Photo-electrochemical and impedance investigation of passive layers grown anodically on titanium alloys

Energy Technology Data Exchange (ETDEWEB)

Oliveira, N.T.C. [Departamento de Quimica, Universidade Federal de Sao Carlos, CP 676, 13560-970 Sao Carlos, SP (Brazil); Biaggio, S.R. [Departamento de Quimica, Universidade Federal de Sao Carlos, CP 676, 13560-970 Sao Carlos, SP (Brazil); Piazza, S. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)]. E-mail: piazza@dicpm.unipa.it; Sunseri, C. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Di Quarto, F. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

2004-10-15

The anodic behaviour of two titanium cast alloys, obtained by fusion in a voltaic arc under argon atmosphere, was analyzed in aerated aqueous solutions having different pH values. In all solutions the alloys, having nominal compositions Ti-50Zr at.% and Ti-13Zr-13Nb wt.%, displayed a valve-metal behaviour, owing to the formation of barrier-type oxide films. Passive films, grown potentiodynamically up to about 9 V, were investigated by photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). These passive layers show photoactivity under anodic polarizations, with optical gaps close to 3.55 and 3.25 eV for the binary and the ternary alloy, respectively, independent of the anodizing electrolyte. Films grown on the binary alloy present insulating behaviour and anodic impedance spectra with one time constant; this was interpreted in terms of a single-layer mixed Ti-Zr oxide enriched in Ti with respect to the alloy composition. Also for the ternary alloy the results are consistent with the formation, upon anodization, of Ti-Nb-Zr mixed oxide films, but they display n-type semiconducting behaviour, owing to their poor content of ZrO{sub 2} groups.

Anodic dissolution and corrosion of alloy Cu30Ni in chloride solutions

International Nuclear Information System (INIS)

Zolotarev, E.I.

1989-01-01

The anodic and corrosion behavior of alloy Cu30Ni is studied in a solution of 3 N NaCl + 0.01 N HCl by a radiometric method using gamma isotopes of 58 Co (as a marker for Ni) and 64 Cu in combination with electrochemical measurements. It was established that under stationary conditions there was uniform dissolution of the alloy both during free corrosion and anodic polarization. The authors obtained partial anodic dissolution curves for the components of the alloy. It was shown that the dissolution kinetics differed from the mechanisms controlling dissolution of the corresponding pure metals. During corrosion of the alloy in an oxygen atmosphere a back precipitation of copper on the surface of the alloy was not observed. The characteristics observed in the corrosion-electrochemical behavior of the alloy in concentrated chloride solutions can be explained by the presence of Ni on the surface of the dissolving alloy

Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

Science.gov (United States)

Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

2013-01-01

We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

Corrosion resistance of plasma-anodized AZ91D magnesium alloy by electrochemical methods

International Nuclear Information System (INIS)

Barchiche, C.-E.; Rocca, E.; Juers, C.; Hazan, J.; Steinmetz, J.

2007-01-01

Anodic coatings formed on magnesium alloys by plasma anodization process are mainly used as protective coatings against corrosion. The effects of KOH concentration, anodization time and current density on properties of anodic layers formed on AZ91D magnesium alloy were investigated to obtain coatings with improved corrosion behaviour. The coatings were characterized by scanning electron microscopy (SEM), electron dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and micro-Raman spectroscopy. The film is porous and cracked, mainly composed of magnesium oxide (MgO), but contains all the elements present in the electrolyte and alloy. The corrosion behaviour of anodized Mg alloy was examined by using stationary and dynamic electrochemical techniques in corrosive water. The best corrosion resistance measured by electrochemical methods is obtained in the more concentrated electrolyte 3 M KOH + 0.5 M KF + 0.25 M Na 3 PO 4 .12 H 2 O, with a long anodization time and a low current density. A double electrochemical effects of the anodized layer on the magnesium corrosion is observed: a large inhibition of the cathodic process and a stabilization of a large passivation plateau

Performance of lithium alloy/lithium and calcium/lithium anodes in thionyl chloride cells

Energy Technology Data Exchange (ETDEWEB)

Keister, P.; Greenwood, J.M.; Holmes, C.F.; Mead, R.T.

1985-08-01

A laminar composite anode construction comprising an inner metal completely surrounded by Li foil was studied as a means of obtaining an end-of-life indicator in a thionyl chloride cell. Inner metals of Ca, 14-2.9 at.% Ca in Li alloys, and 6.7-2.1 at.% Mg in Li alloys were evaluated. Discharge characteristics of cells using these sandwich anodes as well as cells containing the inner anode material alone were determined. It was concluded that cells made with inner anode materials of Ca and Ca/Li alloys containing more than 7 at.% Ca showed promise as a means of obtaining a reliable end-of-life indication. (orig.).

Synthesis and electrochemical characteristics of Sn-Sb-Ni alloy composite anode for Li-ion rechargeable batteries

International Nuclear Information System (INIS)

Guo Hong; Zhao Hailei; Jia Xidi; Qiu Weihua; Cui Fenge

2007-01-01

Micro-scaled Sn-Sb-Ni alloy composite was synthesized from oxides of Sn, Sb and Ni via carbothermal reduction. The phase composition and electrochemical properties of the Sn-Sb-Ni alloy composite anode material were studied. The prepared alloy composite electrode exhibits a high specific capacity and a good cycling stability. The lithiation capacity was 530 mAh g -1 in the first cycle and maintained at 370-380 mAh g -1 in the following cycles. The good electrochemical performance may be attributed to its relatively large particle size and multi-phase characteristics. The former reason leads to the lower surface impurity and thus the lower initial capacity loss, while the latter results in a stepwise lithiation/delithiation behavior and a smooth volume change of electrode in cycles. The Sn-Sb-Ni alloy composite material shows a good candidate anode material for the rechargeable lithium ion batteries

Magnesium-based hydrogen alloy anodes for a nickel metal hydrides secondary battery

Energy Technology Data Exchange (ETDEWEB)

Cui, N.; Luan, B.; Zhao, H.J.; Liu, H.K.; Dou, S.X. [Univ of Wollongong, Wollongong, NSW (Australia). Centre for Superconducting and Electronic Materials

1996-12-31

Extensive work has been carried out in our group to try utilizing magnesium-based hydrogen storage alloys as a low cost and high performance anode materials for Ni-MH battery. It was found that the modified Mg{sub 2}Ni alloy anodes were able to be charged-discharged effectively in a KOH aqueous solution at ambient temperature. The discharge capacity and cycle have been substantially improved in four ways: (1) by partial substitution of La, Ti, V, Zr, Ca for Mg and Fe, Co, Cu, Al, Si, Y, Mn for Ni in Mg{sub 2}Ni; (2) by composite of Mg{sub 2}Ni with another hydrogen storage alloys; (3) by room-temperature surface microencapsulation and, (4) by ultrasound treatment of alloy powders. A discharge capacity of 170 mAh/g has been obtained from the modified Mg{sub 2}Ni-type alloy electrode, and the cycle life has exceeded 350 cycles. The high rate dischargeability was also significantly improved by the modification. It was concluded that magnesium-based hydrogen storage alloys would become promising anode materials for Ni- MH secondary battery with further improvement of discharge capacity and cycling performance

Magnesium-based hydrogen alloy anodes for a nickel metal hydrides secondary battery

International Nuclear Information System (INIS)

Cui, N.; Luan, B.; Zhao, H.J.; Liu, H.K.; Dou, S.X.

1996-01-01

Extensive work has been carried out in our group to try utilizing magnesium-based hydrogen storage alloys as a low cost and high performance anode materials for Ni-MH battery. It was found that the modified Mg 2 Ni alloy anodes were able to be charged-discharged effectively in a KOH aqueous solution at ambient temperature. The discharge capacity and cycle have been substantially improved in four ways: (1) by partial substitution of La, Ti, V, Zr, Ca for Mg and Fe, Co, Cu, Al, Si, Y, Mn for Ni in Mg 2 Ni; (2) by composite of Mg 2 Ni with another hydrogen storage alloys; (3) by room-temperature surface microencapsulation and, (4) by ultrasound treatment of alloy powders. A discharge capacity of 170 mAh/g has been obtained from the modified Mg 2 Ni-type alloy electrode, and the cycle life has exceeded 350 cycles. The high rate dischargeability was also significantly improved by the modification. It was concluded that magnesium-based hydrogen storage alloys would become promising anode materials for Ni- MH secondary battery with further improvement of discharge capacity and cycling performance

Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

KAUST Repository

Yin, Jian; Lin, Nan; Zhang, Wenli; Lin, Zheqi; Zhang, Ziqing; Wang, Yue; Shi, Jun; Bao, Jinpeng; Lin, Haibo

2018-01-01

A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

KAUST Repository

Yin, Jian

2018-03-27

A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

Forming lead-based anodes

Energy Technology Data Exchange (ETDEWEB)

Ogorodnichuk, V I; Voitsekhovich, R I

1972-01-01

Lead-based anodes can be produced by forming a layer of lead dioxide by chemical treatment in a solution of sulfuric acid in potassium permanganate at 80 to 100/sup 0/. The solution is mixed by compressed air. (RWR)

Water and oil wettability of anodized 6016 aluminum alloy surface

Science.gov (United States)

Rodrigues, S. P.; Alves, C. F. Almeida; Cavaleiro, A.; Carvalho, S.

