硝酸铵粒度对改性硝酸铵机械感度的影响

为使粉状改性铵油炸药在性能上真正代替铵锑炸药,了解硝酸铵粒度与炸药机械感度的关系,参照GJB772A-97标准对不同粒度的改性硝酸铵的机械感度进行了测定.研究表明,改性硝酸铵的粒度对其机械感度有明显影响,在一定粒度范围内,随着改性硝酸铵粒度的增大,机械感度有所增大;当粒度继续增大时,机械感度随着粒度的增大而下降.从理论上分析了改性硝酸铵粒度变化对机械感度影响的机理.     

不同粒度HMX的重结晶制备和机械感度研究

采用微团化动态结晶方法和溶剂/非溶剂滴加重结晶方法制备出中位径d50分别为0.472、6.266、36.75μm的HMX颗粒,并采用粒度分析仪和扫描电子显微镜（SEM）对3种试样的粒度进行了表征。测定了3种试样的撞击感度（特性落高H50）和摩擦感度（爆炸百分数）值。测试结果表明,撞击感度随粒度减小逐渐降低,并且在粒度降至亚微米级时降到最低;摩擦感度随粒度减小先升高再降低,而且粒度在10μm～50μm时最为钝感。     

PETN粒度对其机械感度的影响

用微团化动态结晶方法和溶剂/非溶剂滴加重结晶方法制备出3种粒径的PETN颗粒,采用粒度分析仪和扫描电子显微镜(SEM)对其粒度进行了表征。测定了3种粒度PETN试样的撞击感度(特性落高H50)和摩擦感度(爆炸百分数)值。结果表明,3种粒度PETN撞击感度分别为33.7、28.3和22.9cm,摩擦感度分别为52%、24.8%和40%。撞击感度随粒度的减小逐渐降低,亚微米级PETN最低。摩擦感度随粒度的减小先降低再升高,而且亚微米PETN最敏感。     

聚奥炸药的机械感度研究

通过对聚奥炸药造型粉和产品在不同的贮存条件和不同状态机械感度的研究 ,分析了炸药药柱经老化后感度数据增高的原因 ;分析了由解剖药柱经不同工艺方法制备成的试样 ,其机械感度也不同的原因 ;对该炸药的安全使用具有指导意义     

RDX粒度对机械感度的影响

系统研究了RDX粒度对撞击感度和摩擦感度的影响．实验测试的RDX平均粒径为1．5～124μm,并在此粒度范围内分为5个粒度等级。其中撞击感度用特性落高法表示,摩擦感度用特性正压力表示。结果表明：炸药的撞击感度、摩擦感度均随粒度的减小而降低。从理论上分析了炸药粒度变化对机械感度影响的机理。     

粒度对硝铵类炸药静电火花感度的影响

采用喷射细化法和滴加法分别制备了3种粒度的RDX、HMX、PETN粉末。采用激光粒度分析仪和扫描电子显微镜（SEM）对样品进行了表征,并对其进行了静电火花感度实验。结果表明,随着粒度的减小,RDX、HMX、PETN 3种样品的静电火花感度均逐渐升高。从理论上分析了硝铵类炸药粒度对其静电火花感度的影响。     

纳米Al对RDX基炸药机械感度和火焰感度的影响

采用机械混合法制备了含纳米Al的RDX基混合炸药,测试了其机械感度和火焰感度,用扫描电镜表征了纳米Al及其炸药的表面形貌,分析了感度变化的原因。结果表明,加入纳米Al后,RDX基炸药的撞击感度、摩擦感度和火焰感度增大;随着纳米Al含量的增加,撞击感度、摩擦感度和火焰感度明显增大;且含纳米Al炸药的撞击感度、摩擦感度和火焰感度均高于含微米Al炸药。纳米Al及含纳米Al炸药均存在微量团聚现象,在一定程度上影响了含纳米Al的RDX基炸药的感度。     

DADE及其混合炸药的机械感度

为了解DADE以及含DADE的混合炸药的安全性能,用显微镜研究了DADE混合炸药降感机理。结果表明,在相同的试验条件下,DADE与TATB、NTO的机械感度相当,具有优良的安全性能;DADE粒度的大小对其感度影响很大,感度随粒度的减小而升高;在B炸药配方中,用DADE部分代替RDX后感度没有明显改变,完全代替RDX后降感效果十分明显。研究表明,DADE颗粒的合理级配以及表面包覆是降低DADE机械感度的重要途径。     

粒度对炸药感度影响的研究进展

主要分析论述了粒度对炸药撞击感度、冲击波感度、热感度、火焰感度、静电火花感度的影响,以及当前的研究现状。     

粒度对RDX热感度和火焰感度的影响

采用喷射细化法和滴加法,制备了3种粒度的黑素今(RDX)粉末.采用激光粒度仪、比表面积分析仪和扫描电子显微镜对样品进行了表征,对其火焰感度、慢烤热感度及热分解特性进行了测试,其中用50%的发火高度表示其火焰感度,用爆发点的温度表示其慢烤热感度.结果表明,随着RDX粒度的减小,RDX的火焰感度和慢烤热感度均逐步升高.从理...     

