AZ31镁合金电镀前处理工艺研究

采用扫描电子显微分析、失重实验等手段和方法探讨AZ31镁合金电镀前处理工艺。结果表明,采用CrO₃+Fe(NO₃)₃+KF酸洗后试样表面光亮,基本无失重;采用H₃PO₄+NH4HF活化,可有效去除试样表层氧化物,增强基体和浸锌层的结合力;采用硫酸盐浸锌工艺可获得致密的浸锌层。通过分析温度、电流密度、pH值对浸锌层的影响规律,获得了最佳的浸锌工艺：30g/L ZnSO_4?7H₂O, 150 g/L K₄P₂O₇10H₂O,7 g/L KF, 5g/L Na₂CO₃, 温度70℃～75℃, pH=10.2～10.4 ,浸锌时间10 min。在此前处理基础上电镀锌,镀层和基体结合力较好。     

28CrMo钢的Ni-P合金镀工艺

研究了制备工艺对28CrMo钢Ni-P合金镀层性能的影响。结果表明,镀液成分中的氯化镍和稀土含量及电流密度和镀液温度都会影响镀层的厚度和硬度。本试验条件下的最佳制备工艺是镀液成分为含50 g/L的氯化镍+2 g/L的稀土(镀液中其他成分为硫酸镍180 g/L、磷酸45 g/L、亚磷酸10 g/L),电流密度为8 A/dm2,镀液温度为65℃。在此条件下得到的镀层为非晶态,镀层性能最好。     

The Electroplating Of Nickel From Aqueous Gluconate Baths

Preliminary experiments were carried out in order to electrodeposit good quality and satisfactory nickel plate on to copper substrates from gluconate baths. The effects were investigated of bath composition, pH, temperature and current density on cathodic polarization, cathodic current efficiency, on the quality of the deposits and on the throwing power of baths. Highly adherent and very bright plates with metallic lustre were obtained from an optimum bath containing: NiSO₄. 7H₂O 0.144 mol l^?1 and sodium gluconate 0.23 mol l¹ at pH = 4.3, temperature 40°C and current density 1 A dm^?2. The surface morphology of the as-plated nickel was examined by scanning electron microscopy (SEM) while the structure was examined by using X-ray diffraction analysis. The throwing power of the bath is greatly improved by increasing the gluconate concentration.     

Electrodeposition of Copper-Nickel Alloys from a Citrate Bath Containing Boric Acid

Copper-nickel alloys have been electrodeposited on steel substrates from a bath containing copper sulphate, nickel sulphate, sodium sulphate, sodium citrate and boric acid. Galvanostatic cathodic polarization, cathodic current efficiency and composition of the alloys were studied as influenced by bath composition, current density and temperature.

The bath is characterized by high cathodic current efficiency. Current density is found to strongly influence the composition of the deposits. At low current densities (lower than a certain transition current density), a copper-rich alloy is deposited with copper (the more noble metal) being the preferentially deposited metal. At larger current densities, nickel becomes the nobler metal and is deposited preferentially. The magnitude of the transition current density depends upon the bath composition and temperature. The structure and surface morphology of the as-deposited alloys were examined by XRD and SEM. The results reveal the presence of a single solid solution phase with face centred cubic structure. The morphology of the deposits is mainly controlled by the alloy composition.     

Nickel electrodeposition from novel lactate bath

Abstract

A new electroplating bath for nickel deposition has been developed. Lactic acid was used as a complexing agent in the bath replacing boric acid. The effect of bath composition, current density, pH and temperature on the cathodic polarisation, cathodic current efficiency, morphology and structure of the deposit was carried out. Optimum conditions for producing sound and satisfactory nickel deposits were: 0·30M NiSO₄.7H₂O, 0·50–1·0M lactic acid and 0·3M Na₂SO₄ at pH=10, c.d.=0·98 to 9·80 mA cm^?2 and 25°C. The surface morphology of the deposited nickel was investigated using SEM. The crystal structure was examined by X-ray diffraction analysis. The results showed that the nickel deposits have a face centred cubic structure.     

AZ91镁合金表面制备Ni-SiO2纳米复合电镀层的工艺研究

采用复合电沉积技术在AZ91镁合金表面制备Ni-SiO2纳米复合镀层,并研究各工艺参数对镀层的影响,从而得出最佳工艺.研究结果表明:在镀液中纳米SiO2的添加量为20 g/L,阴极电流密度为1.0 A/dm2,镀液温度为50℃,活性剂A的添加量为1.0 g/L,pH为5～6的条件下,经过20～30 min电沉积,可获得均匀、平滑的镀层,镀层的显微硬度与耐蚀性最佳.     

