Zr41 Ti14 Ni12.5 Cu10 Be22.5非晶合金冲击压缩行为理论与实验研究

为研究Zr_(41)Ti_(14)Ni_(12.5)Cu_(10)Be_(22.5)非晶合金的冲击压缩响应及物态方程,利用平板冲击试验,测试了受到速度为350 m/s～550 m/s的铜板冲击时,非晶合金试样的自由面粒子速度;采用阻抗匹配法得到了材料的雨贡纽参数,并利用理想混合物模型对材料的雨贡纽参数进行预估,分析对比了理论计算结果与实验结果;将求材料格林艾森物态方程转化为非线性最优化问题,提出了基于模拟退火算法的材料格林艾森物态方程计算方法,设计了退火参数表,并采用解析法计算了材料的布里希-默纳罕物态方程和三项式物态方程,对比研究了三种物态方程与实验结果.理论和实验结果表明,5～10 GPa压力范围内,Zr_(41)Ti_(14)Ni_(12.5)Cu_(10)Be_(22.5)非晶合金的零压体积声速为4 267 m/s,D-u曲线斜率为4.376,曲线斜率远大于一般金属材料,其雨贡纽极限强度为5.60 GPa左右;理想混合物模型仅适用于计算高压区Zr基非晶合金的雨贡纽参数,低压区理论计算结果与实验结果误差较大;在5～10 GPa压力范围内,格林艾森物态方程、三项式物态方程与实验结果吻合度较高,而布里希-默纳罕物态方程误差较大,不适用于计算材料状态参量.     

Numerical calculation of JWL EOS parameters for explosives

JWL equation of state (EOS) parameter for most energetic materials is blank,that makes it impossible for the numerical simulation of the explosive dynamic response and damage effects.In this paper,the ...     

Shock wave compression behavior of aluminum foam

1　INTRODUCTIONInrecentyears ,aluminumfoamsofhighporosityhaveattractedmuchattentionofresearchersonmate rialsduetotheiruniquecompressionbehaviorthatun dergoesalargedeformationatnearlyconstantnominalstress ,andgreatpotentialforapplicationinabsorbingenergyfromimpact[1 3] .Thisapplicationthereforere quirestheknowledgeontheshockcompressionbehav iorofthealuminumfoamundervariousimpactcondi tions.AlthoughanumberofworkonthedynamicpropertyofaluminumfoamshasbeenperformedwithsplitHopkinson pressureba…     

Tribological Properties of Polytetrafluoroethylene Composites Filled with Rare Earths Modified Glass Fibers

1Introduction Polytetrafluoroethyleneisakindofperfectself lubri catingmaterialduetoitsverylowfrictioncoefficient,goodhightemperaturestabilityandchemicalstability.Yetitcannotbeusedasanti wearmaterialalonebecause ofitspoormechanicalproperties,badthermalconductivi tyandhighwearrate.Therefore,variousreinforcement andmodificationofPTFEhavebeentried,andthefric tionandwearpropertiesofPTFEcompositeshavebeen extensivelystudiedbymanyinvestigators[14].Glassfiberexhibitsahightensilestrengthandten sile…     

Excellent tribological behavior of hexadecylphosphonic acid films formed on titanium alloy

Titanium alloy(Ti6Al4V)surfaces are generally modified to achieve some specific surface properties to satisfy requirements of clinical medicine.In our work,hexadecylphosphonic acid(HDPA)films were successfully formed on Ti6Al4V and subsequently confirmed by X-ray photoelectron spectroscopy(XPS)and atomic force microscopy(AFM)measurements.The tribological properties of the HDPA-modified Ti6Al4V were investigated using a ball-on-disk tribometer with a linear reciprocating movement.Experimental results indicate that the HDPA-modified Ti6Al4V can maintain a low friction coefficient(approximately 0.06)for 4 h when sliding against polytetrafluoroethylene(PTFE)balls under a load of 0.8 N in comparison to bare Ti6Al4V(approximately 0.2);the friction coefficient of the HDPA-modified Ti6Al4V shows a 70%decline.In addition,the wear rate of PTFE balls sliding against bare Ti6Al4V was almost twenty times that of PTFE balls sliding against the HDPA-modified Ti6Al4V.Moreover,results of tribological experiments for different speeds(from 3 to 24 mm/s)and loads(from 0.8 to 3.2 N)proved that the HDPA-modified Ti6Al4V was not sensitive to both velocity and load.The friction coefficients were still low and stable even under a high load of 3.2 N or at a high speed of 24 mm/s.This indicates that this soft modification is an optional method of improving tribological properties of Ti6Al4V.     

