Evaluation of initial deposition rate of electroless Ni–P layers by QCM method

Electroless nickel–phosphorus (ENP) initial deposition rates from a glycine bath were studied by means of the quartz crystal microbalance (QCM) method. SEM and EDX methods were also used to study the morphology and elemental analysis of deposits. The effect of pH, temperature and the type of activation process on the initial deposition rate, surface morphology and surface elemental analysis of deposits were evaluated. Increasing the pH and the temperature cause an increase in deposition rate and a decrease in P content of deposits. The phosphorus content of obtained deposits in pre-plate method was greater than in sensitizer–activator process under the same conditions of the alloy deposition. The surface morphology depends on P content of deposits. By decreasing the P content of deposits, the grain size increases.     

Study on photocatalytic deposition of bismuth onto nanocrystalline TiO2 by quartz crystal microbalance and electrochemical method

In situ techniques of quartz crystal microbalance (QCM), differential pulse voltammetry (DPV) and amperometric measurement were employed to investigate the adsorption Bi(III) ions and the photocatalytic deposition Bi process at the surface of nanocrystalline TiO₂. It was obtained that the adsorption of Bi(III) ions onto nanocrystalline TiO₂ accords with the pseudo-second-order reaction and the reaction rate constant k was about 13.3 g mol⁻¹ min⁻¹. In addition, the photocatalytic deposition of Bi onto the surface of TiO₂ was further investigated. It was found that photocatalytic deposition rate at the surface of TiO₂ was enhanced by increasing pH value or initial concentration of Bi(III) ions. The influence of organic hole-scavegeners on the photocatalytic deposition of Bi was also investigated, and it was obtained that formic acid may be the best for the photocatalytic reduction of Bi. The mass ratio between the Bi(III) and Bi metal deposition was calculated as 7.48:1. Therefore, it can be concluded that QCM, DPV and amperometric measurement may be effective and reliable for the investigation of the photocatalytic deposition of Bi onto the surface of nanocrystalline TiO₂.     

Investigation of cobalt deposition using the electrochemical quartz crystal microbalance

Electrodeposition of cobalt from sulfate solutions at different pH values was investigated using the EQCM technique coupled with cyclic voltammetry. The results show that cobalt hydroxide is formed simultaneously with cobalt deposition during the early stages of reduction due to the pH variation near the electrode surface caused by the parallel hydrogen evolution reaction (HER). This result was confirmed using M/z values calculated using the Sauerbrey equation and Faraday's law, which showed the presence of cobalt hydroxide in the electrodeposits. A flux model was developed and it assumes a direct reduction of cobalt, simultaneous HER and the formation of cobalt hydroxide during the early stages of deposition at pH 4.10. When the solution pH is decreased to 3.33 only the direct cobalt reduction is observed without any hydroxylated species formation.     

The activation effect of Pd nanoparticles on electroless nickel-phosphorous deposition

Active colloids regarding responsible for charge transfer and electron transfer are in electroless metal bath. Herein, the electrochemical analysis for the catalytic effect of Pd nanoparticles on deposition kinetic and microstructure in the electroless nickel-phosphorous bath was studied. As supported analysis by leaner sweep voltammetry (LSV), the currents for oxidation peaks corresponding to Pd nanoparticles of increasing amount are measured to be enhanced. It shows that Pd nanoparticles have excellent catalytic power for EN_pD bath. In addition, the deposition rate analyzed by mixed potential theory (MPT) was found and increased from 0.063 to 0.091 μg/cm² s. However, based on the same nanocatalyst quantity, the deposition rates which actually occurred and are in situely monitored by EQCM are measured to be faster than theoretical value given by MPT. It shows that that the cathodic currents for depositing hydrogen and phosphorous in mixed potential theory could not be neglected when the equilibrium potential reached. As an additional information supported by FE-SEM, the continuous growth of nickel crystal is found after the induction time measured by EQCM. The narrowest distribution of nanosize grain is obtained at 120 s. In addition, the deposited layer of P of higher content is found to exist in the deposited microstructure catalyzed by the Pd nanoparticles of high concentration.     

