on HTPB solid propellant.

Energetic Opportunities of Solid Composite Propellants Containing Some Hypothetic Furazano-[3,4-d]-pyridazine-based Derivatives

Six furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants have been investigated.It was shown that the use of some furazano-[3,4-d]-pyridazine-based derivatives as main compounds in solid composite propellants can considerably increase ballistic parameters compared with HMX if the compounds under consideration contain difluoramine groups.And the use of the compounds under consideration may be successful only in the presence of an active binder and 10%-30% of AP or ADN as additional oxidizers.

Ballistic Properties of Some Low Solid Loading Butalites Formulations

The ballistic properties of a low solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB） as fuel binder main backbone, mono and bi-modal system ammonium perchlorate oxidizer （AP）, copper chromite （CC） as burning rate accelerator and aluminum powder （A1） as metallic fuel. Higher pressures and AP contents as well as smaller AP particle size were found to increase burning rate. The same behavior verified with AI and CC addition. A significant increase of burning rate was recorded when CC added to the aluminized formulations compared with the non-aluminized of the same oxidizer solid loading and particle size.

Combustion Properties of Some High Solid Loading Butalites Compositions

The combustion （ballistic） properties of a high solid loading composite solid propellant family （Butalites） was studied experimentally by using propellant formulations based on hydroxy-terminated polybutadiene pre-polymer （HTPB） as a fuel binder main backbone, bimodal system ammonium perchlorate oxidizer （AP） and aluminum powder （AI） as metallic fuel. Burning rates were doubled at various pressures, when solids loading （AP and 17% A1） were increased from 80 to 88% and the measured characteristic velocity values were increased by about 100m/sec. The pressure exponent （n） values were lower with 80-85% solids loading. The burning rates were increased by about 2-5% when comparing the data obtained by static firing with those obtained by the strand burner method.

一种有效评估推进剂药柱老化的方法(英文)

Physical properties of composite propellants used in solid rocket motors change significantly with age. To predict the margin of safety and to reevaluate the remaining service life, the structural integrity analysis of solid propellant grains of aged rocket motors is performed at various stages of their life span. To have the reliable results from these analyses, it is mandatory to use the current physical properties of the propellant at the time of analysis. Change in physical properties due to aging is more significant at exposed surfaces. Traditional methods of assessing current physical properties may not truly rep resent the properties of the batch. The paper presents a novel technique to measure the stress strain response at the exposed surface of propellant grain using a miniature-testing device. This specially designed device is able to measure the stress response while the propellant surface is compressed at a constant rate. This measured stress strain behavior is then co-related with the physical properties measured by routine tensile tests of the similar type of propellant which is aged artificially. It is observed that there exists an excellent correlation between the measured stress values by the sensor and physical properties measured by uni-axial tensile test. This nondestructive technique provides properties of propellant grains of all the motors in the batch comprehensively. The technique is safe as well as economical as compared to the traditional methods.