纳米线高应变率拉伸超塑性

应用分子动力学方法,采用嵌入势EAM与Buckingham势,对金属Cu、半导体化合物CuInSe2和陶瓷化合物MgO纳米线进行拉伸模拟,考察其拉伸应力-应变曲线,并分析拉伸过程中的结构变化.发现当以高于临界应变率的速率对纳米线进行拉伸时,纳米线由脆性断裂向韧性断裂转变,且其延伸率可以超过100%,表现出超塑性的特性,而以较低应变率拉伸时,纳米线仍然表现为脆性断裂,这表明纳米线材料的超塑性对于应变率高度敏感.通过观察纳米线在拉伸过程中的结构变化,发现高应变率拉伸时由于CuInSe2与Cu纳米线晶体结构发生非晶化,在这一转变过程中大量能量被吸收,因而导致其塑性变好.而MgO纳米线则发生面心立方结构向环形结构的相变,相变的发生同样导致了能量的吸收,从而使其塑性大大改善.     

Dynamic recrystallization of electroformed copper liners of shaped charges in high-strain-rate plastic deformation

The microstructures in the electroformed copper liners of shaped charges after high-strain-rate plastic deformation were investigated by transmission electron microscopy (TEM). Meanwhile, the orientation distribution of the grains in the recovered slug was examined by the electron backscattering Kikuchi pattern (EBSP) technique. EBSP analysis illustrated that unlike the as-formed electroformed copper linersof shaped charges the grain orientations in the recovered slug are distributed along randomly all the directions after undergoing heavily strain deformation at high-strain rate. Optical microscopy shows a typical recrystallization structure, and TEM examination reveals dislocation cells existed in the thin foil specimen. These results indicate that dynamic recovery and recrystallization occur during this plastic deformation process, and the associated deformation temperature is considered to be higher than 0.6 times the melting point of copper.     

超塑性锌铝共晶合金成形工艺的研究

根据超塑性锌铝共晶合金的力学性能和超塑性变形特点的试验研究结果,分析制定了锌铝共晶合金塑料模成型镶件的成形工艺参数.发现在300℃及小于40MPa的成形温度和成形压力下,可获得形状符合要求的超塑成形模具镶块,同时其镶块具有较高的力学性能:HB100,σb>370MPa,σ0.2>300MPa.     

Quantitative determination of homogeneous strain value in superplastic tension

After load instability, a passage of homogeneous strain ε can be still continued in superplastic tensile deformation. But untill now, no one has given the precise value of ε corresponding to actual materials, neither in experimental measurements nor in theoretical calculations. Using the elaborate experimental measuring methods of m value and its function expressions, the note first gives the method to determine homogeneous ε, and the homogeneous ε value of typical superplastic alloy Zn-5% Al under 18℃ and 340℃ respectively.     

关于超塑挤压的加热装置设计与分析

首先介绍超塑成形加热装置的不同方式和方法.然后,根据实验需求,设计三种不同的加热装置的布局,并用MATLAB对不同布局的加热装置产生的温度场进行分析与计算.最后用实验来验证所设计的加热装置,并计算此装置的加热效率.     

Mechanical analysis of superplastic bulge in a cylindrical die

Previous mechanical analytical theories of superplastic bulge into a shaped die are all based on uniform thinning assumption, but in fact, the thinning process is obviously non-uniform. In this paper, the non-uniform thinning mechanical analytical equations of superplastic bulge in a cylindrical die based on superplastic bulge constitutive equation with variable m are established and verified by experiments performed on typical superplastic material ZnAl4Cu alloy sheet. Experimental results show that the non-uniform thinning mechanical analytical model can reflect the deformation process of bulging in a cylindrical die.     

