AlCl3-EMIC离子液体电沉积光亮Al和Al-Mn镀层

通过添加光亮剂, 分别在AlCl₃-氯化1-甲基3-乙基咪唑(AlCl₃-EMIC)和MnCl₂-AlCl₃-EMIC离子液体中电沉积Al和Al-Mn镀层, 重点研究了光亮剂对镀层形貌、结构以及光亮性的影响, 探讨了镀层光亮的机理。采用扫描电镜(SEM)和X射线衍射(XRD)对镀层形貌和结构进行观察和分析, 以镀层对图案的反射能力大小对光亮度进行表征。结果表明, 添加光亮剂之后, 可以电沉积出具有镜面光亮的Al和Al-Mn镀层, 并且镀层的光亮度随光亮剂浓度的增加而增加。光亮Al镀层为具有择优取向生长的纳米晶体, 而光亮Al-Mn则是纳米尺寸的非晶颗粒。镀层光亮的产生是由于光亮剂细化了Al晶粒和Al-Mn非晶颗粒, 同时使Al晶体择优取向生长造成的。     

[BMIM]Cl/AlCl3离子液体低温电沉积铝过程

采用玻碳/铂为惰性阳极,以1-丁基-3-甲基咪唑氯盐([BMIM]Cl/AlCl₃)离子液体体系为电解液,研究了离子液体电解铝工艺,优化了电解工艺条件,探讨了电解影响因素。结果表明,当电解液[BMIM]Cl∶AlCl₃摩尔比为1∶2.00时,随着温度的升高,铝的沉积槽电压逐渐减小,电流密度增加,但电解液的稳定性减弱,当温度达到90℃时,电解液分解明显。当电解温度一定时,随着[BMIM]Cl∶AlCl₃摩尔比的增加[(1∶1.25)~(1∶2.00)],电流密度增加。通过赫尔槽实验,SEM、XRD分析了电解铝的沉积形貌和晶相结构。随电流密度的逐渐减小,沉积层变薄,晶相结构变化不大;相同电流密度区随温度的升高,沉积层逐渐变得粗糙。计算了不同槽间距下的槽压与电流密度的关系。     

Electrodeposition of aluminum on needle cathode using AlCl3/urea molten salts at low-temperature and its application to hydrogen generation

The electrodeposition of aluminum(Al) was studied using two electrolyte solutions, such as anhydrous AlCl_3-urea and hydrated AlCl_3·6 H_2 O-urea. A systematic examination using cell voltages 1.0–2.0 V was carried out at temperatures((50–100) ± 2) °C. A needle-shaped cathode was employed for the deposition of aluminum. A dendrite and particulate microstructure of Al were observed on the needle-shaped cathode. An improved condition for the manufacturing of small sizes and high purity of aluminum deposits was obtained. Pure Al with a current efficiency(yield) of 84%–99% was obtained from those of non-aqueous electrolytes and only of 8.6%–9.3% from those of hydrated electrolytes. The electrical conductivities of electrolytes remained considerable at((50–100)± 2) °C. The improved aluminum powders were used for the reaction with water. The aluminum reacts with water at room temperature, producing pure H_2 with 100% yield. The electrodeposited aluminum metal can be used as an excellent energy carrier.     

Electrodeposited TiB2 on graphite as wettable cathode for Al production

Titanium diboride (TiB₂) is considered as a promising cathode material for Al production. However, the manufacture of TiB₂ cathodes is facing numerous challenges. In this study, electrodeposition of TiB₂ on graphite was performed in molten fluoride (FLiNaK) electrolyte at 600°C by using a periodically interrupted current technique for various electrodeposition times (from 10 to 75 minutes) and at two different current densities (−0.12 and −0.5 A/cm²). It is shown that the TiB₂ coating morphology/microstructure strongly depends on the applied current density. Denser coatings were obtained at j_on = −0.12 A/cm² with a growth rate of ca. 0.7 µm/min. The thicker films display a preferential crystallographic orientation along the [110] plan. At j_on = −0.5 A/cm², TiB₂ coatings are deposited at a growth rate of ca. 6 µm/min with no crystallographic texture. They present a porous and stratified morphology with numerous transversal macrocracks. All TiB₂ coatings show excellent wettability for molten Al as confirmed by sessile drop experiments. However, significant molten Al infiltration occurs in the TiB₂ coatings, which accumulates at the coating/graphite interface, inducing the coating delamination.     