Zinc–nickel alloy coatings electrodeposited from a chloride bath using direct and pulse current

Zinc–nickel alloys were electrodeposited on steel from chloride bath by direct and pulse current. Some electric variables (average current density, pulse frequency, duty cycle) and some important bath conditions (ratio of Ni²⁺/Zn²⁺ in bath, temperature) on chemical compositions, current efficiency, microhardness and surface appearance of coatings were studied. At low current densities, transition from anomalous to normal co-deposition was observed for both direct and pulse current. Pulse current seems to increase brightness of the coating and to decrease the precipitation of zinc hydroxide at the cathode surface. In addition, applied pulse current increases the percentage of nickel in deposits. Pulse frequency and duty cycle had little effect on the chemical composition of deposits. The polarization curve of zinc–nickel deposition with pulse current is shifted to positive potentials in comparison with direct current curves. The temperature of the plating bath had a very strong effect on the composition of the deposits. This is primarily the result of intrinsically slow nickel kinetics. The hardness of Zn–Ni alloy coatings (approx. 220 VHN) was greater than the hardness of zinc coating (approx. 161 VHN). The hydroxide suppression mechanism for Zn–Ni co-deposition has been confirmed.     

Preparation and H_2S Gas-Sensing Performances of Coral-Like SnO_2–CuO Nanocomposite

Nanocomposites composed of SnO2 and CuO were prepared by hydrothermal method. The microstructures of obtained SnO2–CuO powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption test. The results show that the nanocomposites exhibited coral-like nanostructure, and the average crystalline size of SnO2 was 12 nm. The specific surface area of the four samples, SnO2–0.2CuO, SnO2–0.5CuO, SnO2–1.0CuO and SnO2–2.0CuO are 72.97, 58.77, 49.72 and 54.95 m2/g, respectively. The gassensing performance of the four samples to ethanol, formaldehyde and H2 S was studied. The sensor of SnO2–0.5CuO exhibited high response to hydrogen sulfide(4173 to 10 ppm H2S, where ppm represent 10-6), and low response to ethanol and formaldehyde. The good selectivity exhibited that the SnO2–0.5CuO nanocomposite can be a promising candidate for highly sensitive and selective gas-sensing material to H2S.     

Ni-P-α-Al2O3纳米复合电镀工艺研究

采用复合电镀技术,在黄铜表面制备高硬度的Ni-P-α-Al2O3纳米复合镀层,研究了阴极电流密度、纳米α-Al2O3添加量、镀液pH值、镀液温度和电镀时间对镀层硬度的影响。结果表明:当镀液温度为45℃,阴极电流密度为4A/dm2,镀液pH值为4.0,电镀时间为40min,镀液中纳米α-Al2O3的质量浓度为10g/L时,所得镀层均匀、细致、平滑,经适当热处理后,显微硬度可达到1 332HV。     

The chemistry of copper patination

The chemistry of copper patination was investigated by two series of experiments. The chemistry of an aqueous copper-sulphate solution was studied at concentrations and pH values near those predicted in an electrolyte on copper exposed to the atmosphere. The electrochemical reactions in an electrolyte in contact with cuprite were investigated in a reaction vessel which used cuprite powder in artificial rainwater to study the electrochemistry of the atmospheric corrosion and patination of copper. Typical sulphate concentrations in rainwater are sufficient to precipitate posnjakite (Cu₄SO₄ (OH)₆2H₂O)), a possible precursor to brochantite, within an hour of wetting a cuprite surface. Brochantite (Cu₄SO₄ (OH)₆), the most commonly found copper salt in natural patinas is responsible for their green appearance. Precipitation of brochantite from the electrolyte resulted from an increase in pH due to the cathodic reduction of oxygen and an increase in cupric ion concentrations by cuprite oxidation.     

化学机械抛光304不锈钢用抛光液成分研究

由于304不锈钢的优良特性,未来其将成为柔性显示器衬底的主要材料之一。为提高304不锈钢化学机械抛光的速率和质量,研究不同氧化剂在不同质量浓度或体积浓度及不同pH值下, 对材料去除率和表面粗糙度的影响。结果表明:氧化剂Fe₂O₃、H₂O₂、FeCl₃都在pH=2时抛光效果最佳,氧化剂KMnO₄在pH=10时抛光效果达到最佳。在最佳的pH值下进行抛光,H₂O₂的体积浓度为10 mL/L时,表面粗糙度R_a最好,为4 nm;在FeCl₃质量浓度为4.0 g/L时,材料去除率最高,为209 nm/min。      