Al_2O_3-ZrO_2复相陶瓷的超塑压缩变形织构

为了验证Al2O3-ZrO2复相陶瓷压缩变形后是否出现织构,采用X射线衍射（XRD）、极图和扫描电镜（SEM）对Al2O3-ZrO2复相陶瓷超塑压缩变形后的组织进行了分析。结果表明：复相陶瓷压缩变形后,Al2O3晶粒在（110）、（113）和（300）晶面出现择优取向,织构强度高达6.21,而ZrO2取向不明显。     

一种新的墙地砖等级在线自动分拣装置

提出了一种新的墙地砖智能全自动等级分拣装置,并详细介绍了该装置的工作原理、相关的方案设计和选用．设计中综合运用了工控机、可编程控制器(PLC)实现了墙地砖的在线检测、等级分类与自动分拣输出．     

一种用于压电陶瓷水听器极性检测的方法

压电陶瓷水听器在水声信号检测应用中有着广泛的应用,其极性直接关系到水声信号的相位信息,决定了水声采集数据的质量。文章提出了一种用于压电陶瓷水听器极性检测的方法,该方法通过计算机控制激励模块(测试盒)产生主动式测试信号源,并配合极性测试算法分析水听器所采集到的波形信息,判断出水听器的极性。测试结果表明,该方法能够快速有效地对待测水听器极性做出准确判断,且简单可靠,可广泛应用于水声信号检测领域中。     

新型压电陶瓷涡街流量计

介绍一种新型的压电陶瓷涡街流量计,该流量计采用ＢＳＴ压电陶瓷元件来检测旋涡释放频率,使该流量计能在高温工况下工作,一年多的工业现场运行试验结果表明,新研制的涡街流量计可靠性高、稳定性好,在４００℃高温和１０ＭＰａ高压下能长期连续正常运行。     

A strategy to obtain a high-density and high-strength zirconia ceramic via ceramic injection molding by the modification of oleic acid

Despite its unique high efficiency and good environmental compatibility, the water-soluble binder system still encounters problems achieving a desired sintered part via ceramic injection molding because of the poor compatibility and the powder-binder segregation between ceramic powders and binders. The objective of this study was to obtain a sintered part with excellent properties by introducing a small quantity of oleic acid to the surface of zirconia powders before the mixing process. As opposed to many previous investigations that focused only on the rheological behavior and modification mechanism, the sintering behavior and densification process were systematically investigated in this study. With the modified powders, debound parts with a more homogeneous and smaller pore size distribution were fabricated. Also, a higher density and greater flexural strength were achieved in the sintered parts fabricated using the modified powders.     

Phase boundary sliding model controlled by diffusionsolution zone in superplastic deformation

With scanning electron microscope (SEM), the surface morphology of phase boundary sliding (PBS) in superplastic deformation (SPD) of Zn-Al alloy and the diffusion behavior of Zn, Al interfaces in their powers' sintering have been investigated. The results show that Zn-Al eutectoid microstructure can be achieved through their powders' sintering, and the diffusion characteristic between Zn and Al is just a demonstration of Kirkendall effect, in which Zn can dissolve into Al whereas A1 can hardly dissolve into Zn. During sintering, a diffusion-solution zone ?′ has formed and subsequently transformed into a eutectoid microstructure in the cooling process. The superplastic deformation mechanism of Zn-Al eutectic alloy is phase boundary sliding which is controlled by the diffusion-solution zone ?′. If the diffusion-solution zone ?′ is unsaturated, it will have much more crystal defects and the combination between ?′ and phase ? is weak, thus the process of phase boundary sliding becomes easily; on the contrary, if the diffusion-solution zone ?′ becomes thick and saturated, the sliding will be difficult.     

A bulk metal/ceramic composite material with a cellular structure

Metal/ceramic composite materials can be divided into two groups: one is ceramic reinforced metal matrix composite, and the other is metal toughened ceramic matrix composite. The research on these materials mainly focuses on the mechanical properties due …     

A microwave ceramic band-pass filter for mobile communications with new coupling structure

