脉冲电沉积工艺对镍镀层结构与硬度的影响

为了优化脉冲电镀镍工艺,采用扫描电子显微镜、X射线衍射仪和显微硬度仪研究了脉宽、脉间、峰电流密度对镀层的晶粒尺寸、表面形貌、晶体取向和硬度的影响.结果表明,保持峰电流密度和脉间不变,镀层的晶粒尺寸随着脉宽的增加先减小后增加.当脉宽由0.1ms增至8ms,晶体取向由(111)织构向(200)织构转变.保持峰电流密度和脉宽不变,当脉间的增加,晶粒尺寸增大,但晶体的取向不变.增加峰电流密度能够显著降低镀层的晶粒尺寸.当峰电流密度由0.2A/cm2增至2.0A/cm2,晶体取向由随机态向强的(200)织构转变.镀层的硬度与镀层的晶粒尺寸有关,晶粒尺寸较大时,服从Hall-Petch关系,晶粒尺寸较小时,产生纳米效应,反Hall-Petch关系.因此,脉宽、脉间、峰电流密度均能显著影响镀层的显微硬度.     

电流密度对自动化电刷镀Ni镀层组织结构和性能的影响

为提高电沉积镀层质量和自动化程度,开发了新型的自动化电刷镀技术。利用扫描电镜、X射线衍射仪、透射电镜、X射线应力测试仪、数显显微硬度计和显微磨损试验机考察了不同电流密度下制备的电刷镀Ni镀层的组织结构和性能,并与电镀Watts Ni对比。结果表明,应用电刷镀制备的镍镀层组织平整致密,无针孔、麻点等缺陷;随着电流密度从4A/dm2增加到16A/dm2,电刷镀Ni镀层的(111)面择优取向逐渐降低,(200)面择优取向逐渐增加,镀层的晶粒尺寸和应力逐渐增大,硬度约在500～600HV之间波动,镀层磨损失重由6.8mg降低到5.2mg。     

喷射电沉积Ni及Ni-ZrO2复合镀层的表面形貌和硬度

采用喷射电沉积技术在45钢基体上制备了Ni及Ni-ZrO2复合镀层,并对各种镀层进行扫描电子显微镜(SEM)表面形貌观察、能谱分析(EDS)、X射线衍射仪(XRD)晶粒尺寸测定以及镀层显微硬度测定。比较了不同电流密度、温度和纳米颗粒浓度对镀层表面形貌和硬度的影响规律。结果表明:电流密度由0.55A/cm2提高到1.00A/cm2后,镀层表面越粗糙,晶粒尺寸由15nm增大到23nm,显微硬度由571HV降低到364HV;温度由20℃升高到50℃后,表面呈现先变粗糙后变平整趋势,且镀层中Ni含量上升,Fe含量下降,镀层硬度由551HV降低到364HV;ZrO2纳米颗粒质量浓度由0g/L提高到25g/L时,表面仍呈现先变平整后变粗糙趋势,镀层晶粒尺寸由22nm降低到13nm,硬度由384HV提高到521HV。     

钛上电镀铜工艺对镀层性能的影响

钛材表面采草酸刻蚀、预镀等工艺处理后,表面积和粗糙度都增大,从而可获得结合力良好的铜镀层。研究了在钛基上镀铜时,电流密度在1－3A/dm^2间变化时对镀层性能以及微观结构的影响。结果显示,随着电流密度的增加,沉积物晶料尺寸增大,镀层粗糙度增加。认为控制电镀晶粒尺寸的主要因素是Cu^2 在阴极与电解质界面的含量及阴极表面吸附的杂质量;另外,晶粒尺寸越大,镀层越厚,室温电阻率越低。     

硫代硫酸盐无氰镀银工艺

无氰镀银是电镀银的发展方向,目前仍存在许多问题.采用硫代硫酸盐无氰镀银工艺,分别以AgNO3和AgBr为主盐进行镀银,研究了主盐含量、电流密度对镀层表观质量、沉积速率、显微硬度的影响,测量了镀层结合强度、晶粒尺寸,确定了2种体系制备镀层的最佳工艺.结果表明:AgNO3体系AgNO3最佳用量为40 g/L,最佳电流密度为0.25 A/dm2,制备的镀层光亮平整,晶粒尺寸为35 nm;AgBr体系AgBr最佳用量为30 g/L,最佳电流密度为0.20 A/dm2,制备的镀层光亮平整,晶粒尺寸为55 nm;与AgBr体系相比,AgNO3体系适宜电镀的电流密度范围较宽,制备的镀层显微硬度较大,晶粒尺寸小;2种体系制备的镀层均为纳米晶.     