Electrodeposition and mechanical properties of Ni-W-B composites from tartrate bath

Electrodeposition of Ni-W-B alloys from plating baths containing tartrate in the absence of ammonia is studied. Detailed studies on the effects of bath temperature, pH, cathode current density and plating time have led to optimum operational conditions for obtaining satisfactory alloy deposits. The operational conditions for deposition the alloy with high hardness are; current density 30 mA cm^?2, pH 6.0 and bath temperature of 60°C. The results have shown that the adherence of Ni-W-B is better than the Ni and Chromium on Cu substrate. It adheres to Cu substrates better than electrodeposited Ni and chromium. The morphology of the deposits was studied by SEM and the analysis of composition performed by EDX and inductively coupled plasma (ICP). The as-deposited alloy contained 21.66 wt % W and the highest cathode current efficiency for deposition of the alloy was about 38%. The deposit obtained under these conditions had an amorphous character with a hardness of about 800 HV, which is comparable to the hardness of chromium, occurred at a heat treatment temperature of 400°C. When heat treated up to this temperature, the initial metastable structure decomposed into fine particles of Ni₄W in a nickel solid solution.     

硬质合金粉末表面电泳沉积制备金刚石涂层

采用电泳沉积法在硬质合金粉末表面涂覆金刚石涂层，分析硬质合金含量和MgCl₂·6H₂O含量对涂层沉积效果的影响，并对制备的涂层粉末进行性能表征。结果表明:电泳沉积法可实现硬质合金粉末表面涂覆金刚石涂层；硬质合金粉末为28.0 g，金刚石粉末为4.0 g，MgCl₂·6H₂O为1.0 g时，制备的金刚石涂层均匀且致密度好。      

影响金刚石微粉化学镀镍品质的因素

用化学镀的方法在线锯用金刚石微粉表面镀覆一层镍,通过正交试验、SEM,探究镀液配比和工艺条件对金刚石微粉化学镀结果的影响。结果表明:镀液中络合剂对化学镀增重影响的主次排序为:柠檬酸>氨水>柠檬酸钠,但去掉柠檬酸钠会降低增重;化学镀增重率与金刚石颗粒表面沉积的镍晶粒大小有关,且镀液pH为4左右时,能得到漏镀少连晶少的镀覆金刚石微粉;当溶液中不添加稳定剂时,会有镍渣生成,而添加量过多又会抑制反应进行,此时若增大分散剂的量,可以使不反应的溶液正常发生反应;随着金刚石装载量变大,增重率降低,且装载量以6 g为好;随着温度增高,增重率变大,最佳温度应选取在80～85 ℃。      

工艺参数对连续碳纤维表面电磁搅拌化学镀镍的影响

目的解决连续碳纤维在镀覆过程中易出现黑心现象以及无法完全浸泡于镀液中的问题,制备镀层均匀的连续碳纤维镍镀层。方法引入外加电磁搅拌对连续碳纤维进行化学镀镍,研究了施镀时间、镀液温度、镀液pH值以及电磁搅拌转速对连续碳纤维表面微观形貌及镀层沉积速率的影响规律。结果当搅拌转速一定时,随着施镀时间、镀液温度、镀液pH值的不断增加,碳纤维表面镀层逐渐变得均匀完整,且镀层厚度逐渐增大。但当施镀时间超过20 min,镀液温度超过75℃,镀液pH值超过8时,镀层表面沉积了大量形状不一的胞状镍颗粒,形成粗糙的表面形貌。镀层的沉积速率随着镀液温度、镀液pH值的升高而增大。当搅拌转速由200 r/min增加到300 r/min时,镀层的沉积速率随着搅拌转速的增加而不断增大;当搅拌转速由300 r/min增加到400 r/min时,镀层的沉积速率随着搅拌转速的增加而不断减小。结论电磁搅拌辅助连续碳纤维化学镀镍的最佳施镀工艺参数为:施镀时间15~20 min,镀液温度75℃,镀液pH为8,搅拌转速200~250 r/min。采用此工艺参数能获得表面致密、均匀完整的镍镀层。     

Nickel Electrodeposition from all-Sulphate and all-Chloride baths. Texture and Microhardness

In the nickel electrocrystallization process there appears a strong specific inhibition of crystal growth. Various chemical species, such as Ni(OH)₂ gaseous H₂ or H_ads which exist or are formed in the metal-electrolyte interface according to the electrolysis conditions, are selectively adsorbed in the continually regenerated metallic surface and determine the texture of the electrodeposits.

