电沉积增材制造微镍柱的工艺研究

目的 探究电沉积工艺参数对无掩模定域性增材制造微镍柱的微观形貌、直径和沉积速率的影响.方法 采用尖锥形铂丝作为阳极、铜板作为阴极,电镀液从阳极和导流腔之间的微缝隙以射流方式流到阴极表面,电化学沉积增材制造微镍柱.采用体视显微镜和扫描电子显微镜对镍柱微观结构进行检测.通过单因素试验研究极间电压和初始极间距对微镍柱微观形貌、沉积速率和直径的影响规律.结果 初始极间距为10μm、电压为3.8～4.4 V时,可以制备出直径均匀、圆柱度较高的微镍柱;电压增至4.7 V时,微镍柱形状不规则,常伴有分叉现象或呈瘤状沉积.极间电压从3.8 V增加到4.7 V时,微镍柱体积沉积速率由539μm3/s增长至4159μm3/s,直径由55μm增长至102μm.此外,当极间电压为4.1 V、初始极间距为20～40μm时,随着初始极间距的增大,微镍柱顶端从圆柱形逐渐转向锥形沉积.结论 极间电压对微镍柱微观形貌、沉积速率和直径的影响明显,初始极间距主要影响微镍柱顶端的沉积生长形状.     

射流电沉积镍工艺研究

通过射流电沉积瓦特镍电解液研究了电压、电解液温度、射流速度、主盐浓度、阳极喷嘴口径对沉积电流、沉积速率、电流效率的影响.结果表明:在电压为45V,温度为50℃,阴阳极间距离为17mm,NiSO4·6H2O浓度为280g/L时,从沉积电流、沉积速率、电流效率来看,效果最好.电压的增大使得沉积电流、沉积速率、电流效率增大,当电压增大到45V后,电流效率不再增大,而是趋于平稳,到55V后,沉积层烧焦.试验还发现,电解液流速和阳极喷嘴口径越大,沉积速率、电流效率也越大.     

定域性电化学增材制造三维微螺旋构件工艺

针对电化学增材制造已有较多探究，但研究内容多为工艺参数对柱体成形质量的影响，工艺参数对微螺旋构件的影响尚缺乏系统研究。通过单因素试验法研究极间电压、脉冲占空比和初始极间隙对微螺旋结构直径、体沉积速率和表面形貌的影响，采用数字显微镜及扫描电镜对微螺旋构件进行检测，得出极间电压为4.0～4.4 V时，可以制备出直径均匀、形状规整的微螺旋结构，微螺旋结构体沉积速率由210μm³/s增长至5 728μm³/s；而电压增至4.6 V时，微螺旋结构出现大量瘤状沉积。当初始极间隙从5μm增加到20μm时，微螺旋结构平均直径由128μm增长至163μm。极间电压为4.2 V、初始极间隙为10～20μm时，随着初始极间隙的增大，微螺旋结构底部明显变粗，直径波动较大。研究结果表明，采用三轴联动控制阳极运动轨迹，定域电化学增材制造三维微螺旋构件，是三维金属微结构一种可行的技术方法。试验优化参数为极间电压4.2 V、脉冲占空比60%和初始极间隙5μm时，得到微观形貌质量较好、直径均匀的微螺旋构件(圈数为2圈、螺距为400μm)。     

Formation and Characterization of Hydroxyapatite Coating Prepared by Pulsed Electrochemical Deposition

采用交流脉冲沉积法在AZ91D镁合金表面合成了羟基磷灰石涂层。考察了交流脉冲电压、沉积时间及电解液添加剂等电化学沉积参数对羟基磷灰石涂层的形貌、微观结构、元素组成及电化学性能的影响。结果表明,当脉冲电压为110 V时,纳米级别的羟基磷灰石涂层表面更为均匀,孔隙度更小,且其XRD的特征衍射峰更为突出。当电解液中添加了NaN O3和H2O2后,羟基磷灰石颗粒和涂层表面形貌均得到优化;同时,极化曲线和交流阻抗测试结果表明该涂层在模拟体液中的耐蚀性能提高。浸泡实验结果表明,该涂层有利于诱导羟基磷灰石的形成,从而提高涂层的生物活性。     

双脉冲电源参数对电铸金刚石-镍复合膜品质的影响

采用电铸法制备了金刚石-镍复合膜,研究了平均电流密度、正向脉冲频率、正向脉冲占空比、反向脉冲占空比等双脉冲电源参数对镀层厚度的均匀性、沉积速率、硬度、表面形貌的影响.结果表明:随着平均电流密度的增加,沉积速率增大并趋于稳定,复合膜硬度先增大后减小,厚度的均匀性变差;随着正向脉冲频率的增加,沉积速率和硬度都增大,厚度的均...     

