炸药热冲击损伤破坏及超声波特性参量检测

进行了 JOB- 90 0 3炸药试样的热冲击试验和热冲击前后的超声波特性参量检测试验 ,观察并检测到试样在热冲击试验的不同阶段出现损伤破坏及超声波特性参量的具有一定典型性的变化。试验初步表明 ,初始损伤或裂纹对炸药的力学性能有十分明显的影响 ,超声波特征参量对炸药的损伤及破坏进一步表现出一些可识别的特征     

JOB-9003炸药的载荷环境试验

在5 MPa轴向压应力条件下,对JOB-9003炸药进行了温度循环试验,结果表明,试验后炸药性能发生了明显的变化.JOB-9003炸药在载荷环境和温度循环的共同作用下其径向尺寸增加,轴向尺寸减小,而且径向尺寸的增加量与轴向尺寸的减小量相当.与轴向尺寸相比,径向尺寸对样品体积的影响更大,试验后样品体积变大,密度降低,同时炸药的压缩强度、最大蠕变应变和压缩蠕变断裂时间出现了明显降低,而模量变化不明显.分析认为,JOB-9003炸药内部的微孔隙和微损伤在载荷环境试验下发生变化,从而使JOB-9003炸药的尺寸、密度和力学性能出现了上述变化规律.     

HMX基PBX的温度环境适应性

对HMX基PBX进行了-40～+75℃温度循环试验和温度冲击试验,采用超声波参量检测方法对炸药的内部损伤进行了分析和表征。并对环境试验前后炸药的力学性能和破坏方式进行了实验研究。结果表明,温度循环试验和温度冲击试验将导致HMX基PBX产生热损伤,使HMX基PBX压缩强度轻微下降,而对拉伸强度影响不大。     

JOB-9003炸药释出气体研究

采用固相微萃取(SPM E)、GC、GC/M S技术,对JOB-9003炸药及Φ10 mm×8 mm小药柱加速老化贮存初期释出气体进行了研究。检测到的气体物质主要包括JOB-9003的各组分生产过程中使用的溶剂和原料、JOB-9003造粒过程中使用的溶剂、JOB-9003的组分、JOB-9003释出物质互相反应的产物。研究表明,JOB-9003加速老化贮存初期释出气体以生产过程中被封闭在材料中或溶入材料中的气体为主。随着贮存温度的升高和贮存时间的延长,JOB-9003造型粉及小药柱释出的各种气体组分的浓度大都呈升高的趋势。     

多组分气体在JOB-9003炸药表面吸附的动力学模拟

为研究多组分气体(CO2、H2O、HCHO、HCN、N2、O2)在JOB-9003炸药(1 0 0)、(0 1 0)、(0 0 1)晶面的吸附机理以及对炸药力学性能和感度的影响,用MS软件构建炸药模型,采用分子动力学(MD)方法得到气体在炸药表面的吸附量和吸附结构,分析了吸附后气体分子与JOB-9003表面分子的径向分布函数,计算了吸附前后引发键的键长分布和炸药体系的弹性系数。结果表明,(1 0 0)晶面的吸附能力最强;多组分气体在晶体表面发生竞争吸附,吸附量由多到少依次为H2O、HCN、CO2、N2、O2、HCHO,这主要与气体分子与炸药表面分子间形成的氢键、分子的极性、气体分子的体积有关;JOB-9003炸药表面吸附的多组分气体使炸药的撞击感度和热感度升高;吸附后炸药的韧性减弱,刚性降低,力学性能变差。     

PBX炸药细观损伤的实验研究

为研究PBX炸药在冲击作用下的物理损伤、化学损伤及成热的物理机制,采用炸药爆炸驱动隔板实验技术对PBX炸药进行了冲击压缩实验,回收炸药试样并对其不同位置处的断面形貌进行SEM分析.结果表明,随着冲击能量的增加,其温度效应的影响越来越显著,损伤模式从物理损伤向化学损伤过渡.这为XDT问题中的"热点"形成机制等研究提供了实验基础.     

用小药量至爆时间试验研究炸药爆发分解反应动力学

用小药量至爆试验测定了10种炸药:单质炸药3-硝基-1,2,4-三唑-5-酮(NTO)及其铵盐(ANTO)、铅盐(PbNTO)、钾盐(KNTO)、乙二胺盐(ENTO)、混合炸药JO-6、JOB-9003、JP-1、JD-1、JH-16在不同温度下的爆发延滞期(t_(ind)).依据谢苗诺夫方程lnt_(ind,i)=(E_σ)/(RT_i),-lnA_,由lnt_(ind,i)对1/T_i的关系,用最小二乘法计算了爆发分解反应的表观活化能(E_α)、指前因子(A_σ)和1 000 s时的热爆炸临界温度(T_b).用非线性等转化率积分法所得的表观活化能(E_σ)校验了由lnt_(ind,i)~1/T_i关系得到的E_σ值.借助热力学关系式,计算了爆发分解反应的活化反应热力学参量[活化自由能(ΔG~≠),活化焓(ΔH~≠)和活化熵(ΔS~≠].结果表明:(1) 以T_b和ΔG~≠作判据,知5种单质炸药和5种混合炸药的对热抵抗能力次序分别为:NTO＞ENTO＞ANTO＞KNTO＞PbNTO和JP-1＞JD-1＞JO-6＞JOB-9003＞JH-16;(2) E_α=E_α的事实佐证不同温度下爆发分解反应延滞期内分解深度相等,由此所得A_σ值可信,谢苗诺夫方程推导过程中A_σG(α)的假设合理.     

