高聚物黏结炸药的力学性能研究进展

从材料的力学行为特性、实验方法、本构模型和强度理论4个方面对高聚物黏结炸药(PBX)的力学性能特征进行了归纳和评述。指出应变率和温度对材料应力状况的影响及动态力学性能分析是目前PBX研究的热点和难点。认为可以借鉴研究混凝土和高聚物的一些方法来建立PBX的本构模型和失效准则。指出选择和改进现有测试技术时,须考虑PBX的含能敏感性、大变形等特性。对PBX力学性能的理论研究、实验技术及数值模拟等方面需要开展的工作提出了一些看法。认为复杂环境下的力学响应和细观建模模拟应是今后研究的重点方向。附参考文献93篇。     

高聚物黏结炸药的冲塞试验研究

用冲塞试验评价大药量装药在撞击、剪切、绝热加热等综合作用条件下的安全性.用火药加速装置对试件加速,并通过高速摄像机拍摄炸药试验件跌落撞靶、点火等试验过程,利用冲击波压力传感器测试冲击波超压表征炸药试验件的反应程度.结果表明,PBX-1炸药在撞靶速度高达37.6 m/s时没有发生反应,且PBX-2炸药在撞靶速度为27.7 m/s时发生了爆燃反应,在撞击速度低于25.5 m/s时未发生反应,说明PBX-2炸药的冲塞试验撞击感度高于PBX-1炸药.     

热老化对HMX基高聚物黏结炸药撞击感度的影响

参照GJB 736.8—1990的试验方法,对奥克托今(HMX)基高聚物黏结炸药在71℃高温条件下进行了长达203 d的加速老化试验,每隔一定时间测定其撞击感度。研究发现:炸药的撞击感度在加热到147 d以后有下降的趋势,与老化前相比下降了20%,但初期下降比较明显,后期下降比较缓慢,主要是由于热老化首先引起炸药中硝化棉分解,硝化棉的分解产物进一步引起HMX分解。     

炸药粉末压制工艺参数对药柱质量的影响

为了提高炸药粉末的压制成型质量,采用将炸药粉末视为连续体的建模方法,利用Shima-Oyane材料模型,以Φ26mm×22mm的JO-9159炸药药柱为例,采用高级非线性Msc.Marc建立了粉末压制过程仿真模型,分析了不同位置粉末位移及相对密度变化规律,研究了压制速率、初始密度对炸药粉末成型后相对密度及回弹量的影响。结果表明,Shima-Oyane材料模型可以较好地模拟粉末压制成型过程;炸药粉末流动的方向主要为轴向流动,与模具接触区域流动相对缓慢;压制速率以及初始密度影响炸药粉末成型后的质量,初始相对密度的提高有助于提高炸药粉末成型后的质量;压制速率在230~250mm/s时,粉末成型后相对密度较为均匀、回弹量较小,即粉末成型质量较好。     

稀土磁性材料压制密度与产品成型性的研究

生产磁性材料的企业都必须经过压制成型这一环节,压制成型后的毛坯经过烧结才会成为合格的坯料。本文对压制密度与产品成型性的关系进行了分析研究,并成功应用于实际生产。     

改性粉体压制成型近似模型

表面改性后的无硬团聚超细粉具有良好的压制成型性能。表面酯膜的减摩润滑作用，使粉体在一定应力下流动性和分散性显著提高，压制过程的中后期应力传递准符合帕斯卡模型及均匀递减模型。     

压制成型砖坯的质量问题及压制制度的选择

介绍了压制成型的砖坯容易出现的质量问题及防止措施，依此选择最佳压制制度。     

高聚物溶液在固体炸药表面上的湿润性

通过测试接触角，从湿润热力学和动力学2方面研究了丙烯腈苯乙烯共聚物(AS)溶液在不同粒径的三氨基三硝基苯(TATB)炸药表面湿润性，并结合紫外光谱法探讨了湿润性与吸附量之间的关系。研究结果表明，随着聚合物溶液浓度的增加，AS溶液在TATB表面上的湿润性变差．湿润速度减小。溶剂种类和该炸药粒径不同，其湿润性也不同；若聚合物溶液在固体炸药表面湿润性好．则其在炸药表面上的吸附量大。     

聚合物合金的成型性

介绍在不损失聚合物合金所具有的固有力学性质的前提下,聚合物合金成型性的提高用掌握流动性及反应性处理,控制异种聚合物间的界面,提高其成型性。     

压制过程中PBX炸药颗粒的破碎及损伤

用扫描电镜及激光粒度仪研究了PBX炸药在不同压制条件下的微观结构变化及粒度分布。结果表明,随着成型试件密度的增加,晶体的破碎、损伤情况加重;成型试件中HM X的平均粒径随着压力的增加而减小(压制前的33.05μm到250M Pa压制后的16.92μm);在相同压力条件下,热压(70℃)制品的密度更高,但晶体的破碎却更小,热压(70℃)制品中HM X的平均粒径要大于冷压(25℃)制品中HM X的平均粒径。     