2017-11-01

This paper reports on the control of wettability behaviour of a 6000 series aluminum (Al) alloy surface (Al6016-T4), which is widely used in the automotive and aerospace industries. In order to induce the surface micro-nanostructuring of the surface, a combination of prior mechanical polishing steps followed by anodization process with different conditions was used. The surface polishing with sandpaper grit size 1000 promoted aligned grooves on the surface leading to static water contact angle (WCA) of 91° and oil (α-bromonaphthalene) contact angle (OCA) of 32°, indicating a slightly hydrophobic and oleophilic character. H2SO4 and H3PO4 acid electrolytes were used to grow aluminum oxide layers (Al2O3) by anodization, working at 15 V/18° C and 100 V/0 °C, respectively, in one or two-steps configuration. Overall, the anodization results showed that the structured Al surfaces were hydrophilic and oleophilic-like with both WCA and OCA below 90°. The one-step configuration led to a dimple-shaped Al alloy surface with small diameter of around 31 nm, in case of H2SO4, and with larger diameters of around 223 nm in case of H3PO4. The larger dimples achieved with H3PO4 electrolyte allowed to reach a slight hydrophobic surface. The thicker porous Al oxide layers, produced by anodization in two-step configuration, revealed that the liquids can penetrate easily inside the non-ordered porous structures and, thus, the surface wettability tended to superhydrophilic and superoleophilic character (CA OCA. This inversion in favour of the hydrophilic-oleophobic surface behaviour is of great interest either for lubrication of mechanical components or in water-oil separation process.

Environmental friendly anodizing of AZ91D magnesium alloy in alkaline borate-benzoate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Liu Yan [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Department of Chemistry, Tianshui Normal University, Tianshui 741000 (China); Wei Zhongling [Magnesium Technology Co., Ltd., Chinese Academy of Sciences, Jiaxing 314051 (China); Yang Fuwei [Department of Chemistry, Tianshui Normal University, Tianshui 741000 (China); Zhang Zhao, E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Key Laboratory for Light Alloy Materials Technology, Jiaxing 314051 (China)

2011-06-02

Highlights: > Environmental friendly PEO technology for AZ91 magnesium alloy is developed. > NaBz is used as new additive and it is low-cost and environmental friendly. > The effect of NaBz additive on the properties of the anodized film was studied. > Anodized film with excellent corrosion resistance is obtained. > The forming mechanism of anodized film in the presence of NaBz is approached. - Abstract: A kind of environmental friendly anodizing routine for AZ91D magnesium alloy, based on an alkaline borate-sodium benzoate electrolyte (NaBz) was studied. The effect of NaBz on the properties of the anodized film was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results showed that the anodizing process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of NaBz. In the presence of adequate NaBz, a thick, compact and smoothing anodized film with excellent corrosion resistance was produced. Moreover, the forming mechanism of the anodized film in the presence of NaBz additive was also approached, which was a suppression of arc discharge process by the adsorption of Bz{sup -} on the surface of magnesium alloy substrate.

Influence of Alkali Treatment on Anodized Titanium Alloys in Wollastonite Suspension

Directory of Open Access Journals (Sweden)

Alicja Kazek-Kęsik

2017-08-01

Full Text Available The surface modification of titanium alloys is an effective method to improve their biocompatibility and tailor the material to the desired profile of implant functionality. In this work, technologically-advanced titanium alloys—Ti-15Mo, Ti-13Nb-13Zr and Ti-6Al-7Nb—were anodized in suspensions, followed by treatment in alkali solutions, with wollastonite deposition from the powder phase suspended in solution. The anodized samples were immersed in NaOH or KOH solution with various concentrations with a different set of temperatures and exposure times. Based on their morphologies (observed by scanning electron microscope, the selected samples were investigated by Raman and X-ray photoelectron spectroscopy (XPS. Titaniate compounds were formed on the previously anodized titanium surfaces. The surface wettability significantly decreased, mainly on the modified Ti-15Mo alloy surface. Titanium alloy compounds had an influence on the results of the titanium alloys’ surface modification, which caused the surfaces to exhibit differential physical properties. In this paper, we present the influence of the anodization procedure on alkali treatment effects and the properties of obtained hybrid coatings.

ROLE OF ULTRASOUND IN MECHANISMS OF ANODE-CATHODE INTERACTIONS DURING ELECTROSPARK ALLOYING

Directory of Open Access Journals (Sweden)

N. M. Chigrinova

2016-01-01

Full Text Available The paper reveals results of investigations on mass transfer kinetics and dynamics of coating formation while using integral electrospark alloying method with additional ultrasonic exposure at different stages of formation. Nowadays, a classical method for electrospark alloying with hard-alloy anodes and impulse AC voltage frequency on the vibration exciter coil from 20 to 1600 Hz has been mainly used for application of protective and strengthening coatings within permissible thickness and characteristics. The key aspect of ultrasonic exposure application (frequency 22–44 kHz during electrospark alloying is the possibility to increase further thickness of coatings to be formed even after reaching a brittle fracture threshold of the coating material. Methodology of the executed research activity has been based on integrated studies (gravimetric, metallographic, X-ray diffraction and electron microscopic of coatings which are to be formed through compositions produced while using method of high-energy hot compaction and a “refractory carbide (WC and a binding material“ system in the form of alloy based on nickel from the series of “colmonoy” Ni – Ni3B system which is alloyed with additions of copper and silicon. The initial surface treatment within ultrasonic frequency range (22–44 kHz contributes to a noticeable increase in the mass transfer rate, which is primarily determined by chemical composition and thermodynamic stability of anodes. It is due to surface activation in the process of its preliminary deformation at ultrasonic frequency which creates additional conditions for striking of a spark.The final ultrasonic treatment improves coating quality due to its additional forging that leads to an increase of its structure homogeneity and density.

Anodic behavior of nickel alloys in media containing bicarbonate ions

International Nuclear Information System (INIS)

Zadorozne, N.S; Carranza, R. M.; Giordano, C.M.

2011-01-01

Alloy 22 has been designed to resist corrosion in oxidizing and reducing conditions. Thanks to these properties it is considered a possible candidate for the fabrication of containers of high-level radioactive waste. Since the containers provide services in natural environments characterized by multi-ionic solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is required in order to produce cracking. It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media potentials below trans-passivity. The aim of this work is to study the anodic behavior of Alloy 22 in different media containing bicarbonate and chloride ions in various concentrations and temperatures and compare the results with other alloys containing nickel, and relate them to the susceptibility to stress corrosion cracking in a future job. Polarization curves were made on alloy 22 (Ni-Cr-Mo), 600 (Ni- Cr-Fe), 800h (Ni-Fe- Cr) and 201 (Ni commercially pure) in the following environments: 1.148 mol/L NaHCO 3 , 1.148 mol/L NaHCO 3 + 1 mol/L NaCl, 1.148 mol/L NaHCO 3 + 0.1 mol/L NaCl. The tests were performed at the following temperatures: 90°C, 75°C, 60°C and 25°C. It was found that alloy 22 has a current peak in the anodic domain at potentials below trans-passivity between 200 and 300 m VECS, when the test temperature was 90°C. The potential, at which this peak occurred, increased with decreasing temperature. Also there was a variation of the peak with the composition of the solution. When bicarbonate ions were added to a solution containing chloride ions, the peak potential shifted to higher current densities, depending on the concentration of added chloride ions. It was found that diminishing the content of

Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

Science.gov (United States)

Pratesa, Yudha; Ferdian, Deni; Togina, Inez

2017-05-01

One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

Science.gov (United States)

Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

2015-02-01

Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

Enhanced corrosion resistance and biocompatibility of β-type Ti–25Nb–25Zr alloy by electrochemical anodization

Energy Technology Data Exchange (ETDEWEB)

Huang, Her-Hsiung [Department of Dentistry, National Yang-Ming University, Taipei, 112 Taiwan (China); Graduate Institute of Basic Medical Science, China Medical University, Taichung, 404 Taiwan (China); Department of Biomedical Informatics, Asia University, Taichung, 413 Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei, 112 Taiwan (China); Wu, Chia-Ping; Sun, Ying-Sui; Huang, Hsun-Miao [Institute of Oral Biology, National Yang-Ming University, Taipei, 112 Taiwan (China); Lee, Tzu-Hsin, E-mail: biomaterials@hotmail.com [School of Dentistry, Chung Shan Medical University, Taichung, 402 Taiwan (China); Oral Medicine Center, Chung Shan Medical University Hospital, Taichung, 402 Taiwan (China)

2013-12-31

The biocompatibility of implants is largely determined by their surface characteristics. This study presents a novel method for performing electrochemical anodization on β-type Ti–25Nb–25Zr alloy with a low elastic modulus (approximately 70 GPa). This method results in a thin hybrid layer capable of enhancing the surface characteristics of the implants. We investigated the surface topography and microstructure of the resulting Ti–25Nb–25Zr alloy. The corrosion resistance was evaluated using potentiodynamic polarization curve measurements in simulated body fluid. The cytotoxicity was evaluated according to International Organization for Standardization 10993–5 specification. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed using scanning electron microscopy and fluorescence microscopy. The anodization produced a thin (approximately 40 nm-thick) hybrid oxide layer with a nanoporous outer sublayer (pore size < 15 nm) and a dense inner layer. The thin hybrid oxide layer increased the corrosion resistance of the Ti–25Nb–25Zr alloy by increasing the corrosion potential and decreasing both the corrosion rate and passive current. Ti–25Nb–25Zr alloys with and without anodization treatment were non-toxic. Surface nanotopography on the anodized Ti–25Nb–25Zr alloy enhanced protein adsorption and cell adhesion. Our results demonstrate that electrochemical anodization increases the corrosion resistance and cell adhesion of β-type Ti–25Nb–25Zr alloy while providing a lower elastic modulus suitable for implant applications. - Highlights: • An electrochemical anodization was applied to β-type Ti–25Nb–25Zr alloy surface. • Anodized surface had nanoscale hybrid oxide layer. • Anodized surface increased corrosion resistance due to dense inner sublayer. • Anodized surface enhanced cell adhesion due to nanoporous outer sublayer. • Electrochemical anodization has potential as implant surface treatment.

