Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment

The surface modification of magnesium alloys （AZ31 and AZ91 HP） was studied by a high current pulsed electron beam（HCPEB）. The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone（ HAZ）, but also beyond HAZ, reaching over 250μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples.     

激光一同轴电弧复合焊接热源焊接

在建立和研究空心钨极电弧的基础上，对激光一同轴电弧复合焊接热源焊接特性进行了深入研究。试验结果表明，激光与电弧相互作用增强的效果十分显著，采用同轴电弧作为辅助热源增大焊接熔深的效力优于激光一旁轴电弧复合焊接热源焊接效果。在试验的基础上，得到了激光一同轴电弧复合焊接热源焊接熔深的变化规律。     

Investigation into the evolution of corrosion product layer (CPL) of 1018 C-steel exposed to multiphase environment using FIB and EIS techniques

This communication reports into the effects of flow, fluid composition and the effectiveness of imidazoline inhibitors on the evolution and distribution of corrosion products on 1018 C-steel exposed to CO₂ corrosion. Focused ion beam technique was used to measure the thickness of the corrosion product layer (CPL), in contrast to the conventional techniques used to observe the cross-section of specimens. Morphological analysis using scanning electron microscopy revealed topographical variations on the surface with the change in the multiphase environment. The CPL was found to be more porous in nature with the presence of oil in the multiphase environment. Electrochemical impedance spectroscopy was also used in the present study to measure the corrosion rates and was subsequently correlated to the CPL evolution for 1018 C-steel in multiphase environment.     

Investigation of the oxidation behavior of Mg-implanted steel samples

Mg-implanted AISI 321 steel samples (implantation-energy 40 keV, dose: 2 * 10¹⁷ ions/cm²), were oxidized in air in the temperature region 350–650°C for several days. Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectroscopy (RBS) were used to determine the oxygen concentration in the oxidized samples. An enhancement of the oxidation rate on the implanted material in comparison to the non-implanted was observed at high temperatures. It was demonstrated that the oxidation of Mg-implanted steel proceeds by two different mechanisms, at 350–550°C on the one hand and at 550–650°C on the other. The magnesium-depth distribution, determined by NRA (using the²⁴Mg(, P)²⁷Al reaction), RBS and X-ray Photoelectron Spectroscopy (XPS) also indicated a diffusion of the element at high temperatures confirming these assumptions. Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) were applied to investigate the surface morphology and to explain the influence of Mg-ion implantation on the oxidation behavior of AISI 321 austenitic stainless steel.     

离子束增强沉积Si─N膜

用离子束增强沉积方法制备了ＳｉＮ薄膜，其中Ｓｉ由一束Ａｒ离子从Ｓｉ靶上溅射下来，在溅射沉积的同时，以一束Ｎ离子轰击正在沉积的膜层，于是获得了ＳｉＮ膜。采用卢瑟福背散射、红外光谱和透射电镜对膜层的成分和结构进行了分析，结果表明：膜面平整，膜层为非晶或微晶结构，由Ｓｉ和βＳｉ３Ｎ４组成     

CH_4离子束增强沉积对TiC薄膜显微硬度的影响机制

研究了双离子束沉积ＴｉＣ薄膜的形成．离子束反应溅射膜的显微硬度比ＣＨ_４高子束增强沉积膜的显微硬度高．ＸＰＳ，ＴＥＭ和ＡＥＳ分析表明后者硬度低的一个重要原因是ＣＨ_４离子束轰击引入过量的自由碳原子．     

EBY1-60×134型电子束焊机控制系统的设计

介绍了EBY1-60×134型法兰环缝局部真空电子束焊机的基本组成及作用,对该焊机的控制系统的组成和工作原理进行了分析,提出以工控机作为上位机控制核心,可编程控制器作为下位机控制核心的控制系统主要组成,设计了上位机工控机的控制软件,下位机PLC的控制软件,实现对法兰环缝局部真空电子束焊机的真空系统控制、焊接过程控制和焊接工艺过程的数据管理,应用该设备已成功地焊接了某大型航天飞行器典型结构件上的法兰环缝。设备运行表明:焊机的控制系统硬、软件设计合理,功能完善,工作可靠,满足了法兰环缝局部真空电子束焊接的需要。     

异形坯连铸结晶器内三维流场的数值模拟

根据湍流理论及异形坯连铸的特点, 建立了异形坯结晶器三维流场数学模型, 对不同条件下的流场进行了数值模拟, 分析了水口结构和工艺参数变化时异形坯结晶器内涡心深度的变化规律及液面湍动能的分布状态. 结果表明 采用上倾式水口, 水口夹角为120°, 拉速为0.9m/s时, 结晶器内流场分布较为合理, 液面较稳定. 模拟结果与水模实验结果吻合较好. 该模型可对连铸过程进行离线分析, 确定最佳参数, 并可作为在线控制模型的基础.     

Metallographic sample prepared by ion beam etching

Ion beam etching technique was used to reveal the metallograhpic microstructure and interface morphology of electroplating chromium coating, in particular, whose substrate surface layer was treated in advance by laser quenching. Chemical etchings were also conducted for comparison. The reveal microstructures were observed and analyzed by scanning electron microscopy. The results show that ion beam etching can reveal well the whole microstructures of composite coating-substrate materials.     

用丝束电极研究SO_4~(2-)对纯铝缝隙腐蚀的影响

采用动电位极化和丝束电极技术测量了纯铝在2mol/L NaCl和2mol/L NaCl 0.8mol/L Na2SO4溶液中的极化曲线、缝隙内外的自腐蚀电位和电化学阻抗分布,研究了SO42-对铝缝隙腐蚀的影响。结果表明,在NaCl溶液中,缝隙内的铝为阳极、缝隙外为阴极;随浸泡时间增加,腐蚀不均匀性增加。加入Na2SO4后,减小了缝隙内外腐蚀电位差,显著降低了铝的腐蚀速度。Na2SO4是中性溶液中铝的吸附型缓蚀剂,延缓了缝隙腐蚀的发生。