The aim of this work is to study the correlation between the texture and the microhardness of nickel deposits. The preferred orientation of the deposits, prepared from all sulphate and all chloride baths, was studied by X-ray diffractometry and the corresponding texture diagrams were traced as a function of the solution pH and the cathodic current density. The microhardness of the deposits was determined by the Vickers method.

It is shown that the textures and the microhardness of the deposits depend on the electrolysis conditions. but the hardness seems to be independent of the crystallite orientation, in spite of the related bibliographic references. The preferred orientations and the microhardness of the nickel deposits are produced by the same cause: the specific inhibition of the cathodic surface during the electrodeposition determines the orientation of the crystallites, produces deformation of the crystal lattice and increases the hardness of the deposits.     

The Electrolytic Preparation and Characterization of Ni-Fe Alloys

The electrodeposition of nickel rich Ni-Fe alloys from an alkaline (pH 8.5) bath containing serine and sodium pyrophosphate has been studied. The functional properties (hardness, coercivity and corrosion resistance) and their dependence on plating variables (bath composition and working conditions) are discussed. The deposited alloy under optimum plating conditions is fine grained with fcc structure. The composition of the alloy varied with cd, pH and composition of the bath solution. The solution affords 90% current efficiency and 35% throwing power under some experimental conditions. The anomalous co-deposition of Ni-Fe alloy is minimized considerably by the presence of complexing agents in the solution. Spectral studies (UV-Visible) indicated the presence of Ni^2- ions in the complex state in preference to Fe^2- ions.     

钛基镍钴合金电极的制备及析氢性能

目的降低电极的析氢过电位,提高析氢性能,从而降低电解水制氢的成本,促进氢储能技术的发展。方法通过异相共沉积法,制备了镍钴合金电极。利用场发射扫描电镜(SEM)、电化学交流阻抗(EIS)对纯镍电极及镍钴合金电极进行表征,采用阴极极化曲线(LSV)探究了电沉积液中Ni/Co元素的比例、电沉积电位及电沉积时间对镍钴合金电极析氢性能的影响。结果 SEM结果揭示了纯镍电极及镍钴合金电极表面分别是粒径约为100 nm左右的镍颗粒和镍钴颗粒。EIS结果说明了镍钴合金电极的导电性能优于纯镍电极。此外,纯镍电极、镍钴合金电极的阴极极化曲线测试表明在电流密度为30 mA/cm~2时,镍钴合金电极的析氢过电位比纯镍电极降低55 mV,降低了近20%。结论通过异相共沉积法制备镍钴合金电极,制备方法简单、方便、快速,其析氢性能优于纯镍电极。镍钴合金电极的最优制备工艺条件为:NiSO_4·6H_2O 27 g/L,CoSO_4·7H_2O_3 g/L,H_3BO_3 10 g/L,Na_2SO_4 10 g/L,柠檬酸10 g/L,十二烷基硫酸钠0.1 g/L,pH值4.0,电沉积电位-1.3 V,电沉积时间10 s。     

铝合金化学镀镍工艺研究

对6061铝合金化学施镀了Ni-P合金镀层.以硬度为考察指标正交优化了化学镀镍液,其优化配方为:NiSO4·6H2O 25g/L,NaH2PO2·H2O 25 g/L,CHCOONa·3H2O 20 g/L,C3H6O3(乳酸)20 g/L.探讨了十二烷基硫酸钠、温度、pH值对镀层性能的影响,研究结果表明:当质量浓度为...     

氨络合物体系中杂质Zn~(2+)对电沉积镍的影响

通过霍尔槽试验研究氨络合物体系中杂质Zn~(2+)对镍电沉积的影响,采用电化学工作站测试不同Zn~(2+)浓度时的循环伏安曲线、稳态极化曲线及电流时间暂态曲线.结果表明:杂质Zn~(2+)的含量为0.1 g/L时,在小于2.78 A/dm的电流密度范围内可正常沉积出金属镍;杂质Zn~(2+)含量大于0.5 g/L时,在较大的电流密度范围内均无法正常沉积出金属镍;过电位小于640 mV时,Zn~(2+)的存在不影响阴极反应的传递系数,且不改变阴极反应机理;当过电位大于640 mV,且杂质Zn~(2+)的浓度大于0.5 g/L时,阴极反应的传递系数减小,阴极反应机理发生改变;杂质Zn~(2+)浓度大于0.5 g/L时,严重影响镍电结晶过程的成核速率,这是其抑制金属镍电沉积的主要原因.因此,采用镍氨络合物体系电积金属镍,应控制杂质Zn~(2+)的含量小于0.1 g/L.