化学镀镍在工业生产应用中的要素

以实践经验总结了化学镀镍工业生产应用中前处理、镀液、设备、工艺维护、三废处理等关键工序的控制要素,提出相应的措施,供化学镀镍生产厂借鉴。     

化学镀镍石墨粉体的制备

采用化学镀方法在天然鳞片石墨颗粒表面镀镍,对镀镍石墨表面的形貌、成分、结构进行了观察和分析,对镀镍石墨的抗氧化性及表面电位进行了测定。结果表明:在石墨表面形成了较为均匀的镀层,镀层由非晶态的镍和磷组成;镀镍石墨粉体与氧气反应的峰值温度比没有化学镀处理的普通石墨粉体的提高了近80℃,抗氧化性提高;镀镍石墨粉体在水中的Zeta电位绝对值在pH>4.3的位置(等电位点pH=9附近除外)明显大于没有化学镀处理的普通石墨粉体的,分散性有很大的改善。     

Preparation of nickel coating on ZTA particles by electroless plating

With the aim to effectively improve the interface between ZrO₂ toughened Al₂O₃ (ZTA) particles and metal matrix, nickel was deposited on the surface of ZTA particles by electroless plating method. Formation mechanism of nickel coating and effects of the solution pH, loading capacity of ZTA particles and temperature on the nickel deposition were investigated. Microstructures, thickness and element distributions of nickel coating were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the nickel was successfully deposited on the surface of ZTA particles by electroless plating without noticeable defects. The process of electroless nickel plating could be explained by combination of atomic hydrogen and electrochemistry theories. The interfacial nucleation of nickel is easier to form than spontaneous nucleation in the solution. Deposited Nickel has priority on the surface of ZTA particles comparing to that in solution. The optimal conditions to coat nickel on the surface of ZTA particles are: solution pH 4.7–4.8, loading capacity 15–20?g/L, and electroless plating temperature 85?°C. The ZTA particle reinforced iron matrix composites prepared by powder metallurgy could have better interfacial bonding between ZTA particle and iron matrix because of the nickel coating on the surface of ZTA particle. Nickel diffuses into the iron matrix during the sintering preparation of composite materials. The interface between ZTA particle and iron matrix presents the evidence of non-chemical bonding.     

The observation of the nucleation and growth of electrolessly plated nickel deposited from different bath pH by TEM and QCM method

The important factors for fabricating thinner and more uniform films by electroless plating were discussed. Two kinds of Ni-P films were electrolessly plated from hypophosphite baths. The number density of the grains was low in the Ni-5.3 wt%P deposits which were plated from the pH 9 bath. As deposition proceeded, the grains grew and merged to form a continuous structure. In case of the Ni-12.6 wt%P deposits, which were plated from the pH 6 bath, the number density of the grains was more than twice that of the Ni-5.3 wt%P deposits. The grains formed a continuous structure, with nucleation governed by the initial deposition. Thus, the transition thickness, i.e., the thickness at which the deposits assumed a continuous structure, was lower in the case of pH 6. The difference was caused by the different autocatalytic activity of the deposits due to the difference in phosphorus content. It was found that the thinner and more uniform nickel films could be electrolessly plated under lower autocatalytic activity.     

化学镀镍磷合金镀速的研究

研究了化学镀镍磷合金中镀液成分及操作条件对金镀层沉积速度的影响。     

An electrochemical quartz crystal microbalance study into the deposition of manganese dioxide

An electrochemical quartz crystal microbalance (EQCM) has been used to study the effects of electrolyte composition (MnSO₄ and H₂SO₄ concentrations) and anodic current density on the electrodeposition of manganese dioxide. The EQCM, in tandem with the electrode voltage during deposition, has been used to characterize features of the deposition mechanism such as the relative lifetime of the Mn(III) intermediate, the rate of soluble Mn(III) hydrolysis to form MnOOH, and the porosity of the resultant manganese dioxide deposit as a function of crystal nucleation. The connection between the results obtained here and commercial electrodeposition of manganese dioxide were also discussed.     

