射流电沉积工艺参数对沉积层形貌的影响

射流电沉积技术具有特殊的定域性和材料特性,可用于机械零件修复,但沉积层的均匀性和质量需要改善。研究了电解液喷射流速、电流密度、沉积层数等对沉积层形貌的影响。结果表明:喷射流速在1~10m/s范围内,随着喷射流速的增大,沉积层的表面质量逐渐改善;电流密度在100~600A/dm2范围内,随着电流密度的增大,沉积层形貌逐渐恶化,产生析氢副反应;沉积层数在400~1 600层范围内,沉积层的表面质量随层数的增加而逐渐恶化。得到了一系列的优化参数,有助于改善沉积层的质量。     

喷射电沉积块体多孔镍的研究

采用喷射电沉积方法制备块体多孔镍.分别选择不同的扫描方式、电流密度进行试验,分析了各试验参数对块体多孔镍形貌的影响规律,并应用图形处理软件ImageJ对多孔镍的孔隙率和相对密度进行分析,获得最佳试验参数.结果表明:采用扫描速率中间部位慢于边界部位、在块体各点均暂停的扫描方式,有利于多孔镍沉积均匀平整.随着电流密度的增加,镍沉积层明显变得致密,孔径减小,而孔隙率增大.     

高速喷射电沉积镍工艺研究

利用自行研制的高速喷射电沉积装置电沉积镍。研究了电流密度与沉积速率的关系,并将所得沉积层与槽镀沉积层进行比较。结果表明：采用此装置,允许使用的极限电流密度及沉积速度均增大,所得沉积层硬度值（Ｈｖ）比一般槽镀层高出２００左右,镀层生形态由枝晶生长转变为柱状生长。     

TMPAC-AlCl3离子液体中恒电流电沉积铝

合成了不同TMPAC和AlCl₃摩尔比的TMPAC-AlCl₃离子液体,并测定了其在不同温度下的电导率。在摩尔比为1:2的TMPAC-AlCl₃离子液体中进行了恒电流电沉积实验,研究了温度、电流密度、搅拌速度和添加剂甲苯等对沉积层的影响。结果表明:在相同条件下摩尔比为1:2的TMPAC-AlCl₃离子液体电导率最大,当温度为80℃,电流密度为20 mA·cm^-2,搅拌速度为500 r·min^-1时,沉积层质量较好且电流效率较高;甲苯的加入,增大了TMPAC-2AlCl₃离子液体的电导率,降低了槽电压,当添加甲苯的体积分数为50%,电流密度为23 mA·cm^-2时,可以得到较为致密、色泽良好、平整而均匀的沉积层。     

电流密度对熔融盐电沉积金属钨镀层性能的影响

采用二元熔盐氧化物Na2WO4和WO3,以脉冲电沉积的方法在占空比0.5、脉冲频率1000Hz、电沉积温度850°C的条件下,于热沉材料CuCrZr之上获得了金属钨镀层。讨论了电流密度对钨镀层微观结构、显微硬度、结合强度等性能的影响。当电流密度为20～30mA/cm2时,能够获得表面致密均匀的钨镀层。随着电流密度的增大,电流效率呈现先增大后下降的趋势,当电流密度为30mA/cm2时,电流效率达到最大值92.64%。     

用于煤浆槽防沉降射流搅拌系统CFD研究

采用计算流体力学(CFD)方法考察了射流搅拌替代煤浆槽现有机械搅拌的可行性,进行了不同初始流速及射流位置下槽体内流场特征的数值模拟,在此基础上探讨了不同射流条件对颗粒沉降的影响。模拟结果表明,在射流初始速度为5~15 m/s的条件下,底部射流易造成槽体左侧低速区,不利于颗粒悬浮,且随着流速的增加,这一状况未得到有效改善;侧向射流可有效防止煤粉颗粒在槽体底部沉积,且随着射流速度的增加,槽内颗粒分布均匀性得到改善,但同时会导致操作能耗增加。     

