The effect of interlayer on corrosion resistance of ceramic coating/Mg alloy substrate in simulated physiological environment

Ceramic coatings are deposited on biodegradable magnesium alloys by physical vapor deposition to reduce the electrochemical activity in the simulated physiological environment. Although an interlayer is generally used to reduce the mismatch between the hard coating and soft substrate, the effects of the interlayer on the electrochemical corrosion behavior have seldom been explored. In this work, AlO_xN_y ceramic coatings were deposited on AZ31 magnesium alloys with Al or Ti interlayers. Polarization tests and electrochemical impedance spectroscopy (EIS) were conducted to evaluate the corrosion resistance in the cell culture medium. The AlO_xN_y ceramic coating significantly improved the bio-corrosion resistance of the magnesium alloy, but the Ti interlayer accelerated the corrosion rate. In comparison, although the addition of an Al interlayer led to smaller enhancement in the surface mechanical properties of the AlO_xN_y coating, corrosion could be impeded effectively. Our results indicate that an Al interlayer is preferred over Ti and the corrosion failure mechanism is discussed from the perspective of defects.     

Effects of Cu and Cu/Ti interlayer on adhesion of diamond film

Diamond film were deposited on the cemented WC + 6% Co substrates by a microwave plasma chemical vapor deposition (CVD) system. The effects of Cu and Cu/Ti as interlayer on adhesion of diamond film were investigated. The surface morphology and composition of the film and microstructure of film/substrate interface were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and Raman spectrometer, respectively. The adhesion of diamond film was evaluated by indentation adhesion testing. The results show that Cu/Ti would be a suitable interlayer system to improve film adhesion. It was considered that Cu atoms replaced most voids left by leached Co, recovered the surface strength and toughness, and inhibited the diffusion of Co to the substrate surface. Ti atoms act as promoter for diamond nucleation, and the formation of TiC enhanced the adhesion of diamond film. Furthermore, Cu/Ti interlayer system restrained the growth of diamond grain and promoted the formation of nano-crystalline, which increased the contact area of the film/substrate interface.     

Effect of pretreatment, seeding and interlayer on nucleation and growth of HFCVD diamond films on cemented carbide tools

The direct deposition of diamond on carbide tools is difficult because formation of graphitization and thus leading to poor adhesion, due to presence of cobalt on the surface. Various methods were adopted to suppress the effect of cobalt during deposition. One of them was by putting an interlayer. In this study, carbide substrates with coatings of Ti, TiN and TiC were used. Ti coating has a strong tendency to form intermediate carbide leading to the highest nucleation density of diamond. A comparison was made on nucleation and growth of diamond crystals on various interlayers by hot filament CVD method. At the same time, the variations of diamond film growth morphology have been studied on unseeded and seeded carbide inserts. The SEM pictures revealed that among interlayer, Ti coating gave highest nucleation density compared to TiN and TiC coatings. At the same time, diamond seeded inserts, pretreated by Treat 1 [HCl + HNO₃ + H₂O (1:1:1)] for 15 min ultrasonically resulted in the highest nucleation density, compared to Treat 2 [K₃[Fe(CN)₆] + KOH + H₂O] solution in (1:1:10) for 15 min, at constant process parameters.     

Role of nickel as an interlayer in dissimilar metal friction welding of maraging steel to low alloy steel

Continuous drive friction welding of dissimilar metals, maraging steel and low alloy steel was carried out. It was observed that the hardness, ductility and impact toughness of maraging steel are low due to the diffusion of elements such as carbon, manganese, silicon and phosphorus from low alloy steel to maraging steel. An attempt was made in this study to improve the properties by friction welding of maraging steel and low alloy steel with nickel as an interlayer. The hardness, tensile strength and impact toughness are observed to be improved, as nickel acted as diffusion barrier. The effect of post-weld heat treatments on microstructure and mechanical properties of dissimilar metal friction welds with and without interlayer was also studied. Maraging steel responded to solutionizing & aging and low alloy steel responded to quenching and tempering. The notch tensile strength and impact toughness in case of dissimilar metal weld with interlayer are observed to be more than that of the dissimilar metal weld without interlayer.     