交流脉冲电沉积羟基磷灰石涂层的制备及其性能(英文)

采用交流脉冲沉积法在AZ91D镁合金表面合成了羟基磷灰石涂层。考察了交流脉冲电压、沉积时间及电解液添加剂等电化学沉积参数对羟基磷灰石涂层的形貌、微观结构、元素组成及电化学性能的影响。结果表明,当脉冲电压为110 V时,纳米级别的羟基磷灰石涂层表面更为均匀,孔隙度更小,且其XRD的特征衍射峰更为突出。当电解液中添加了NaN O3和H2O2后,羟基磷灰石颗粒和涂层表面形貌均得到优化;同时,极化曲线和交流阻抗测试结果表明该涂层在模拟体液中的耐蚀性能提高。浸泡实验结果表明,该涂层有利于诱导羟基磷灰石的形成,从而提高涂层的生物活性。     

基于超短电压脉冲的Cu2O微区电沉积研究

目的 实现基于纳秒级超短电压脉冲的Cu2O微区电沉积。方法 开发了可视化超短电压脉冲微区电化学加工系统,通过脉冲发生器施加纳秒长的超短电压脉冲到微电极与工作电极之间使局部极化发生,采用原位倒置光学显微镜实时监控微区电沉积的动态过程。使用扫描电子显微镜对Cu2O微结构的微观形貌进行表征,研究不同加工参数,包括电极间距、脉冲长度和微电极运动速度对微区电沉积Cu2O的尺寸及微观形貌的影响。结果 电极间距、脉冲长度和微电极运动速度均对沉积的Cu2O微圆盘的直径和晶粒形貌有显著影响。电极间距的增大,使沉积的Cu2O微圆盘的直径和晶粒尺寸均有所减小。电压脉冲长度越小,Cu2O微圆盘的面积越小。微电极移动的速度越快,Cu2O微圆盘的直径越小,结晶性变差。电极间距为14 µm、脉冲长度为30~40 ns以及降低微电极运动速度能够获得轮廓清晰的微区电沉积结构。结论 基于纳秒级超短电压脉冲可视化微区电化学加工系统成功地在ITO导电玻璃表面沉积了直径为50~100 µm的Cu2O微圆盘,为高效率Cu2O基光电器件的微加工提供了简单有效的方法。     

基于氧化铝模板直接电沉积法镍纳米线的制备与表征

在未氧化铝和氧化铝之间经过降压剪薄阻挡层直接进行电沉积,采用不同电压进行电沉积制备了镍纳米线,并采用SEM,TEM和X射线衍射对所制备的镍纳米线进行了表征,研究了电沉积电压对纳米线结构的影响。结果表明：镍纳米线的外形决定于氧化铝模板的形貌,其直径和最大长度分别依赖于模板孔洞的直径和长度,当电沉积电压为1,1.5和2V时制备的镍纳米线为多晶结构,随着电沉积电压的升高,镍纳米线为沿[220]择优取向的单晶结构（电沉积电压分别为3V和4V）,当电沉积电压进一步升高时,择优取向由[220]转为[111]方向（电沉积电压5V）。     

柠檬酸铵浓度对脉冲电镀Ni-Cr-Mo合金镀层的影响

目的揭示柠檬酸铵浓度对脉冲电镀Ni-Cr-Mo合金镀层元素含量、沉积速率、表面形貌和耐蚀性的影响规律。方法采用脉冲电镀法在Q235钢表面制备Ni-Cr-Mo合金镀层,利用辉光放电光谱仪、扫描电镜、Tafel曲线和电化学阻抗谱考察柠檬酸铵浓度对镀层元素含量、沉积速率、表面形貌和耐蚀性的影响。结果随柠檬酸铵浓度的增大,镀层镍含量减小,铬、钼含量增大,镀层沉积速率减小,镀层表面颗粒的尺寸减小,镀层在3.5%Na Cl溶液中的耐蚀性先增强后减弱。结论柠檬酸铵质量浓度为196 g/L时,镀层具有最大的自腐蚀电位(-0.537 V)、最小的腐蚀电流密度(0.313μA/cm~2)和最大的电荷转移电阻(2075?·cm~2),耐蚀性最好。     

脉冲偏压电弧离子镀室温沉积非晶TiO2薄膜

采用脉冲偏压电弧离子镀技术在玻璃基片上室温制备了均匀透明的非晶TiO2薄膜,在0--900 V范围内改变脉冲偏压幅值,考察其对薄膜沉积速率、表面形貌和光学性能的影响.结果表明,随着脉冲偏压的升高,非晶薄膜沉积速率以-100 V为界先高后低;薄膜的吸收边先红移后蓝移,但光学带隙Eg基本无变化,约为3.27 eV;-300 V偏压时薄膜达到原子级表面平滑度,均方根粗糙度Rrms≈0.113 nm,因而薄膜折射率n也最高(nλ=550 nm达到已有报道的最高值2.51).     

