Electropolishing and electrolytic etching of Ni-based HIP consolidated aerospace forms: a comparison between deep eutectic solvents and aqueous electrolytes

It is reported in this study that the deep eutectic solvent (DES), (Ethylene glycol)₂(Choline chloride), (2Eg:ChCl) is an effective medium in the electrolytic removal of the Fe-rich layer from Ni-based hot isostatic press (HIP) consolidation and that it is capable of sustaining etching at higher rates and at higher current efficiencies than a comparable aqueous electrolyte formulated from methane sulphonic acid/glycolic acid (MSA/GA). At high etch rates, the surface finish is not as good using 2Eg:ChCl, but high etch rates, current efficiency and excellent surface finish can be obtained from a 90%/10% hybrid mixture of 2Eg:ChCl MSA/GA electrolytes. This study has set out to compare the electropolishing and bulk electrolytic etching of HIP-formed bodies fabricated from RR1000 Ni-based superalloys in aqueous methane sulphonic acid/glycolic acid (MSA/GA) electrolyte and in DES-type ionic liquids. It is shown that the HIP alloy can be effectively removed under mild conditions using DES electrolytes that are of low toxicity, environmentally sustainable, relatively low cost and without the use of strong acids or chemical etchants.     

Effect of water on the electrodeposition of copper on nickel in deep eutectic solvents

ABSTRACT

Most studies of metal electrodeposition in ionic liquids dry the electrolyte thoroughly, as water is thought to be detrimental. In some cases, water has a beneficial effect on deposit morphology. The electrodeposition of copper has been studied in 1ChCl: 2EG-water mixtures. It is shown here that the presence of water increases the apparent brightness of the deposit due to changes in the electrodeposit surface feature size, up to a water content of approximately 20 wt-%. This study characterises speciation and mass transport in solution, and shows that diffusion can be controlled independently of speciation. It is shown that there is an optimal water content, which is thought to originate from formation of a bi-continuous micro-emulsion phase in DES-water mixtures. Additionally, the copper species remains in a predominantly ionic medium at low water content but moves to an aqueous environment when water is the main component.     

The electrochemical deposition of Zn–Mn coating from choline chloride–urea deep eutectic solvent

Electrochemical and microscopic techniques were used for the characterisation of Zn–Mn coatings electrodeposited from choline chloride–urea deep eutectic solvent. Cyclic voltammograms show that there was no discernible Mn reduction peak when only Mn²⁺ was present in DES solution. The distinct Mn peak developed only upon addition of Zn²⁺ to the solution, probably due to previous Zn nucleation on the steel substrate. It was found that 22–27?wt-% Mn deposited at current densities of 3–8?mA?cm^?2, amounts significantly higher than those obtained from aqueous electrolytes. Since higher deposition current densities resulted in the formation of a porous surface consisting of clusters of nodular crystallites, the optimal deposition c.d was determined to be 3?mA?cm^?2.     

Study of silver electrodeposition in deep eutectic solvents using atomic force microscopy

The electrodeposition of metals in ionic liquids and deep eutectic solvents leads to deposits with significantly different morphologies to those seen with aqueous solutions. The classical methods of fitting amperometric data to nucleation and growth mechanisms do not fit the data well in ionic systems and tend to focus on the short time-scale aspects of nucleation. In the current study, ex-situ AFM was used to model crystallite sizes and distributions by digitising and modelling the images. The deposition of silver from a deep eutectic solvent was chosen as it has been studied by several groups with a variety of techniques. The crystallite size data obtained from AFM and chronoamperometry for long time-scale deposition studies are compared and it is shown that the trends are similar, but there is a discrepancy in the nuclear number density of approximately an order of magnitude. The nuclear number density was found to be consistent with aqueous nucleation studies once differences in concentration and mass transport were accounted for.     