Investigation of the mechanical properties of electrodeposited nickel and magnetron sputtered chromium nitride coatings deposited on mild steel substrate

Electrodeposition and magnetron sputtering techniques have been employed for the deposition of Ni and bilayer NiCrN coatings, respectively, on mild steel substrate. Ni electrodeposition was performed using sulfate Watt’s bath, while magnetron sputtering was performed on electrodeposited Ni using DC power 350 W and base pressure of 3 × 10^?5 Torr in order to prepare bilayer NiCrN coatings. Structural and mechanical properties of Ni and bilayer NiCrN coatings have been investigated using various characterization techniques such as SEM-EDX, XRD, hardness, adhesion testing, etc. SEM analysis reflects the formation of spherical/nodular particles of varying sizes in NiCrN coating whereas Ni coating shows irregular, agglomerated, and non-uniform distribution of particles. Formation of hard CrN phase in NiCrN coating has been confirmed by XRD and EDX. NiCrN coating exhibits better hardness in comparison with Ni coating due to the formation of nitride phase. Micro scratch testing of bilayer NiCrN coating shows better interlayer adhesion and adhesion with mild steel substrate. The combination of electrodeposition and magnetron sputtering can produce inexpensive NiCrN coating containing hard CrN phase with better mechanical properties for automotive applications.     

Dense Alumina–Zirconia Coatings Using the Solution Precursor Plasma Spray Process

For the first time, dense coatings have been made by the solution precursor plasma spray (SPPS) process. The conditions are described for the deposition of dense Al₂O₃–40 wt% 7YSZ (yttria-stabilized zirconia) coatings; the coatings are characterized and their thermal stability is evaluated. X-ray diffraction analysis shows that the as-sprayed coating is composed of α-Al₂O₃ and tetragonal ZrO₂ phases with grain sizes of 72 and 56 nm, respectively. The as-sprayed coating has a 95.6% density and consists of ultrafine splats (1–5 μm) and unmelted spherical particles (<0.5 μm). The lamellar structure, typical of conventional plasma-sprayed coatings, is absent at the same scale in the SPPS coating. The formation of a dense Al₂O₃–40 wt% 7YSZ coating is favored by the lower melting point of the eutectic composition, and resultant superheating of the molten particles. Phase and microstructural thermal stabilities were investigated by heat treatment of the as-sprayed coating at temperatures of 1000°–1500°C. No phase transformation occurs, and the grain size is still in the nanometer range after the 1500°C exposure for 2 h. The coating hardness increases from 11.8 GPa in the as-coated condition to 15.8 GPa following 1500°C exposure due to a decrease in coating porosity.     

Electrodeposition of high phosphorus Ni–P alloys in emulsified supercritical CO2 baths

The use of an emulsified supercritical CO₂ (sc-CO₂) bath for electrodeposition of Ni–P alloys was attempted. The material characteristics of the deposits with various P contents, formed by varying the electrolyte composition and deposition current density, were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) for surface morphology and chemical composition and crystal structure analyses. The experimental results showed that the presence of sc-CO₂ in the electrodeposition bath could substantially improve the microhardness and the corrosion performance of the as-deposited Ni–P coatings. The roles of phosphorus and carbon in modifying the material properties of the deposits are discussed in detail.     