Enhanced corrosion resistance and biocompatibility of β-type Ti–25Nb–25Zr alloy by electrochemical anodization

International Nuclear Information System (INIS)

Huang, Her-Hsiung; Wu, Chia-Ping; Sun, Ying-Sui; Huang, Hsun-Miao; Lee, Tzu-Hsin

2013-01-01

The biocompatibility of implants is largely determined by their surface characteristics. This study presents a novel method for performing electrochemical anodization on β-type Ti–25Nb–25Zr alloy with a low elastic modulus (approximately 70 GPa). This method results in a thin hybrid layer capable of enhancing the surface characteristics of the implants. We investigated the surface topography and microstructure of the resulting Ti–25Nb–25Zr alloy. The corrosion resistance was evaluated using potentiodynamic polarization curve measurements in simulated body fluid. The cytotoxicity was evaluated according to International Organization for Standardization 10993–5 specification. Cell adhesion of human bone marrow mesenchymal stem cells on the test specimens was observed using scanning electron microscopy and fluorescence microscopy. The anodization produced a thin (approximately 40 nm-thick) hybrid oxide layer with a nanoporous outer sublayer (pore size < 15 nm) and a dense inner layer. The thin hybrid oxide layer increased the corrosion resistance of the Ti–25Nb–25Zr alloy by increasing the corrosion potential and decreasing both the corrosion rate and passive current. Ti–25Nb–25Zr alloys with and without anodization treatment were non-toxic. Surface nanotopography on the anodized Ti–25Nb–25Zr alloy enhanced protein adsorption and cell adhesion. Our results demonstrate that electrochemical anodization increases the corrosion resistance and cell adhesion of β-type Ti–25Nb–25Zr alloy while providing a lower elastic modulus suitable for implant applications. - Highlights: • An electrochemical anodization was applied to β-type Ti–25Nb–25Zr alloy surface. • Anodized surface had nanoscale hybrid oxide layer. • Anodized surface increased corrosion resistance due to dense inner sublayer. • Anodized surface enhanced cell adhesion due to nanoporous outer sublayer. • Electrochemical anodization has potential as implant surface treatment

Environmental friendly anodizing of AZ91D magnesium alloy in alkaline borate-benzoate electrolyte

International Nuclear Information System (INIS)

Liu Yan; Wei Zhongling; Yang Fuwei; Zhang Zhao

2011-01-01

Highlights: → Environmental friendly PEO technology for AZ91 magnesium alloy is developed. → NaBz is used as new additive and it is low-cost and environmental friendly. → The effect of NaBz additive on the properties of the anodized film was studied. → Anodized film with excellent corrosion resistance is obtained. → The forming mechanism of anodized film in the presence of NaBz is approached. - Abstract: A kind of environmental friendly anodizing routine for AZ91D magnesium alloy, based on an alkaline borate-sodium benzoate electrolyte (NaBz) was studied. The effect of NaBz on the properties of the anodized film was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results showed that the anodizing process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of NaBz. In the presence of adequate NaBz, a thick, compact and smoothing anodized film with excellent corrosion resistance was produced. Moreover, the forming mechanism of the anodized film in the presence of NaBz additive was also approached, which was a suppression of arc discharge process by the adsorption of Bz - on the surface of magnesium alloy substrate.

Band gap structure modification of amorphous anodic Al oxide film by Ti-alloying

DEFF Research Database (Denmark)

Canulescu, Stela; Rechendorff, K.; Borca, C. N.

2014-01-01

The band structure of pure and Ti-alloyed anodic aluminum oxide has been examined as a function of Ti concentration varying from 2 to 20 at. %. The band gap energy of Ti-alloyed anodic Al oxide decreases with increasing Ti concentration. X-ray absorption spectroscopy reveals that Ti atoms...... are not located in a TiO2 unit in the oxide layer, but rather in a mixed Ti-Al oxide layer. The optical band gap energy of the anodic oxide layers was determined by vacuum ultraviolet spectroscopy in the energy range from 4.1 to 9.2 eV (300–135 nm). The results indicate that amorphous anodic Al2O3 has a direct...

The influence of Ti and Sr alloying elements on electrochemical properties of aluminum sacrificial anodes

Energy Technology Data Exchange (ETDEWEB)

Saremi, M.; Sina, H.; Keyvani, A.; Emamy, M. [Metallurgy and Materials Department, University of Tehran, P.O. Box 11365/4563, Tehran (Iran)

2004-07-01

Aluminum sacrificial anodes are widely used in cathodic protection of alloys in seawater. The interesting properties due to low specific weight, low electrode potential and high current capacity are often hindered by the presence of a passive oxide film which causes several difficulties in their practical application. In this investigation, the electrochemical behavior of Al- 5Zn-0.02In sacrificial anode is studied in 3 wt. % sodium chloride solution. The experiments focused on the influence of Ti and Sr as alloying elements on electrochemical behavior of aluminum sacrificial anode. Ti and Sr are used in different concentrations from 0.03 to 0.1 wt.% 0.01 to 0.05 wt.%, respectively. NACE efficiency and polarization tests are used in this case. It is shown that by using 0.03 wt.% Ti and 0.01 wt.% Sr as the alloying elements to investigate the anodic behavior of the anodes, homogeneous microstructures are obtained which results in improvement of electrochemical properties of aluminum sacrificial anode such as current capacity and anode efficiency. (authors)

Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

Science.gov (United States)

Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

2013-03-01

The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

Investigation of cerium salt/sulfuric acid anodizing technology for 1420 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Di Li; Yue Peng Deng; Bao Lan Guo; Guo Qiang Li [Beijing Univ. of Aeronautics and Astronautics (China). Dept. of Mater. Sci. and Eng.

2000-07-01

In this paper, the effect of cerium addition agent on the property of anodized coating of 1420 Al alloy has been studied by corrosion experiment (immersion test and neutral salt spray test), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and measurement of polarization curves. The result show that only pitting could be observed in all corrosion tests while intergranular corrosion and exfoliation corrosion did not appear on 1420 Al-Li alloys. When organic carboxylic acid S or the cerium (IV) salt was added into sulfuric acid anodizing electrolyte separately, there was no significant improvement in corrosion resistance of anodized film. However, in the case of adding them into sulfuric acid anodizing electrolyte together, the corrosion resistance of anodized film increased greatly owing to synergistic effect. The synergistic effect may relate to the formation of cerium-organic carboxylic acid S complex compound and its effects on film growth and film structure. (orig.)

The electrochemical properties and mechanism of formation of anodic oxide films on Mg-Al alloys

International Nuclear Information System (INIS)

Kim, Seong Jong; Okido, Masazumi

2003-01-01

The electronchemical properties and the mechanism of formation of anodic oxide films on Mg alloys containing 0-15 mass% Al, when anodized in NaOH solution, were investigated by focusing on the effects of anodizing potential, Al content, and anodizing time. The intensity ratio of Mg(OH) 2 in the XRD analysis decreased with increasing applied potential, while that of MgO increased. Mg(OH) 2 was barely detected at 80 V, while MgO was readily detected. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. The intensity ratio of the β phase increased with aluminum content in Mg-Al alloys. During anodizing, the active dissolution reaction occurred preferentially in β phase until about 4 min, and then the current density increased gradually until 7 min. The dissolution reaction progressed in α phase, which had a lower Al content. In the anodic polarization test in 0.017 mol·dm -3 NaCl and 0.1 mol·dm -3 Na 2 SO 4 at 298 K, the current density of Mg-15 mass% Al alloy anodized for 10 min increased, since the anodic film that forms on the α phase is a non-compacted film. The anodic film on the α phase at 30 min was a compact film as compared with that at 10 min

Polarization behavior of new and used lead alloys in acid sulfate solutions

Energy Technology Data Exchange (ETDEWEB)

Yu, P.; O' Keefe, T.J. [Univ. of Missouri-Rolla, Materials Research Center and Dept. of Metallurgical Engineering, Rolla, Missouri (United States)

2001-07-01

Polarization and Electrochemical impedance were used to study various lead alloys commercially used to electrowin zinc and copper from acidic sulfate solutions. Anode specimens that had been in service at several electrowinning operations were tested and their electrochemical performance was compared to that obtained from new anode samples. Tests were conducted in sulfuric acid. Cyclic voltammetry was used in a potential range in which both Pb{sup +2} and Pb{sup +4} formed stable phases. Selected polarization tests were also made to study a number of variables, including changes in the concentration of cobalt and manganese in the electrolyte. Results showed that the phases formed on the surface of the anode were critical in defining the electrochemical behavior of the anodes. In particular, certain active phases, which were depolarizing were identified on some of the used anodes. It was possible to duplicate some of these phases in the laboratory. (author)

The effect of different aluminum alloy surface compositions on barrier anodic film formation

International Nuclear Information System (INIS)

Panitz, J.K.G.; Sharp, D.J.

