Microstructure and Corrosion Behavior of Electrodeposited Ni-Co-ZrC Coatings

In this present work, ZrC particles incorporated Ni-Co composite coatings were electrodeposited. The objective of this article is to study the influence of Co content on the microstructure and properties of Ni-Co-ZrC coatings. Pure Ni and Ni-ZrC coatings have also been electrodeposited for comparison. Surface morphology, chemical composition, microstructure, and microhardness of Ni-Co-ZrC coatings were characterized by scanning electron microscopy, energy dispersive spectrometer, x-ray diffractometer, and Vicker microhardness tester. The potentiodynamic polarization technique was applied to measure the corrosion behavior of the coatings. By increasing Co concentration in electrolyte, Co content of the coatings was modified from 0 to 80 wt.% and ZrC particles content of the coatings was reduced. As the Co content increased, the dominant phase structure was changed from face centered cubic to hexagonal close packed crystal structure. Surface morphology of the Ni-Co-ZrC coatings was changed from nodular to sharp corner structure, and finally branched morphology with increasing Co content of the coating. Among the electrodeposited coatings, Ni-Co-ZrC coating with 42 wt.% Co content exhibited the highest microhardness. The corrosion potential of the coating was shifted to more positive with increasing the Co content from 0 to 64 wt.%. The lowest corrosion rate of 4.507 × 10^?7 g·h^?1·cm^?2 was found for Ni-Co-ZrC coating at the Co content of 75 wt.%.     

Microstructure and Corrosion Resistance of Electrodeposited Ni-Cu-Mo Alloy Coatings

This paper deals with the electrodeposition of Ni-Cu-Mo ternary alloy coatings on low-carbon steel substrate from an aqueous citrate sulfate bath. The structures and microstructure of coatings were characterized by scanning electron microscopy and x-ray diffractometry. The corrosion resistance of coatings was investigated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy techniques. The results show that the Ni-Cu-Mo coatings are mainly composed of fcc-Ni phase and a small amount of NiCu phase. Ni-Cu-Mo coatings exhibit a nodular surface morphology, and the roughness of electroplated coating increases with the increasing of Na₂MoO₄·2H₂O in the bath. The corrosion performance of the coatings is significantly affected by the Mo content of the alloy coating and their surface morphology. The coating prepared in bath containing 40 g/L Na₂MoO₄·2H₂O has the highest corrosion resistance in 3.5 wt.% NaCl solution, while that prepared in bath containing 60 g/L (or more) Na₂MoO₄·2H₂O shows a lower corrosion resistance due to the presence of microcracks on the coating surface.     

Cr-Fe-ZrO2复合镀层的结构与耐腐蚀性研究

采用复合电沉积工艺制备了Cr-Fe-ZrO2复合镀层。分别用SEM,EDS,XRD和Tafel曲线较系统地研究了Cr-Fe-ZrO2复合镀层的表面形貌、成分、结构和耐蚀性。结果表明：复合镀层的组成（质量分数）为O9.35%,Cr 49.98%,Fe 31.51%,Zr 6.66%时,在ZrO2纳米粒子的弥散强化作用下,Cr-Fe合金镀层的裂纹状况得到明显改善,而且复合镀层成分分布均匀,组织致密,结构呈非晶态特征。在室温下,Cr-Fe-ZrO2复合镀层在0.5 mol/L H2SO4溶液中的耐蚀性较Cr-Fe合金镀层明显提高。     

激光重熔喷射电沉积纳米晶镍涂层微观结构

采用喷射电沉积法在45钢基体表面制备了纳米晶镍涂层,研究了激光重熔工艺对组织的影响.用扫描电镜、X射线衍射仪和显微硬度计分析了涂层表面形貌、微观结构和显微硬度.结果表明,在优化的工艺参数下,喷射电沉积制备的镍涂层表面较平整、结合较致密,由平均尺寸为13.7 nm的纳米晶颗粒组成,但晶粒间仍有一定的间隙;经激光重熔后,熔融区内的晶粒尺寸明显减小,使涂层致密化程度得以提高并使涂层与基体由机械结合变为冶金结合,因此激光重熔处理后涂层的显微硬度明显提高.     

