Electrochemical characterization of Ni–P and Ni–Co–P amorphous alloy deposits obtained by electrodeposition

Ni–P and Ni–Co–P amorphous alloy deposits were obtained by electrodeposition at 80 °C on carbon steel substrates. The influence of the electrolyte Co²⁺ concentration and of applied current density was investigated. The corrosion behaviour of amorphous and crystalline deposits was evaluated by polarization curves and electrochemical impedance spectroscopy in NaCl 0.1 M solution at room temperature. Impedances were measured for samples under total immersion (free potential against time) and for polarized samples in predefined regions of the polarization curves. It was found that the alloy deposit composition is highly affected by the composition of the electrolyte but displays no significant dependence on applied current density. The results showed that the presence of Co on Ni–P amorphous alloys improves the deposit performance in the studied corrosive medium. It was also verified that the amorphous structure provides higher corrosion resistance to both Ni–P and Ni–Co–P alloys.     

Ni—Fe—P,Ni—W—P合金与镀层性能

本文通过研究非晶态Ｎｉ－Ｐ合金电镀体系加入少量Ｆｅ、Ｗ等元素对镀层性能的影响,发现非晶态Ｎｉ－Ｐ合金镀层中引入少量Ｆｅ、Ｗ元素后既能保持镀层优良的耐蚀性又可大大提高镀层的硬度和耐磨性。     

Magnetothermal study of nanocrystalline particle formation in amorphous electroless Ni–P and Ni–Me–P alloys

The microstructure of amorphous Ni–P and Ni–Me–P materials and especially its change during the heat treatment is of great importance for their magnetic, mechanical and corrosion behavior. A new magnetic phase analysis method (magnetothermal) is presented that reveals the precipitation of nanoparticles with strong magnetic properties during phase transformation upon heat treatment. It is applied to electroless Ni–P, Ni–Cu–P and Ni–Sn–P amorphous alloys. The results acquired by this method are compared with data obtained by differential scanning calorimetry, as well as by microhardness measurements using identical heat treatment in all three cases. Due to the high sensitivity of the magnetothermal method a more detailed picture of the precipitation processes in Ni–P alloys is obtained and the new information is discussed. Magnetothermal measurements reveal several stages of precipitation of a phase with strong magnetic properties. This phase is Ni in the Ni–P alloy, and Ni(Me) solid solution in the Ni–Me–P alloys. Though Sn has a stronger effect on the Ni magnetization, Cu is more effective in preventing the appearance of high magnetization in a thermally treated Ni–Cu–P alloy. This is due to Cu incorporation in Ni particles in a quantity above four times larger than Sn.     

正向脉冲占空比对Ni–W–P–CeO_2–SiO_2纳米复合镀层性能的影响

通过Ni、W、P与CeO2、SiO2纳米颗粒的脉冲共沉积,在普通碳钢表面制备了Ni–W–P–CeO2–SiO2纳米复合镀层。在一定的脉冲频率和平均电流密度下,研究了正向脉冲占空比对纳米复合镀层的化学组成、沉积速率、显微硬度和显微组织的影响。结果表明:增大正向脉冲占空比时,纳米复合镀层的晶粒尺寸增大,沉积速率和显微硬度降低。当正向脉冲占空比控制在10%时,沉积速率最快(为48.6μm/h),显微硬度最高(为696HV)。纳米复合镀层中的P含量随着正向脉冲占空比的增大而增加,但CeO2、SiO2纳米颗粒及W的含量不断降低,正向脉冲占空比对W的沉积量影响最明显。     

“电沉积Ni－W、Ni－W－P非晶态合金”简介

“电沉积Ｎｉ－Ｗ、Ｎｉ－Ｗ－Ｐ非晶态合金”简介文献报道，Ｎｉ－Ｗ－Ｐ非晶态合金具有优良的高耐蚀、高耐磨性能，在汽车ＣＡＳＳ抗蚀试验中，Ｎｉ－Ｗ与Ｎｉ－Ｗ－Ｐ镀层的抗蚀性能至少为相同厚度化学镀Ｎｉ－Ｐ合金的三倍，硬度超过镀硬Ｃｒ，为１０００～１３００Ｈ...     

