Effects of pulse reverse electroforming parameters on the thickness uniformity of electroformed copper foil

The non-uniformity of electroformed layers directly affects the mechanical properties and application requirements of micro devices. Therefore, uniformity of electroformed copper foil is significant in ensuring or improving the mechanical properties of micro devices. The influences of duty cycle, current density, power source, and electroforming time on the thickness uniformity of electroformed copper layers were studied, and these parameters were optimised by using the orthogonal experiment method. The thickness distribution rule of electroformed copper foil was also determined. Duty cycle had the largest influence on the uniformity; the uniformity of electroformed layers prepared with pulse reverse current power source was superior to those prepared with direct current power source and pulse current power source. Increasing current density enhanced uniformity. The optimal technical process suggested by this orthogonal experiment adopts pulse reverse current power, 30% of positive duty cycle, 10% of negative duty cycle, 2?A?dm^?2 of current density, and 92?minutes of electroforming time. The minimum coefficient of variation reached 1.54%. The thickness of electroformed copper foil varied directionally.     

基于LIGA技术的微细电火花加工优化研究

比较了活动掩膜法与固定掩膜法得到的PMMA胶结构,实验表明固定掩膜法更适合于多次曝光.结合LIGA技术和微细电火花加工的优点,用LIGA技术制备出具有复杂形状的铜微细工具电极,再用该工具电极进行微细电火花加工,在不锈钢上加工出异形微细孔.并通过进一步调整电火花加工工艺参数,优化了加工尺寸精度和表面粗糙度.     

High cycle fatigue and fracture behavior of LIGA Nickel

The high cycle fatigue response of electrodeposited LIGA Ni structures was determined using cyclic loading and fractography. Extending the lifetime data obtained from tests with R = 0.1 to the condition of fully-reversed loading, the fatigue behavior was found to be comparable to literature values for conventionally processed bulk Ni. Intergranular fatigue cracking of the predominantly ultra-fine-crystalline columnar micro-structure was observed.     

Improvement of deposition uniformity in alloy electroforming for revolving parts

The ability to control the nonuniformity of electrodeposition is a key to successful application of electroforming technology. In this paper, an experimental system is developed to electroform the thin-walled revolving parts. Some measures are employed to improve the uniformity of deposition distribution, such as conformal anode, cathode shield and high-frequency pulse current. The profile of the conformal anode is precisely designed by using the function of electric field analysis of ANSYS software, so as to reduce the experimental works and increase the application effect of conformal anode. The deposition thickness, alloy composition and microhardness of the electroforms are measured to reveal the actual deposition distribution. The results show that the electroforms have a satisfactory deposition distribution, the patterns of which are similar to the current density distribution on cathode.     

合成膜电阻片喷涂过程的雾化仿真

合成膜电阻片是合成膜电位计中的关键零部件,其电阻的线性度直接决定了电位计的精度.喷涂电阻液是合成膜电阻片制造过程中的关键工序,因为喷涂的均匀性对电阻片的电阻线性度有至关重要的影响.影响喷涂均匀性的因素主要有电阻液本身的均匀性、电阻液雾化的均匀性、喷枪与电阻片相对运动速度的均匀性以及喷涂室流场的分布特性等.对电阻液雾化进行了分析,利用有限元仿真,得到了雾化气体压力、电阻液流量以及喷涂距离对电阻液雾化均匀性的影响规律.对于口径0.5 mm的喷枪,当电阻液流量恒定,雾化压力从0.2 MPa增加到0.4 MPa时,雾化均匀区间从距离喷嘴260 mm处变到距离喷嘴150 mm处;当雾化压力恒定,电阻液流量从1.89×10-5 kg/s增加到4.89×10-5 kg/s时,雾化均匀区间从距离喷嘴130 mm处变大到距离喷嘴200 mm处.这些仿真结果将为电阻液喷涂工艺提供一定的参考.     

Effects of nickel coating thickness on electric properties of nickel/carbon hybrid fibers

In this work, nickel/carbon hybrid fibers were prepared by the electrolytic plating on carbon fibers in order to improve electric conductivity of the carbon fibers; the effects of nickel content and coating thickness on the electric conductivity of the fibers were studied. The structural properties and surface morphologies of the hybrid fibers were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electric conductivity of the fibers was measured using a 4-point probe method. As for experimental results, it was observed that the electric conductivity of the nickel/carbon hybrid fibers was dramatically increased in the presence of metallic nickel particles, with the best result in the condition of over 0.75 μm of the thickness due to the minimization of the inner pores.     

金属镍结晶生长对Ni/C微颗粒镍镀层均匀性的影响

采用湿式加压氢还原技术研究不同包覆阶段、不同氢气分压对球形石墨颗粒表面金属镍镀层镀覆均匀性的影响,探讨制备具有致密光滑镀层的Ni/C颗粒的条件及形成机理.结果表明:当气体总压为4 MPa,其中氢气分压为65%时,得到的Ni/C颗粒具有比较致密均匀的镀覆状态;镍镀层的最终形貌由镍晶体形核和生长的动力学过程决定;非均相形核过程有利于形成均匀镀层,均相形核和晶体生长都会使镀层的均匀性降低;通过调节反应速率,可以控制金属镍的结晶过程,实现均匀镀覆.     