脉冲复合镀层Ni-W-P-SiC和RE-Ni-W-P-SiC的组织与相结构分析

运用X射线衍射仪、电子探针X射线能谱仪等手段分析研究了Ni-W-P-SiC和RE-Ni-W-P-SiC脉冲复合镀层的组织结构.结果表明,Ni-W-P-SiC和RE-Ni-W-P-SiC两种脉冲复合镀层表面比相应直流镀层光滑平整细腻得多,脉冲参数不同会得到表面平整程度和粒度不同的镀层,稀土的加入使RE-Ni-W-P-SiC复合镀层比Ni-W-P-SiC复合镀层晶粒更细小、截面更均匀;同时热处理温度和时间对镀层的截面形貌也有影响,Ni-W-P-SiC、RE-Ni-W-P-SiC脉冲镀层在镀态时都是非晶态结构,随着热处理温度的升高,两脉冲复合镀层的非晶态形态逐渐减弱,镀层逐渐向晶态转变,Ni3P相的衍射峰逐渐加强,且不断出现新相的特征峰;稀土元素的加入对脉冲镀层在镀态和热处理时相结构有一定程度影响.     

电沉积纳米晶Ni-Fe合金在碱性溶液中的腐蚀性能

通过脉冲电沉积的方法制备纳米晶Ni和Ni-Fe镀层,采用浸泡法和电化学的方法研究了镀层在10%NaOH溶液中的腐蚀行为.结果表明:在纳米Ni中加入适量的Fe可以提高其耐蚀性能.Ni-7.72?合金镀层的耐蚀性能高于纳米Ni,而Ni-12.65?合金镀层耐蚀性与纳米Ni的相当.在Ni-Fe合金镀层中,耐蚀性随着铁含量的增加而降低.在10%NaOH溶液中,所有镀层的Tafel曲线上均可观察到钝化区,表现了很好的耐蚀性.     

Study on Properties of Pulse Electrodeposited RE-Ni-W-P-SiC Composite Coatings

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.     

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 通过扫描电镜、电化学分析和腐蚀失重等方法，研究了镀液中添加RE对双脉冲电沉积法获得镍镀层的耐蚀性影响。结果表明：镀液中添加适量的RE，可使镀层组织细小且表面平整致密，耐蚀性提高，当镀液中含RE量为0.25 g/L时，镀层耐蚀性较好。     

纳米WC/PTFE镍基复合电刷镀层的摩擦磨损与耐腐蚀性能

针对单一纳米颗粒电刷镀镀层综合性能存在的不足,利用电刷镀技术在45钢基材上制备含纳米WC和PTFE的镍基复合镀层。采用扫描电子显微镜观察电刷镀复合镀层的表面形貌和显微结构,球盘式摩擦磨损试验机测试其干摩擦条件下摩擦磨损性能,在pH=4浓度为0.05mmol/L的硫酸溶液中进行耐腐蚀性试验。结果表明:在镀液中添加不同含量纳米粒子,可以不同程度填补粒子之间的空缺,使镀层表面平整、光滑;含纳米WC和PTFE镍基复合镀层的耐磨损和耐腐蚀性能强于纯镍基镀层和45钢基体,这是由于纳米粒子细晶强化和弥散强化所致;当含1.5g/L纳米WC与7g/L纳米PTFE乳液的复合镀层耐磨损性能最佳;含1g/L纳米WC与5g/L纳米PTFE复合镀层的耐腐蚀性能较纯镍基复合镀层提高一倍;45钢的磨损机制是粘着磨损,纯镍基镀层的磨损机制是剥层磨损,纳米WC/PTFE镍基复合镀层的磨损机制是磨粒磨损。     

含稀土镀液电沉积镍镀层耐蚀性的研究

借用扫描电镜、电化学分析和腐蚀失重实验方法研究了镀液中添加RE经直流和单向脉冲电沉积方法制备的镍镀层的耐蚀性。结果表明：单向脉冲法制备的镍镀层抗腐蚀能力优于直流法制备的镍镀层抗腐蚀能力，其原因主要归于单向脉冲镀层结晶比较细小致密，直流镀层结晶较粗大且致密性差。     

