复合固体推进剂老化特征研究进展

对复合固体推进剂老化特征及其影响因素以及在老化研究中常用试验方法和寿命预估方法进行了概述,详细阐述了国内外HTPB(端羟基聚丁二烯)、NEPE(硝酸酯增塑聚醚)、叠氮聚醚3种不同黏合剂体系推进剂老化性能的研究进展和相关结论。     

复合固体推进剂老化研究

针对复合固体推进剂的老化问题,探讨了复合固体推进剂老化的主要因素;从复合固体推进剂组分的影响、环境湿度、储存温度等方面分析了其影响复合固体推进剂老化的机理;综述了复合固体推进剂贮存寿命的几种预估方法:力学性能法、阿累尼乌斯方程式法、凝胶含量法、傅里叶红外光谱法和动态粘弹法,并对这些研究方法的内容和结果可信度进行了分析。最后对复合固体推进剂老化研究的发展趋势进行了展望。     

某型号导弹固体发动机贮存使用寿命研究

利用推进剂方坯加速老化试验对某型号导弹固体发动机进行了推进剂贮存寿命预估。通过对试验数据的分析,建立了固体推进剂老化速率的动力学方程,预估了固体推进剂的贮存寿命。结果表明,推进剂在25℃下贮存10 a后最大伸长率(εm)为31.57%,与起始εm比较,仅下降了27%,满足发动机安全使用要求。     

丁羟推进剂的热加速老化力学性能及寿命预估

用单轴拉伸试验和扯离试验测试了不同老化温度(55、65、75和85℃)下热加速老化后丁羟(HTPB)推进剂的力学性能及其粘接试件的扯离强度,用Berthlot方程预估了推进剂及其粘接试件的寿命。结果表明,HTPB推进剂的最大延伸率随老化时间的增加呈现降低趋势;老化温度越高,推进剂的最大延伸率降低幅度越大,85℃贮存30d时最大延伸率降幅为29.81%,而55℃贮存30d时最大延伸率降幅仅为4.34%;粘接试件的扯离强度随着老化时间的增加呈降低趋势,老化时间相同时,扯离强度随老化温度的升高而降低。预估HTPB推进剂和推进剂粘接试件的贮存寿命分别为9.4y和15.9y。     

复合固体推进剂老化性能研究综述

从传统老化特征研究、化学老化特征研究和贮存寿命预估3个方面对复合固体推进剂老化性能的研究现状进行了综述。其中,传统老化特征研究包含力学老化特征、图像老化特征和组分含量老化特征3个方面,化学老化特征研究包含特征官能团测定、化学老化的分子模拟分析以及气体含量监测分析3个方面。同时从研究对象、老化特征提取、分子模拟分析和寿命预估模型无损性4个方面对推进剂老化性能的研究进行了总结与展望。     

预估FH－94固体推进剂使用寿命置信下限的研究

通过提高温度，模拟贮存条件下的老化，获得伸长率变化速率与老化时间和温度的关系，以单向拉伸性能伸长率的下限值作为推进剂的寿命终点判据，在一定置信度下，预估了２０℃和２５℃下ＦＨ－９４固体推进剂的使用寿命置信下限。     

复合推进剂老化研究的若干问题

针对复合推进剂老化研究的若干问题作了简要的概述，并在此基础上提出了建议。主要涉及以下三个方面：（1）拓宽复合推进剂防老化措施的领域；（2）增强防老剂的作用效果；（3）开展推进剂老化贮存寿命预估方法的研究等。     

固体火箭发动机海洋环境下的贮存及寿命预估

分析了海洋环境的特点及其对固体火箭发动机贮存性能的影响,并进行了推进剂的湿热老化试验。基于累积损伤模型和艾林（Eyring）寿命模型,建立了Eyring-累积损伤模型。用该模型预估了固体火箭发动机在恒温和交变温度载荷下的寿命。研究表明,Eyring和Arrhenius两种累积损伤模型在恒温载荷下的应用效果是比较一致的;交变温度幅值的变化对寿命的影响较大,即昼夜温差和年温差越大,寿命损失越大。     

