In situ oxidation/lithiation of Ni-Co alloy in the molten Li0.62/K0.38 carbonates eutectics

In situ oxidation/lithiation reaction of the pure Ni and Ni-Co alloy electrodes were studied in molten Li_0.62/K_0.38 carbonate eutectics saturated with a 0.9O₂ + 0.1CO₂ atmosphere at 923 K. Ni-Co alloy electrodes were prepared on the pure Au foil by the galvanostatic pulse plating method. Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) were employed to investigate the in situ oxidation /lithiation reaction of electrodes. OCP variation of Ni and Ni-Co alloy electrodes was divided into four regions and charge transfer resistance (R_ct) and diffusion resistance (R_diff) measured as a function of OCP/immersion time in EIS experiment strongly depended on the composition of Ni-Co alloy electrodes and the electrochemical-catalytic activity of Ni-Co alloy electrodes was affected by the surface roughness. In XRD analysis and micro-Raman spectroscopy (RS), the lithiation content increased proportionally with the amount of cobalt in Ni-Co alloy electrodes, which was an important factor to determine the electrochemical-catalytic activity of electrodes.     

电沉积Ni-Co合金的研究

研究了氨基磷酸盐电沉积Ni-Co合金电解液组成及工艺条件对沉积层中Co含量的影响.并测定了Ni-Co合金沉积层中Co含量与Ni-Co与硬度的关系,以及影响Ni-Co合金沉积层内应力的因素.实验结果表明,将一定量的Co引入Ni沉积层,可以显著地提高其硬度;当在电解液中添加一定量的Ni-1添加剂后,能使Ni-Co合金沉积层的内应力为零.这些有益的实验结果为电铸加工使用寿命长、机械性能好的模具提供了一定的依据.     

镍钴双金属氢氧化物/乙炔黑复合材料的制备及其电化学性能

以氯化钴和氯化镍作为钴源和镍源,六次甲基四胺作为沉淀剂,采用水热法合成镍钴双金属氢氧化物/乙炔黑复合材料,并研究其作为超级电容器电极材料的储能性能。借助X射线衍射和扫描电镜表征手段研究乙炔黑的加入对所得镍钴双金属氢氧化物复合材料结构和形貌的影响。采用循环伏安、恒电流充放电及循环稳定性等电化学测试手段对该复合材料的储能性能进行研究。结果表明：乙炔黑的加入能有效改善镍钴双金属氢氧化物的分散性,同时降低电极材料的电子转移阻力,进而提高镍钴双金属氢氧化物的储能性能。当电流密度为7A/g时,经过500次恒电流充放电后复合材料的比电容量保持率为97%,体现出较好的循环稳定性能。     

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.     

峰值电流密度对脉冲镀镍钴合金纳米镀层机械性能的影响

研究了峰值电流密度对脉冲镍钴合金纳米镀层的成分、晶粒尺寸、显微硬度、抗拉强度的影响.结果发现:在一定范围内,峰值电流密度的增大,可以降低镀层钴含量、表面粗糙度和晶粒尺寸,使菜花胞状结构更明显,提高镀层显微硬度(最高可达600 kg/mm2)和抗拉强度(最高可达1 200 MPa).然而,峰值电流密度太大又会使显微硬度和强度下降.与采用类似方法制得的纯镍纳米镀层相比,镍钴镀层的显微硬度并未明显升高.这说明在该纳米材料中,固溶强化效果并不很明显,而以细晶强化为主.     

Preparation and characterization of the electrodeposited Ni-Co oxide thin films for electrochemical capacitors

Nickel-cobalt (Ni-Co) oxide thin films were electrodeposited onto copper substrates in an electrolyte containing cobalt chloride and nickel chloride, and the electrochemical capacitor behaviors of these films were investigated. The XRD pattern revealed that the electrodeposited Ni-Co oxide thin film was comprised of NiCo₂O₄. In the SEM image, the electrodeposited Ni-Co oxide film was covered with hexagonal and cubical shaped particles. The electrodeposited Ni-Co oxide electrode exhibited a specific capacitance of 148 F/g at a scan rate of 20 mV, and the current density was fairly stable over 200 cycles. The charge-discharge test confirmed that capacitance of the electrodeposited Ni-Co oxide electrode resulted from the electric double layer capacitance and pseudocapacitance.     