Electrodeposited nickel/alumina composite coating on NdFeB permanent magnets

NdFeB magnets are highly susceptible to corrosion in various environments. A nickel/alumina composite coating for NdFeB magnets was investigated in this paper. The microstructures of electrodeposited nickel coating and nickel/alumina composite coating were determined by scanning electron microscope (SEM). The corrosion behavior of nickel coating and nickel/alumina composite coating in 3.5 wt% sodium chloride solution was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the nickel coating and nickel/alumina composite coating can both provide adequate protection to the NdFeB substrate. Furthermore, the free corrosion potential of nickel/alumina composite coating is more positive and the passivation region is more obvious compared with nickel coating, and the capacitance loop diameter of nickel/alumina composite coating is significantly larger than that of nickel coating. With the increase in immersion time, a flat of passivation film is formed on the surface of nickel/alumina composite coating, resulting in excellent corrosion resistance after 288 h immersion in 3.5% sodium chloride solution according to EIS testing.     

NiCl2 含量对电沉积 Ni-纳米 TiN 复合镀层过程的影响

目的针对氨基磺酸镍体系镀镍液,优化活化剂NiCl2的用量,提高Ni-纳米TiN复合镀层的性能。方法采用超声-脉冲电沉积工艺制备Ni-纳米Ti N复合镀层,研究NiCl2含量对镀液的电导率及复合镀层的厚度、显微硬度、表面微观形貌等的影响。结果镀液的电导率及复合镀层的厚度、显微硬度均随NiCl2含量的增加呈现先增大、后减小的变化趋势。当NiCl2的用量为30 g/L时,镀液的导电性能最佳,电导率值为61.3 m S/cm,复合镀层的厚度及显微硬度均达到最大值,分别为84μm和760HV,并且复合镀层表面平整光滑,晶粒尺寸最小。结论 NiCl2含量对镀液及复合镀层的性能有很大影响,适量的NiCl2可以防止阳极钝化,提高镀液的导电能力及沉积速率,使复合镀层的厚度增加,显微硬度提高,晶粒细化,微观形貌获得改善,性能提高。适宜的NiCl2用量为30 g/L。     

Corrosion behavior of composite brake materials

It is very important to study the corrosion behavior of composite brake materials for their design, manufacture, and application. In the study, one kind of composite brake material used in engineering machinery, two kinds used in automobiles, and gray cast iron HT200 were selected as tested materials. Their corrosion behavior in typical acid solution, alkali solution, salt solution, running water, and air were investigated. The results showed that some components of composite brake materials, such as iron matrix, steel fiber, and iron powder, were easily subject to corrosion in acid solution. Corrosive pitting, net‐like cracking, and breakage appeared at their corrosion surfaces, and in the solution of 3.5% NaCl, corrosive pitting took place and corrosion holes of 2–8 µm diameter formed at the corrosion surface of these components. But when brake materials were exposed to the solution of 5% NaOH, the organic binder was corroded seriously, nearly parallel cracks formed at the corrosion surface and some samples even became loose powders because the corrosion makes the binder lose its adhering function. In running water and air, the tested samples have an excellent corrosion resistance, and the composite brake material containing organic binder has a better corrosion resistance compared with other tested materials. The investigation has also indicated that the interface between ingredients easily corrodes.     

电沉积FeNi合金电磁屏蔽性能研究

采用电沉积工艺在铜基体上得到了Fe21Ni79铁镍合金,通过XRD确定了电沉积铁镍合金的晶体结构,通过扫描电镜观察电沉积铁镍合金的表面形貌.运用低频磁场源和交变磁强计自制低频电磁屏蔽效能测试平台测量复合材料在0～1900Hz电磁屏蔽性能,运用Aligent信号源和矢量网络分析仪测量100 kHz～1.5 GHz电磁屏蔽...     