1984-01-01

The authors have grown barrier anodic coatings on samples of aluminum alloy with different elemental surface compositions. In one series of experiments, they characterized the surface composition present on 6061 aluminum alloy samples after different chemical treatments including a detergent-water and methyl-ethyl ketone solvent clean, a 50% nitric acid-water etch, and a concentrated nitric acid-ammonium bifluoride etch. They anodized samples which were prepared similarly to those analyzed to evaluate the practical effects of the three different surface compositions. The anodization voltage rise time to 950V at constant current was used as a figure of merit. The solvent cleaned and the 50% nitric acid etched samples required, respectively, 113% and 41% more time to reach 950V than the concentrated nitric acidammonium bifloride etched samples. In a second series of experiments, they alternately anodized groups of either 6061 or 1100 (commercially pure) aluminum alloy, observed rise times to 950V, and measured chloride ion concentrations in the electrolyte. Longer rise times and higher chloride ion concentrations were observed for the 1100 samples. It was observed that the chloride ion concentration fell from initially high levels when 6061 samples were anodized. The results of both series of experiments augment the results of other investigators, who report that the surface species initially present on aluminum have a significant effect on anodic film formation

Role of Ca in Modifying Corrosion Resistance and Bioactivity of Plasma Anodized AM60 Magnesium Alloys

Energy Technology Data Exchange (ETDEWEB)

Anawati, Anawati; Asoh, Hidetaka; Ono, Sachiko [Kogakuin University, Tokyo (Japan)

2016-06-15

The effect of alloying element Ca (0, 1, and 2 wt%) on corrosion resistance and bioactivity of the as-received and anodized surface of rolled plate AM60 alloys was investigated. A plasma electrolytic oxidation (PEO) was carried out to form anodic oxide film in 0.5 mol dm{sup -3} Na{sub 3}PO{sub 4} solution. The corrosion behavior was studied by polarization measurements while the in vitro bioactivity was tested by soaking the specimens in Simulated Body Fluid (1.5xSBF). Optical micrograph and elemental analysis of the substrate surfaces indicated that the number of intermetallic particles increased with Ca content in the alloys owing to the formation of a new phase Al2Ca. The corrosion resistance of AM60 specimens improved only slightly by alloying with 2 wt% Ca which was attributed to the reticular distribution of Al2Ca phase existed in the alloy that might became barrier for corrosion propagation across grain boundaries. Corrosion resistance of the three alloys was significantly improved by coating the substrates with anodic oxide film formed by PEO. The film mainly composed of magnesium phosphate with thickness in the range 30 - 40 μm. The heat resistant phase of Al{sub 2}Ca was believed to retard the plasma discharge during anodization and, hence, decreased the film thickness of Ca-containing alloys. The highest apatite forming ability in 1.5xSBF was observed for AM60-1Ca specimens (both substrate and anodized) that exhibited more degradation than the other two alloys as indicated by surface observation. The increase of surface roughness and the degree of supersaturation of 1.5xSBF due to dissolution of Mg ions from the substrate surface or the release of film compounds from the anodized surface are important factors to enhance deposition of Ca-P compound on the specimen surfaces.

The electrochemical properties and mechanism of formation of anodic oxide films on Mg-Al alloys

Energy Technology Data Exchange (ETDEWEB)

Kim, Seong Jong; Okido, Masazumi [Nagoya Univ., Nagoya (Japan)

2003-07-01

The electronchemical properties and the mechanism of formation of anodic oxide films on Mg alloys containing 0-15 mass% Al, when anodized in NaOH solution, were investigated by focusing on the effects of anodizing potential, Al content, and anodizing time. The intensity ratio of Mg(OH){sub 2} in the XRD analysis decreased with increasing applied potential, while that of MgO increased. Mg(OH){sub 2} was barely detected at 80 V, while MgO was readily detected. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. The intensity ratio of the {beta} phase increased with aluminum content in Mg-Al alloys. During anodizing, the active dissolution reaction occurred preferentially in {beta} phase until about 4 min, and then the current density increased gradually until 7 min. The dissolution reaction progressed in {alpha} phase, which had a lower Al content. In the anodic polarization test in 0.017 mol{center_dot}dm{sup -3} NaCl and 0.1 mol{center_dot}dm{sup -3} Na{sub 2}SO{sub 4} at 298 K, the current density of Mg-15 mass% Al alloy anodized for 10 min increased, since the anodic film that forms on the {alpha} phase is a non-compacted film. The anodic film on the {alpha} phase at 30 min was a compact film as compared with that at 10 min.

Improvements in the corrosion resistance and biocompatibility of biomedical Ti–6Al–7Nb alloy using an electrochemical anodization treatment

Energy Technology Data Exchange (ETDEWEB)

Huang, Her-Hsiung [Department of Dentistry, National Yang-Ming University, Taipei 112, Taiwan (China); Department of Dentistry, Taipei City Hospital, Taipei 115, Taiwan (China); Department of Stomatology, Taipei Veterans General Hospital, Taipei 112, Taiwan (China); Wu, Chia-Ping; Sun, Ying-Sui [Department of Oral Biology, National Yang-Ming University, Taipei 112, Taiwan (China); Lee, Tzu-Hsin, E-mail: biomaterials@hotmail.com [School of Dentistry, Chung Shan Medical University, Taichung 402, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung 402, Taiwan (China)

2013-01-01

The biocompatibility of an implant material is determined by its surface characteristics. This study investigated the application of an electrochemical anodization surface treatment to improve both the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for implant applications. The electrochemical anodization treatment produced an Al-free oxide layer with nanoscale porosity on the Ti–6Al–7Nb alloy surface. The surface topography and microstructure of Ti–6Al–7Nb alloy were analyzed. The corrosion resistance was investigated using potentiodynamic polarization curve measurements in simulated blood plasma (SBP). The adhesion and proliferation of human bone marrow mesenchymal stem cells to test specimens were evaluated using various biological analysis techniques. The results showed that the presence of a nanoporous oxide layer on the anodized Ti–6Al–7Nb alloy increased the corrosion resistance (i.e., increased the corrosion potential and decreased both the corrosion rate and the passive current) in SBP compared with the untreated Ti–6Al–7Nb alloy. Changes in the nanotopography also improved the cell adhesion and proliferation on the anodized Ti–6Al–7Nb alloy. We conclude that a fast and simple electrochemical anodization surface treatment improves the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for biomedical implant applications. - Highlights: ► Simple/fast electrochemical anodization was applied to biomedical Ti–6Al–7Nb surface. ► Anodized surface had nano-porous topography and contained Al-free oxide layer. ► Anodized surface raised corrosion resistance in three simulated biological solutions. ► Anodized surface enhanced cell adhesion and cell proliferation. ► Electrochemical anodization has potential as biomedical implant surface treatment.

Improvements in the corrosion resistance and biocompatibility of biomedical Ti–6Al–7Nb alloy using an electrochemical anodization treatment

International Nuclear Information System (INIS)

Huang, Her-Hsiung; Wu, Chia-Ping; Sun, Ying-Sui; Lee, Tzu-Hsin

2013-01-01

The biocompatibility of an implant material is determined by its surface characteristics. This study investigated the application of an electrochemical anodization surface treatment to improve both the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for implant applications. The electrochemical anodization treatment produced an Al-free oxide layer with nanoscale porosity on the Ti–6Al–7Nb alloy surface. The surface topography and microstructure of Ti–6Al–7Nb alloy were analyzed. The corrosion resistance was investigated using potentiodynamic polarization curve measurements in simulated blood plasma (SBP). The adhesion and proliferation of human bone marrow mesenchymal stem cells to test specimens were evaluated using various biological analysis techniques. The results showed that the presence of a nanoporous oxide layer on the anodized Ti–6Al–7Nb alloy increased the corrosion resistance (i.e., increased the corrosion potential and decreased both the corrosion rate and the passive current) in SBP compared with the untreated Ti–6Al–7Nb alloy. Changes in the nanotopography also improved the cell adhesion and proliferation on the anodized Ti–6Al–7Nb alloy. We conclude that a fast and simple electrochemical anodization surface treatment improves the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for biomedical implant applications. - Highlights: ► Simple/fast electrochemical anodization was applied to biomedical Ti–6Al–7Nb surface. ► Anodized surface had nano-porous topography and contained Al-free oxide layer. ► Anodized surface raised corrosion resistance in three simulated biological solutions. ► Anodized surface enhanced cell adhesion and cell proliferation. ► Electrochemical anodization has potential as biomedical implant surface treatment

Evaluation of lithium alloy anode materials for Li-TiS2 cells

Science.gov (United States)

Huang, C.-K.; Subbarao, S.; Shen, D. H.; Deligiannis, F.; Attia, A.; Halpert, G.