New process for synthesis of nickel oxide thin films and their characterization

Sol-gel spin coating method has been successfully employed for the deposition of nanocrystalline nickel oxide (NiO) thin films. The films were annealed at 400-700 °C for 1 h in an air and changes in the structural, morphological, electrical and optical properties were studied. The structural properties of nickel oxide films were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis shows that all the films are crystallized in the cubic phase and present a random orientation. Surface morphology of the nickel oxide film consists of nanocrystalline grains with uniform coverage of the substrate surface with randomly oriented morphology. The electrical conductivity showed the semiconducting nature with room temperature electrical conductivity increased from 10⁻⁴ to 10⁻² (Ω cm)⁻¹ after annealing. The decrease in the band gap energy from 3.86 to 3.47 eV was observed after annealing NiO films from 400 to 700 °C. These mean that the optical quality of NiO films is improved by annealing.     

Ellipsometry of passive oxide films on nickel in acidic sulfate solution

Nickel passive film has been studied in acidic sulfate solutions at pH 2.3 and 3.3 by ellipsometry. During anodic passivation followed by cathodic reduction, the roughness increases with dissolution of nickel, being indicated by gradual decrease of reflectance. However, the ellipsometric parameters, Ψ (arctan of relative amplitude ratio) and Δ (relative retardation of phase), are relatively insensitive to the roughness increase. From the change of Ψ and Δ, δΨ and δΔ, during the anodic passivation and reduction, thickness of the passive oxide film was estimated with assumption of refractive index of n_f = 2.3 of the film. The thickness estimated is a range between 1.4 and 1.7 nm in the passive potential region from 0.8 to 1.4 V vs. RHE, having a tendency of thickening with increase of potential. Cathodic reduction at constant potential induces a change of the oxide film to an oxide film with lower refractive index of n_f = 1.7, accompanied by thickening of the film about 30% more in the initial stage of reduction for 30 s. The gradual decrease of thickness takes place for the oxide with the lower refractive index in the latter stage. The potential change from the passive region to cathodic hydrogen evolution region may initially cause hydration of the passive oxide of NiO, i.e., NiO + H₂O = Ni(OH)₂, and during the latter stage of reduction, the hydrated nickel oxide gradually dissolves.     

利用LIGA技术研制微细电火花异形和阵列结构电极

利用LIGA技术的优势,针对电火花电板结构特点开发出相应的加工工艺,完成电火花复杂结构电极的制造.电火花电极的特点是大高宽比的金属柱状结构,这对于LIGA技术工艺具有特殊的难度,需要突破深孔显影和电铸工艺难题.通过大量的工艺试验,优化出电火花电极阵列结构的工艺路线,圆满完成阵列结构和异形复杂结构的电极制造,为电火花技术...     

New type of micro-bipolar plate for micro-fuel cells using LIGA technology together with improved and cost-effective electroplating processes for PCBs

A new type of micro-bipolar plate for micro-fuel cells was developed. This micro-bipolar plate was realised using LIGA technology (laser lithography system) together with improved electroplating processes for printed circuit boards (copper, nickel, gold) to produce micro-fuel cells with reduced precious metal loading, increased activity and durability, lower weight and negligible corrosion, and, in addition, lower production cost.     

定偏心和不定偏心平面研磨均匀性的研究

对修正环形抛光机定偏心和不定偏心平面研磨进行了运动分析,给出了研磨盘上一点相对于工件的速度矢量与轨迹方程,讨论了研磨盘上不同位置的点的相对轨迹。在Preston方程基础上,建立了材料去除函数和研磨均匀性函数。实验结果与理论分析表明通过设置选择适当的转速比组合,可使工件获得均匀研磨,有利于工件平面度的提高。     

Structure uniformity and limits of grain refinement of high purity aluminum during multi-directional forging process at room temperature

The effect of forging passes on the refinement of high purity aluminum during multi-forging was investigated. The attention was focused on the structure uniformity due to deformation uniformity and the grain refinement limitation with very high strains. The results show that the fine grain zone in the center of sample expands gradually with the increase of forging passes. When the forging passes reach 6, an X-shape fine grain zone is initially formed. With a further increase of the passes, this X-shape zone tends to spread the whole sample. Limitation in the structural refinement is observed with increasing strains during multi-forging process at the room temperature. The grains size in the center is refined to a certain size (110 μm) as forging passes reach 12, and there is no further grain refinement in the center with increasing the forging passes to 24. However, the size of the coarse grains near the surface is continuously decreased with increasing the forging passes to 24.     