脉冲电流密度对Ni-WC/Co纳米复合镀层摩擦磨损性能的影响

目前,通过脉冲电沉积制备Ni-WC/Co复合镀层的研究报道较少。为了探究Ni-WC/Co纳米复合镀层对材料表面摩擦性能的影响,采用脉冲电沉积制备Ni-WC/Co纳米复合镀层,研究脉冲峰值电流密度对复合镀层晶体结构、晶粒尺寸和硬度的影响;室温下,在MM-W1B立式万能摩擦磨损试验机上测试复合镀层的摩擦磨损性能,分析其磨损机理。结果表明:随着峰值电流密度的增加,复合镀层晶粒尺寸先减小后增大,硬度则是先增大后减小,复合镀层的摩擦系数和磨损量都是先降低后升高;当峰值电流密度为10 A/dm2时,复合镀层的平均晶粒尺寸最小,硬度最高,摩擦系数和磨损量最低,耐磨性能最佳,复合镀层表面主要呈现轻微的划痕,且磨痕较窄,无疲劳磨损。     

脉冲电沉积CeO2-SiO2／Ni—W-P纳米复合镀层性能研究

为了探讨脉冲参数对CeO2-SiO2/Ni-W-P四元纳米复合镀层性能的影响,采用脉冲沉积的方法,在普通碳钢表面制备了CeO2-SiO2/Ni-W-P纳米复合镀层.在脉冲关断时间1 000μs和脉冲峰值电流密度30 A/dm2下,研究了脉冲导通时间对纳米复合镀层组织及性能的影响,采用能谱分析、硬度测试、扫描电镜(SEM)等技术对镀层化学组成、沉积速率、显微硬度和表面形貌进行了表征.结果表明,纳米复合镀层中CeO2和SiO2颗粒的质量分数随着脉冲导通时间的延长而增加,当脉冲导通时间为400～600μs时,沉积速率为32.33～38.22μm/h,显微硬度为609～674 HV;脉冲导通时间由100μs增加到400μs时,纳米复合镀层晶粒尺寸降低,但当脉冲导通时间再由400μs增加到1000μs时,纳米复合镀层晶粒尺寸又有所增加.     

脉冲电流密度对Ni-SiC镀层微观结构和显微硬度的影响

采用脉冲电沉积方法,在压缩机阀片表面制备Ni-SiC镀层。利用原子吸收分光光度计、透射电镜和硬度计研究脉冲电流密度对Ni-SiC镀层SiC粒子复合量、微观结构和显微硬度的影响。结果表明,随着脉冲电流密度的增大,Ni-SiC镀层SiC粒子的复合量先增加后略有降低。在脉冲电流密度为7A/dm2时,镀层SiC粒子的复合量高达9.92%(质量分数)。脉冲电流密度为7A/dm2时,镀层致密、晶粒细小,SiC粒子均匀分布于镀层中,且团聚现象较少。当脉冲电流密度为7A/dm2时,镀层的显微硬度高达842.9Hv。     

Zn-ZrO_2复合镀层的性能

复合镀层具有良好的性能,在氯化铵镀锌溶液中加入ZrO2,制备出了Zn-ZrO2复合镀层.讨论了阴极电流密度、镀液pH值对镀层中ZrO2含量的影响,采用扫描电镜对镀层的表面形貌进行了分析.结果表明:当阴极电流密度低于4 A/dm2时,镀层不存在ZrO2微粒,当阴极电流密度为10 A/dm2、pH值为2.5时,镀层中ZrO2的质量分数为2.47%;纯锌镀层晶粒粗大,晶粒间距较大,而Zn-ZrO2复合镀层不仅晶粒细小,平整,且组织均匀、致密;Zn-ZrO2复合镀层在5%NaCl溶液中比纯锌镀层具有更好的耐蚀性能,镀层与基体结合良好.     

NdFeB表面镀镍层不同脉冲参数时的形貌及性能

与直流电镀相比,脉冲电镀具有许多优点;而目前有关脉冲参数对NdFeB表面镀镍层耐蚀性影响的研究少有报道.以NdFeB为基体材料,以不同的电流密度和占空比脉冲电镀镍,利用扫描电镜(SEM)观察镀层表面形貌,在3.5％ NaCl溶液中进行极化曲线和交流阻抗谱测试考察镀层的耐蚀性能,并测量镀层硬度以及结合强度,以获得最佳脉冲电镀工艺.结果表明:NdFeB表面脉冲电镀镍层较直流电镀层晶粒更细,表面更光滑平整;电流密度为2 A/dm2,占空比为0.4时,镀层表面晶粒均匀致密,表现出良好的耐腐蚀性能;脉冲电镀层的硬度大于直流电镀层,且在电流密度2 A/dm2,占空比0.4时硬度最大,达497.5 HV0.98N,热震20次表现出良好的结合性能.     