化学镀Ni-W-P镀液及工艺优化研究

采用正交试验,以镀层的耐硝酸变色时间为评价标准,得到化学镀Ni—W—P溶液最佳配方为：20g／L硫酸镍、20g／L钨酸钠、20g／L次磷酸钠、40g／L络合剂、20g／L缓冲剂、pH值为60对该优化镀层的沉积速度、耐蚀性、孔隙率及结合力进行了测定,并与Ni—P二元合金镀层进行了比较。结果表明,该优化镀层的性能优于Ni—P二元合金。采用扫描电镜及X-射线衍射仪分别对该优化镀层的微观形貌、组成及结构进行的分析表明,该镀层结构致密,磷含量高达13.9％,且为非晶态结构。     

中温化学镀镍稳定剂的研究

在由NiSO4·6H2O 25 g/L、NaH2PO2·H2O 30 g/L、CH3COONa 20 g/L、乳酸15 mL/L和十二烷基硫酸钠8 mg/L组成的中温(75℃)化学镀镍液(pH 4.60 ～ 4.65)中,研究了不同稳定剂对镀液稳定性、沉积速率、镀层磷含量、镀层性能等的影响.结果表明,低质量浓度(＜8 ...     

A quartz crystal microbalance study of the kinetics of interaction of benzotriazole with copper

The kinetics of interaction of benzotriazole (C₆H₅N₃, BTAH) with the surface of copper in salt water were studied using an electrochemical quartz crystal microbalance and X-ray photoelectron spectroscopy (XPS). Upon injecting BTAH into the electrolyte, three regions appear in the time response of the microbalance. Region I (at short time of few minutes), exhibits rapid linear growth of mass with time, which is attributed to the formation of a protective Cu(I)BTA complex. Region II reveals attachment of BTAH at a slower rate onto the inner Cu(I)BTA complex. Region III is a plateau indicating that the BTAH film attains an equilibrium mass and thickness, which increase with the concentration of BTAH. The intensity of the N1s peak in the XPS spectra increases with the time of immersion, indicating more BTAH on the surface. The results suggest a duplex inhibitor film composed of an inner thin layer of Cu(I)BTA and an outer layer of physically adsorbed BTAH which increases in thickness with time and BTAH concentration. They also offer an explanation for the much documented findings of simultaneous increase of the polarization resistance and decrease of double layer capacity with inhibitor concentration and time of immersion.     

酸性化学镀镍工艺条件优化研究

以硫酸镍为主盐,次亚磷酸钠为还原剂,采用复合络合剂在酸性条件下对45钢镀件进行化学镀镍,在硫酸镍浓度、次亚磷酸钠浓度、醋酸钠浓度、络合剂A浓度、镀液pH值和镀液温度等单因素实验的基础上,以镀层沉积速率为指标,用正交设计法对酸性化学镀镍工艺进行了系统优化,结果表明,最佳施镀条件为:硫酸镍浓度35 g/L,次亚磷酸钠浓度30 g/L,络合剂A浓度10 g/L,镀液pH值6.0。在此条件下镀件的镀层沉积速率高达17.38μm/h,且其质量符合国家相关标准。     