工艺参数对尼龙6选择性激光烧结制件致密度的影响

针对高性能聚合物尼龙6材料的选择性激光烧结(SLS)工艺,研究了不同激光功率与扫描速度对成型件致密度的影响并进行了工艺优化。实验中激光功率10~50 W,扫描速度1 000~5 000 mm/s,其他工艺参数保持恒定。引入能量密度对激光功率与扫描速度的综合作用进行研究。结果表明:随着激光功率的增加或扫描速度的增大,制件的致密度呈现先增大后减小的趋势;随着能量密度的增加,制件的致密度呈现先增大后减小的趋势。在不同工艺参数下,获得制件的最大致密度为86.74%,此时激光功率为30 W,扫描速度为2 000mm/s,能量密度为0.043 J/mm^2。选定致密度为衡量指标,通过响应面回归分析模型建立了激光功率、扫描速度与致密度的优选工艺图谱,得到最优的工艺参数为激光功率45 W,扫描速度3 465 mm/s,此时预测的制件致密度为88.971%。     

电沉积Sn—Bi合金工艺的研究

采用硫酸盐镀液在铜基体上电沉积Sn-Bi镀层,利用能谱仪(EDS)、扫描电子显微镜(SEM)和X射线衍射仪(XRD)研究了电沉积参数对镀层成分和微观结构的影响.结果表明:镀层中Sn的质量分数随着镀液中Sn的质量浓度的增大而增大,同时随着电流密度的增大,Sn的质量分数不断减少;Sn-Bi镀层主要由四方晶系的Sn和菱形晶系的Bi组成;另外,研究发现电流密度对镀层形貌影响较大.     

基于PIV技术的七喷嘴气化炉流场研究

为研究七喷嘴气化炉的流场分布,建立了顶置七喷嘴气化冷模试验装置,采用激光粒子成像测速系统(PIV)在气化炉的上部、中部及下部视窗进行了流场测试,比较分析了颗粒流量、分散风流量对气化炉流场的影响。结果表明,在颗粒流量20~150 kg/h,分散风流量740~880 m3/h的工艺条件下,气化炉上部流场呈现自由射流特点,射流长度为40 cm,平均射流速度为25 m/s,中下部流场则以返混区为主,流速在8 m/s以下;颗粒流量增大会使得最大射流速度由40 m/s降低至15 m/s,且气化炉上部射流粒子束的径向脉动增强,造成射流弥散;分散风流量增大使得最大射流速度由25 m/s增至35 m/s,射流长度无明显变化。颗粒流量和分散风流量对流场的影响主要体现在气化炉上部,对中下部流场的影响逐渐减弱。     

[BMIM]Cl/AlCl3离子液体低温电沉积铝过程

采用玻碳/铂为惰性阳极,以1-丁基-3-甲基咪唑氯盐([BMIM]Cl/AlCl₃)离子液体体系为电解液,研究了离子液体电解铝工艺,优化了电解工艺条件,探讨了电解影响因素。结果表明,当电解液[BMIM]Cl∶AlCl₃摩尔比为1∶2.00时,随着温度的升高,铝的沉积槽电压逐渐减小,电流密度增加,但电解液的稳定性减弱,当温度达到90℃时,电解液分解明显。当电解温度一定时,随着[BMIM]Cl∶AlCl₃摩尔比的增加[(1∶1.25)~(1∶2.00)],电流密度增加。通过赫尔槽实验,SEM、XRD分析了电解铝的沉积形貌和晶相结构。随电流密度的逐渐减小,沉积层变薄,晶相结构变化不大;相同电流密度区随温度的升高,沉积层逐渐变得粗糙。计算了不同槽间距下的槽压与电流密度的关系。     

电沉积制备镍箔的SEM形貌和抗拉强度

研究了电沉积法制取镍箔的实验条件,并对不同条件下得到的镍箔表面、断面SEM形貌以及抗拉强度进行了分析. 结果表明,动态条件下电沉积镍箔,能够显著提高其极限电流密度,此时SEM形貌显示沿电沉积箔的厚度增长方向,纯镍箔的晶粒逐渐增大. 加入5 g/L糖精能够有效地细化晶粒,并使镍箔表面更加光亮,其抗拉强度也有所提高.     

