直缝焊管焊缝质量电磁超声检测方法研究

为实现直缝焊管焊缝内缺陷检测,采用周向电磁超声SH0导波检测技术,研究了基于磁致伸缩效应激励周向SH0模态导波,确定了周向SH0导波激励频率,设计了一款一发双收差分接收的直缝焊管焊缝缺陷检测探头。结果表明:该系统能够激发单一模态周向SH0导波,实际波速与模型分析结果吻合;针对直径116 mm、壁厚3.5 mm的激光直缝焊管焊缝的Φ0.6 mm盲孔和Φ1.0 mm通孔,通过差分探头的信号处理,能够实现焊缝处Φ1.0 mm通孔和Φ0.6 mm盲孔缺陷的检测。     

Fabrication and properties of low oxygen grade Al2O3 dispersion strengthened copper alloy

The low oxygen grade Al2O3 dispersion strengthened copper alloy without hydrogen-fired expansion was fabricated by the technique of vacuum hot press and hot extrusion. The mechanical and electrical properties measurements and microstructures observation on as-hot extruded, as-cold drawn and as-annealed Cu-Al2O3 alloy were conducted. The results show that the addition of a suitable amount of boron in the alloy can lower the residual free oxygen content and then inhibit the hydrogen-fired expansion. The density, σb, σ0.2, hardness, δ and electrical conductivity of the alloy reach 8.86 g/cm^3 (relative density of 99.6%), 340MPa, 250MPa, HB95,24% and 93%(IACS) respectively after hot extruded with the extrusion ratio of 30:1. Its properties have no change after annealed at 900℃ for 1h. Its strength increases after cold drawing, while its ductility and electrical conductivity drop gradually. Various properties of the cold drawn alloy can recover to those of as-extruded after annealed at 900℃ for 1h without the occurrence of recrystallization.     

Analysis of corrosion behavior of LY12 in sodium chloride solution with wavelet transform technique

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Effects of PSMA and experimental conditions on the morphologies of BaCO3 whiskers

BaCO3 whiskers exhibiting different morphologies were fabricated by a simple precipitation reaction of barium ch/oride with sodium carbonate in the absence and presence of poly-（styrene-alt-maleic acid） （PSMA） as a crystal growth modifier at room temperature. The as-prepared products were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. The influences of experimental parameters on the size and morphology of BaCO3 whiskers were investigated and discussed. It was found that the as-prepared BaCO3 whiskers are single crystals with diameter ranging from 100 to 300 run, and grow along the crystallographic a-axis or [100] direction. BaCO3 whiskers with different morphologies, such as branching and dendritic structure, can be obtained depending on the experimental conditions. With increasing PSMA concentration, the diameter of BaCO3 whiskers decreases.     

用含Pb、As、Sn地方生铁砂型铸造生产D型石墨铸铁的研究

基于Ph、As、Sn等元素有增大铁液过冷倾向的作用，利用含Ph、As、Sn的地方生铁，采用合金化和砂型铸造可以获得D型石墨铸铁，对其工艺方案进行了研究。用正交试验法设计试验方案，得到最佳工艺方案为：在亚共晶成分（WB％：3．2C，2．1si）的铁液中加入适量的铝（0．6％）和钛（0．8％），可以得到含有100％D型石墨的铸铁，其抗拉强度最高可达276MPa。     

影响薄壁球墨铸铁白口倾向和球墨数量的因素分析

研究了不同的冷却速度、稀土加入量、碳量、硅量、Si／C、Mn／S及孕育处理等工艺时薄壁球墨铸铁球墨数量和白口深度的影响。结果表明，随着冷却速率增加，薄壁球墨铸铁石墨小球越多，但容易产生白口。冷速较大时，加入稀土元素进行孕育和控制碳当量，可以有效的消除薄壁球墨铸铁的白口现象，当Si／C大于0．80、Mn／S大于20时薄壁件白口倾向较小。     

基于Pro/E二次开发的轴类件铸造工艺CAD系统

三维工艺设计代表了铸造工艺CAD的发展方向,它有利于对铸件实体剖分、凝固进程模拟以及缺陷分析的研究.利用Pro/Engineer2001强大的三维实体造型功能,采用Pro/Engineer自带的二次开发软件包Pro/Toolkit,以及Visual C 程序的一个重要软件资源MFC,充分利用VC 开发环境提供的先进技术的工具,实现了程序界面的可视化设计.并建立了铸造工艺参数数据库,实现了对数据的调用、修改、添加和删除等功能,与Pro/Engineer的UDF相结合,从而以Pro/Engineer2001为平台开发出了三维铸造工艺CAD系统.     

基于加油时间最短的流量平衡设计方法研究

基于飞机地面压力加油系统管路模型，运用运筹学方法，建立了求取加油时间最短的数学模型，求触得出只有在流量平衡的条件下，加油时间最短。系统研究的结果验证了该结论的正确性。     

X射线在炸药柱中衰减规律的试验研究

为了对武器进行X射线无损检测，必需掌握X射线在炸药中的衰减规律。通过试验测定，利用线性回归方法对不同情况下测得的X射线在某炸药中的穿透率进行拟合，分析拟合结果得出X射线在某炸药中的衰减规律。研究结果表明，X射线在某炸药中的衰减是比较明显的，其衰减规律符合三次方程形式。     

燃烧合成法制备的Al2O3基多孔陶瓷

研究了Al2O3-TiC和Al2O3-TiB2两个体系的多孔陶瓷的制备过程,分析和讨论了产物的相组成、显微结构及成型性以及影响多孔陶瓷性能,如孔径大小、耐腐蚀性能和压缩强度的诸多因素.实验结果表明:布料时有序地改变反应物料的化学组成,可以在产物中不同区域产生不同尺寸的孔洞,形成梯度多孔陶瓷.利用燃烧合成法,可制备出孔径尺寸为1～500μm、酸碱腐蚀质量损失率小于2%、压缩强度为10 MPa左右的多孔陶瓷.