汽车活塞销镀Ni-Co合金镀层表面改性及性能研究

利用电镀技术,在汽车活塞销表面制备Ni-Co合金镀层实现表面改性。概述了活塞销表面改性的工艺过程,观察了表面改性后活塞销的形貌,检测了Ni-Co合金镀层与活塞销基体的结合强度以及表面改性后活塞销的硬度、抗拉强度及耐摩擦磨损性能。结果表明,Ni-Co合金镀层与活塞销基体结合牢固,表面改性后活塞销的表面平整均匀,硬度和抗拉强度均提高,表现出较好的耐摩擦磨损性能。Ni-Co合金镀层有效改善了活塞销的表面状况,使活塞销的硬度提高约17%,抗拉强度提高约7.2%,磨损量和磨损速率分别下降17.5%和17.9%。     

The effect of pulse-reverse electroplating bath temperature on the wear/corrosion response of Ni-Co/tungsten carbide nanocomposite coating during layer deposition

In this article, the effect of bath temperature during layer deposition on the electrochemical/abrasion responses of Ni-Co/tungsten carbide nanocomposite coating has been investigated. The Ni-Co/tungsten carbide nanocomposite coating was obtained using simultaneous deposition of tungsten carbide nanoparticles in three Ni-Co bath temperatures of 20, 40, and 60?°C. Afterwards, in order to characterize the obtained coatings, Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM), X-Ray diffraction (XRD), MAP analysis, potentiodynamic polarization and electrochemical impedance spectroscopy methods in 3.5?wt% NaCl, and also abrasion test using a pin on disc method were carried out. The results of this study revealed that the deposition obtained from Ni-Co bath contains tungsten carbide nanoparticles and results in strong (200) and hard (111) textures in the coating at different temperatures. Also increasing the bath temperature from 20 to 40?°C results in the absorption of cobalt and tungsten carbide nanoparticles, as well as reducing the nickel content and corrosion resistance in the coating, and on one hand it increases the abrasion resistance of the coating. However, a bath-temperature increase from 40 to 60?°C results in reducing the absorption of cobalt and tungsten carbide nanoparticles, and increasing the nickel content and corrosion resistance in the coating as well as reducing the abrasion resistance of the coating.     

Ti(C,N)基金属陶瓷的力学性能与显微结构的研究

烧压烧结制备了不同Mo2C和Cr3C2含量的Ti(C0.7N0.3)-(Ni—Co)-Mo2C—Cr3C2金属陶瓷，对其性能测试表明，低Mo2C，Cr3C2含量材料具有良好力学性能。利用透射电镜、能谱分析和扫描电镜对低Mo2C，Cr3C2含量金属陶瓷显微组织进行了分析。研究表明，材料显微组织中没有发现明显可见的环形相，Mo元素富集在硬质相颗粒边缘附近，Cr元素富集在粘结相中。未完全溶解的Cr3C2分布在粘结相内和相界上抑制了裂纹的扩展，断口上沿晶断裂面弯曲不规整以及穿晶解理条纹较多，这是材料具有较高的断裂韧性的原因。     

焙烧温度对双金属催化剂甲苯加氢重整反应催化性能的影响

以类层柱Ni-Co/Mg(Al)O水滑石为前驱体,经不同温度焙烧制备了系列焦炉煤气中焦油模型化合物甲苯加氢重整制合成气催化剂. 在常压、反应温度800℃、水/碳摩尔比0.7和体积空速12000 h-1的条件下,在35 h评价时间内850℃焙烧的催化剂可完全转化甲苯,CH4和CO的平均产率分别为34%和66%,而低于750和高于950℃焙烧的催化剂活性较差. 850℃焙烧时催化剂比表面积较大,形成了尖晶石和固溶体,活性金属与载体间的相互作用较强,还原后活性金属颗粒小且均匀分布. 催化剂上有少量须状碳生成,绝大部分积碳可被H2消除,积碳是可逆过程.     

Preparation and Properties of Alumina/Nickel-Cobalt Alloy Nanocomposites

High-density nickel-cobalt alloy-dispersed Al₂O₃ (Al₂O₃/Ni-Co alloy) composites were obtained via the hydrogen reduction and hot pressing of Al₂O₃, Ni(NO₃)₂6H₂O, and Co(NO₃)₂6H₂O powder mixtures. Microstructural investigations revealed that nanometer-sized alloy particles were dispersed homogeneously at the matrix grain boundaries, forming the intergranular-type nanocomposite. High strength (>1 GPa) was registered for the Al₂O₃/10 wt% Ni-Co alloy composite. An inverse magnetostrictive response to applied stress was observed, because of the Ni-Co alloy dispersions, which indicates promise for incorporating new functions such as stress and fracture sensing into the structural ceramics without any loss of mechanical properties.     

Catalytic synthesis of carbon nanotubes using Ni- and Co-doped calcium tartrates

Calcium tartrate doped with Ni and/or Co has been used as a catalyst source in the chemical vapor deposition synthesis of carbon nanotubes (CNTs). Thermolysis of doped calcium tartrate in an inert atmosphere was shown to yield Ni, Co or Ni-Co nanoparticles ∼6 nm in diameter dispersed in a calcium oxide matrix. The CNT synthesis was carried out by ethanol vapor decomposition at 800 °C. The structure of the products was characterized by transmission electron microscopy and Raman spectroscopy. It was found that Ni nanoparticles embedded in CaO provide the narrowest diameter distribution of CNTs, while the bimetallic Ni-Co catalyst allows the formation of the thinnest CNTs with the outer diameter of ∼2 nm. This type of CNT is more likely to be responsible for the lowest value of the turn-on field (∼1.8 V/μm) for the emission current detected for the latter sample.     