1991-01-01

A study was performed to select candidate lithium alloy anode materials and establish selection criteria. Some of the selected alloy materials were evaluated for their electrochemical properties and performance. This paper describes the criteria for the selection of alloys and the findings of the studies. Li-Si and Li-Cd alloys have been found to be unstable in the EC+2-MeTHF-based electrolyte. The Li-Al alloy system was found to be promising among the alloy systems studied in view of its stability and reversibility. Unfortunately, the large volume changes of LiAl alloys during charge/discharge cycling cause considerable 'exfoliation' of its active mass. This paper also describes ways how to address this problem. The rate of disintegration of this anode would probably be surpressed by the presence of an inert solid solution or a uniform distribution of precipitates within the grains of the active mass. It was discovered that the addition of a small quantity of Mn may improve the mechanical properties of LiAl. In an attempt to reduce the Li-Al alloy vs. Li voltage, it was observed that LiAlPb(0.1)Cd(0.3) material can be cycled at 1.5 mA/sq cm without exfoliation of the active mass.

Nanoporous alumina formed by self-organized two-step anodization of Ni3Al intermetallic alloy in citric acid

International Nuclear Information System (INIS)

Stępniowski, Wojciech J.; Cieślak, Grzegorz; Norek, Małgorzata; Karczewski, Krzysztof; Michalska-Domańska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jóźwik, Paweł; Bojar, Zbigniew

2013-01-01

Highlights: ► Anodic porous alumina was formed by Ni 3 Al intermetallic alloy anodization. ► The anodizations were conducted in 0.3 M citric acid. ► Nanopores geometry depends on anodizing voltage. ► No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni 3 Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni 3 Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 μm/h was found for the anodization at 0 °C and 2.0 V. The highest one – 2.29 μm/h – was noticed for 10.0 V and 30 °C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 °C) to 32.0 nm (12.0 V, 0 °C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 °C) to 177.9 nm (12.0 V, 30 °C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/μm 2 (2.0 V, 0 °C) to 94.9 pores/μm 2 (12.0 V, 0 °C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni 3 Al intermetallic alloy are depending on the operating conditions.

Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

Energy Technology Data Exchange (ETDEWEB)

Son, In Joon; Nakano, Hiroaki; Oue, Satoshi; Fukushima, Hisaaki; Horita, Zenji [Kyushu University, Fukuoka (Japan); Kobayashi, Shigeo [Kyushu Sangyo University, Fukuoka (Japan)

2007-12-15

The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl{sub 3} and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m{sup 2} at 293 K in a solution containing 1.53 mol/L of H{sub 2}SO{sub 4} and 0.0185 mol/L of Al{sub 2}(SO{sub 4}){sub 3}. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be

Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

International Nuclear Information System (INIS)

Son, In Joon; Nakano, Hiroaki; Oue, Satoshi; Fukushima, Hisaaki; Horita, Zenji; Kobayashi, Shigeo

2007-01-01

The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl 3 and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m 2 at 293 K in a solution containing 1.53 mol/L of H 2 SO 4 and 0.0185 mol/L of Al 2 (SO 4 ) 3 . The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in

PEO of pre-anodized Al–Si alloys: Corrosion properties and influence of sealings

Energy Technology Data Exchange (ETDEWEB)

Mohedano, M., E-mail: marta.mohedano@hzg.de [Helmholtz Zentrum Geesthacht, Magnesium Innovation Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain)

2015-08-15

Highlights: • A356 gravity-cast and rheocast pre-anodized aluminium alloys were coated by PEO. • Different sealing techniques were applied after the coating process. • Iron-rich constituents of the substrate occlude the continuity of the porous anodic film. • PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. • Post-treatments improved both hydrophobic and corrosion properties. - Abstract: Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

Science.gov (United States)

Danford, M. D.

1994-01-01

The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

Electrochemical machining of titanium alloys with the use of anodal activating pulses

International Nuclear Information System (INIS)

Davydov, A.D.; Klepikov, R.P.; Moroz, I.I.

1980-01-01

A comparative investigation of electrochemical machining of VT-6 titanium alloy by direct current and in different pulse mode is carried out taking into account the peculiarities of anodal behaviour of titanium alloys at high current desities. The mode of electrochemical machining of VT-6 alloy with activating pulses is chosen. It allows to conduct a process at lower voltages and small interelectrode gaps

Influence of silver on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloys as positive grids in lead acid batteries

International Nuclear Information System (INIS)

Tizpar, A.; Ghasemi, Z.

2006-01-01

The influence of silver addition in the range 0.01-0.09 wt.% on the anodic corrosion and gas evolution of Pb-Sb-As-Se alloy in 1.28 sp.gr. H 2 SO 4 solution at 25 deg. C was studied using linear sweep voltammetry, cyclic voltammetry, weight loss measurements and scanning electron microscopy. The results drawn from different techniques are comparable. The effect of different concentration of silver on the corrosion behavior of Pb-Sb-As-Se was investigated. The experimental results show that the silver added to Pb-Sb-As-Se alloy inhibits the growth of anodic corrosion layer. A decrease in the oxygen evolution overpotential and an increase in the hydrogen evolution overpotential with the addition of Ag were also observed during the experiments. Cyclic voltammetric measurements provided information on the effect of Ag on the oxidation of PbSO 4 to PbO 2

Dendrite-Free Electrodeposition and Reoxidation of Lithium-Sodium Alloy for Metal-Anode Battery

Science.gov (United States)

2011-11-01

Dendrite-Free Electrodeposition and Reoxidation of Lithium-Sodium Alloy for Metal-Anode Battery Johanna K. Star 1 , Yi Ding 2 , and Paul A. Kohl ,1, * 1...Journal Article 3. DATES COVERED 01-11-2011 to 01-11-2011 4. TITLE AND SUBTITLE DENDRITE-FREE ELECTRODEPOSITION AND REOXIDATION OF LITHIUM-SODIUM...can short circuit the anode and cathode . Anode- cathode short circuits are especially dangerous when a flammable organic solvent is used as the

Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode

International Nuclear Information System (INIS)

Zaifol Samsu; Muhammad Daud; Siti Radiah Mohd Kamarudin; Nur Ubaidah Saidin; Azali Muhammad; Mohd Shaari Ripin; Rusni Rejab; Mohd Shariff Sattar

2010-01-01

This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

Characterization and Tribological Properties of Hard Anodized and Micro Arc Oxidized 5754 Quality Aluminum Alloy

Directory of Open Access Journals (Sweden)

M. Ovundur

2015-03-01

Full Text Available This study was initiated to compare the tribological performances of a 5754 quality aluminum alloy after hard anodic oxidation and micro arc oxidation processes. The structural analyses of the coatings were performed using XRD and SEM techniques. The hardness of the coatings was determined using a Vickers micro-indentation tester. Tribological performances of the hard anodized and micro arc oxidized samples were compared on a reciprocating wear tester under dry sliding conditions. The dry sliding wear tests showed that the wear resistance of the oxide coating generated by micro arc oxidation is remarkably higher than that of the hard anodized alloy.

Study of Shell Zone Formation in Lithographic and Anodizing Quality Aluminum Alloys: Experimental and Numerical Approach

Science.gov (United States)

Brochu, Christine; Larouche, André; Hark, Robert

Shell thickness is an important quality factor for lithographic and anodizing quality aluminum alloys. Increasing pressure is placed on casting plants to produce a thinner shell zone for these alloys. This study, based on plant trials and mathematical modelling highlights the most significant parameters influencing shell zone formation. Results obtained show the importance of metal temperature and distribution and mould metal level on shell zone formation. As an answer to specific plant problems, this study led to the development of improved metal distribution systems for DC casting of litho and anodizing quality alloys.

Exploring As-Cast PbCaSn-Mg Anodes for Improved Performance in Copper Electrowinning

Science.gov (United States)

Yuwono, Jodie A.; Clancy, Marie; Chen, Xiaobo; Birbilis, Nick

2018-06-01

Lead calcium tin (PbCaSn) alloys are the common anodes used in copper electrowinning (Cu EW). Given a large amount of energy consumed in Cu EW process, anodes with controlled oxygen evolution reaction (OER) kinetics and a lower OER overpotential are advantageous for reducing the energy consumption. To date, magnesium (Mg) has never been studied as an alloying element for EW anodes. As-cast PbCaSn anodes with the addition of Mg were examined herein, revealing an improved performance compared to that of the industrial standard PbCaSn anode. The alloy performances in the early stages of anode life and passivation were established from electrochemical studies which were designed to simulate industrial Cu EW process. The 24-hour polarization testing revealed that the Mg alloying depolarizes the anode potential up to 80 mV; thus, resulting in a higher Cu EW efficiency. In addition, scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the alteration of the alloy microstructure and the corresponding interfacial reactions contribute to the changes of the anode electrochemical performances. The present study reveals for the first time the potency of Mg alloying in reducing the overpotential of PbCaSn anode.