湿热条件下复合固体推进剂老化特性研究

为研究HTPB(端羟基聚丁二烯)、NEPE(硝酸酯增塑聚醚)2种复合固体推进剂在湿热贮存环境中的老化机理,开展了77%相对湿度、60℃和77%相对湿度、20℃条件下的贮存老化试验,实时监测了推进剂最大抗拉强度、冲击感度、邵氏硬度、热老化过程中质量的变化规律。研究发现:2种推进剂在湿热贮存环境下,最大抗拉强度随老化时间的延长持续下降;黏合剂分解是造成2种推进剂硬度变化的主要因素,且HTPB推进剂内部黏合剂受影响更大;NEPE推进剂冲击感度随老化时间增加逐渐降低,而HTPB推进剂则存在感度值回升现象;2种推进剂在湿热环境中质量均增大,且HTPB推进剂吸湿性更强。     

固体推进剂老化性能研究进展

研究固体推进剂的老化性能,预测其安全储存寿命,对弹药安全储存具有重要意义。本文从固体推进剂的老化性能机理、影响因素、测试方法以及储存寿命预测等方面综述了近年来国内固体推进剂老化性能的研究进展,认为固体推进剂的老化失效主要是由黏合剂氧化交联所致,推进剂自身的组成、结构和力学性能是决定其老化性能的内因,而外部因素主要有环境温度、湿度等。研究手段多采用分析仪器与实验相结合的方法,以缩短实验周期,提高结果准确性。以计算机为载体的多尺度模拟研究将是今后固体推进剂性能研究的重点。     

Characterization of Aging Behavior of Butacene® Based Composite Propellants by Loss Factor Curves

Butacene® is a polymeric binder with ferrocenyl groups chemically bonded to HTPB backbone. Through incorporation in the AP−Al composite propellant formulation, it leads to high burning rates (BR) >20 mm/s at 7 MPa, and low pressure exponents n<0.5, allowing more flexibility to the rocket design, keeping the characteristics (process, mechanical properties, pot‐life) of HTPB binder formulations together with a lower vulnerability (IM) contribution by Butacene®. The key molecular level characteristic of such HTPB based elastomeric binder systems of solid composite rocket propellants (SCRP) is the glass‐rubber transition region, which is mainly defined by the molecular mobility of the components in the polymeric network during the transition from energy to entropy elasticity with respect to temperature. The molecular rearrangement regions or binder mobility fractions related to the glass‐rubber transition of such composite propellants during storage are important in terms of in‐service time estimations. They are detectable by dynamic mechanical analysis (DMA). Formulations with and without Butacene® were prepared and analyzed using the loss factor curves obtained by torsion DMA. A special modelling with so named Exponentially Modified Gaussian (EMG) distribution was used to define and quantify sub‐transition regions in the loss factor curve. SEM images revealed the network formation connected with AP bonding, which correlate to the tensile results. DMA loss factors revealed a strong oxidation with Butacene® containing formulations during aging. Burning rates of the formulations show slight increases with aging.     

Effect of Pre‐strain Aging on the Damage Properties of Composite Solid Propellants based on a Constitutive Equation

Accelerated aging tests under pre‐strain were conducted on HTPB‐based composite solid propellant with the goal of investigating the effect of pre‐strain aging on its damage properties. A statistical damage constitutive model based on continuum damage theory and statistical strength theory was established. The aging damage coefficient, making aging process of propellant equivalent to a form of damage, was introduced to correct the damage variable. Experimental results show that theoretical model has good agreement with experimental results and can accurately describe the mechanical behavior of propellant during pre‐strain aging. Further analysis indicated that the damage effects caused by pre‐strain can be identified from the equation of the aging damage coefficient. Aging time influences both tensile strength and shape characteristics of the stress‐strain curve of propellant in the damage stage, while pre‐strain only decreased the tensile strength. The strain damage threshold value decreased linearly over the aging period and with increasing pre‐strain level during the aging process.     