Extraction studies of cobalt （ Ⅱ ） and nickel （ Ⅱ ） from chloride solution using PC88A

1 Introduction Since the first commercial process using di-2-ethyl hexyl phosphoric acid (D2EHPA) was developed by RITCEY et al[1], the organophosphorus extractants have been proved to be primary solvents for separation cobalt from nickel in acidic media…     

Selective recovery of zinc from zinc oxide dust using choline chloride based deep eutectic solvents

Deep eutectic solvents (DESs) are a kind of potential lixiviant for selective metal processing due to their versatile complexation properties. In this study, we investigated the recovery of zinc from zinc oxide dust using choline chloride−urea− ethylene glycol (ChCl−urea−EG) DESs. The zinc extraction efficiency can be up to 85.2% when the slurry concentration is 50 g/L, leaching temperature is 80 °C and stirring speed is 600 r/min. The leaching process is controlled by the diffusion and the corresponding activation energy is 32.1 kJ/mol. The resultant solution was directly used for the electrodeposition of zinc. The pure zinc deposit is obtained with a current efficiency of 82.6%. Furthermore, the ChCl−urea−EG DESs can be recycled. This approach is shown to be promising for the recycling of zinc from the zinc-containing dust.     

Separation of nickel, cobalt and copper by solvent extraction with P204

Separation of nickel, cobalt and copper by solvent extraction with P204@钱东 @王开毅 @潘春跃 @唐有根 @蔡春林 @蒋金枝~~Project ( 99JJY2 0 0 10 )supportedbytheNaturalScienceFoundationofHunanProvince     

Morphology of corrosion products formed on cobalt and nickel in argon-oxygen-chlorine mixtures at 1000 K

The morphology of corrosion products formed on cobalt and nickel in argonoxygen-chlorine mixtures at 1000 K have been examined using optical microscopy, scanning electron microscopy, and X-ray diffraction. The corrosion products formed under conditions where the oxides are thermodynamically stable consist of porous oxides containing little or no chlorine. This morphology is consistent with a corrosion mechanism involving vapor phase transport of volatile metal chlorides.     

Effect of angle of incidence on the combined erosion-oxidation attack of nickel and cobalt

The combined erosion-oxidation of cobalt and nickel at 600 and 780°C over a range of particle-impact angles has been studied by using weight change vs. time measurements and extensive morphological and microstructural characterization of exposed specimens. The oxidation process has been found to affect the angular dependence of the degradation rates. The effect is especially significant at low-impact angles where ripples and flakes are developed upon the surfaces of specimens.     

Extraction of arsenic from arsenic-containing cobalt and nickel slag and preparation of arsenic-bearing compounds

The arsenic extraction from the arsenic-containing cobalt and nickel slag, which came from the purification process of zinc sulfate solution in a zinc smelting factory, was investigated. The alkaline leaching method was proposed according to the mode of occurrence of arsenic in the slag and its amphoteric characteristic. The leaching experiments were conducted in the alkaline aqueous medium, with bubbling of oxygen into the solution, and the optimal conditions for leaching arsenic were determined. The results showed that the extraction rate of arsenic was maximized at 99.10% under the optimal conditions of temperature 140 °C, NaOH concentration 150 g/L, oxygen partial pressure 0.5 MPa, and a liquid-to-solid ratio 5:1. Based on the solubilities of As₂O₅, ZnO and PbO in NaOH solution at 25 °C, a method for the separation of As in the form of sodium arsenate salt from the arsenic-rich leachate via cooling crystallization was established, and the reaction medium could be fully recycled. The crystallization rate was confirmed to reach 88.9% (calculated on the basis of Na₃AsO₄) upon a direct cooling of the hot leachate down to room temperature. On the basis of redox potentials, the sodium arsenate solution could be further reduced by sulfur dioxide (SO₂) gas to arsenite, at a reduction yield of 92% under the suitable conditions. Arsenic trioxide with regular octahedron shape could be prepared successfully from the reduced solution, and further recycled to the purification process to purify the zinc sulfate solution. Also, sodium arsenite solution obtained after the reduction of arsenate could be directly used to purify the zinc sulfate solution. Therefore, the technical scheme of alkaline leaching with pressured oxygen, cooling crystallization, arsenate reduction by SO₂ gas, and arsenic trioxide preparation, provides an attractive approach to realize the resource utilization of arsenic-containing cobalt and nickel slag.     