Nanoporous alumina formed by self-organized two-step anodization of Ni{sub 3}Al intermetallic alloy in citric acid

Energy Technology Data Exchange (ETDEWEB)

Stepniowski, Wojciech J., E-mail: wstepniowski@wat.edu.pl [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland); Cieslak, Grzegorz; Norek, Malgorzata; Karczewski, Krzysztof; Michalska-Domanska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jozwik, Pawel; Bojar, Zbigniew [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland)

2013-01-01

Highlights: Black-Right-Pointing-Pointer Anodic porous alumina was formed by Ni{sub 3}Al intermetallic alloy anodization. Black-Right-Pointing-Pointer The anodizations were conducted in 0.3 M citric acid. Black-Right-Pointing-Pointer Nanopores geometry depends on anodizing voltage. Black-Right-Pointing-Pointer No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni{sub 3}Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni{sub 3}Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 {mu}m/h was found for the anodization at 0 Degree-Sign C and 2.0 V. The highest one - 2.29 {mu}m/h - was noticed for 10.0 V and 30 Degree-Sign C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 Degree-Sign C) to 32.0 nm (12.0 V, 0 Degree-Sign C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 Degree-Sign C) to 177.9 nm (12.0 V, 30 Degree-Sign C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/{mu}m{sup 2} (2.0 V, 0 Degree-Sign C) to 94.9 pores/{mu}m{sup 2} (12.0 V, 0 Degree-Sign C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni{sub 3}Al intermetallic alloy are depending on the

A Study on Sealing Process of Anodized Al Alloy Film

Science.gov (United States)

Tsujita, Takeshi; Sato, Hiroshi; Tsukahara, Sonoko; Ishikawa, Yuuichi

Since sealing is an important process to improve the corrosion resistance in practical application of anodized aluminum, we prepared anodic oxide films on A5052 alloy in an oxalic acid bath and a sulfuric acid bath, sealed them at various conditions, and analyzed them by scanning electron microscopy, acid-dissolution examination, admittance measurements and infrared spectroscopy. The pore radius of the oxalic acid anodized film was about 5 times larger than that of sulfuric acid anodized film, while the corrosion resistance of the former showed about 2 times higher value than the latter with the same sealed state and amount of hydroxide formed by sealing process of the former was 6 times larger than the latter, respectively. Steam sealing formed dense hydroxide and boiling water sealing formed big coral-like hydroxide, whereas the corrosion resistance of the film sealed by the former showed about 1.5 times higher value than that sealed by the latter, respectively. Thus microstructure of anodic oxide films and their surface morphology after sealing process clearly depended on their anodizing solution and the sealing condition and showed obvious relation to electric and corrosive properties.

PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

Science.gov (United States)

Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

2015-08-01

Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

Lead and lead-based alloys as waste matrix materials

International Nuclear Information System (INIS)

Arustamov, A.E.; Ojovan, M.I.; Kachalov, M.B.

1999-01-01

Metals and alloys with relatively low melting temperatures such as lead and lead-based alloys are considered in Russia as prospective matrices for encapsulation of spent nuclear fuel in containers in preparation for final disposal in underground repositories. Now lead and lead-based alloys are being used for conditioning spent sealed radioactive sources at radioactive waste disposal facilities

Anodic characteristics and stress corrosion cracking behavior of nickel rich alloys in bicarbonate and buffer solutions

International Nuclear Information System (INIS)

Zadorozne, Natalia S.; Giordano, Mabel C.; Ares, Alicia E.; Carranza, Ricardo M.; Rebak, Raul B.

2016-01-01

Highlights: • We investigate which element in alloy C-22 may be responsible for the cracking susceptibility of the high nickel alloy. • Six nickel based alloys with different amount of Cr and Mo were selected for the electrochemical tests and response to SSRT. • Polarization tests showed that an anodic peak appear in the passive region in Cr containing alloys. • Cracking of Ni alloys in carbonate solutions seem to be a consequence of the instability of the passivating chromium oxide. • Alloys containing both Cr and Mo have the highest susceptibility. - Abstract: The aim of this work is to investigate which alloying element in C-22 is responsible for the cracking susceptibility of the alloy in bicarbonate and two buffer solutions (tungstate and borate). Six nickel based alloys, with different amount of chromium (Cr) and molybdenum (Mo) were tested using electrochemical methods and slow strain rate tests (SSRT) at 90 °C. All Cr containing alloys had transgranular cracking at high anodic potential; however, C-22 containing high Cr and high Mo was the most susceptible alloy to cracking. Bicarbonate was the most aggressive of three tested environments of similar pH.

Structure of the Copper–Enriched Layer Introduced by Anodic Oxidation of Copper-Containing Aluminium Alloy

International Nuclear Information System (INIS)

Hashimoto, T.; Zhou, X.; Skeldon, P.; Thompson, G.E.

2015-01-01

This paper investigates the structure of the copper–enriched layer formed at the alloy/anodic film interface during anodizing of Al–2 wt.% Cu binary alloy using transmission electron microscopy. It was revealed that θ′ phase was formed within the copper–enriched layer. For the copper–enriched layer formed on {1 0 0} aluminum planes, the interface between the aluminum matrix and the θ′ phase within the copper-enriched layer is coherent. For the copper–enriched layer formed on {1 1 0} and {1 1 1} aluminum planes, the interfaces between the aluminum matrix and the θ′ phase within the copper-enriched layer are semi-coherent or incoherent. The interfacial coherency influences the formation of oxygen gas bubbles within the resultant anodic films.

Remediation of phosphate-contaminated water by electrocoagulation with aluminium, aluminium alloy and mild steel anodes.

Science.gov (United States)

Vasudevan, Subramanyan; Lakshmi, Jothinathan; Jayaraj, Jeganathan; Sozhan, Ganapathy

2009-05-30

The present study provides an electrocoagulation process for the remediation of phosphate-contaminated water using aluminium, aluminium alloy and mild steel as the anodes and stainless steel as the cathode. The various parameters like effect of anode materials, effect of pH, concentration of phosphate, current density, temperature and co-existing ions, and so forth, and the adsorption capacity was evaluated using both Freundlich and Langmuir isotherm models. The adsorption of phosphate preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The results showed that the maximum removal efficiency of 99% was achieved with aluminium alloy anode at a current density of 0.2 A dm(-2), at a pH of 7.0. The adsorption process follows second-order kinetics.

Effect of temperature on the anodizing process of aluminum alloy AA 5052

Science.gov (United States)

Theohari, S.; Kontogeorgou, Ch.

2013-11-01

The effect of temperature (10-40 °C) during the anodizing process of AA 5052 for 40 min in 175 g/L sulfuric acid solution at constant voltage (15 V) was studied in comparison with pure aluminum. The incorporated magnesium species in the barrier layer result in the further increase of the minimum current density passed during anodizing, as the temperature increases, by about 42% up to 30 °C and then by 12% up to 40 °C. Then during the anodizing process for 40 min a blocking effect on oxide film growth was gradually observed as the temperature increased until 30 °C. The results of EDAX analysis on thick films reveal that the mean amount of the magnesium species inside the film is about 50-70% less than that in the bulk alloy, while it is higher at certain locations adjacent to the film surface at 30 °C. The increase of anodizing temperature does not influence the porosity of thin films (formed for short times) on pure aluminum, while it reduces it on the alloy. At 40 °C the above mentioned blocking effects disappear. It means that the presence of magnesium species causes an impediment to the effect of temperature on iss, on the film thickness and on the porosity of thin films, only under conditions where film growth takes place without significant loss of the anodizing charge to side reactions.

Bacterial adherence to anodized titanium alloy

International Nuclear Information System (INIS)

Peremarch, C Perez-Jorge; Tanoira, R Perez; Arenas, M A; Matykina, E; Conde, A; De Damborenea, J J; Gomez Barrena, E; Esteban, J

2010-01-01

The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

Formation of barrier-type anodic films on ZE41 magnesium alloy in a fluoride/glycerol electrolyte

International Nuclear Information System (INIS)

Hernández-López, J.M.; Němcová, A.; Zhong, X.L.; Liu, H.; Arenas, M.A.; Haigh, S.J.; Burke, M.G.; Skeldon, P.; Thompson, G.E.

2014-01-01

Highlights: • Barrier anodic films formed on ZE41 Mg alloy in glycerol/fluoride electrolyte. • Films contain oxygen and fluorine species; formation ratio ∼1.3 nm V −1 . • Nanocrystalline film structure, with MgO and MgF 2. • Zinc enrichment in alloy beneath anodic film. • Modified film formed above Mg-Zn-RE second phase. - Abstract: Barrier-type, nanocrystalline anodic films have been formed on a ZE41 magnesium alloy under a constant current density of 5 mA cm −2 in a glycerol/fluoride electrolyte, containing 5 vol.% of added water, at 293 K. The films contain magnesium, fluorine and oxygen as the major species, and lower amounts of alloying element species. The films grow at an efficiency of ∼0.8 to 0.9, with a formation ratio in the range of ∼1.2 to 1.4 nm V −1 at the matrix regions and with a ratio of ∼1.8 nm V −1 at Mg-Zn-RE second phase. At the former regions, rare earth species are enriched at the film surface and zinc is enriched in the alloy. A carbon- and oxygen-rich band within the film suggests that the films grow at the metal/film and film/electrolyte interfaces

Anodic solution of alkali earth alloys in potassium chloride-sodium chloride melts

International Nuclear Information System (INIS)

Volkovich, A.V.

