不同粒度及包覆改性高氯酸铵的热分解性能和安全性能研究

采用扫描电子显微镜和X射线衍射仪对不同粒度及包覆改性高氯酸铵(AP)颗粒的分散性及晶相进行了表征,并通过差示扫描量热法和机械感度测试研究不同AP样品的热分解性能和安全性能。结果表明,随着AP粒度增加,颗粒分散性得到一定改善,相同粒度的包覆改性AP分散性优于普通AP;不同粒度及包覆改性AP的晶相均一致;AP粒度越小,其热分解性能越好,对于粒度相同的AP,包覆改性对其热分解性能影响不大;随着AP粒度增加,其撞击感度和摩擦感度均降低,平均粒径(d_(50))分别为1μm、3μm和6μm的AP其撞击感度和摩擦感度分别为96%、80%、64%和28%、28%、16%;包覆改性可以明显降低AP的感度,d_(50)为3μm的包覆改性AP与粒度相同的普通AP相比,撞击感度和摩擦感度分别降低了28%和16%。     

CL-20晶体粒度和形貌对其机械感度及火焰感度的影响

采用筛分、手工研磨和高速剪切方法对 CL-20进行预处理,制备出了不同形貌和粒度的 CL-20粉末。利用激光粒度仪和扫描电子显微镜（SEM）对样品进行了表征,并测试了撞击感度、摩擦感度及火焰感度。结果表明,筛分法制备的 CL-20样品随着样品粒度的减小,机械感度明显降低,火焰感度有降低趋势;由以上3种方法制备的粒度相似而形貌不同的 CL-20样品中,筛分法制备的 CL-20样品机械感度和火焰感度最高,其他两种方法制备的 CL-20样品,撞击和摩擦感度均大幅降低。     

降低超细高氯酸铵感度的方法研究

为了降低超细高氯酸铵(AP)的机械感度,以十八烷胺为包覆剂,经气流粉碎工艺,制备了超细AP包覆粒子。通过对超细AP包覆粒子进行粒度分析、SEM分析、DSC分析及感度检测,研究了超细AP包覆粒子的包覆效果、热分解特性及感度特性。试验结果表明:超细AP包覆粒子,粒度为D50=5.8μm,表面有包覆层存在;超细AP包覆粒子的感度,与超细AP样品相比,当包覆剂质量分数为1%时,撞击感度降低31.2%,摩擦感度降低12.0%;当包覆剂质量分数为3%时,撞击感度降低34.5%,摩擦感度降低22.0%,且包覆剂用量越大,撞击感度和摩擦感度越低;但包覆剂对AP的热分解会产生一定的负面影响,质量分数应≤1%。     

纳米RDX基PBX混合炸药的热分解特性和感度研究?

采用溶液-水悬浮法,通过控制料液质量比、包覆温度、搅拌速度等工艺参数制备了纳米RDX基PBX。使用TG/DSC同步热分析仪研究其热分解特性,并依据GJB 772A—1997分别对其撞击感度和摩擦感度进行了测试。结果表明:与微米RDX基PBX相比,纳米RDX基PBX的DTG峰温提前约0.6℃,活化能降低约2.5 k J/mol;纳米RDX基PBX撞击感度H_(50)为46.3 cm,微米RDX基PBX H_(50)为29.8 cm,相对降低55.4%;纳米RDX基PBX摩擦感度比微米RDX基PBX相对降低21.1%。     

膨化高氯酸铵的制备及其性能研究

使用膨化剂在减压条件下制备出膨化高氯酸铵（AP）。利用扫描电镜、粒度分析仪、傅里叶红外光谱仪、比表面积仪、差示扫描量热仪、热失重分析仪及感度仪分别对膨化AP进行形貌分析和性能测试。结果表明:膨化AP颗粒表面具有沟壑,内部具有孔洞结构,粒径D₅₀=22.559 μm;与未膨化的原料AP相比,膨化AP低温分解温度提高16.0 ℃,高温分解温度提高6.7 ℃,分解热提高322.3 J/g;比表面积增大92.2%,吸湿性增大;极限撞击能为10 J,撞击感度提高。制备AP/HTPB(端羟基聚丁二烯)和膨化AP/HTPB复合推进剂并测定其燃速,膨化AP/HTPB复合推进剂燃速提高4.1%。     