镍基合金电解加要渣泥中镍和钴的回收

根据镍基合金电解加工渣泥的组成和热力学分析,用水洗-浸出-水争沉淀工艺处理这种渣泥,试验结果表明：氯化钠、硝酸钠和部分铬盐等可溶性化合物可以从渣泥中洗出;继而的硫酸浸出过程中,可将洗后渣泥中的镍、钴和铬浸出,而钨和钼留在浸出渣中,在浸出过程中,镍和钴的浸出率达98%,浸出液中的铬可通过水解沉淀法以氢氧化铬的形态除去,铬的脱除率达94.44%。     

Reline低熔溶剂中铝纳米颗粒和叶状显微组织的电化学形核和长大:温度和工作电极角速度的影响

利用电化学和表面表征技术,研究在不同温度和工作电极角速度(ω)下,含Al(III)离子的Reline低共熔溶剂中铝在玻碳电极上形核和长大的电化学行为.结果表明,随着温度的升高,Al(III)DES的还原发生在较低的负电位,而此时伏安图中的电流峰增大,这对Al沉积动力学和热力学条件有利.实际上,由于Al被Al(OH)3(...     

Property of cobalt nickel silicide by thermal annealing of Co/Ni bilayer on a silicon substrate

15 nm-Co/15 nm-Ni/p−Si (100) was thermally annealed using rapid thermal annealing for 40 s at 700∼1100°C. The annealed bilayer structure developed into the composite CoNiSi_x and the resulting changes in sheet resistance, microstructure, and composition were investigated using a four-point probe, transmission electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The final thickness of the composite CoNiSi_x was approximately 100 nm and it maintained its sheet resistance below 5 Ω/sq after silicidation annealing at 1100°C. The proposed CoNiSi_x silicides may be superior to conventional single phased silicides due to their improved thermal stability and thickness adjustment.     

红土镍矿深度还原-磁选工艺富集镍和铁（英文）

提出采用"深度还原-磁选"工艺从红土镍矿中富集镍和铁。结果表明,在还原温度1275℃、还原时间50 min、渣相碱度1.0、配碳系数2.5和磁场强度72 kA/m的条件下,可得到镍品位为6.96%、回收率为94.06%和铁品位为34.74%、回收率为80.44%的镍铁精矿产品。分析表明,还原温度和时间影响深度还原发生的可能性及反应进度,渣相碱度影响炉料中渣的组成及镍铁元素从基体中溢出富集形成镍铁颗粒的速度,深度还原反应过程中镍铁颗粒生成、聚集并逐渐长大,经磁选后可有效促进镍铁矿物与脉石矿物分离。     

Formation of black nickel in leaching solution containing ammonia and chloride

The black nickel formation process in leaching solution containing ammonia and chloride was investigated in terms of cyclic voltammetric and galvanostatic reduction techniques. The structure of black nickel was examined by means of X-ray diffraction technique. The results show that in the scanning region, two oxidization current peaks are observed during the positive sweep, one of which is attributed to a valence state transformation of Ni(OH)2 to high valence nickel compound(black nickel), and the other is caused by nitrogen evolution. During the formation process of black nickel, γ-NiOOH probably tends to self-discharge with water to form a-Ni(OH)2. As a result, it is observed that Ipa/Ipc (Ipc-anodic peak current; Ipc-cathodic peak current) maintains at a constant with the scanning rate increasing. Two reduction current peaks in cyclic vohammogram and two potential plateaus in galvanostatic reduction curve for black nickel are ascribed to the reduction of various oxidization states of nickel oxide. The potential plateaus at about 0.75 V reach the maximum in galvanostatic reduction curves. Black nickel presents amorphous structure.     