1997-01-01

Generalized results of studying the process of anodic dissolution of alkaline-earth metal alloys with zinc, aluminium and copper in the melts of KCl-NaCl equimolar mixture containing alkaline-earth metal chlorides, are presented. It is shown that during dissolution of both pure liquid metals and their alloys there is no electrode polarization in the range of the current densities lower or comparable in their values to corrosion current

Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

Directory of Open Access Journals (Sweden)

Hidetatsu Tanaka

Full Text Available Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

Discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys as anodes for Mg-air battery

International Nuclear Information System (INIS)

Wang, Naiguang; Wang, Richu; Peng, Chaoqun; Peng, Bing; Feng, Yan; Hu, Chengwang

2014-01-01

Highlights: • We investigate the effect of indium on the discharge behaviour of Mg-Al-Pb alloy. • We evaluate the performance of Mg-air batteries with Mg-Al-Pb and Mg-Al-Pb-In anodes. • We analyze the activation mechanism of Mg-Al-Pb-In alloy in the discharge process. - Abstract: The discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys in 3.5 wt.% NaCl solution is investigated by electrochemical techniques, and compared with that of pure magnesium. The results show that Mg-Al-Pb-In alloy provides a more negative potential and exhibits a higher utilization efficiency in contrast with Mg-Al-Pb alloy and pure magnesium during the half-cell test at a large current density, and gives desirable discharge performance when used as anode for Mg- air battery. The peak power density of the Mg-air battery with Mg-Al-Pb-In anode is 94.5 mW cm −2 , which is comparable with those of Mg-H 2 O 2 semi-fuel batteries. Moreover, the activation mechanism of Mg-Al-Pb-In alloy during the discharge process is also analyzed

Aluminum alloy and associated anode and battery

International Nuclear Information System (INIS)

Tarcy, G.P.

1990-01-01

This patent describes an aluminum alloy. It comprises: eutectic amounts of at least two alloying elements selected from the group consisting of bismuth, cadmium, scandium, gallium, indium, lead, mercury, thallium, tin, and zinc with the balance being aluminum and the alloying elements being about 0.01 to 3.0 percent by weight of the alloy

Formation of titanium dioxide nanotubes on Ti–30Nb–xTa alloys by anodizing

Energy Technology Data Exchange (ETDEWEB)

Kim, Eun-Sil [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State University, Columbus, OH (United States)

2013-12-31

The goal of this study was to investigate the formation of titanium dioxide nanotubes on the surface of cast Ti–30Nb–xTa alloys by anodizing. The anodization technique for creating the nanotubes utilized a potentiostat and an electrolyte containing 1 M H{sub 3}PO{sub 4} with 0.8 wt.% NaF. The grain size of the Ti–30Nb–xTa alloys increased as the Ta content increased. Using X-ray diffraction, for the Ti–30Nb alloy the main peaks were identified as α″ martensite with strong peaks of β phase. The phases in the Ti–30Nb–xTa alloys changed from a duplex (α″ + β) microstructure to solely β phase with increasing Ta content. The nanotubes that formed on the surface of the Ti–30Nb–xTa alloys were amorphous TiO{sub 2} without an evidence of the crystalline anatase or rutile forms of TiO{sub 2}. Scanning electron microscopy revealed that the average diameters of the small and large nanotubes on the Ti–30Nb alloy not containing Ta were approximately 100 nm and 400 nm, respectively, whereas the small and large nanotubes on the alloy had diameters of approximately 85 nm and 300 nm, respectively. As the Ta content increased from 0 to 15 wt.%, the average lengths of the nanotubes increased from 2 μm to 3.5 μm. Energy-dispersive X-ray spectroscopy indicated that the nanotubes were principally composed of Ti, Nb, Ta, O and F. Contact angle measurements showed that the nanotube surface had good wettability by water droplets. - Highlights: • TiO{sub 2} nanotube layers on anodized Ti-30Nb-xTa alloys have been investigated. • Nanotube surface had an amorphous structure without heat treatment. • Nanotube diameter of Ti-30Nb-xTa decreased, whereas tube layer increased with Ta content. • The nanotube surface exhibited the low contact angle and good wettability.

Formation of titanium dioxide nanotubes on Ti–30Nb–xTa alloys by anodizing

International Nuclear Information System (INIS)

Kim, Eun-Sil; Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A.

2013-01-01

The goal of this study was to investigate the formation of titanium dioxide nanotubes on the surface of cast Ti–30Nb–xTa alloys by anodizing. The anodization technique for creating the nanotubes utilized a potentiostat and an electrolyte containing 1 M H 3 PO 4 with 0.8 wt.% NaF. The grain size of the Ti–30Nb–xTa alloys increased as the Ta content increased. Using X-ray diffraction, for the Ti–30Nb alloy the main peaks were identified as α″ martensite with strong peaks of β phase. The phases in the Ti–30Nb–xTa alloys changed from a duplex (α″ + β) microstructure to solely β phase with increasing Ta content. The nanotubes that formed on the surface of the Ti–30Nb–xTa alloys were amorphous TiO 2 without an evidence of the crystalline anatase or rutile forms of TiO 2 . Scanning electron microscopy revealed that the average diameters of the small and large nanotubes on the Ti–30Nb alloy not containing Ta were approximately 100 nm and 400 nm, respectively, whereas the small and large nanotubes on the alloy had diameters of approximately 85 nm and 300 nm, respectively. As the Ta content increased from 0 to 15 wt.%, the average lengths of the nanotubes increased from 2 μm to 3.5 μm. Energy-dispersive X-ray spectroscopy indicated that the nanotubes were principally composed of Ti, Nb, Ta, O and F. Contact angle measurements showed that the nanotube surface had good wettability by water droplets. - Highlights: • TiO 2 nanotube layers on anodized Ti-30Nb-xTa alloys have been investigated. • Nanotube surface had an amorphous structure without heat treatment. • Nanotube diameter of Ti-30Nb-xTa decreased, whereas tube layer increased with Ta content. • The nanotube surface exhibited the low contact angle and good wettability

Anodic Fabrication of Ti-Ni-O Nanotube Arrays on Shape Memory Alloy

Directory of Open Access Journals (Sweden)

Qiang Liu

2014-04-01

Full Text Available Surface modification with oxide nanostructures is one of the efficient ways to improve physical or biomedical properties of shape memory alloys. This work reports a fabrication of highly ordered Ti-Ni-O nanotube arrays on Ti-Ni alloy substrates through pulse anodization in glycerol-based electrolytes. The effects of anodization parameters and the annealing process on the microstructures and surface morphology of Ti-Ni-O were studied using scanning electron microscope and Raman spectroscopy. The electrolyte type greatly affected the formation of nanotube arrays. A formation of anatase phase was found with the Ti-Ni-O nanotube arrays annealed at 450 °C. The oxide nanotubes could be crystallized to rutile phase after annealing treatment at 650 °C. The Ti-Ni-O nanotube arrays demonstrated an excellent thermal stability by keeping their nanotubular structures up to 650 °C.

Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid

International Nuclear Information System (INIS)

Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W.; Shih, H.C.

2008-01-01

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al x CrFe 1.5 MnNi 0.5 (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm 2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm 2 ). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H 2 SO 4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al 0.3 CrFe 1.5 MnNi 0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe 1.5 MnNi 0.5 and Al 0.3 CrFe 1.5 MnNi 0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al x CrFe 1.5 MnNi 0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion

Effects of benzotriazole on anodized film formed on AZ31B magnesium alloy in environmental-friendly electrolyte

International Nuclear Information System (INIS)

Guo Xinghua; An Maozhong; Yang Peixia; Li Haixian; Su Caina

2009-01-01

An environmental-friendly electrolyte of silicate and borate, which contained an addition agent of 1H-benzotriazole (BTA) with low toxicity (LD50 of 965 mg/kg), was used to prepare an anodized film on AZ31B magnesium alloy under the constant current density of 1.5 A/dm 2 at room temperature. Effects of BTA on the properties of the anodized film were studied by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), loss weight measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results demonstrated that anodized growth process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependant on the BTA concentration, which might be attributed to the formation of an BTA adsorption layer on magnesium substrate surface. When the BTA concentration was 5 g/L in the electrolyte, a compact and thick anodized film could provide excellent corrosion resistance for AZ31B magnesium alloy.

Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

Science.gov (United States)

Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

2016-01-01

Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

Influence of 8-hydroxyquinoline on properties of anodic coatings obtained by micro arc oxidation on AZ91 magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, R.F. [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Zhang, S.F., E-mail: zhangshufang790314@sina.com [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Yang, N.; Yao, L.J.; He, F.X.; Zhou, Y.P.; Xu, X.; Chang, L.; Bai, S.J. [School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

2012-10-25

Highlights: Black-Right-Pointing-Pointer 8-HQ can promote the coating formation and change the coating color. Black-Right-Pointing-Pointer 8-HQ can increase the coating thickness and decrease the pore size. Black-Right-Pointing-Pointer Insoluble Mg(HQ){sub 2} is formed in anodic coatings in an alkaline solution with 8-HQ. Black-Right-Pointing-Pointer 8-HQ improves the corrosion resistance of the anodized magnesium alloys. - Abstract: The influence of 8-hydroxyquinoline (8-HQ) on formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on AZ91 magnesium alloys was studied by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy and potentiodynamic polarization tests. The results demonstrate that 8-HQ can decrease the solution conductivity, take part in the coating formation and change the coating color. By developing anodic coatings with increasing thickness, insoluble Mg(HQ){sub 2} and small pore size, 8-HQ improves the corrosion resistance of the anodized magnesium alloys. The coating shows the best corrosion resistance in the solution of 10 g/L NaOH and 18 g/L Na{sub 2}SiO{sub 3} with 2 g/L 8-HQ.