一种含LLM-105的HMX基低感高能PBX炸药

研究了不同颗粒形态的LLM-105对HMX的降感作用以及HMX/LLM-105基炸药配方用的黏结体系和钝感体系.设计出一种HMX/LLM-105配方,采用机械感度和冲击波感度以及板痕试验和圆筒试验对其安全性能和爆轰性能进行了测试.结果表明,LLM-105可作为含能钝感剂用于HMX基PBX炸药,该种含LLM-105的HMX基PBX爆速约8700 m/s、爆压34 GPa以上、比动能为1.560 kJ/g,冲击波感度比JOB-9003炸药低10%,是一种新型的低感高能炸药.     

JOB-9003炸药中组分迁移及其迁移物的表征

塑料粘结炸药JOB-9003加速老化试验后。利用扫描电子显微镜(SEM)观察到炸药表面有针状晶体析出,在75IC贮存3个月的条件下。贮存器皿壁上已有晶体迁移出。利用高效液相色谱(HPLC)对其中的炸药成分含量进行了分析。发现TNT含量下降了17．65%。XPS结果显示在不同贮存温度下表面元素含量不同。并利用气相色谱一质谱(GC／Ms)对迁移出的组分进行了表征,表明迁移物除TNT外,还有低熔点物质及炸药杂质。     

炸药损伤及损伤炸药环境适应性的实验研究

为研究炸药损伤及损伤炸药的安全性,对有边界限定的压装PBX炸药,采用高、低温贮存、温度冲击的方法进行温度损伤实验;采用冲击、振动、跌落的方法进行冲击损伤实验,并利用CT扫描对炸药的损伤情况进行观察;同时通过冲击、振动、跌落实验,对损伤炸药的环境适应性进行了实验研究.结果表明,低温贮存、温度冲击、冲击实验都会使炸药产生裂纹损伤,温度冲击条件下更易引起炸药裂纹损伤.存在裂纹损伤的炸药经过环境适应性实验,未发生爆炸或燃烧现象.     

Double Shock Experiments on PBX Explosive JOB‐9003

One‐dimensional plate impact experiments have been performed to study the double shocks to detonation transition and Hugoniot state in the HMX‐based explosive JOB‐9003. The flyer was a combination of sapphire and Kel‐F, which can pass two different pressure waves into PBX Explosive JOB‐9003 sample after the impact. The particle velocities at interface and different depths in the JOB‐9003 sample were measured with Al‐based electromagnetic particle velocity gauge technique, thus obtaining particle velocity‐time diagram. According to the diagram, the corresponding Hugoniot state can be determined based on the particle velocity and shock wave velocity in the sample. Comparing with sustained pulse experiments, PBX Explosive JOB‐9003 shows desensitization feature due to the pre‐pressed shock wave.     

JOB-9003炸药燃烧转爆轰现象研究

HMX颗粒炸药和JOB－9003炸药进行了燃烧转爆轰（DDT）实验，研究了炸药组分，装药密度以及约束条件对DDT过程的影响，分析了炸药DDT的机理，实验结果表明炸药DDT过程和炸药组分以及装药状态有很大关系。HMX颗粒炸药容量发生DDT现象，而以HMX为主要成分的JOHB－9003压装装药不容易发生DDT现象。     

Statistical Study of Thermal Shock Damage of a Borosilicate Glass

The statistical aspects of thermal shock damage were addressed by examining the strength distributions of quenched specimens. It was observed that slow crack growth effects were minor, and that severe damage commenced near K _Ic. The increased range of retained strengths observed after thermal shock occurs because the low-strength portion of the distribution experiences the initial thermal shock damage. Crack arrest in the damaged specimens, examined by an energy balance, indicated that a large number of surface flaws actively extend during the initial stages of thermal shock damage.     

Thermal Shock Damage Assessment in Ceramics Using Ultrasonic Waves

Structural ceramics are susceptible to microcrack damage by thermal shock. There is a critical temperature for thermal shock damage initiation with damage severity increasing at greater shock temperatures. In this work the applicability of an ultrasonic method to determine the critical temperature and the accumulated damage is demonstrated in alumina. Information is obtained via velocity and attenuation measurements using surface and obliquely incident bulk ultrasonic waves. The elastic anisotropy effect due to preferred crack orientation has been estimated. The critical temperature for the alumina is about 200°C. The damage increases steeply from 200° to 400°C and grows significantly above 400°C. Changes of up to 17% from the original values in the effective shear moduli and up to 45% in the longitudinal effective modulus in the direction transverse to crack orientation are measured at high thermal shock temperatures.     