氯化胆碱-尿素低共熔溶剂中锌的电沉积研究

目的研究锌在氯化胆碱-尿素低共熔溶剂(ChCl-Urea DES)中的电化学行为、电结晶机理、电沉积历程和耐蚀性。方法采用循环伏安(CV)和计时电流技术(CA),研究了锌在玻碳电极上的电化学行为和电结晶机理。采用扫描电子显微镜(SEM)和X射线衍射技术(XRD)对锌镀层的微观形貌和物相组成进行了表征。采用动电位极化曲线和电化学阻抗谱,对比研究了ChCl-Urea DES和水溶液中锌镀层的耐蚀性。结果CV测试表明,在Zn(Ⅱ)的氧化还原过程中仅出现了一对氧化还原峰,这说明Zn(Ⅱ)在ChCl-Urea DES中为一步还原及氧化,且还原峰电位为?1.207 V(vs.Ag)。不同扫描速度下的CV曲线表明,还原峰和氧化峰的峰值电位Ep和峰值电流I_p均随扫描速率v的变化而有规律的偏移,这符合不可逆电极反应的特征。对I_p和v^1/2的关系进行了线性拟合,发现I_p与v^1/2之间符合线性关系,故可认为Zn(Ⅱ)的还原反应是受扩散控制的,进一步计算出扩散系数DZn(Ⅱ)为6.67×10^?8cm²/s。在–1.141~–1.147 V下测定CA曲线,通过对比拟合CA曲线和理论曲线发现,Zn(Ⅱ)在ChCl-Urea DES中的形核方式不符合三维瞬时成核和三维连续成核,是一种具有两种形核方式特征的混合形核。SEM结果表明,不同沉积时间下锌镀层的微观形貌相差较大。随着沉积时间的增加,锌晶粒由细小、粒径均一的颗粒逐渐变化成大小颗粒交叠存在的六方形立体结构,然后又变成线状或棒状的结构,最终转变为六方形的片状晶粒。XRD表明,锌镀层由六方晶相的多晶锌构成。动电位极化曲线测试和电化学阻抗图谱表明,在没有任何添加剂的情况下,ChCl-Urea DES可获得与水溶液中耐蚀性相当的锌镀层,且ChCl-Urea DES中锌镀层的沉积速率略高于水溶液。结论Zn(Ⅱ)在ChCl-Urea DES中的电沉积过程是受扩散控制的不可逆电极过程,形核方式不符合三维瞬时成核和三维连续成核,是一种具有两种形核方式特征的混合形核。锌镀层是由六方晶相的多晶锌构成的。在ChCl-Urea DES中可获得与水溶液中耐蚀性相当的锌镀层,且沉积速率略高于水溶液。     

化学计量学在新型十八胺复配缓蚀剂开发中的应用

目的改善十八胺在低温下的成膜性能。方法以吡啶和二异丙胺混合液为溶剂,添加辅助缓蚀剂进行复配。以pH、温度和各药剂的浓度为变量设计均匀试验,利用高压釜模拟发电厂水汽环境进行挂片实验,结合硫酸铜点滴试验和交流阻抗测试,评价试片的成膜效果。以膜电阻为定量评价指标,经化学计量学计算得到最优的复配配方。结果最优复配配方为:十八胺50 mg/L,辅助缓蚀剂A、B、C、D质量浓度分别是45、30、25、30 mg/L,成膜pH=9.4,成膜时间3.5 h,成膜温度100~130℃。复配缓蚀剂成膜试片硫酸铜点滴试验初红时间达41 s,保护膜电阻值达82 420?·cm2。结论通过复配,有效改善了十八胺在100℃左右温度下的成膜效果,该配方可对停备用期间发电机组低温段设备提供有效的成膜保护。