Ni–Mo and Ni–W sulfide catalysts prepared by decomposition of binary thiometallates

Ni–Mo and Ni–W sulfide catalysts with atomic ratio R = 0.5 (Ni/(Ni + M), with M = Mo or W) prepared by decomposition of Ni-impregnated thiometallates were evaluated in the reaction of thiophene hydrodesulfurization. Catalysts derived from impregnated thiometallates (DTI samples) presented improved catalytic activity and higher synergistic effect than catalysts prepared by co-precipitation (HSP samples) despite the fact that co-precipitated catalysts showed larger surface area. Structure characterization by high-resolution electron microscopy (HREM) and X-ray diffraction (XRD) revealed different crystalline phases in DTI and HSP catalysts. A mixture of phases (MS₂, NiS_1.03 and MO₂) was observed in catalysts obtained by co-precipitation. Only the poorly crystalline MS₂ phase was observed in DTI catalysts suggesting that the Ni promoter is very well dispersed on the chalcogenide structure.     

化学镀Ni—W—P合金工艺研究

研究镀液组成及工艺参数对镀层成分和沉积速率以及合金镀层表面形貌、结构、成分及硬度的影响。结果表明,添加剂的加入能显著地抑制镀液的自发分解。Ni-W-P 合金具有优异的耐蚀性。     

多孔Ni–P与NiCo2O4/Ni–P电极的过氧化氢传感性能

在以聚酰亚胺覆铜板为基体制备的聚苯乙烯模板上电沉积多孔Ni–P合金,继而采用水热法在其表面制备NiCo_2O_4。研究表明,多孔Ni–P合金电极和NiCo_2O_4/Ni–P复合电极对H_2O_2的还原有优异的电化学催化活性,且不受抗坏血酸、尿酸、多巴胺、葡萄糖等分子的干扰。NiCo_2O_4的负载可以显著提高电极的检测灵敏度。     

Structure–Function Relations in Supported Ni–W Sulfide Hydrogenation Catalysts

Ni–W catalysts were prepared by impregnation of commercial -alumina and silica supports. The sulfidation, performed directly after drying at 100°C, yielded fully sulfided Ni–W species on both supports (SEM-EDAX, XPS, XRD). At optimal metals loading (50 wt% NiO + WO₃, Ni/W = 2), the sulfided catalysts had similar texture (N₂ adsorption) and displayed similar activity in dibenzothiophene hydrodesulfurization (DBT HDS), while the activity of the Ni–W/SiO₂ catalyst in toluene hydrogenation (HYD) was six times higher than that of Ni–W/Al₂O₃. This is due to the more than two times higher WS₂ slabs stacking number in Ni–W/SiO₂ compared with Ni–W/Al₂O₃ (XRD, HR-TEM), yielding stronger adsorption of toluene (TPD).     

W—Ni—P合金电刷镀溶液研究

介绍了以钨酸钠，硫酸镍，次亚磷酸钠为主要试剂的钨合金溶液的配制，比较详细地分析了溶液的配制过程和应注意的问题，提出了解决钨酸钠在强酸性介质中稳定存在的办法，说明该溶液理化性能工艺参数，对镀层质量进行了讨论。     

低应力Ni–W/Ni叠层微模具的制备与特性

采用UV-LIGA技术和Ni–W/Ni叠层电镀方法,在微喷嘴模具上制备出低应力Ni–W沉积层。研究了热处理条件对低应力Ni–W电沉积层硬度的影响。考察了沉积态及热处理态的Ni–W层、Ni层的耐磨性。结果发现,热处理后Ni–W/Ni叠层微模具界面结合良好,在干摩擦条件下,经过热处理的Ni–W层的耐磨性是Ni层的6倍;在550°C、2h真空热处理条件下,Ni–W电沉积层应力最低,为230MPa,硬度大于950HV。     

Ni—P—W—SiC复合镀层的研制

前言晶化处理因提高 Ni—P 耐蚀镀层的显微硬度值。可明显改善镀层的耐磨性;外加硬质相又进一步提高了这类复合镀层的耐磨性.400℃真空处理后,这类复合化学镀层的耐磨试验结果表明(图一)。SiC 硬质颗粒对改善复合镀层耐磨性的效果最佳.复合镀层具有优良的使用性能和较明显的经济效益,是当前涂层技术发展的一个重要前沿.本文叙述了 Ni—P—W—SiC 复合电镀层的研制、质量和部分性能测试结果.     