Electrodeposition of Zn-Co alloys with pulse containing reverse current

The electrodeposition of Zn-Co alloy deposits was studied by means of pulse-plating technique. The surface morphologies of Zn-Co alloy deposits were examined using scanning electron microscopy (SEM), and an attendant energy dispersive X-ray analyser (EDA) was used to analyse the composition of Zn-Co alloy deposits. Results obtained showed that the average current density and reverse current density amongst all the variables investigated had very strong effects on the cobalt content in the Zn-Co alloy deposits. It is possible to electrodeposit Zn-Co alloy coatings with a very wide cobalt content range of 10-90 wt.% by modulating pulse parameters. Grain size, surface appearance and internal stress in the deposits were also improved significantly by introducing reverse current.     

添加剂对喷射电沉积纳米晶Co-Ni合金的影响

在氯化镍-硫酸钴体系电解液中采用添加剂喷射电沉积纳米晶Co-Ni合金,测定了其阴极极化曲线.研究了添加剂对阴极过电位、电流效率、镀层中Co含量、镀层的相结构、晶粒尺寸、表面形貌及显微硬度、软磁性能等影响.结果表明:添加剂增加了极化作用,影响了Co、Ni电沉积的动力学过程.当添加剂为2.5g/L时,与未加添加剂相比较,阴极过电位从3.594V增大到4.755 V,电流效率和沉积层中Co含量变化不大,但沉积层晶粒尺寸从12.8 nm明显降低到5.5 nm,维氏硬度从423升高到511,同时Co-Ni合金的软磁性能得以提高.     

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co²⁺ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co²⁺ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co²⁺ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits.     

二维喷嘴内稠密气固射流稳定性实验

利用高速摄像仪对二维喷嘴内稠密气固射流稳定性进行了实验研究，考察了颗粒粒径、料仓压力以及喷嘴收缩角等因素对射流流动模式及稳定性的影响。结果表明：对于颗粒粒径为78μm的气固射流，随着料仓压力的增大，射流出口速度增大，射流固含率降低，在料仓压力≥0.03MPa、射流速度≥4.82m/s、射流固含率≤0.168时，喷嘴内稠密气固射流出现气泡型的不稳定流动模式；随着颗粒粒径的增大，气固射流固含率降低，喷嘴内稠密气固射流从气泡模式转变为颗粒团不稳定流动模式；改变喷嘴收缩角对射流不稳定模式影响不大。利用微型压力传感器对喷嘴直管不同位置压力进行测量，结果表明压力脉动主要是由于气固射流中气泡及颗粒团的产生及演变导致的。研究表明，随着料仓压力增大，颗粒在喷嘴内向下运动过程中压降增加，渗透进颗粒流的气体分率增加，将导致喷嘴内气固相互作用增强，进而引起气固射流不稳定。     

Effect of additive and current mode on surface morphology of palladium films from a non-aqueous deep eutectic solution (DES)

Electrodeposition of palladium from a non-aqueous electrolyte solution [choline chloride/urea/palladium(II)chloride] has been carried out by direct and pulse current electroplating. In this study, the influence of an organic additive (nicotinic acid amide), current mode (direct current or pulse current deposition) and hydrodynamic on the surface morphology of electroplated palladium films was investigated. In order to determine the surface morphology and thickness of the electrodeposited palladium layers, a scanning electron microscope and an energy dispersive X-ray fluorescence spectroscope were used. In addition, the cell voltage during the different electrodeposition experiments was recorded and analysed. The experimental results showed that the surface morphology of the palladium deposits could be remarkably affected either by addition of the additive or by applying pulse current. Pulse plating and the selected inhibitor mutually interfere with each other, causing changes in the microstructure of the palladium deposits (e.g. smoothening or forming of micro-cracks). It was possible to optimise the palladium deposit quality by applying pulse current or by addition of the appropriate inhibitor.     