电沉积制备羟基磷灰石-碳化硅复合涂层

采用电沉积技术在碳/碳复合材料表面制备出羟基磷灰石-碳化硅复合涂层,通过扫描电镜、x.射线衍射仪、能谱仪、傅里叶红外光谱仪研究了电解液浓度与电流密度对复合涂层形貌与组成的影响,采用粘接拉伸法测试羟基磷灰石-碳化硅涂层、羟基磷灰石涂层与基体的结合强度.结果表明:随着电解液浓度的降低,涂层的组成由磷酸氢钙转变为羟基磷灰石,晶体从大尺寸的片状逐渐转变为纳米级球状.随着电流密度的升高,涂层的钙、磷摩尔比逐渐升高,晶体向疏松的针状转变.选取适当的工艺参数,羟基磷灰石-碳化硅与基体结合强度高于羟基磷灰石涂层.     

Molten salt synthesis of in-situ TiC coating on graphite flakes

TiC coating was synthesized on graphite flakes (G_f) by molten salt synthesis (MSS) using metal Ti powder and alkali salts. Three different alkali chloride salts of KCl, NaCl, and NH₄Cl were selected as the molten salt media substrate. Two mass ratios of 1:3 and 1:5 were chosen for Ti: G_f ratio, and the mass ratio of the powder (Ti + G_f) to the salt was 1:1. The synthesis was carried out at a temperature of 1100°? for 4 h. XRD was used to study the effect of alkali chloride salts and the Ti: G_f mass ratio on the synthesized coating. FE-SEM and AFM were accomplished to investigate the carbide formation and microstructure of the samples. Results showed that TiC coating was formed at 1100 °C for 4 h with both mass ratios in all three alkali chloride salts, but KCl was found to be the optimum alkali chloride salt or reaction medium. FE-SEM results displayed the formation of uniform coatings, and results from AFM indicated that the surface roughness increased from 0.72 for G_f to 4.94 nm for TiC coated G_f.     

铝在路易斯酸性1-烯丙基-3甲基米唑氯铝酸离子液体中的低温电沉积(英文)

Lewis acidic 1-allyl-3-methylimidazolium chloroaluminate ionic liquids were used as promising elec-trolytes in the low-temperature electrodeposition of aluminium.Systematic studies on deposition process have been performed by cyclic voltammetry and chronoamperometry.The surface morphology and X-ray diffraction(XRD) patterns of deposits prepared at different experimental conditions were also investigated.It was shown that the nu-cleation density and growth rate of crystallites had a great effect on the structure of aluminium deposited.The crys-tallographic orientation of deposits was mainly influenced by temperature and current density.Smooth,dense and well adherent aluminium coatings were obtained on copper substrates at 10-25 mA?cm?2 and 313.2-353.2 K.More-over,the current efficiency of deposition and purity of aluminium have been significantly improved,demonstrating that the ionic liquids tested have a prospectful potential in electroplating and electrorefining of aluminium.     

Preparation of a titanium carbide coating on carbon fibre using a molten salt method

A method for preparing protective titanium carbide (TiC) coatings on carbon fibres has been developed using a molten salt synthesis method. The TiC coatings were formed on the surface of carbon fibres in a reaction medium consisting of Ti powder in a mixture of molten LiCl-KCl-KF salts under an argon atmosphere at 900 and 950 °C. The structure and morphology of the TiC coatings were characterized by XRD, SEM and energy dispersive X-ray (EDX) analyses. The coatings consisted of homogeneous single phase cubic TiC with thicknesses in the range of 60-800 nm. Variation of the synthesis time and reaction mixture was found to significantly affect the thickness and integrity of the TiC coating although variation of the reaction temperature had little effect. The coating thickness was closely related to the composition of the molten salts and to the molar ratio between the carbon fibre and titanium.     

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co²⁺ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co²⁺ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co²⁺ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits.     