纳米HMX的制备及热性能分析和感度研究

采用机械球磨法批量制备了纳米奥克托今(HMX),用激光粒度仪分析其粒度分布,并用扫描电子显微镜(SEM)观察其大小和形貌;使用热重分析仪(TG)和差示扫描量热仪(DSC)分析其热分解特性和热安定性;同时对纳米HMX的5 s爆发点和感度进行了测试。结果表明,制备的HMX颗粒大部分在100 nm以下;与原料HMX相比,纳米HMX的最大热失重温度降低了3.66℃,表观活化能E a降低了11.19 kJ/mol,自发火温度降低了2.11K;5s爆发点降低了4.9℃,纳米HMX的静电感度和火焰感度与原料HMX相当,纳米HMX的摩擦感度、撞击感度和冲击波感度分别降低了32.5%、20.2%和56.4%。     

高品质RDX的抗压性能研究

研究了压药过程是否会破坏高品质黑索今(H-RDX)的完整性，导致H-RDX失去低感度优势。通过扫描电镜和激光粒度仪对单个H-RDX颗粒、H-RDX和H-RDX造型粉在压制前、后的表面形貌和粒度进行了表征，测试了压制前、后的撞击、摩擦和冲击波感度，并与普通RDX进行比较。研究表明：40 MPa压药压力已经引起了H-RDX、普通RDX及造型粉颗粒的碎裂和损伤。H-RDX的抗压性能比普通RDX更好，虽然压药过程会破坏H-RDX和普通RDX颗粒的完整性，但H-RDX依旧能保持安全性能优势，且经过包覆后，安全性能可以进一步提升。单个H-RDX颗粒的耐压压力(不低于400 MPa)远高于单个普通RDX颗粒(小于40 MPa);H-RDX及H-RDX造型粉在颗粒集合体中的碎裂程度也分别低于普通RDX 25%和65%以上。经过压制后，H-RDX比普通RDX的撞击感度低50%,摩擦感度低25%。H-RDX造型粉压制的高聚物黏结炸药(PBX)的冲击波感度低于普通RDX基PBX。压制后与压制前相比，H-RDX的撞击感度降低50%,摩擦感度升高17%,冲击波感度增加16%;而使用黏合剂包覆后，冲击波感度可降低...     

纳米/亚微米/微米粒度标准物质研究进展

纳米/亚微米/微米粒度标准物质在微/纳米粒度测量仪器设备的检定校准,粒度尺寸测量技术的可靠性评估,以及对样品的粒度质量控制等方面都具有重要作用。本文介绍了粒度标准物质的制备和定值技术进展,对国内外纳米/亚微米/微米粒度标准物质的研制和生产状况进行概述,总结了部分聚苯乙烯、二氧化硅、金、二氧化铈材质的纳米/亚微米/微米粒度标准物质的粒径、不确定度和定值方法信息。     

7-氨基-4,6-二硝基苯并氧化呋咱的精制及性能研究

实验室直接制备的7-氨基-4,6-二硝基苯并氧化呋咱的含酸量较高,而炸药的酸度较高非常不利于使用及储存,所以需要对其进行进一步的精制除酸才能安全使用。该文研究采用甲醇、N,N-二甲基甲酰胺(DMF)、二甲亚砜(DMSO)3种溶剂对粗品进行精制,并研究了精制后的样品在含酸量、粒度、微观形貌、机械感度及热安定性方面的性能改变。试验表明,采用甲醇除酸效果最好:精制后的样品pH值为6.6;样品颗粒的尺寸最小,粒度主要分布在0.4~30.0μm,但存在少量的团聚现象;撞击感度和摩擦感度分别为28%和20%;真空安定性测试表明100℃时,真空放气量为0.047 mL/g,200℃时为0.85 mL/g;24 h的热质量损失率为0.80%。     

超细DADNBF的性能研究

为了研究超细颗粒5,7-二氨基-4,6-二硝基苯并氧化呋咱(DADNBF)的性质,采用溶剂-非溶剂法制备了超细DADNBF颗粒。研究了超细DADNBF的粒径分布、撞击感度、热稳定性、真空安定性、冲击波感度和飞片起爆感度等性能,并与普通DADNBF和超细HNS-Ⅳ进行比较。研究结果表明:DADNBF超细化后,样品粒度主要分布在0.035~0.316μm范围内;比表面积为25.1 m2/g;撞击感度H50为108 cm;DSC分解放热峰温为300℃,比细化前降低13℃;飞片起爆实验最低起爆电压为2.4 kV;冲击波感度X50=7.54 mm。超细DADNBF综合性能与超细HNS-Ⅳ接近。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...