Influence of pulse electrodeposition parameters on microhardness,grain size and surface morphology of Ni–Co/SiO<Subscript>2</Subscript> nanocomposite coating

Ni–Co/SiO ₂ nanocomposite coatings and Ni–Co alloy coatings were prepared on steel substrate using direct and pulse electrodeposition methods. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray map and energy dispersive X-ray spectroscopy (EDX) were employed to investigate the phase structure, surface morphology, and elemental analysis of coatings, respectively. In high discharge rates, the surface morphology was rough, disordered and gross globular; on the contrary, in the low rates, it was smoother, more ordered and fine globular. Also, effect of electrodeposition parameters such as average current density, pulse frequency and duty cycle on the microhardness and grain size of nanocomposite coatings that produced through the pulse current electrodeposition method have been investigated. By amplifying both duty cycles up to 50% and average current density from 2 to 6 A dm^?2, microhardness increased, while the grain size decreased. But when duty cycle mounted on more than 50% and the average current density went up to 8 A dm^?2, microhardness lessened, while the grain size rose. The optimum value for pulse frequency was about 25 Hz. Results showed that microhardness of nanocomposite coatings which were produced by pulse current method was higher than that of produced by direct current method.     

Microstructure and mechanical properties of nanocrystalline nickel prepared by pulse reverse microelectroforming

Nanocrystalline nickel was produced by pulse reverse microelectroforming. The pulse microelectroforming was also performed for the comparative purposes. The surface morphology and microstructure of electroformed nickel layers were investigated by scanning electron microscopy and X-ray diffractometry. The microhardness of nickel layers was measured with a Vickers microhardness tester. The friction and wear experiments for nickel layers were performed on a friction and wear tester. The results indicate that the nickel layers prepared by pulse reverse microelectroforming exhibit higher density and their grain sizes in the nanometer range. The nickel layers with fine grains, high microhardness and better wear resistance are obtained at positive current density of 20?A/dm² and negative current density of 2?A/dm². The microhardness and wear resistance of nickel layers are improved as the positive and negative current densities are increased.     

电解铜箔截面微观组织的EBSD分析

目的 通过树脂包埋结合离子截面抛光的制备方法,实现铜箔样品的截面EBSD分析,进而利用截面EBSD分析方法探究电流密度对铜箔组织性能的影响。方法 通过使用热固性树脂对铜箔进行包埋,使用加热平台使胶体凝固,对得到的包埋好的铜箔试样在砂纸上进行截面打磨,放入截面离子抛光仪中进行离子切割,样品制备完成后,将样品取下。使用电子背散射(EBSD)作为电镜附件,进行晶体学取向的表征。结果 结合截面微观组织的EBSD分析方法,分析了电流密度对铜箔组织性能的影响,结果表明,随着电流密度的增大,电解铜箔的晶粒尺寸呈现出先减小后增大的趋势,孪晶密度和位错密度呈现出先增大后减小的趋势,抗拉强度在45 A/dm²时达到最大547.05 MPa。结论 该方法可以利用EBSD分析软件自动分析铜箔截面的晶粒粒度分布、孪晶密度等,并将这些微观结构特征与力学性能结果进行详细对比分析,验证了电流密度对铜箔组织和性能的显著影响。     

块体多孔金属镍的逐层扫描喷射电沉积制备

介绍了基于喷射电沉积的逐层扫描法制备块状多孔金属镍的原理,利用该工艺在自行研制的试验装置上制备块状多孔金属镍.利用电子扫描显微镜(SEM)对多孔金属镍块状试样的表面形貌、微观组织结构及孔隙率进行检测,对表面显微硬度和压缩性能进行测试.结果表明:多孔金属镍样品的多孔层由向上生长的枝状晶围成三维连通孔隙,通孔分布均匀致密.经SEM分析铸层表面,可见枝状晶分支由菜花状的晶胞叠加生长形成.使用加工电流密度为900A/dm2时,制备的块状样品孔隙率为61.5%.表面的显微硬度HV为330.5.压缩性能的检测结果表明,多孔金属的抗压屈服极限为11.85MPa.应力曲线存在一个很宽的塑性平台,具有典型的塑性多孔材料特征.     