AP粒度对底排药燃速的影响

为了研究底排药的燃烧性能,用底排药试验装置研究了含有不同粒度AP及分布的底排药的燃速。结果表明,影响底排药燃速的主要因素是AP晶粒的总表面积,AP粒度越小,底排药的燃速越高。不同粒度级配对底排药燃速的影响取决于单位质量底排药中AP晶粒总表面积的变化量。     

含微米级AP的HTPB推进剂工艺性能和力学性能

制备了含微米级AP(质量分数大于50%)的HTPB推进剂药浆和标准试件,利用流变仪测试了+20℃和-40℃时药浆的表现黏度,用材料试验机测试了标准试件的力学性能,讨论了增塑比、AP粒度级配、键合剂等对HTPB推进剂工艺性能和力学性能的影响。结果表明,当增塑比为0.42、AP粒度级配采用25%的120μm AP、30%的6~8μm AP和20%的1μm AP时,推进剂样品6h的表观黏度为1 267Pa·s,低温延伸率达到38%。     

不同添加剂对钛酸钙粒径的影响

选取方法较好的水热合成法,以硝酸钙,四氯化钛,氢氧化钠为原料,添加剂为氯仿与无水乙二胺来制取钛酸钙。研究了不同添加剂对钛酸钙粒径的影响,并使用粒度分析仪对样品进行分析。结果表明:添加无水乙二胺对钛酸钙的粒径影响是较好的。溶液总体积为37 m L的条件下,选取水热温度200℃,反应时间6 h,硝酸钙与四氯化钛的用量分别为2 m L,氢氧化钠30 m L(2 mol/L),无水乙二胺用量为3 m L,可得到粒度小且分散性好的钛酸钙粉末。     

Effect of Coating of Ammonium Perchlorate with Fluorocarbon on Ballistic and Sensitivity Properties of AP/Al/HTPB Propellant

Fluorocarbon polymers are used to enhance thermal stability and electrostatic protection of composite propellant compositions. A precipitation technique has been developed to coat ammonium perchlorate (AP) using a copolymer of hexafluoropropylene and vinylidene fluoride (HFP‐VF) with the help of solvent‐counter solvent method. The coated AP has been used to prepare propellant compositions in different ratio based on hydroxyl terminated polybutadiene (HTPB), aluminium powder along with uncoated AP and studied for viscosity build‐up and visco‐elastic behaviour as well as mechanical, ballistic, thermal and sensitivity properties keeping 86% solid loading. The data on viscosity build‐up indicate that as the percentage of viton coated AP increases end of mix viscosity and viscosity build‐up increase accordingly. The mechanical properties data reveal that tensile strength and percentage elongation are found in increasing order. The burn rate of the composition also increases on higher percentage of HFP‐VF coated AP. The thermal stability of composition increases as the percentage of HFP‐VF coated AP increases. The data on sensitivity indicate that impact sensitivity decreases on increasing the percentage of HFP‐VF coated AP while no change is observed in friction sensitivity value.     

Mechanical Properties of Composite AP/HTPB Propellants Containing Novel Titania Nanoparticles

Modern chemical synthesis techniques have allowed for improved incorporation of nano‐scale additives into solid propellants. Various methods were implemented to incorporate titania nanoparticles into three representative ammonium perchlorate composite propellants (APCP), and the mechanical properties of each formulation were tested and compared to those of an analogous baseline. Advanced imaging techniques were applied to all particle synthesis methods to characterize particle size and particle network type and size. Uniaxial tensile testing was performed to measure propellant ultimate strength, ductility, and elastic modulus. In general, the addition of nano‐titania additives to the propellant decreased propellant strength and modulus, but improved ductility. Propellant formulations containing in‐situ titania exhibited an increase in ductility of 11 %, 286 %, and 186 % with a corresponding reduction in strength of 82 %, 52 %, and 17 % over analogous baselines. These trends corresponded to a simultaneous decrease in propellant density, indicating that when implementing nano‐sized additives, care must be taken to monitor the effect of the altered manufacturing techniques on propellant physical properties in addition to just monitoring burning rates. Tailoring of propellant manufacturing procedures and the addition of Tepanol bonding agent to an in‐situ APCP formulation fully recovered the propellant density and ultimate strength while retaining the enhanced ductility.     

Mechanical Properties of Dental Porcelain with Different Leucite Particle Sizes

This research aims to investigate the effect of leucite particle size on the mechanical properties of dental porcelain with a similar leucite content and chemical composition. Leucite powders of different particle sizes were synthesized by a hydrothermal method and a high-temperature fusing-crystallization method, respectively. Dental porcelains with different average leucite particle sizes (i.e., 0.5±0.2, 1.2±0.3, and 5±2 μm) were prepared by sintering the mixture of different leucite powders and a low temperature frit. The crystalline phase, crystalline content, relative density, hardness, flexural strength, and fracture toughness of the porcelains were measured by X-ray diffraction (XRD), quantitative XRD analysis, the Archimedes method, a Vickers microhardness tester, a universal testing machine, and a single-edge precracked beam method, respectively. The microcrack density and the distribution of leucite particles were also quantitatively assessed from micrographs. The results showed that the leucite particle size did not have a significant effect on the average of the measured flexural strength, fracture toughness, and hardness of dental porcelains. However, because of a existence of the large number of microcracks, the relative density and the Weibull modulus of the sample groups with an average leucite particle size of 5 μm were statistically lower.