Studies on High Temperature Oxidation of Electrodeposited RE-Ni-W-P-SiC Composite Materials

WITH the rapid development of modern industries theproducts in engineering industry were continuallychallenged by the requirements of long-term and stableworking at higher temperature,pressure,speed andunder adverse conditions.Consequently,the surfaceproperties of the products,such as the resistance tooxidation at high temperature,the resistance to wearand the resistance to corrosion,should be improvedcontinually.Although the equipment or parts made outof expensive metals or alloys wholly can…     

电沉积技术制备纳米SiO2/Ni复合镀层工艺的研究

利用电沉积方法制备了纳米SiO2／Ni复合镀层。研究了阴极电流密度、微粒浓度、pH值、搅拌方式和表面活性剂种类以及浓度等对镀层沉积速率的影响，为正确制定电镀工艺提供了依据。扫描电镜观察表明，纳米微粒的加入增加了镀层表面的不工整性。     

Effects of Diffusion from Brass Substrates into Electrodeposited Tin Coatings on Corrosion Resistance and Whisker Growth

Tin coatings electrodeposited direct on brass have an initial trace zinc content which makes them liable to tarnish in atmospheres containing sulphur dioxide. When more zinc reaches the surface by diffusion from the substrate, susceptibility to corrosive agents increases. Undercoats of copper or nickel are effective long-lasting barriers to zinc diffusion but permit the slower and less damaging growth of intermetallic compounds. Increased thickness of tin coating delays the arrival of diffusing metal at the surface and also reduces the effect on solderability of corrosion of a diffused coating. Diffusion is faster in tin coatings deposited bright. Tests to assess the extent of zinc diffusion and the liability of a coating to deteriorate in long storage with corrosion risk are discussed. Susceptibility of tin coatings to whisker growth has some parallel with their tendency to interdiffuse with the substrate.     

Microstructure,Morphology and Corrosion Resistance of Electrodeposited Zinc-Cobalt Compositionally Modulated Alloy Multilayer Coatings

The morphologies and corrosion resistance of electrodeposited zinc-cobalt compositionally modulated alloy multilayer coatings produced from a sulphate bath have been investigated and reported in this paper. Various current density waveforms were designed using a computer-aided pulse plater unit to deposit zinc-cobalt alloy layers of alternate compositions from 10% cobalt to 70% cobalt. Different numbers of layers with different thicknesses were deposited by designing a variety of current density waveforms. It was shown that designing waveforms with steps to produce a gradual increase or decrease in current densities can prevent crack formation and improves the quality of Zn/Co CMAM coatings. Neutral salt spray corrosion tests showed that Zn/Co CMAM coatings have better corrosion resistance than single layer Zn-Co alloy coatings. Effects of bath temperature and agitation on the corrosion resistance of these CMAM coatings were also investigated. It was found that the best corrosion protection could be achieved for a two layered Co/Zn CMAM coating deposited at 25–30 °C from a bath with a high rate of agitation.     

电铸制备TiB_2/Cu复合材料的性能

使用粒度约为3μm的导电陶瓷TiB_2颗粒作为铜基复合材料的增强相,在酸性硫酸铜溶液中用电铸方法制备TiB_2/Cu电火花加工用工具电极。用扫描电镜和金相显微镜观察其组织结构,用维氏硬度计测量硬度,用中性盐雾试验测量其耐腐蚀性,用电火花加工脆硬材料衡量其抗电蚀性。结果表明:电铸Cu与TiB_2/Cu晶粒平均直径分别为30,10μm,硬度分别为984,1235 MPa,腐蚀失重分别为47.8,40.3 mg;TiB_2颗粒的加入可显著细化晶粒,提高硬度、耐腐蚀性和抗电蚀性。     

辅助磨擦对镍电铸层力学性能的影响

在磨擦辅助电铸镍过程中,通过改变游离微珠对电铸层表面的磨擦强弱,制备不同力学性能的镍电铸层。对所制备镍电铸层的表面形貌、织构等微观结构和显微硬度、抗拉强度及伸长率等性能进行测试和分析。结果表明:采用卧式放置的阴极能制得材料组织结构均匀的电铸层。且随着阴极表面线速度的提高,游离微珠对电铸层的整平作用和晶粒细化作用增强。在不同线速度下采用旋转阴极可以制备大范围力学性能的镍电铸层,其表面粗糙度为0.15~0.03μm、硬度为185~410HV、抗拉强度为525~1 020 MPa、伸长率为24%~4%。