Effect of current density on the microstructure and hardness of Ni-CeO2 nanocomposite coating synthesized by pulse electrodeposition technique

The Ni-CeO2 nanocomposite coatings have been synthesized by pulse electrodeposition technique with different current densities (0.10, 0.30, 0.40, 0.50, 0.70 and 0.90 A/cm2) from a Watts-type electrolyte containing nano-sized ceria particles. The Ni-CeO2 coatings produced with different current densities have been characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) coupled with an energy dispersive spectrometer (EDS). The hardness of the coatings has been measured by Vickers microhardness tester (VMHT). It has been found that the crystallite size decreases and hardness increases with the increasing current density. However, the co-deposition of ceria in the nickel matrix increases up to the current density of 0.5 A/cm2, beyond which it decreases.     

双脉冲工作时间对Ni-W-P/CeO2-SiO2纳米复合材料电沉积的影响

通过Ni,W,P与CeO2,SiO2纳米颗粒的双脉冲电沉积,在普通碳钢表面制备了Ni-W-P/CeO2-SiO2纳米复合材料沉积层.在正、反向脉冲占空比(10%,30%)和正、反向脉冲平均电流密度(15.0,1.5 A/dm2)恒定下,研究了正、反向脉冲时间对纳米复合材料电沉积的影响.采用能谱、硬度测试和扫描电镜等方法,对纳米复合材料沉积层的化学组成、沉积速率、显微硬度和表面形貌进行了表征.结果表明:当正、反向脉冲时间分别控制在300 ms和40 ms时,Ni-W-P基质金属轮廓清晰,晶粒细小而均匀,CeO2和SiO2纳米颗粒在基质金属中均匀弥散分布;沉积层的化学组成(质量分数)为:70.89%Ni,9.89%W,8.59%P,7.35%CeO2,2.81%SiO2;沉积速率为45.1μm/h,显微硬度为706 HV.     

Structural and morphological investigations on DC-magnetron-sputtered nickel films deposited on Si (100)

Pure nickel thin films were deposited on Si (100) substrates under different conditions of sputtering using direct current magnetron sputtering from a nickel metal target. The different deposition parameters employed for this study are target power, argon gas pressure, substrate temperature and substrate-bias voltage. The films exhibited high density of void boundaries with reduction in <111> texture deposited under high argon gas pressures. At argon gas pressure of 5 mTorr and target power of 300 W, Ni deposition rate was ~40 nm/min. In addition, coalescence of grains accompanied with increase in the film texture was observed at high DC power. Ni films undergo morphological transition from continuous, dense void boundaries to microstructure free from voids as the substrate-bias voltage was increased from −10 to −90 V. Furthermore, as the substrate temperature was increased, the films revealed strong <111> fiber texture accompanied with near-equiaxed grain structure. Ni films deposited at 770 K showed the layer-by-layer film formation which lead to dense, continuous microstructure with increase in the grain size.     

Texture and morphology of pulse plated zinc electrodeposits

Zinc coatings were deposited under pulse-current plating conditions from an acidic sulphate bath on low-carbon steel cathodes. The effect of the (peak) deposition current density, duty cycle and pulse frequency on the microstructural texture and morphology of the deposits was studied by X-ray diffractometry and scanning electron microscopy. The zinc films consisted of crystallites having an average size controlled by deposition current density, and oriented mostly with basal (00.2) and high index (10.3), (10.4), (10.5) pyramidal planes parallel to the surface. Pulse plating resulted in coatings which were microstructurally different to those prepared under similar conditions by direct current deposition. Texture and grain size modification is illustrated. The effect of pulse current is explained in terms of enhanced nucleation and inhibited growth.     

PI衬底上电沉积Cu薄膜的晶面择优取向

采用硫酸盐电沉积法,利用X射线衍射仪(XRD)、扫描电镜(SEM)等手段研究了不同电沉积条件下在PI膜表面制备的Cu薄膜的品而择优取向、平均晶粒尺寸及表面形貌.结果表明,沉积层的晶面择优取向受Cu薄膜厚度和电流密度影响,电流密度较小(0.2 A/dm2)和较大(3.5～5.5 A/dm2)时,电沉积Cu膜分别容易得到(111)和(220)晶面择优取向,较大电流密度有利于晶核的形成,薄膜表面平均颗粒尺寸较小.