磷酸中铁铝镁杂质对开阳磷矿分解速率的影响

研究了铁、铝、镁杂质对磷酸分离开阳磷矿的反应过程的影响,实验中通过测试氢离子活度的变化,以及对微观过程的观测与分析,发现影响反应过程的因素是多方面的,但主要自于生成的产生固物形复盖了矿料表面的活性点,阻塞了物质输0运的孔隙,增大了扩散阻力。     

Failure behavior of cellular titanium under dynamic loading

The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the material. Dynamic compression experiments are conducted at room temperature using a single-stage light gas gun. The Hugoniot relations between shock wave velocity and particle velocity for the cellular titanium samples with porosities 20% and 30% are obtained. The shock response of the regular cellular titanium shows a clear wave attenuation effect. Numerical simulations are also conducted to supplement the experimental study. Inelastic deformation is observed in the samples using optical micrographs, indicating that the deformation of pores contributes significantly to the shock wave attenuation of the cellular titanium material.     

Dynamical Mechanical Properties for AD90 Alumina

The dynamic response of polycrystalline alumina was investigated in the pressure range of 0-13 GPa by planar impact experiments. Velocity interferometer system for any reflector(VISAR) was used to obtain free surface velocity profile and determine the Hugoniot elastic limit, and manganin gauges were employed to obtain the stress-time histories and determine Hugoniot curve. Both the free surface particle velocity profiles and Hugoniot curves indicate the dispersion of the "plastic" wave for alumina. With the measured stress histories, the complete histories of strain, particle velocity, specific volume and specific internal energy are gained by using path line principle of Lagrange analysis. The dynamic mechanical behaviors for alumina under impact loading are analyzed, such as nonlinear characteristic, strain rate dependence, dispersion and declination of shock wave in the material.     

挡墙形状对二维爆炸场影响的数值模拟研究

研究二维爆炸场中挡墙的形状对冲击波传播的影响 .在整个模拟过程中不考虑外力、外源和热交换的影响 ,采用流体网格得到了可压缩流体的偏微分守恒方程 ;并且通过使用多流体网格方法及运用“和”分裂格式完成了输运步的计算 ;同时对于爆轰产物采用了JWL状态方程 ,并将空气简化成理想气体 .最终获得了挡墙的两侧边缘的形状对冲击波传播影响的具体情况 ,并列出了二者之间的关系 .可以看出靠近爆源一侧的挡墙形状对冲击波传播的影响更明显 .     

Experimental Investigation of Two-Dimensional Shock Initiation Process of Cast Composition B

A two-streak high-speed photography measuring system is designed, which can successfully record the reactive shock front and the reaction profile within the run distance of shock initiation under two-dimensional shock initiation. The strong reaction delay time and the shape of reaction shock front are determined in the cast composition B (RDX/TNT/60/40). A low level reaction zone has been found and analyzed.     

SiC粉体在硫酸铝-硫酸钠复合熔盐中的反应转化

对碳化硅粉体在硫酸铝-硫酸钠复合熔盐反应转化成莫来石晶须的过程进行了研究。借助X射线粉末衍射仪(XRD)、红外光谱仪(IR)、高分辨透射电镜(TEM)、扫描电镜(SEM)和能谱仪(EDS),研究碳化硅与熔盐反应后的物相和微观形貌的变化。XRD和IR的结果表明,碳化硅在高温熔盐体系中可完全转化成莫来石晶须;SEM分析结果表明,莫来石沿[111]晶面优先生长形成晶须。并提出了循环的氧化-溶解机理,对碳化硅陶瓷粉体在复合熔盐中的反应过程进行了解释。     

爆炸冲击波的环流效应数值模拟研究

利用任意拉格朗日欧拉（ALE）算法和炸药爆轰产物的JWL状态方程。针对有障碍物阻档时空气冲击波的环流现象进行数值模拟，得到在爆源周围有障碍物时爆炸场初始发展、环流情况及整个传播过程，并分析了空气冲击波的环流规律。研究结果表明，所采用的方法可以很好地描述空气冲击波环流流场参量分布与变化规律。数值模拟结果符合物理规律。     

钢管混凝土柱对爆炸冲击波影响的数值模拟研究

通过LS-DYNA软件对两种截面的钢管混凝土柱在爆炸荷载下爆炸冲击波的传播过程进行了三维数值模拟。混凝土采用HJC模型,钢管采用了考虑应变率的随动硬化塑形模型,炸药采用TNT炸药,使用LS-DYNA程序中的高能炸药爆轰产物压力-体积关系的JWL状态方程分析了爆炸冲击波的传播过程,得到了在不同比例距离下爆炸冲击波在通过两种截面柱子时超压峰值的衰减及增大规律。     