钢模压制下高品质HMX晶体的损伤规律

为了揭示粒度分布与压制期内含能晶体损伤程度的关系,研究了3种不同粒径的高品质HMX炸药在压制后微结构和粒度分布的变化。结果表明,随着HMX晶体粒径的增大,晶体表面逐渐形成裂纹,其尖端和棱角发生破碎。当晶体尺寸达到222.5μm时会出现明显的穿晶断裂。采用两种粒度的HMX级配,可减少对晶体中的损伤。压缩刚度法所得HMX的黏结强度和光电子能谱所得PBX造型粉的包复度表明,随着颗粒粒径的增大,炸药的包覆效果和力学强度降低,导致压制PBX中更多晶体的破碎。     

干压结合冷等静压成形对陶瓷力学性能的影响

本文通过研究在不同压力下进行干压结合冷等静压成形过程对陶瓷素坯体和烧结体的结构、性能的影响,得出了最佳的成形工艺条件,即干压压力为20T、冷等静压压力为200MPa。     

等静压技术的应用与发展

简要介绍了等静压技术的原理、分类及特点;介绍了冷等静压(CIP)与热等静压(HIP)技术的应用领域以及等静压设备的发展概况。     

Hot Isostatic Pressing of Alumina and Examination of the Hot Isostatic Pressing Map

The hot isostatic pressing (HIP) of four alumina powders is studied in the temperature range 1100° to 1400°C, at 5- to 200-MPa applied pressure, and for times ranging from 0.5 to 4 h. Density increases with increasing HIP temperature, pressure, and time; decreasing grain size results in increased density after HIP. An empirical relation is derived for grain growth during HIP, and the HIP map proposed by Helle et al. is found applicable to the present results. Densification is governed by the grain-boundary diffusion of aluminum ions; with the transport coefficient and the grain-growth values found in the present study, the map can be used to express experimental results to within a factor of 4 for all densification stages except near full density.     

冷等静压成型压力对反应烧结氮化硅陶瓷性能的影响

将硅粉冷等静压成型,通过反应烧结得到氮化硅陶瓷,研究了成型压力对反应烧结氮化硅(RBSN)陶瓷性能的影响。结果表明,当成型压力从100MPa增加到300MPa,反应烧结氮化增重率逐渐下降,从60.25%降到47.31%;而残余硅含量随着增加,从10%增加到29%;RBSN开气孔率随着成型压力的增大而减小,开气孔率从20.50%降到13.81%。成型压力小于等于200MPa时,RBSN的密度和强度随成型压力的增大而增大;成型压力大于200MPa时,RBSN的密度随成型压力的增大而减小,强度随成型压力的增大变化不大,变化约为5%;在200MPa时,RBSN的密度达到最大值2.52 g/cm3。冷等静压成型RBSN由晶须状α-Si3N4,柱状β-Si3N4和残余硅组成。     

Densification of Precursor-Derived Si-C-N Ceramics by High-Pressure Hot Isostatic Pressing

Densification behavior of precursor-derived Si-C-N ceramics by hot isostatic pressing (HIP) has been investigated to obtain dense ceramics derived from polymer precursor. An as-pyrolyzed ceramic monolith, which had a porosity of about 17%, could be deformed up to a strain of 8% in preliminary uniaxial compression tests. The flow stress of the material was much higher than 200 MPa at 1600°C; thus high stress was necessary for densification by HIP. The density of the monolith increased from 1.9 to 2.4 g/cm³ by HIP at 1600°C and 980 MPa. Although the number of pores decreased, large pores were formed in the hot isostatically pressed monolith. On the other hand, denser ceramics, in which pores were not observed by optical microscopy, were obtained by hot isostatically pressing the pyrolyzed powder compact.     

Mechanical Properties of Submicrometer‐Grained Transparent Yttria Ceramics by Hot Pressing with Hot‐Isostatic Pressing

Here, we report the fabrication and mechanical properties of submicrometer‐grained (0.29–0.58 μm) transparent yttria ceramics by hot pressing combined with hot‐isostatic pressing. The effects of the grain size on the microhardness and the fracture toughness were studied. An unusual decrease of the fracture toughness with an increase in the grain size was revealed, which may be attributed to the different grain size dependence of the fracture behavior of the ZrO₂‐doped yttria ceramics compared to that of other yttria ceramics. The microhardness and fracture toughness of the transparent yttria ceramics were found to be better than those of the large‐grained yttria ceramics.     

Compression Deformation Mechanism of Silicon Carbide: I, Fine-Grained Boron- and Carbon-Doped β-Silicon Carbide Fabricated by Hot Isostatic Pressing

The deformation behavior of boron- and carbon-doped β-silicon carbide (B,C-SiC) with an average grain size of 260 ± 18 nm containing 1 wt% boron was investigated by compression testing at elevated temperatures. Extensive grain growth during deformation was observed. The stress–strain curves were compensated for grain growth by assuming power-law type of dependence on grain size and strain rate. The stress exponent n was ∼1.3 and the grain size exponent p was ∼2.7 at temperatures ranging from 1593° to 1758°C. The apparent activation energy of deformation Q _d was ∼760 kJ/mol, which was lower than the activation energy for lattice diffusion of silicon and carbon in SiC and higher than that for grain-boundary diffusion of carbon in SiC. These results suggest that the deformation mechanism of the fine-grained B,C-SiC is grain-boundary sliding accommodated by the grain-boundary diffusion.