Al2O3对电沉积Ni-Co/Al2O3复合镀层性能的影响

应用直流复合电沉积技术制备Ni-Co/Al2O3复合镀层,并研究了Al2O3对电沉积Ni-Co/Al2O3复合镀层性能的影响。结果表明:在本试验范围内,镀层的硬度和耐磨性随着Al2O3含量的增加而提高。     

用膜相渗透化学镀法制备NiCo/PTFE磁性复合膜

为促进金属粒子在膜孔中生成,采用膜相渗透和化学镀结合的方法,研究了化学镀NiCo/PTFE磁性复合膜的工艺.在正交试验结果基础上探讨了主盐离子浓度比、NaOH浓度、N2H4浓度、反应温度和反应时间对NiCo/PTFE复合膜中金属含量和磁性能的影响.本工艺最佳配方为:0.14 mol/L CoCl2·6H2O,0.06 mol/L NiCl2·6H2O,0.90 mol/L NaOH,0.45 mol/L C4H4O6KNa·4H2O,0.45 mol/L N2H4·H2O;最佳参数为:70～75℃,75 min.结果表明,相对于传统的双面金属化处理,引入膜相渗透的单面活化有助于镍钴金属粒子在膜孔内原位生成.     

Inquire into degradation process of Ni-Co coating in 3.5% NaCl solution by EIS北大核心CSCD

The degradation process of Ni-Co coating on plate of Kovar alloy 4J42 in 3.5%NaCl solution was studied by means of electrochemical impedance spectroscope (EIS). Four distinguished electrical equivalent circuits (EEC) were proposed to simulate the degradation process. At the very beginning of immersion, the coating exhibited excellent corrosion resistance, which could be treated as a barrier layer with a high resistance in parallel with a low capacitance. After a short time of immersion, a double-layer capacitance Cdl and a charge-transfer resistance Rct were introduced, indicating that the electrochemical reactions at the metal/coating interface may take place. In the late stage of immersion, Warburg impedance was adopted to characterize the corrosion products. With the accumulation of the corrosion products, the diffusion process of corrosive medium was affected, and the EEC comprising a diffusion capacitance (Cdiff) and a diffusion resistance (Rdiff) was then introduced to fit the impedance spectra. The evolution of coating resistance and coating capacitance were investigated to illuminate the Ni-Co coating degradation process. The results showed that the degradation process of Ni-Co coating could be described by three stages: the permeation of corrosive medium, the corrosion of metal at the interface of coating/substrate and finally the failure of coating. © 2016, Corrosion Science and Protection Technology. All rights reserved.     

Carbon-coated Ni-Co alloy catalysts: preparation and performance for in-situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons using methanol as the hydrogen donor

Carbon-coated Ni, Co and Ni-Co alloy catalysts were prepared by the carbonization of the metal doped resorcinol-formaldehyde resins synthesized by the one-pot extended Stöber method. It was found that the introduction of Co remarkably reduced the carbon microsphere size. The metallic Ni, Co, and Ni-Co alloy particles (mainly 10–12 nm) were uniformly distributed in carbon microspheres. A charge transfer from Ni to Co appeared in the Ni-Co alloy. Compared with those of metallic Ni and Co, the d-band center of the Ni-Co alloy shifted away from and toward the Fermi level, respectively. In the in-situ aqueous phase hydrodeoxygenation of methyl palmitate with methanol as the hydrogen donor at 330 °C, the decarbonylation/decarboxylation pathway dominated on all catalysts. The Ni-Co@C catalysts gave higher activity than the Ni@C and Co@C catalysts, and the yields of n-pentadecane and n-C₆–n-C₁₆ reached 71.6% and 92.6%, respectively. The excellent performance of Ni-Co@C is attributed to the electronic interactions between Ni and Co and the small carbon microspheres. Due to the confinement effect of carbon, the metal particles showed high resistance to sintering under harsh hydrothermal conditions. Catalyst deactivation is due to the carbonaceous deposition, and the regeneration with CO₂ recovered the catalyst reactivity.     

AC/Ni-Co复合电极材料的制备及其催化析氢性能

采用复合电沉积法制备了AC(活性炭) / Ni-Co 复合电极。XRD 和SEM 测试结果表明, AC 微粒的复合未改变Ni-Co 合金电极的物相结构, 但使镀层的表面粗糙度和真实表面积增大。通过稳态阴极极化曲线和电化学交流阻抗技术考察了不同电极在1 mol·L-1 NaOH 溶液中的催化析氢性能, 结果表明, 镀液中AC 含量为3 g·L-1时所制备的AC/ Ni-Co 复合电极较Ni 电极和Ni-Co 合金电极具有更高的催化析氢活性, 电流密度为30 mA·cm-2时, 析氢反应极化电位分别比Ni 电极和Ni-Co 合金电极正移230 mV 和140 mV , 表观交换电流密度分别是Ni 电极和Ni-Co 合金电极的42 倍和9 倍, 复合电极催化析氢性能的提高主要归因于电极真实表面积的增大。      