Prediction and Comparison of Shelf Life of Solid Rocket Propellants Using Arrhenius and Berthelot Equations

The Arrhenius equation and the Berthelot equation for the prediction of shelf life of composite propellant formulations are compared. The elongation has a measurable variation with time and is taken as the fastest degrading parameter for HTPB/AP/Al based composite solid rocket propellants. An HTPB based aluminized composite propellant with 85 % solid loading and an initial elongation of 63.24 % is prepared. It is kept at an elevated temperature of 60 °C to achieve a higher rate of degradation for a prolonged time period (1 year). The elongation is monitored at regular intervals using JANNAF class C dog bone specimen in uni‐axial tensile mode. A reduction of the elongation to less than 50 % is taken as the end‐of‐shelf life of the propellant. The shelf life of the propellant is calculated to be 1.2 years at 60 °C. For the extrapolation of the shelf life at 60 °C to the shelf life at 27 °C, the results of both the Arrhenius equation and the Berthelot equation are compared. The activation energy (E) in the Arrhenius equation is obtained as 72.8 kJ mol⁻¹ and the 10 °C reaction rate rise factor (γ₁₀) is found to be 2.4. This comparison is independent of the propellant formulation and other researchers have reported a similar range of values for these parameters. The shelf life of this propellant formulation at 27 °C is conservatively predicted to be 20 years using both equations. In addition to estimation of shelf life by both equations using elongation as control parameter, this paper gives scaling curves, which are valid universally for predicting shelf life at 27 °C from data of shelf life at 60 °C. The use of scaling curves is independent of properties, propellant formulation and degradation mechanism considered for analysis.     

高固体含量高强度丁羟推进剂工艺调节技术研究

阐述不同燃速的高固体含量高强度丁羟推进剂的工艺调节技术,研制出了中低燃速、中燃速和高燃速3种燃速范围,固体质量分数≥90%、20℃最大抗拉强度≥2.5MPa的丁羟推进剂配方,其工艺性能良好,并成功应用于高性能固体火箭发动机。     

湿度对丁羟推进剂及其粘接性能的影响研究

固体火箭发动机燃烧室内绝热层、人工脱黏层及推进剂药柱,均为高分子材料复合体系。在成型及贮存过程中,湿度是影响丁羟推进剂药柱性能及各界面的联合粘接强度的首要因素。探讨了绝热层、衬层及推进剂药柱在不同环境湿度下的吸湿特性,通过模拟实际生产过程的环境湿度,研究了丁羟推进剂药柱性能及各界面的联合粘接强度变化状况。     

BuNENA含能增塑剂的性能及应用

BuNENA(N–丁基硝氧乙基硝胺)是一种性能优良的新型含能增塑剂,在枪炮发射药和火箭推进剂应用中均受到研究者的广泛关注,并被进行系统研究。在发射药中,BuNENA具有塑化能力强、工艺性能好、感度低、能量高等优点,能进一步提高配方力学性能,其应用前景广阔。而在HTPE(端羟基聚环氧乙烷–四氢呋喃嵌段共聚醚)火箭推进剂中,BuNENA已被证明是一种对提高能量、降低感度和提高推进剂力学性能等具有明显作用的新型含能增塑剂,使用HTPE/BuNENA黏合剂体系的钝感固体推进剂的综合性能优于HTPB/AP(端羟基聚丁二烯/高氯酸铵)推进剂,并可满足钝感弹药(IM)要求,已在各种战术发动机中获得了实际应用。     

Use of Dynamic Mechanical Measurements to determine the aging behavior of solid propellant

A process for determining the aging characteristics of solid rocket propellants by measuring their dynamic mechanical properties is described. Samples of rocket propellant are tested using a mechanical spectrometer at low strain levels and low frequencies. The change in the dynamic storage modulus of the propellant with aging time and temperature is used to determine the aging rate anf the likely mechanisms occuring during aging. The technique is advantageous is several respects:

• (1) because the tests are non-destructive and use small test specimens, and entire aging program can be conducted using much less propellant than is required ihn traditional aging programs (propellant requirements are reduced by more than an order of magnitude)
• (2) the technique can be applied to samples with unusual or unique geometries which cannot be tested using traditional methods;
• (3) test specimens can be obtained directly from live, operational solid rocket motors, and service life and mechanical property degradation can be determined.

     

Viscosity Prediction of Composite Solid Propellant Slurry

The viscosity of composite solid propellant slurry is an important parameter in charging technical performance of solid rocket motors. It is affected not only by the liquid phase ingredients of propellants, but also by the size, content, shape and surface properties of solid fillers in propellants. This paper will present a prediction formula of viscosity of composite solid propellant and will also give a method for calculating the maximum packing volume fraction of solid in the formula. One can predict the viscosity of propellant slurry with the formula if the composition of the propellant is known.