化学镀Ni—W—P合金镀层的XPS分析

利用红外光谱和Ｘ射线光电子能谱对化学镀Ｎｉ－Ｗ－Ｐ合金镀层表面膜进行了研究,结果表明,Ｎｉ－Ｗ－Ｐ合金镀层表面存在一层薄而致密的氧化膜,而镀层内的Ｎｉ、Ｗ、Ｐ则均以零价态形式存在。     

化学镀Ni—W—P三元合金的研究

采用化学镀技术,通过改变主盐、还原剂及络合剂的浓度以及操作条件,成功地制备了含W量为5.5％、含P量为12.3％的Ni-W-P合金镀层。其沉积速度为11μm/h。文中以化学镀镍基合金的电化学机理为依据,分析了影响镀层中W含量及P含量的因素     

Ni—Fe／Ni—P—W双层合金镀层的制备及性能

采用电沉积法,在45#钢上制备了Ni-Fe/Ni-P-W双层合金镀层.采用原子吸收分光光度法和X射线衍射分别测定了镀层的化学成分及相结构,并测试了其显微硬度和耐腐蚀性能.结果表明,该双层合金镀层具有较强的显微硬度,在5%(质量分数)NaCl溶液中具有比Ni-P-W合金镀层更优异的耐蚀性能.因此,该双层合金镀层可用作防腐耐磨镀层.     

电沉积Ni—W—P活性阴极的制备研究

研究了电沉积Ni—W—P电极的析氢电催化活性、长期稳定性,并对其催化活性进行了分析。此电极具有优良的析氢电催化活性和长期电解稳定性,是制作活性阴极的材料之一。     

Preparation of Ni(Co)–W–B amorphous catalysts for cyclopentanone hydrodeoxygenation

Ni–Co–W–B, Ni–W–B and Co–W–B catalysts were prepared by chemical reduction method and showed high activity in the HDO of cyclopentanone. Co–W–B had higher thermal stability than Ni–Co–W–B and Ni–W–B catalyst. The conversion of cyclopentanone could be high to 96.6% with a cyclopentanol selectivity of 0.4% and a deoxygenation rate of 95.4%. The HDO activity of the catalyst was related to its thermal stability, surface area, hydrogen supplying ability and Brönsted acid sites.     

Pulse current electrodeposition and corrosion properties of Ni–W alloy coatings

Ni–W alloy coatings were prepared on a mild steel substrate by means of pulse current (PC) and compared to the coatings electrodeposited by direct current (DC). In particular the study dealt with the influence of the frequency using pulse current on the surface morphology while maintaining a constant duty cycle. A constant charge for DC and PC electrodeposition of Ni–W alloy coatings was used. The morphology of the coatings was explored by scanning electron microscopy and the composition of the coatings was analysed by X-ray powder diffraction and energy dispersive X-ray analysis. Corrosion resistance of Ni–W alloy coatings was investigated by potentiodynamic polarization in a chloride medium. The corrosion products were analysed by Raman spectroscopy. It was found that the temperature of the electrolysis affects current efficiency of the DC and PC electrodeposition. The frequency of pulse electrodeposition alters the morphology of the Ni–W alloy coatings. There was evidence of the positive influence of increased tungstate concentration in the electrolyte on corrosion resistance of the Ni–W alloy coatings.     

Ni—W合金电镀

概述了Ｎｉ－Ｗ合金电镀工艺。Ｎｉ－Ｗ合金具有高硬度、耐蚀性和耐磨性，有着广泛的用途。