双轴钻床钻轴刚度失谐对钻削颤振的影响

运用近频摄动理论分析了双轴钻床钻轴刚度失谐后对钻轴系统固有振动频率的影响。模拟计算结果表明：引入适当的钻轴刚度失谐量，能够分离原钻轴系统彼此接近的固有频率，避免两钻轴间固有近频振型之间的耦合，从而抑制钻削颤振现象的发生.     

高频群脉冲电解加工的极间平衡间隙

给出了脉冲电解加工极间平衡间隙的数学模型，并据此讨论了高频群脉冲电解加工极间电压、阴极进给速度和电源脉冲频率与平衡加工间隙(极限平衡间隙)间的关系。模拟和实验表明：极限平衡间隙随极间电压升高而升高，它们呈近似的线性关系；随阴极进给速度增加，极间平衡间隙非线性地降低；而极限平衡间隙与脉冲频率则呈严格的线性关系，即随频率增加平衡间隙线性减小。极限平衡间隙与初始加工间隙无关，即一定的阴极进给速度和极间电压对应的稳定平衡间隙是不变的。     

GMAW根部间隙及焊枪对中信息的视觉检测

焊缝跟踪是焊接质量控制的一个重要内容。采用普通CCD摄像机配合窄带复合滤光器,拍摄出了GMAW根部间隙图像,根据对图像中根部间隙的特征分析,设计了图像处理算法,提取出了根部间隙边缘,获得了根部间隙的大小和焊枪对中信息,为下一步实现GMAW的焊缝跟踪奠定了基础。     

Microstructure and mechanical properties of diffusion bonded titanium/304 stainless steel joint with pure Ag interlayer

Abstract

In the present study, diffusion bonding of commercially pure titanium to 304 stainless steel (SS) using a pure Ag interlayer was carried out. It is found that the pure Ag interlayer can effectively block the interdiffusion and interaction between Ti and SS. The resultant joints were composed of Ti substrate, Ti–Ag solid solution, TiAg intermetallic phase, the remnant Ag interlayer and SS. Upon tensile loading, fracture took place through the remnant Ag interlayer, indicating that the TiAg intermetallic phase exhibits no detrimental effect on the strength of the joints. A maximum tensile strength of 421 MPa was achieved, which is notably improved compared with previous results. Furthermore, extensive dimples were observed on the fracture surfaces, clearly indicating that the joints were ductile in nature.     

Color stable and interlayer free hybrid white organic light-emitting diodes using an area divided pixel structure

Color stable and interlayer free hybrid white organic light-emitting diodes were fabricated by using an area divided pixel structure. The area divided pixel structure was realized by stacking red and blue emitting layers using a fine metal mask. A phosphorescent red emitting layer was patterned by a metal mask and a blue fluorescent emitting layer was commonly deposited on the patterned red emitting layer. The blue fluorescent emitting layer could play a role of a hole-blocking layer and a white emission could be obtained due to separate emission of red and blue emitting layers. The interlayer free hybrid WOLEDs showed color stability from 100 cd/m² to 10,000 cd/m².     

我国大型预焙阳极铝电解生产与国际先进水平的差距

就我国大型预焙阳极铝电解技术渐进过程、我国铝电解生产主要技术经济指标与铝电解生产线设计和装备水平、铝电解阴极和阳极材料、铝电解生产使用的原材料和铝电解生产控制和操作水平等几个方面分析了我国大型预焙阳极铝电解生产技术和装备水平与国际先进水平的差距。     

An analytical finite element technique for predicting thrust force and torque in drilling

An analytical finite element technique was developed for predicting the thrust force and torque in drilling with twist drills. The approach was based on representing the cutting forces along the cutting lips as a series of oblique sections. Similarly, cutting in the chisel region was treated as orthogonal cutting with different cutting speeds depending on the radial location. For each section, an Eulerian finite element model was used to simulate the cutting forces. The section forces were combined to determine the overall thrust force and drilling torque. Good agreement between the predicted and measured forces and torques was found in orthogonal and oblique cutting and in drilling tests. The drilling tests were performed on AISI 1020 for several drill diameters, spindle speeds, and feed rates. An extension of the technique for predicting drill temperatures has also been described.     