Behavior of silicon carbide/cordierite composite material after cyclic thermal shock

In the present work Mg-exchanged zeolite and silicon carbide were used as starting materials for obtaining cordierite/SiC composite ceramics with weight ratio 30:70. Samples were exposed to the water quench test from 950 °C, applying various number of thermal cycles (shocks). Level of surface deterioration before and during quenching was monitored by image analysis. Ultrasonic measurements were used as non-destructive quantification of thermal shock damage in refractory specimens. When refractory samples are subjected to the rapid temperature changes crack nucleation and propagation occurs resulting in loss of strength and materials degradation. The formation of cracks decreases the density and elastic properties of material. Therefore by measuring these properties one can directly monitor the development of thermal shock damage level. Dynamic Young's modulus of elasticity and strength degradation were calculated using measured values. Level of degradation of the samples was monitored before and during testing using Image Pro Plus program for image analysis. The capability of non-destructive test methods such as: ultrasonic velocity technique and image analysis for simple, and reliable non-destructive characterization are presented.     

TNT和JOB-9003炸药的爆轰产物成分分析

采用气相色谱仪测定了铸装 TNT和塑料粘结 JOB- 90 0 3炸药在密封爆炸容器中爆炸产生的爆轰产物成分 ,实验结果表明在这种爆轰条件下 ,爆轰产物主要由 N2 、H2 、CO、CO2 、CH4、C2 H2 、C2 H4和 Nx Oy等气体组成 ,而且这些气体组分的含量随实验条件改变而变化。分析结果为爆轰产物的净化处理提供了定量依据     

Experimental analysis of the evolution of thermal shock damage using transit time measurement of ultrasonic waves

Thermal shock is a principal cause of catastrophic wear of the refractory lining of high temperature installations in metal making processes. To investigate thermal shock experimentally with realistic and reproducible heat transfer conditions, chamotte and corund refractory samples of ambient temperature were subjected to surface contact with molten aluminium followed by passive cooling in ambient air. The evolution of damage was characterized by measuring the transit time of ultrasonic longitudinal waves at various sample locations after each test cycle. The mechanical validity of transit time measurement was confirmed in independent experiments. The single test cycle performed with chamotte material indicated the reproducibility and reliability of the experimental set-up and damage characterization method. Multiple test cycles performed with corund material yielded a reliable set of data, to be used for model validation purposes. Both non-uniform damage due to temperature gradients as well as uniform damage due to exposure to a uniform temperature were determined experimentally. The interaction between both damage mechanisms requires further investigation as well as the possible shielding of heat transport by damage.     

Thermal shock of ground and polished alumina and Al2O3/SiC nanocomposites

The thermal shock behaviour of sintered alumina and alumina/SiC nanocomposites with 1, 2.5 and 5 vol.% SiC was studied. The thermal shock testing was carried out by means of quenching into water from high temperatures (ΔT in the range 0–750 °C). Both single shocks and repeated shocks were used. The damage introduced by thermal shock was characterised by degradation of strength in four-point bending and by changes in Young's modulus. The effects of the surface finish of the test specimens (either ground or highly polished surfaces) on the thermal shock resistance were also studied. In both alumina and nanocomposite materials, specimens with ground surfaces showed a better resistance to thermal shocks than specimens with polished surfaces. However, the resistance of the nanocomposite material to single and repeated thermal shocks was no better than that of the pure alumina.     

Study of the castable selection for blast furnace blowpipe

The contradictory properties required of castable refractories makes selecting castable refractories for industrial applications challenging. This paper seeks to describe the material selection for a blast furnace blowpipe application that is subjected to sudden temperature changes and must prevent heat loss. Three commercial high alumina castables containing andalusite or mullite from different manufacturers were characterized. Thermal shock damage resistance was evaluated using thermal shock damage resistance theory and experiments. The castables’ coefficient of thermal expansion was estimated using quantitative X-ray diffraction. Crack propagation resistance was measured using the work-of-fracture technique. Thermal shock damage was experimentally evaluated by measuring the modulus of elasticity and rupture prior to and after thermal cycles. Ultimately, the microstructure of the castables was related to the thermal shock damage behavior by estimating the aggregate size and the fracture toughening mechanisms using light optical and scanning electron microscopes. Heat loss was evaluated by calculating the blowpipe shell temperature using a one-dimensional steady-state heat conduction model. The best commercial castable refractory for blowpipe showed high thermal shock damage resistance and low thermal conductivity. The results in this study agreed with thermal shock damage resistance parameters and showed a correlation between coarse microstructure with large aggregate and higher thermal shock damage resistance.