AlCl3·6H2O在盐酸体系中的结晶行为

研究了AlCl₃·6H₂O在盐酸体系中的结晶行为,考察了铁、钙、镁、钾、钠等杂质对AlCl₃·6H₂O结晶行为的影响,并利用聚焦光束反射测量技术（FBRM）和颗粒录影显微镜（PVM）探讨了不同盐酸滴加速度下AlCl₃·6H₂O的结晶粒度分布及形貌。结果表明,AlCl₃·6H₂O的结晶量随着盐酸加入量的增加而增加,当浓盐酸加入量为AlCl₃饱和溶液体积的2.25倍时,25℃时的结晶效率可达到80%。溶液中Fe的存在可促进AlCl₃·6H₂O的结晶,在1.5 mol·kg^-1的AlCl₃溶液中,当铝铁摩尔比低于3：1时,得到的AlCl₃·6H₂O晶体中铁的含量小于0.1%。钾、钙、镁、钠等杂质对AlCl₃·6H₂O的结晶影响不大。盐酸添加速度影响AlCl₃·6H₂O的形貌,快的盐酸添加速度易使晶体发生团聚,颗粒粒径小,盐酸添加速度较慢时,可得到颗粒较大、形貌好的单晶。     

Ionic liquids: the link to high-temperature molten salts?

Due to their wide thermal windows, ionic liquids can be regarded as the missing link between aqueous/organic solutions and high-temperature molten salts. They can be employed efficiently for the coating of other metals with thin layers of tantalum, aluminum, and presumably many others at reasonable temperatures by electrochemical means. The development of ionic liquids, especially air and water stable ones, has opened the door for the electrodeposition of reactive elements such as, for example, Al, Ta, and Si, which in the past were only accessible using high-temperature molten salts or, in part, organic solvents.     

Pulsed electrodeposition of carbon nanotubes-hydroxyapatite nanocomposites for carbon/carbon composites

Carbon nanotubes-hydroxyapatite (CNTs-HA) composite coatings, which behaved like single composites, were synthesized by a combined method composed of electrophoretic deposition and pulsed electrodeposition. The phase compositions and the microstructure of the composite coatings were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectrometry (FTIR). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed that the CNTs-HA composite coatings protected the bare carbon/carbon composites from corrosion in simulated body fluid (SBF) solution. The adhesion strength of CNTs-HA composite coating prepared by the combined method is 14.57±1.06 MPa achieved at the CNTs EPD time of 10 min. Compared to the other CNTs-HA composite coatings with different content of CNTs, the CNT-HA composite coating with the electrophoretic deposition of 10 min showed the best corrosion resistance. The morphology of CNTs-HA composite coatings immersed in SBF solution rendered the formation of HA crystallites. In addition, in vitro cellular responses to the CNTs-HA composite coatings were assessed to investigate the proliferation and morphology of mouse cells 3T3 cell line.     

Preparation of TiC-Ti3AlC composite coated graphite flakes and their improved oxidation resistance

The weak oxidation resistance has severely hindered graphite from various high temperature applications, therefore in this paper a molten salt technique was proposed to prepare titanium aluminium carbide based coatings on graphite flakes to overcome this problem. The resultant TiC-Ti₃AlC coated graphite showed higher peak oxidation temperature (~?900?°C) than the uncoated one (700?°C), suggesting that the coatings will afford graphite with superior oxidation resistance. Such improvements can be largely ascribed to not only the homogenous and crack-free TiC-Ti₃AlC coatings and their resultant relicts of TiO₂ and Al₂O₃, but also the molten salt technique for preparing the coatings. Especially the molten salts offer fast dissolution/melting/dispersion of Ti/Al powders, rapid reaction with graphite in the salt melts, and homogenous growth of the carbide coatings on the surface of graphite flakes at as low temperatures as 950–1150?°C.     