金刚石化学镀铜工艺研究

介绍了金刚石化学镀铜工艺流程、工艺配方。研究了不同络合剂体系对镀液稳定性以及不同预处理方法对化学镀铜层表面形貌的影响。探讨了硫酸铜质量浓度、络合剂物质的量之比和不同pH下甲醛质量浓度对金刚石表面沉积铜速率的影响。结果表明:使用胶体钯敏化活化能显著提高金刚石表面镀铜质量,多元络合剂的加入可以增加镀液的稳定性。获得了化学镀铜最佳工艺条件:CuSO4·5H2O15g/L,甲醛(w(HCHO)=36%)15g/L,酒石酸钾钠14g/L,EDTA14.6g/L,NaOH适量,二联吡啶0.02g/L,亚铁氰化钾0.01g/L,温度(43±0.5)°C,pH=12.5。采用此工艺在金刚石颗粒表面获得了良好的镀铜层。     

柠檬酸盐体系低温化学镀镍的研究

提出一种柠檬酸三铵体系的低温化学镀镍工艺。研究了该镀液的温度、pH及镀液组成对沉积速度的影响。得出适宜的工艺条件为:40g/L硫酸镍、35g/L次亚磷酸钠、30g/L柠檬酸三铵,pH9~9.5,θ为45℃。经扫描电子显微镜观察,镀层表面均匀平整;经X-射线衍射分析,镀层具有晶态结构。该工艺稳定,沉积速度可达4.5mg/(cm2·h)。     

新型化学镀镍光亮剂的研究

采用正交试验对以铋盐和吡啶衍生物为主要成分的新型化学镀镍复合光亮剂的组成进行了优化,化学镀镍液的组成及工艺条件为:NiSO4·6H2O 25 g/L,NaH2PO2·H2O 28 g/L,CH3COONa 15 g/L,苹果酸6g/L,乙酸10 mL/L,乳酸10 mL/L,装载量1.0 dm2/L,pH 4.5 ～ 5.5,80～ 85℃,20～30 min.得到光亮剂的最佳组成为:Bi(NO3)3 6 mg/L,白屈菜氨酸或邻菲啰啉2 mg/L,十二烷基磺酸钠2 mg/L,CuSO4·5H2O 2 mg/L.化学镀镍液中加入新型复合光亮剂后,可制得几乎为镜面光亮的、耐蚀性和结合力良好的镍镀层.该光亮剂的用量小,对镀速影响较小(仍在20 μm/h以上).     

小体积化学镀镍工艺

以尺寸不规则的Y1Cr18Ni9不锈钢片为基底,研究了在约2 mL镀液的条件下,化学镀镍工艺中主盐与还原剂浓度之比、pH、反应时间及反应温度对镀层沉积速率的影响.结果表明:当c(Ni2+):c(H2PO2-)=0.75:1,pH为6,温度为77℃,反应2 h的条件下,镀层沉积速率快,含镍量高于72%,且颗粒分布均匀、密实.     

碱金属阳离子对化学镀镍的影响

研究了碱金属阳离子(以柠檬酸盐的形式加入,浓度为0.143 mol/L)对黄铜基体上化学镀层中镍磷含量、化学沉积速率、镀层耐硝酸腐蚀性能和镀层外观等的影响.镀液基础配方为:NiSO<,4>·6H<,2>O 25 g/L,NaH<,2>PO<,2>·H<,2>O 25 g/L,甘氨酸1g/L,乙酸铵4.5 g/L,乳酸1...     

Preparation of the molecularly imprinted polymers-based capacitive sensor specific for tegafur and its characterization by electrochemical impedance and piezoelectric quartz crystal microbalance

Molecularly imprinted polymers (MIPs)-based capacitive sensor specific for tegafur was constructed by electropolymerization of m-aminophenol onto the surface of gold electrode and the Au-coated quartz crystal electrodes. Electrochemical impedance (EI) and quartz crystal microbalance (QCM) were employed to characterize the modified gold electrodes and the modified Au-coated quartz crystals, respectively. Unlike the capacitive sensors reported in the previous literatures, the present sensors were not treated with alkanethiol after electropolymerization and show even more satisfactory performance. QCM measurements also confirmed the imprinting effect of the polymer layers.