高频脉冲电沉积镍-钴合金镀层的耐蚀性

用电化学的方法研究了高频脉冲电镀镍钴复合镀层在NaOH溶液中的耐蚀性,采用扫描电镜观察了碱蚀前后镍-钴合金镀层的表面形貌,并测定了镀层在NaOH溶液中的极化曲线.结果表明:随着频率的增加,沉积速率提高,沉积层表面更加致密、均匀,在10%NaOH溶液中镍-钴合金镀层的腐蚀质量损失明显减小,腐蚀速率变慢;高频和直流电镀镍-钴合金镀层的极化曲线形状相似,高频脉冲电镀相比于直流电镀,更能提高镀层的耐腐蚀性.高频率对沉积层的细化可能有重要影响,并使镀层的耐蚀性提高.     

电沉积梯度Ni-Co纳米合金镀层的研究

采用直流电沉积技术制备了梯度Ni-Co纳米合金厚镀层。测定了该镀层的内应力及显微硬度,采用X射线衍射仪及能谱仪分别对镀层的晶相结构与成分进行了分析,采用扫描电镜对镀层的表面形貌和磨痕进行了观察,并对其摩擦、磨损性能进行了研究。结果表明,该合金镀层具有较好的成分梯度和相应的结构梯度,具有优异的抗磨减摩性能。说明梯度化的设计可以有效降低合金镀层的内应力,提高镀层的抗磨和减摩性能。     

双金属Ni-Co/HZSM-5催化剂上甲烷二氧化碳重整反应

采用等体积浸渍法制备一系列双金属Ni-Co/HZSM-5催化剂,考察反应温度和Ni与Co质量比对甲烷二氧化碳催化重整性能的影响。采用BET和H2-TPR表征催化剂的孔结构和还原性能,结果表明,负载的活性组分均匀分散在HZSM-5载体孔道内。Ni与Co之间存在协同作用,促进了Ni-Co/HZSM-5催化剂的还原性能。单金属Co催化剂几乎对甲烷没有转化活性,双金属Ni-Co催化剂催化活性明显提高,Ni与Co质量比6∶4时,催化剂甲烷二氧化碳重整反应的催化活性和稳定性优于单金属Ni催化剂。     

由氨基磺酸盐和硫酸盐电解液电沉积Ni－Co合金的对比研究

通过大量实验对比了氨基磺酸盐和硫酸盐两种电解液电沉积Ｎｉ－Ｃｏ合金Ｃｏ含量的影响因素，以及Ｎｉ－Ｃｏ合金沉积层的硬度、内应力与Ｃｏ含量的关系。结果表明，与硫酸盐电解液相比，从氨基磺酸盐电解液中沉积的Ｎｉ－Ｃｏ合金硬度高、内应力低。     

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.     

The role of anion additives in the electrodeposition of nickel-cobalt alloys from sulfamate electrolyte

Nickel-cobalt alloys have been deposited from sulfamate electrolyte with acetate and citrate-anion additives and evaluated for structure and properties, such as microhardness, tensile strength, internal stress and high-temperature oxidation. XRD data show that at low Co content, the alloys exhibit face-centered cubic (fcc) growth orientations. Above 60% Co, the deposit is completely hexagonal close packed (hcp) with pronounced (100) and (110) lines. It seems likely that the Ni-Co deposits from typical sulfamate electrolyte at pH 5, as well as at current density higher than 5 A/dm², include metal hydroxides. This is followed by the formation of a more strained structure. The high-temperature oxidation rate of the Ni-Co coating from sulfamate electrolyte at pH 5 is twice that of the alloy deposited from the electrolyte with anion additives. We believe that, citrate complexes of Ni and Co, which are assumed to be involved in alloy deposition, eliminate the incorporation of hydroxides into the deposits and enable low-internal-stress coating. The anion-modified bath offers stability of structure and properties of the alloy over a wide range of acidity and current density.     

耐高温焦炉煤气氨分解催化剂的研究

研究了经过改进的MgO载体对NH3分解活性和反应热稳定性的影响。在容易造成催化剂烧结的高温、水蒸气等条件下,对催化剂进行活性评价;通过超高温处理,观察催化剂活性下降情况,配合XRD分析结果以及SEM照片,发现通过ZrO2修饰载体和特定方法制备的催化剂,在高温下能够较好地抑制Ni、Co活性组分的烧结,具有良好的热稳定性。     

脉冲电镀Ni－Co合金的研究

研究了脉冲参数对电沉积Ｎｉ－Ｃｏ合金镀层的钴含量与硬度的影响。确定了最佳的脉冲参数。应用Ｘ射线和扫描电镜分析了Ｎｉ－ＣＯ合金镀层的结构和形貌。比较了脉冲电流（ＰＣ）和直流电流（ＤＣ）电镀Ｎｉ－Ｃｏ合金镀层的各种性能。