脉冲镀和直流镀对钨镀层性能的影响

在耐热钢基体上用Na2WO4-ZnO-WO3体系熔盐镀钨,比较了脉冲镀与直流镀对钨镀层性能的影响.在相同镀液配比条件下,脉冲镀可扩大电流密度范围,钨镀层的表面形貌、厚度、结晶度、纯度等都优于直流电镀.     

羟基磷灰石/TiO2复合涂层在模拟脑脊液中生物相容性（英文）

应用阳极氧化法在Ti-6Al-4V钛合金（TC4）表面制备了多孔TiO2涂层,在TiO2涂层表面电沉积制备了羟基磷灰石（hydroxyapatite,HA）/TiO2复合涂层,用实验用人工脑脊液（artificial cerebrospinal fluid,ACSF）体液模拟人体的脑脊液,以TC4和TiO2涂层为对比,研究了HA/TiO2涂层在浸泡过程中发生的物理化学变化,考察了HA/TiO2复合涂层抑制钛合金中元素Al和V的析出情况。结果表明：3种样品随浸泡时间的延长遵循的生长规律为：HA成核→HA晶粒长大→HA晶粒相互团簇形成一体→涂层逐渐扩大覆盖到整个基体表面;TC4,TiO2以及HA/TiO2涂层在ACSF中都能够诱导HA的生成,表现出了良好的生物活性。检测浸泡后溶液中Al和V的浓度可知,阳极氧化法制备的TiO2涂层对于Al,V元素的析出起到了一定的抑制作用,能够进一步提高钛合金的生物相容性。

Abstract：

Porous TiO2 coating was prepared on Ti-6Al-4V titanium alloy （TC4） substrate by the potentiostatic anodic oxidation method,and hydroxyapatite （HA） coating was prepared on the surface of TiO2 coating by the electrodeposition method to form HA/TiO2 composite coating. By using artificial cerebrospinal fluid （ACSF） to simulate human cerebrospinal fluid,the physicochemical changes of the HA/TiO2 coatings when soaked in ACSF were studied and compared with TC4 and TiO2 coating. Its inhabitation effects on Al and V were also studied. The results show that these three samples follow such a growth pattern：HA nucleation forma-tion,crystal growth,agglomeration,coatings formation. The bioactivity of TC4,TiO2 coating and TiO2/HA composite coating can be induced by the formation of HA in ACSF. According to the concentration of Al and V in ACSF,the TiO2 coating formed by anodic oxidation could inhibit the element precipitation more or less,and enhance the biocompatibility of titanium alloy.     

硫酸铝铵-氯化氢反应制备六水氯化铝过程中晶体形貌的研究

以十二水合硫酸铝铵为原料,采用氯化氢通气结晶法制备了六水氯化铝晶体,考察了通气速率、通气时间、反应温度、铝离子初始浓度对六水氯化铝晶体形貌的影响。结果表明,50 mL硫酸铝铵酸溶液中,当通气速率为60 mL/min、通气时间为2 h、反应温度为30 ℃、铝离子初始质量浓度为20 g/L时,可以得到形貌比较规整的棱柱形六水氯化铝晶体。该研究为提取、制备高品质六水氯化铝晶体提供了技术参考。     

Analysis of Phase Distribution for Ceramic Coatings Formed by Microarc Oxidation on Aluminum Alloy

The phase distribution for ceramic coatings formed by microarc oxidation (MAO) on 2024 aluminum alloy was investigated using X-ray diffraction. The results showed that the ceramic coatings mainly consisted of α-Al₂O₃ and γ-Al₂O₃ phases. The percentage of α-Al₂O₃ gradually increased from the external surface to the interface between the coating and the substrate of samples. The surface layer of coatings mainly contained the γ-Al₂O₃ phase, and its fraction of the composition remained almost constant with oxidation time. It is believed that the difference in the amounts of α-Al₂O₃ and γ-Al₂O₃ phases in the different layers of coatings was caused by the various cooling rates of molten Al₂O₃, which temporarily existed in the microarc zone.