A surface mounted device (SMD) microwave ceramic band-pass filter for mobile communication with a new coupling structure is reported in this paper. In this filter, the external and internal coupling structures are fabricated on an alumina substrate and both resonators and coupling structures are placed into a metal house to cut off its radiation. The relationship between the coupling structures and the performance of filter is analyzed by high frequency structure software (HFSS) and the filter with the center frequency of 836.5 MHz, the bandwith of 40.0 MHz, the pass-band ripple of 0.1 dB and the insertion loss of 1.5 dB has been successfully designed and fabricated. The measured results show a good agreement with the simulation results. Foundation item: Supported by Sino-British Excellent Youth Scholar Foundation (2005362) and the Natural Science Foundation of Hubei Province (2008CDB315)     

微波对陶瓷材料的作用

研究了微波对陶瓷材料的作用,综合了Ｍａｘｗｅｌ电磁理论及介质理论,从理论上分析了微波与物质相互作用的机理。指出了介质吸收微波源于介质对微波的电导损耗和极化损耗,高温下,电导损耗将占主要地位。即使在介质吸收为零的情况下,由于介质的反射,微波也不能百分之百穿过介质。利用微波加热物质,物质的损耗有一定的限制,对于２．４５ＧＨｚ的微波,物质电导率应在１０－４～１Ω－１ｃｍ－１之间。对微波场中非均匀固体的行为进行了简单的分析和预测。     

Effect of superplastic deformation on precipitation behavior of sigma phase in 3207 duplex stainless steel

Owing to excellent strength, toughness and corrosion resistance, duplex stainless steels(DSS) are widely used in constructional and petrochemical applications. Sigma phase, which has detrimental impact on the properties, is readily precipitated during hot working of DSS. However, precipitation behavior of sigma phase during superplastic deformation, which is the most significant processing method of DSS, is still unclear. In the current study,the effect of superplastic deformation on the precipitation behavior of sigma phase was investigated in 3207 duplex stainless steel. The result shows that superplastic deformation could prevent sigma phase precipitation generally by increasing mobility of grain boundaries and decreasing misorientation of the sigma phase boundaries, resulting in some sigma phase precipitated on the twin boundaries. Most of the sigma phase precipitated on ferrite-austenite interface with misorientation of 20–25°, while it precipitated in ferrite or austenite with the misorientation of 40°–45°. The orientation relationship between sigma phase and matrix matched well in austenite and on the ferrite/austenite interfaces, while it showed a small misfit in ferrite. The prevention effect of the superplastic deformation on the sigma phase precipitation was beneficial to quasi stable deformation stage,resulting in longer elongation.     

Hpb59—1黄铜超塑性压缩变形后金相组织的变化

本文对Hpb59-1黄铜超塑性压缩变形后的试样进行金相分析。不同的原始组织、变形温度和应变速率,对超塑性压缩变形后的金相组织都产生较大影响。     

AlN-BN复合陶瓷及在微波输能窗上的应用

介绍了微波输能窗材料及AlN-BN复合陶瓷研究现状.AlN-BN复合陶瓷具有导热率高、微波透射率高、可加工性好等优点.着重探讨了AlN-BN复合陶瓷的介电性能及影响因素,以及利用AlN-BN复合陶瓷开发新型大功率输能窗的方法和措施.     

陶瓷硅材料的制备及其特性

文章研究了用来作为多晶硅薄膜太阳电池衬底的陶瓷硅材料的制备方法及其结构。对不同烧结条件制备的样品进行了XRD和SEM的测试和分析。测试分析的结果表明：形成了表面平整的陶瓷硅材料，用此方法可以获得性能良好的硅太阳电池衬底材料。     

压电陶瓷变压器的激光钎焊

针对压电陶瓷变压器 ( PECT)侧电极的连接问题 ,提出了激光钎焊的工艺方法 ,采用金属网辅助钎膏钎接片单元工艺 ,很好地解决了多层元件不同性质分割区域表面的连接问题 ,激光钎焊接头全连通率高 ,热影响小 ,质量好。建立了三维多层异质复合结构 PECT的激光钎焊温度场数学模型 ,通过数值模拟的方法计算了 PECT激光钎焊温度场的分布情况 ,取得了比较理想的结果 ,激光钎焊工艺及温度场的分析研究 ,将会推动压电陶瓷变压器的实用化进程 ,对类似问题的解决也会有一定的借鉴意义