Reactive Processing and Mechanical Properties of Al/SiCP Composite

0　ＩｎｔｒｏｄｕｃｔｉｏｎＡｌ/ＳｉＣＰｃｏｍｐｏｓｉｔｅｓｈａｖｅｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈａｎｄｍｏｄｕｌｕｓ,ｈｉｇｈｗｅａｒｒｅｓｉｓｔａｎｃｅａｎｄｇｏｏｄｗｏｒｋａｂｉｌｉｔｙ .Ｔｈｅｙｓｈｏｗｇｏｏｄｐｒｏｓｐｅｃｔｆｏｒｉｎｄｕｓｔｒｙａｐｐｌｉｃａｔｉｏｎ .Ｔｈｅｃｏｓｔ ｅｆ ｆｅｃｔｉｖｅｐｒｏｃｅｓｓｉｎｇｔｅｃｈｎｏｌｏｇｉｅｓｏｆＡｌ/ＳｉＣＰｃｏｍｐｏｓｉｔｅｓｃｏｎ ｔｉｎｕｅｔｏｂｅａｋｅｙｒｅｓｅａｒｃｈａｒｅａ .Ｓｔｉｒｃａｓｔｉｎｇｉｓｔｈｅｍｏ…     

改性高岭土吸附城市生活污水中铅的实验研究

测试了高岭土去除城市生活污水中铅离子的能力。高岭土用硫酸溶液处理,再用有机硅烷偶联剂KH580和NaOH进行表面改性。X-射线荧光分析结果显示处理过的样品SiO2/Al2O3比值为2.6：1,而未处理高岭石两者之比为1.5：1。改性高岭土吸附试验符合Shawabkeh-Tutunji等温吸附模型。在本试验中,改性高岭石表面化学吸附的最大吸附容量为54.35 mg/g。     

掺Al对TaN薄膜微结构及电性能的影响

采用反应直流磁控溅射法在Al2O3陶瓷基片上制备TaAlN薄膜,通过调节复合靶Al/Ta面积比调节Al掺杂量,研究了Al/Ta面积比对TaAlN薄膜微结构及电性能的影响。XRD结果表明,TaN薄膜中掺杂Al可在2θ为38.5°和65.18°处分别有立方结构的AlN(101)和AlN(202)相出现。随Al/Ta面积比的增大,TaAlN薄膜的沉积速率、电阻率、方阻以及TCR绝对值逐渐增大。当Al/Ta面积比为零时,TaN薄膜的电阻率和TCR绝对值分别为247.8μΩ⋅cm和12ppm/℃,当Al/Ta面积比增大到29%时,TaAlN薄膜的电阻率和TCR绝对值分别增大到2560μΩ⋅cm和270ppm/℃。     

Preparation of β-SiC by combustion synthesis in a large-scale reactor

The feasibility of 5 kg β-SiC synthesized in one batch was demonstrated through igniting the mixture of Si, C-black and polytetrafluoroethylene (PTFE) under different nitrogen pressures. The effect of experimental parameters, including the contents of PTFE, nitrogen pressure, preheating, and raw materials distribution forms were investigated. The results show that the products are β-SiC with equiaxed grains. The average grain size is less than 200 nm. The powders loaded loosely promote reaction heat dispers...     

电化学有机合成

总结了电化学有机合成的发展历史和现状，论述了工业化的可行性和应解决的几个关键问题．按照反应机理将电化学有机合成分为阳极氧化反应和阴极还原反应，并根据有机化合物的种类进行了总结和讨论，形成了一系列有机化合物的电化学合成法．最后对电化学有机合成的未来进行了展望．     

Thermodynamic Analysis of the Formation of In-situ Reinforced Phases In Cast AI-4.5Cu Alloy

The thermodynamic analysis of the formation of in-situ reinforced phases in (TiB2 Al3Ti)/Al-4.5Cu composites prepared by mixed salts reaction was conducted, and heat changes of mixed salts system were analyzed by differential thermal analysis (DTA). The results show that although TiB2 possesses the strongest formation ability in Al-Ti-B ternary system, [Ti] is relatively excessive in the in-situ reaction and it combines with Al to form Al3Ti phase. The reinforced phases are TiB2 and Al3Ti in the produced composites due to the reaction taking place to form reinforced phase with the addition of mixed salts into Al-4.5Cu melt between 900℃ and 1032℃.     

Experiment Study on Shock Induced Reaction Process of Ti+Si Reactive Powder

A phenomenon of shock wave reacceleration was studied when Ti+Si reactive powder is loaded by a high-speed flyer. The self-propagating reaction in the Ti+Si reactive powder was triggered by the high speed impaction of the flyer launched by a two-stage gas gun. In the process of self-propagating reaction, a strand of optical fiber and the electric pins were used to measure the velocity of shock wave propagation. The experimental results showed that the initial velocity of shock wave in the reactive powder was a few hundred meters per second, and then it decreased obviously with the increase of propagation distance. This phenomenon was also verified in the process of a pure Si powder loaded by a shock, while the phenomenon of shock wave reacceleration was not observed in the Ti+Si reactive powder.