国产铝电解多功能天车与进口天车的差距和改进

通过对国产铝电解多功能天车与进口天车存在的技术差距进行全面分析,论述了国产天车制造业应重点做好的几方面工作。     

Size effects of micro drilling in steel

The main objective of this research work is to investigate size effects by downscaling the twist drilling process into the micro range (diameter: d = 50 μm to 1 mm). Therefore, experimental micro drilling tests in steel AISI 1045 (normalized and full-annealed) are performed with different cutting conditions (drill diameter, feed, cutting speed) and compared with data obtained from conventional drilling. Various size effects and its significant influence on the micro cutting process are characterized with help of the experimental results. Additionally, the formula of Victor–Kienzle is adjusted to model the feed force in micro drilling operations.     

Tool wear in friction drilling

This study investigates the tool wear in friction drilling, a nontraditional hole-making process. In friction drilling, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. The wear of a conical tungsten carbide tool used for friction drilling a low carbon steel workpiece is studied. Tool wear characteristics are quantified by measuring its weight change, detecting changes in its shape with a coordinate measuring machine, and making observations of wear damage using scanning electron microscopy. Energy dispersive spectrometry is applied to analyze the change in chemical composition of the tool surface due to drilling. In addition, the thrust force and torque during drilling and the hole size are measured periodically to monitor the effects of tool wear. Results indicate that the carbide tool is durable, showing minimal tool wear after drilling 11,000 holes, but observations also indicate the progressively severe abrasive grooving on the tool tip.     

轧辊辊缝差和轧机组装间隙对精轧钢带尾板侧偏的影响

为了探讨精轧区轧辊辊缝差和轧机组装间隙这两个重要因素对精轧钢带尾板侧偏的影响,依据热轧生产线的操作条件,运用Abaqus软件建立了钢带热轧的第1、2和4机架精轧模型与尾端弯曲钢带。通过设定不同层级的轧缝差与变换上、下轧辊相对位置,模拟分析了各机架的轧辊辊缝差和组装间隙对轧辊两侧轧制力差、钢带尾端中心偏移、钢带运动行为的影响。结果表明:调整轧辊辊缝差可以有效地矫正钢带中心线偏移量,降低因钢带中心线偏移所产生的轧制力差,减少尾板撞击的发生概率;轧机组装间隙不对称会使钢带轧制时发生侧偏并撞击边导器,影响钢带运行的稳定性与钢带的成形质量。最后,试验验证进一步证实了上述结论的正确性与合理性。     

铝合金焊接图像焊缝位置和间隙提取

基于自行设计的CCD被动视觉传感系统,在仅依靠电弧光照明的情况下,实现了钨极氩弧焊过程中实时提取清晰的熔池正前方图像.通过分析退化恢复、平滑后的图像间隙处灰度值特点,采取了特定区域自动域值分割、空穴检出法统计各8-连通域面积、基于8-领域面积阈值去噪、面积统计转换等步骤可以求得间隙值,进一步进行间隙细化,最后采用Hough小变换对细化后的间隙点进行拟合,检测出焊缝位置.     

Effects of use of higher strength interlayer and external cooling on properties of friction stir welded AA6061-T6 joints

Although sound AA6061-T6 joints can be produced by friction stir welding, a loss in strength takes place in the weld region. In this study, it was demonstrated that the strength of the nugget could be increased by the use of a higher strength interlayer during friction stir welding. This strength recovery cannot, however, be attainable in the heat affected zone. Although an external cooling was applied during welding in order to increase strength in the heat affected zone, it was not sufficient for achieving the required cooling condition for improved strength.     

脉冲电化学光整加工的流场及间隙特性

通过系统的试验研究，分析了工作液流场分布、流量、加工间隙等工艺参数对加工质量的影响。研究结果表明：合理控制加工间隙和工作液流场分布，对保证加工表面的质量极为重要；在优选的工艺参数下，可快速获得优质表面。     

PLC在深孔钻组合机床控制系统中的应用

本文简要介绍了深孔钻组合机床的控制原理，并给出其PLC控制系统的流程图和梯形图程序设计。     

霍耳膜片侧冲缺模具设计

在分析零件结构特点的基础上,设计了1副4缺口同冲模具,并详细介绍了模具设计要点,与以往单冲模相比,降低了生产成本,实现了产品质量及生产效率的提高,对同类零件的设计制造具有一定的参考作用。