钛-铝双丝超音速电弧喷涂过程中熔滴粒子几何特性研究

为了研究工艺参数对钛-铝双丝超音速电弧喷涂熔滴粒子尺寸的影响规律,通过对喷枪出口处气流速度、气体质量流率和金属熔滴质量流率的分析测定,以Nukiyama-Tanasawa模型为基础,建立了喷涂粒子的平均直径与喷涂电压和电流间的解析关系,并对喷涂电压和电流对熔滴粒子平均直径的影响进行了计算机模拟仿真.结果表明:在喷枪结构和雾化气体压力一定时,雾化粒子的平均直径随喷涂电流的增大而增大,随喷涂电压的升高而减小,但总的变化幅度却较小.利用激光粒度分析仪对一定喷涂工艺条件下所得的粒子平均直径进行实验分析,结果与计算值之间的相对误差为9.52%,扫描电镜观察表明粒子形态以球形颗粒为主.     

Effects of operating conditions on droplet deposition onto surface of atomization impinging spray

A comprehensive model based on the Navier-Stokes equation and particle tracking method is used to study the effervescent atomization impinging spray, and another model is used to establish the relationship between the droplet velocity near the plate and the different operating conditions. The models and numerical code are validated by comparing the numerical results with the published experimental results. The effects of air-to-liquid ratio, nozzle diameter, liquid mass flow rate, and the position of impinging plate on the Weber number and K number as well as the droplet deposition onto the plate are discussed. The results show that the droplet velocity near the plate increases with increasing air-to-liquid ratio and liquid mass flow rate, and with decreasing nozzle diameter and axial distance from the nozzle exit to the plate. The droplet diameter near the plate increases with increasing axial distance from the nozzle exit to the plate, and with decreasing air-to-liquid ratio. As a function of the nozzle diameter and liquid mass flow rate, the variation of droplet diameter is not monotonous and the effect of liquid mass flow rate on the droplet diameter is insignificant. In the studied operating conditions, it is difficult for the droplet to rebound off the plate when impinging on the plate but it is easier for the droplet to splash. In order to create a condition which can benefit the droplet deposition when impinging on the plate, the suggested ways are to reduce the air-to-liquid ratio and liquid mass flow rate, increase the nozzle diameter, and select a suitable range of axial distance from the nozzle exit to the plate.     

Study on arc characteristics and behavior of metal transfer in pulse current flux-cored arc welding of mild steel

The variation in arc characteristics and behavior of metal transfer with the change in pulse parameters has been studied by high speed video camera during pulse current flux cored arc weld deposition. A comparative study of similar nature has also been carried out during flux-cored arc weld deposition in globular and spray transfer modes. The effect of pulse parameters has been studied by considering their mean current and arc voltage. The arc characteristics studied by its root diameter, projected diameter and length, and the behavior of metal transfer noted by the metal transfer model and the droplet diameter have been found to vary significantly with the pulse parameters. The observation may help in understanding the arc characteristics with respect to the variation in pulse parameters which may be beneficial in using pulse current FCAW to produce desired weld quality.     

Ni-W-P-CeO_2-SiO_2纳米复合薄膜材料制备

通过Ni、W、P和CeO2、SiO2纳米颗粒的脉冲共沉积,在碳钢基体表面制备出了Ni-W-P-CeO2-SiO2纳米复合薄膜材料,研究了电解液中硫酸镍和柠檬酸浓度对纳米复合薄膜化学组成、沉积速率、显微硬度和微观组织的影响.结果表明:当硫酸镍和柠檬酸浓度分别控制在70 g/L,和120 g/L,时,纳米复合薄膜材料沉积速率(25.32 ìm/h)和显微硬度(6140 MPa)最高.增加硫酸镍浓度,纳米复合薄膜材料晶粒得到细化,但基质金属晶粒轮廓模糊,纳米颗粒在基质金属中分布不均匀.在适宜的柠檬酸浓度(120 g/L)下,纳米复合薄膜材料表面平整光滑、结构致密、晶粒细小,基质金属晶粒轮廓清晰,呈规则圆球型,CeO2纳米颗粒在基质金属中镶嵌均匀,但Si02纳米颗粒沉积量较少且分布不均匀.     

