A comparative study of surface integrity of Ti–6Al–4V alloy machined by EDM and AECG

The electrical discharge machining (EDM) process produces the recast layer with or without cracks on the surface that requires a remedial post-treatment in the manufacture of critical or highly stressed surfaces. One of the frequently used post-treatment processes is also the abrasive electrochemical grinding (AECG) and it has been widely used in the precision machining of difficult-to-cut materials due to an enhanced surface integrity and productivity. The aim of this study is to investigate improvability of surface integrity in terms of machining voltage, electrolyte flow rate and table feed rate parameters of AECG in EDMed Ti6Al4V alloy. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrograph (EDS) and surface roughness measurement were performed to study the surface characteristics of the machined samples. Experimental results indicate that the AECG process effectively improves the surface roughness and eliminates the EDM damages completely by setting suitable grinding parameters.     

Hydrogen sorption properties of Mg-20wt.%Fe 23 Y8 composite prepared by reactive mechanical alloying

Mg-20wt.% Fe23Y8 composite was successfully prepared by reactive mechanical alloying (RMA). X-ray diffraction (XRD) measurement shows that the main phases of composite are MgH2 and Mg2FeH6. The composite exhibits excellent hydrogen abs/desorption properties and can absorb 4.36wt.% and 5.72wt.% hydrogen at 473 and 573 K in 10 min under 3.0 Mpa hydrogen pressure, respectively. The composite can desorb 5.27wt.% hydrogen at 573 K in 30 min under 0.02 Mpa hydrogen pressure. Compared with the pure MgH2, the hydrogen desorption temperature of Mg-20wt.% Fe23Y8 composite is decreased about 40 ℃. It is supposed that both the catalyst effect of Fe-Y distributed in Mg substrate and the crystal defects play the main role in improving hydrogen sorption properties of Mg-20wt.% Fe23Y8 composite.     

钛合金表面等离子喷涂制备ZrO2─Ti系功能梯度涂层

研究了等离子喷涂法制备ＺｒＯ２Ｔｉ系功能梯度涂层。结果表明，采用等离子喷涂工艺制备功能梯度涂层是可行的，涂层与基体除以机械咬合方式结合外，还存在着少量冶金化学反应结合，添加Ｎｉ／Ａｌ和ＳｉＯ２有助于提高涂层的结合强度     

1Cr18Ni9Ti不锈钢半固态浆料的制备和轧制

研究了1Cr18Ni9Ti不锈钢半固态浆料的制备和轧制规律，结果表明：在本实验条件下，当搅拌时间为2—3min时，可以获得尺寸大小为10m-200μm、固相率为50％—60％的球状初生奥氏体的半固态浆料，便于从搅拌室底孔中放出，浆料可以实现顺利轧制，但球状初生固相颗粒与液相发生了分离，球状初生固相颗粒集中在轧材的心部，而液相偏聚在轧材的四周；经过一道次轧制，1Cr18Ni9Ti不锈钢半固态浆料轧制板材的常温强度比常规热轧板材的强度高，但延伸率下降。     

HSn70-1B铜管在碱性NaCl溶液中的腐蚀行为

利用表面分析技术和电化学方法研究了HSn70- 1B 铜管在碱性NaCl溶液中的腐蚀行为.在自腐蚀状态下，HSn70-1B铜管表面生成以Cu2 O为主的表面膜；在阳极极化电位下表面CuCl的生成反应为一级反应，电极表面形成CuCl膜 后，存在极限电流密度；电化学阻抗频谱(EIS)有2个容抗弧，随Cl-含量的增加，容抗弧 逐渐收缩，弥散性增大.     

Structural investigation of thin films of Ti1−xAlxN ternary nitrides using Ti K-edge X-ray absorption fine structure

Thin films of Ti_1−xAl_xN nitrides were prepared over a large range of composition (0 ≤ x < 1) on Si substrates using nitrogen reactive magnetron sputtering from composite metallic targets. Ti K-edge X-ray Absorption Spectroscopy experiments were carried for a better understanding of the local structure. The evolution of the intensity of Ti K-edge pre-edge peak gives evidence of the incorporation of Ti in hexagonal lattice of AlN for Al-rich films and in cubic lattice of TiN for Ti-rich films. An attempt to determine their atomic structure by combining X-ray diffraction and Ti K-edge Extended X-ray Absorption Fine Structure is presented. The evolution of the nearest neighbour and next-nearest neighbour distances depending on the composition is presented and discussed together the cubic and hexagonal lattice parameters. A possible contribution of amorphous nitrides is suggested.     

预处理工艺对W6Mo5Cr4V2高速钢组织与性能的影响

研究了预处理工艺对Ｗ６Ｍｏ５Ｃｒ４Ｖ２高速组织与性能的影响。试验结果表明，与退火预处理相比，调质预处理的奥氏体晶粒细小，未溶碳化物少，残留奥氏体量多，屈服强度高，低应力区疲劳寿命长，但抗弯强度，塑性，冲击韧度，断裂韧性都较低，高应力区疲劳寿命也短。     

飞来峡电厂1~#主变保护装置技术改造

飞来峡电厂1#主变压器保护装置因超期服役、双重化配置要求和省网安评考核需要等原因进行技术改造。该文介绍了本次技改方案的内容,重点阐述方案对新增保护装置选型、配置的技术要求和具体实施过程,点明本次技术改造起到设备更新换代、提高安全系数和满足新形势需要的效果。