基于棒材的多通道超声检测系统的高温合金组织均匀性检测

高温合金锻件出现混晶或者组织不均匀现象时,材料的性能会下降,有效的超声无损检测方法可以对高温合金组织的均匀性进行评价。由于组织均匀性影响超声波信号在材料中的传播,故超声波在高温合金材料中的散射噪声分布,可以反映材料的组织差异。以某牌号高温合金锻造棒材作为试验对象,采用基于棒材的多通道超声自动检测系统进行超声波数据采集,在Ф0.8mm平底孔当量的灵敏度条件下对每个深度噪声信号进行分析。通过处理超声检测相应部位的显微组织数据,得到噪声信号的平均值与晶粒直径在99%置信区间显著正相关,噪声信号标准差与晶粒直径变异系数在95%置信区间显著正相关的结论。进一步结合聚类分析可以确定:当噪声平均值为1.6%~1.79%,噪声标准差为0.6~0.8时,材料为混晶组织;当噪声平均值为1.81%~2.6%,噪声标准差大于1时,材料含有树枝晶组织。     

Nanocrystallization process and mechanism in a nickel alloy subjected to surface severe plastic deformation

Bulk components made of a Ni-base C-2000 alloy with a face-centered cubic crystal structure and a very low stacking fault energy have been severely plastically deformed at the surface region to attain a grain size gradient ranging from nanocrystalline at the surface to coarse grained in the bulk. The evolution of microstructural characteristics has been studied as a function of the processing time employing a variety of analytical techniques, including extensive conventional and high-resolution transmission electron microscopy analyses. The thickness of the nanocrystalline surface layer is found to increase with the processing time. Deformation twinning is ubiquitous and occurs at the earliest stage of deformation and the deepest region of the material where plastic deformation has taken place in the surface severe plastic deformation process. A grain-refinement mechanism led by deformation twins and complemented by dislocation activity has been put forth to explain the nanocrystallization of the coarse-grained material employed in this investigation.     

Influence of spike current in different shaped waveforms on the surface finish of nickel electroforms

This paper studies the effects of ramp-down spike-shaped waveform on the surface finish of nickel electroforms in pulse current electroforming. Experimental results show that the quality of the electroforms, in terms of surface roughness improvement, influenced by the types of waveform is of the order of ramp-down and triangular both with spike>rectangular with spike>ramp-down and triangular both with relaxation time>rectangular. The results show that at the same cathodic peak current density, pulse period and a fixed electro-deposition time or electro-deposition thickness, the surface roughness can be reduced by as much as 2–3 times when a ramp-down spike was used in the cases of triangular, rectangular and ramp-down waveforms. The best surface finish was obtained when a ramp-down spike in a ramp-down waveform was used. These results are supported by the theoretical predictions and the study of the surface morphology of the electroforms by scanning electron microscopy.     

泡沫铝泡体均匀性的定量表征

基于数字图像处理与分析技术,提出一种可取代目测这种定性评价泡沫铝中泡体均匀性的定量表征方法。泡沫铝中泡体均匀性的定量表征主要包括如下3个步骤：首先通过表面修饰使泡沫铝截面上的孔洞同孔筋之间产生适当的反差,同时获取泡沫铝样品截面照片;然后用图像处理软件Photoshop将截面照片转化成灰度图,并用大型科学计算软件Matlab、选取适当的阀值将所获得的灰度图二值化,得到黑白化图像;最后利用图像分析软件进行相关参数的计算。结果表明：该泡沫铝中泡体均匀性的定量表征结果与感观分析基本一致;另外,该方法还可以用来计算泡沫铝的面孔隙率,用该方法计算的泡沫铝面孔隙率与测试出的体孔隙率之间的误差约为4%。     

1050合金0.01 mm厚包装用箔材生产工艺改进

对0.01 mm厚的1050-O箔材不平整的原因进行了分析,通过对轧制工艺润滑油的配比进行试验及生产工艺的改进,生产出表面平整的箔材.     

Optimization of the nickel fluoride cold sealing process

This paper investigates the effect of varying sealing parameters, in order to optimize the conditions used to achieve a good seal quality for nickel fluoride cold sealed anodized aluminium. The effect of time, temperature and solution pH on seal quality was studied by British/ISO standards tests such as phosphoric acid/chromic acid, dye absorption and admittance. The quantity of nickel absorbed in the pores of anodic films as a function of solution parameters was measured by Atomic Absorption Spectroscopy (AAS), in order to find out the relationship between seal quality tests and nickel absorption.

Although all the sealing parameters were found to have an effect on sealing quality and quantity of nickel absorbed in the pores, the major effect resulted from temperature which was found to be critical. The best results were found to be at a temperature of ≤ 25°C for a 20μm film. The quantity of nickel absorbed in the pores as shown by AAS, tends to correlate with the results of the seal quality tests.

The effect of post-treatment (final rinse) with hot deionized water (70°C) was also investigated. The post-treatment was found to accelerate the aging of cold sealed finishes and the results of optimized cold sealed samples which have been post-treated are very promising for commercial use.