Effect of Microstructure on the Solid Particle Erosion Properties of Ni Plating

The effect of microstructure on erosion resistance of nickel plating was investigated in this study. Two electrode nickel plating processes, one with conventional nickel sulfamate electrolyte and the other with carbon nanotubes (CNTs) dispersed in the electrolyte, at various pulse frequencies were used to generate surface depositions of different microstructures. The samples were subjected to microstructural evaluations and mechanical property testing for microhardness and elastic modulus. Subsequently, erosion tests were conducted to evaluate the material’s erosion resistance under various plating conditions. It was found that both changes in pulse frequency and the addition of CNTs resulted in grain size refinement and surface morphology modification. Microhardness of the plating was observed to increase with the pulse frequency in the absence of CNTs. Erosion resistance increased with grain refinement initially due to the surface hardness increase but this effect subsided as the thickness of the deposition approached that of the plastic deformation layer caused by the erodent.     

Arc characteristics and behaviour of metal transfer in pulsed current GMA welding of stainless steel

The variation in arc characteristics, stability in shielding of arc environment and behaviour of metal transfer with a change in pulse parameters have been studied by high speed video-photography during pulsed current gas metal arc (P-GMA) weld deposition using austenitic stainless steel filler wire. A comparative study of similar nature has also been carried out during gas metal arc (GMA) weld deposition in globular and spray transfer modes. The effect of pulse parameters has been studied by considering their hypothetically proposed summarized influence defined by a dimensionless factor ? = [(I_b/I_p) ft_b], mean current and arc voltage and correlation between welding parameters and arc characteristics have been established. The arc characteristics studied by its root diameter, projected diameter, length and stiffness measured in terms of arc pressure and the behaviour of metal transfer noted by the droplet diameter and velocity of droplet at the time of detachment have been found to vary significantly with the variation in ?. At a given ? the experimentally measured values of the behaviour of metal transfer are found well in agreement to their corresponding theoretical values estimated through mathematical expressions reported earlier. The increase of ? and the ratio of (I_b/I_p) have been found to adversely affect the stability of shielding jacket and arc profile especially at high arc voltage.     

Nanocrystalline Nickel Deposition on the Titanium Alloys Using High Solution Flow Velocity

An innovative process has been developed for electroplating of nickel on titanium surface using fast solution flow technique. Nickel was directly deposited on a titanium alloy without using any pre-treatment process. Level of adhesion was determined using quantitative peel test and characterization of the deposition was performed by scanning electron microscopy. Results showed that the rate of nickel deposition at 60 °C was higher than that of the rate of nickel deposition at 40 °C. Moreover, Watts solution provided higher rate of nickel deposition compared to the sulfate-based nickel solution. The rate of deposition increased with increasing the solution flow velocity from 1.5 to 3 m/s and raising current density from 0.4 × 10⁴ to 1.6 × 10⁴ A/m² for both solution baths. Adhesion test indicated good level of adhesion between the deposited nickel and titanium surface. The bonding toughness increased to 4 J/m² for 1.2 × 10⁴ A/m² as a result of higher deposition rate. However, the mechanism responsible for the coating process was discussed in detail.     

Microstructure and properties of nanocrystalline nickel coatings prepared by pulse jet electrodeposition

The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel. The effects of average current density on the surface morphology, microstructure, average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and microhardness measurement. In addition, the corrosion resistances of coating and substrate were compared. It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density, although some pores and defects are still present in coatings. With the increase of average current density, the average grain size of nickel coatings is reduced at first and then increased. The coating with the optimum compactness, the smallest average grain size (13.7 nm) and the highest microhardness are obtained at current density of 39.8 A/dm2. The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition; however, the corrosion rate is increased after a certain period due to the penetration of the corrosive media.     

SCH13钢表面微弧火花沉积Stellite合金

采用高能微弧火花沉积技术在SCH13钢表面制备Stellite合金涂层.利用扫描电子显微镜、能谱仪、X射线衍射仪对沉积层的显微组织形貌、成分及结构进行分析,并对微弧火花单脉冲沉积斑的形成与生长机制进行重点研究.结果表明,高能微弧火花作用下Stellite合金单脉冲沉积斑呈飞溅状,大量单脉冲斑的不断叠加最终形成具有一定厚度的沉积涂层.微弧火花沉积层依附于基体的界面以柱晶组织呈外延生长,并与基体形成良好的冶金结合,涂层稀释率较低,主要由γ-Co固溶体和铬的碳化物组成.随着工作电压的增加,沉积层显微组织略有粗化,其平均硬度较Stellite合金电极材料有显著提高.