板坯连铸结晶器内流场数值模拟

利用FLUENT软件对1300 mm′230 mm的板坯结晶器建立了三维稳态数学模型,以流体表面流速和射流冲击深度作为主要参考指标,研究了水口的特性及拉速、水口浸入深度对该水口作用下结晶器内流场的影响. 结果表明,A水口作用下具有表面流速大,射流冲击深度小,液面波动大,卷渣的可能性大等特点,且随拉速的增加而逐渐增大;随拉速的增加,结晶器内最大表面流速以0.06 m/s的幅度逐渐增大,射流冲击深度呈减小趋势,在150, 170和190 mm浸入深度下,结晶器液面表面流速最大值分别为0.599, 0.518和0.465 m/s,射流冲击深度分别为385, 410和420 mm,随水口浸入深度的增加,结晶器内表面流速逐渐减小,射流冲击深度逐渐增加;在实际生产过程中,使用A水口时应适当降低拉速、增大水口浸入深度;在高拉速的情况下,需用平行水口替换A水口.     

Influence of pulse plating parameters on the synthesis and preferred orientation of nanocrystalline zinc from zinc sulfate electrolytes

The influence of pulse electrodeposition parameters (current on-time T_on, current off-time T_off, and pulse current density J_p) was investigated on the surface morphology and grain size of zinc electrodeposited from a sulfate bath containing polyacrylamide and thiourea additives. The grain size and surface morphology of zinc deposits were studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), and the preferred orientation of the deposits was studied by X-ray diffraction. At constant current off-time and pulse current density, the grain size decreased asymptotically with increasing current on-time. In contrast, increase in the current off-time at constant current on-time and pulse current density resulted in grain growth. A progressive decrease of the grain size was observed with increasing pulse current density at constant current on-time and off-time. Nanocrystalline zinc with an average grain size of 38 nm was obtained at a pulse current density of 1200 mA/cm². The crystallographic orientations developed were correlated with the change in the cathodic overpotential, the angle between the preferred oriented plane and the lowest energy of formation plane (0 0 0 2), and the pulse electrodeposition parameters.     

Maskless zinc electrodeposition assisted by a pulsed laser beam

This paper deals with jet electrodeposition for the production of maskless deposits and patterns of a well-defined shape, and the potential improvements allowed by a pulsed laser beam. On the basis of the example of zinc deposition in a sulphate medium, several aspects of this type of deposition (mass transfer rate, i-E curves, morphology of the deposit, and the effect of a pulsed YAG laser beam at 532 nm) are presented. Laser assistance has no significant effect on the deposition current. Pulsed irradiation improves zinc morphology by an appreciable grain coalescence and a reduction in grain size; this results in increased precision of the maskless deposits, the central zones of which are as wide as the nozzle.     

Induced electrodeposition of tungsten with nickel from acidic citrate electrolyte

Induced electrodeposition of Ni–W alloys was carried out onto steel substrates from acidic citrate baths (pH 4.5) under different conditions of concentration of electrolyte, current density and temperature. Bright and highly adherent Ni–W deposits were successfully obtained with a relatively high cathodic current efficiency CCE (80–85%). The CCE increases greatly with increasing pH and Ni²⁺ ion content in the bath. The W% in the alloy deposits is in the range of 4–20 wt% depending on the operating condition. The W content in the deposit was found to increase with an increase in Ni²⁺ ion content, pH and temperature. The surface morphology was examined by scanning electron microscopy while the structure of the alloy was examined by X-ray diffraction analysis.