电沉积Ni－Co合金及其结构研究

采用硫酸盐体系电沉积Ｎｉ－Ｃｏ合金，研究了电镀工艺参数对镀层组成及电流效率的影响，测定了镀层结构。实验发现：在Ｎｉ－Ｃｏ合金镀层中，当Ｃｏ含量低于７６ｗｔ％时，合金由两种面心立方结构的固溶体组成；Ｃｏ含量介于７６～９０ｗｔ％之间时，由面心立方和六方密排两种结构的固溶体组成；Ｃｏ含量超过９０ｗｔ％时，合金只由一种六方密排结构的固溶体相成。     

Electrodeposition of Ni, Co and Ni-Co alloy powders

In this paper the polarization characteristics of the processes of Ni and Co powders and Ni-Co alloy powders electrodeposition from ammonium sulfate containing supporting electrolyte are investigated as a function of Ni²⁺ and Co²⁺ ions concentrations. It is shown that the correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition could be obtained only after IR drop correction, since the total current density of electrodeposition at the most negative potential of −1.4 V versus Ag|AgCl is extremely high (up to about 3-6 A cm⁻²) as a consequence of simultaneous hydrogen evolution which starts immediately after the beginning of metals (alloys) deposition. After determining the current density for hydrogen evolution and its subtraction from the total current density, correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition are obtained. They are found to be different for each ratio of Ni²⁺/Co²⁺ ions concentration. It is also concluded that the shape of the polarization curves in all cases is practically defined by the shape of the polarization curve for hydrogen evolution. The morphology and composition of electrodeposited powders were also found to be sensitive to the ratio of Ni²⁺/Co²⁺ ions concentration.     

脉冲电沉积镍及其合金的研究现状与展望

回顾了近几年来脉冲电沉积在镀镍及Ni-P、Ni-Fe、Ni-Zn、Ni-Co及Ni-Cu等镍合金镀层的应用研究现状,对直流电沉积和脉冲电沉积所得镀层的硬度、耐磨性、耐蚀性、孔隙率及镀层的晶粒尺寸等进行了比较,并对脉冲电沉积今后的发展前景作了展望.     

不同结构纳米晶镍钴合金的力学性能

采用直流电沉积方法制备晶粒尺寸为15 nm的Ni-49.2%Co(质量分数)和16 nm的Ni-66.7%Co(质量分数)合金。采用XRD、TEM和MTS?810万能材料试验机对其微观结构和力学性能进行分析。结果表明：两种合金分别是单相FCC结构和FCC与HCP共存的双相结构。固溶强化和晶粒细化的作用使两种Ni-Co合金都具有很高的抗拉强度;且Co元素的引入降低材料的层错能,提高其应变硬化能力,使Ni-Co合金的塑性也明显提高;Ni-49.2%Co合金的抗拉强度(σb )和断裂伸长率(δ)分别为1650 MPa和9%,Ni-66.7%Co合金的σb和δ分别为2200 MPa和12%。Ni-66.7%Co合金中FCC和HCP结构相互协调,在变形过程中释放内应力,使材料应变硬化能力得以保持,所以获得更高的强度和塑性。     

模芯钴含量对仿荷叶PDMS制件表面疏水性的影响

目的在采用电铸镍钴合金提高模芯硬度的基础上,研究模芯钴含量对仿荷叶PDMS制件表面质量与疏水性的影响,探明镍钴合金模芯用于模板法制备仿荷叶超疏水表面的可行性。方法采用电铸-聚二甲基硅氧烷(PDMS)二次复制模板法先后制备荷叶母模、镍钴合金电铸模芯与仿荷叶疏水表面PDMS制件。采用数字式显微硬度仪、超景深三维显微镜、Image-Pro Plus图像处理软件、激光共聚焦显微镜等分析模芯钴含量对模芯硬度与PDMS制件表面微结构、粗糙度及疏水性的影响。最后采用接触角测量仪进一步测量与分析PDMS制件表面的疏水性能。结果当镍钴合金模芯钴含量(质量分数计)达到22.4%以上时,模芯硬度较纯镍模芯由244.1HV提升至450HV以上。当模芯钴含量从0增加到51.5%时,仿荷叶PDMS制件表面微结构深宽比先从2.12减小至1.72,再增加至2.38;微结构面积占比从19.15%减小至15.03%;表面粗糙度Ra值从59.01μm增加至74.93μm;静态接触角从166.22°线性减小至149°左右,疏水性降低。结论相比微结构深宽比与面积占比,表面粗糙度对PDMS制件疏水性的影响占主导作用。镍钴合金模芯硬度显著提高的同时,随钴含量的增大,仿荷叶PDMS制件的静态接触角从166.22°减小至149°左右,但仍具有良好的疏水性。