Anodic behavior of Al-Zn-In sacrificial anodes at different concentration of zinc and indium

Energy Technology Data Exchange (ETDEWEB)

Keyvani, Ahmad [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering; Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saremi, Mohsen [Tehran Univ. (Iran, Islamic Republic of). School of Metallurgy and Materials; Saeri, Mohammad Reza [Shahrekord Univ. (Iran, Islamic Republic of). Dept. of Materials Engineering

2012-12-15

Al-Zn-In anodes show better performance due to the beneficial effects of Zn and In on prevention of aluminum passivity and producing a homogeneous structure for uniform corrosion of the anodes. However, there are different views about the optimum concentration of each element in the anode. In this study, the anodic behavior of Al-Zn-In alloy with different concentrations of zinc from 1 to 6wt.% and indium from 0.01 to 0.05wt.% are studied. The NACE efficiency test and polarization are used in 3wt.% NaCl solution for corrosion characterization. The results showed that zinc and indium change the anode potential to more active potentials and improve the microstructure uniformity of anodes. The latter leads to more uniform corrosion. Optimum concentrations of zinc (5wt.%) and indium (0.02wt.%) were found in this respect. (orig.)

Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

1999-11-01

The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

Advances in aluminum anodizing

Science.gov (United States)

Dale, K. H.

1969-01-01

White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

Manufacturing and characterization of magnesium alloy foils for use as anode materials in rechargeable magnesium ion batteries

Science.gov (United States)

Schloffer, Daniel; Bozorgi, Salar; Sherstnev, Pavel; Lenardt, Christian; Gollas, Bernhard

2017-11-01

The fabrication of thin foils of magnesium for use as anode material in rechargeable magnesium ion batteries is described. In order to improve its workability, the magnesium was alloyed by melting metallurgy with zinc and/or gadolinium, producing saturated solid solutions. The material was extruded to thin foils and rolled to a thickness of approximately 100 μm. The electrochemical behavior of Mg-1.63 wt% Zn, Mg-1.55 wt% Gd and Mg-1.02 wt% Zn-1.01 wt% Gd was studied in (PhMgCl)2-AlCl3/THF electrolyte by cyclic voltammetry and galvanostatic cycling in symmetrical cells. Analysis of the current-potential curves in the Tafel region and the linear region close to the equilibrium potential show almost no effect of the alloying elements on the exchange current densities (5-45 μA/cm2) and the transfer coefficients. Chemical analyses of the alloy surfaces and the electrolyte demonstrate that the alloying elements not only dissolve with the magnesium during the anodic half-cycles, but also re-deposit during the cathodic half-cycles together with the magnesium and aluminum from the electrolyte. Given the negligible corrosion rate in aprotic electrolytes under such conditions, no adverse effects of alloying elements are expected for the performance of magnesium anodes in secondary batteries.

Using sewage sludge pyrolytic gas to modify titanium alloy to obtain high-performance anodes in bio-electrochemical systems

Science.gov (United States)

Gu, Yuan; Ying, Kang; Shen, Dongsheng; Huang, Lijie; Ying, Xianbin; Huang, Haoqian; Cheng, Kun; Chen, Jiazheng; Zhou, Yuyang; Chen, Ting; Feng, Huajun

2017-12-01

Titanium is under consideration as a potential stable bio-anode because of its high conductivity, suitable mechanical properties, and electrochemical inertness in the operating potential window of bio-electrochemical systems; however, its application is limited by its poor electron-transfer capacity with electroactive bacteria and weak ability to form biofilms on its hydrophobic surface. This study reports an effective and low-cost way to convert a hydrophobic titanium alloy surface into a hydrophilic surface that can be used as a bio-electrode with higher electron-transfer rates. Pyrolytic gas of sewage sludge is used to modify the titanium alloy. The current generation, anodic biofilm formation surface, and hydrophobicity are systematically investigated by comparing bare electrodes with three modified electrodes. Maximum current density (15.80 A/m2), achieved using a modified electrode, is 316-fold higher than that of the bare titanium alloy electrode (0.05 A/m2) and that achieved by titanium alloy electrodes modified by other methods (12.70 A/m2). The pyrolytic gas-modified titanium alloy electrode can be used as a high-performance and scalable bio-anode for bio-electrochemical systems because of its high electron-transfer rates, hydrophilic nature, and ability to achieve high current density.

Aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance

International Nuclear Information System (INIS)

Imaizumi, S.; Mikami, K.; Yamada, K.

1980-01-01

An aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance, which consists essentially of, in weight percentage: zinc - 0.3 to 3.0%, magnesium - 0.2 to 4.0%, manganese - 0.3 to 2.0%, and, the balance aluminum and incidental impurities; said alloy including an aluminum alloy also containing at least one element selected from the group consisting of, in weight percentage: indium - 0.005 to 0.2%, tin - 0.01 to 0.3%, and, bismuth - 0.01 to 0.3%; provided that the total content of indium, tin and bismuth being up to 0.3%

Impact of ac/dc spark anodizing on the corrosion resistance of Al-Cu alloys

Energy Technology Data Exchange (ETDEWEB)

Alsrayheen, Enam, E-mail: ealsrayh@ucalgary.ca [Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB, T2N 1N4 (Canada); McLeod, Eric, E-mail: hmolero@ucalgary.ca [Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB, T2N 1N4 (Canada); Rateick, Richard, E-mail: richard.rateick@honeywell.com [Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB, T2N 1N4 (Canada); Molero, Hebert, E-mail: Eric.McLeod@stmu.ab.ca [Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB, T2N 1N4 (Canada); Birss, Viola, E-mail: birss@ucalgary.ca [Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary AB, T2N 1N4 (Canada)

2011-07-01

An ac/dc spark anodization method was used to deposit an oxide film (6 {+-} 3 {mu}m in thickness) on the Al-Cu alloy AA2219. The oxide films were formed at 10 mA/cm{sup 2} for 30 min in an alkaline silicate solution, showing three main stages of growth. Scanning electron microscopy and electron microprobe analysis revealed that the oxide films are not uniform and consist of three main layers, an inner Al-rich barrier layer ({approx}1 {mu}m), an intermediate Al-Si mixed oxide layer ({approx}2 {+-} 1 {mu}m), and an outer porous Si-rich layer ({approx}3 {+-} 3 {mu}m). In addition, microscopic analysis showed that the Al{sub 2}Cu intermetallics present in the alloy have not been excessively oxidized during the anodization process and thus are retained beneath the oxide film, as desired. The coating passivity and corrosion resistance, evaluated using linear sweep voltammetry (LSV) in pH 7 borate buffer solution and electrochemical impedance spectroscopy (EIS) in 0.86 M NaCl solution, respectively, were both significantly improved after spark-anodization.

Anodizing of magnesium alloy AZ31 in alkaline solutions with silicate under continuous sparking

International Nuclear Information System (INIS)

Chai Liyuan; Yu Xia; Yang Zhihui; Wang Yunyan; Okido, Masazumi

2008-01-01

Anodization is a useful technique for forming protective films on magnesium alloys and improves its corrosion resistance. Based on the alkaline electrolyte solution with primary oxysalt developed previously, the optimum secondary oxysalt was selected by comparing the anti-corrosion property of anodic film. The structure, component and surface morphology of anodic film and cross-section were analyzed using energy dispersion spectrometer (EDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion process was detected by electrochemical impedance spectroscopy (EIS). The results showed that secondary oxysalt addition resulted in different anodizing processes, sparking or non-sparking. Sodium silicate was the most favorable additive of electrolyte, in which anodic film with the strongest corrosion resistance was obtained. The effects of process parameters, such as silicate concentration, applied current density and temperature, were also investigated. High temperature did not improve anti-property of anodic film, while applying high current density resulted in more porous surface of film

Process of film formation by anodizing AZ91D magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Qian Jiangang; Li Di; Zhang Feng [School of Materials Science and Engineering, Beijing Univ. of Aeronautics and Astronautics (China)

2005-07-01

The kinetics of film-forming process by anodizing AZ91D Mg alloy has been studied by ways of voltage-time and thickness-time curve, and the surface morphology, structure, composition and valence of element, phase constituent of anodic films have been analyzed by SEM, EDS, XPS and XRD respectively. The results show that the film-forming course can be divided into four stages. Formation of dense layer before sparking is the first stage. Formation of porous layer accompanied with a bit of small sparking is the second stage. Porous layer fast growth along with middle sparking is the third stage. Porous layer slowly-growth along with bigger sparking is the fourth stage. The anodic films contains approximately Mg,O,Si and B, which is composed mainly of MgO, MgSiO{sub 3} and Mg{sub 3}B{sub 2}O{sub 6}. (orig.)

Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

Directory of Open Access Journals (Sweden)

Michael D. Blanton

2012-09-01

Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

Influence of annealing and deformation on optical properties of ultra precision diamond turned and anodized 6060 aluminium alloy

DEFF Research Database (Denmark)

Tabrizian-Ghalehno, Naja; Hansen, Hans Nørgaard; Hansen, P.E.

2010-01-01

Influence of cold forging, and subsequent heat treatment and diamond turning on optical quality of anodized film on 6060 (AlMgSi) alloy was investigated and compared with microstructural changes. Heat treatment of the samples was carried out either prior to forging, post-forging, or both. The sur......Influence of cold forging, and subsequent heat treatment and diamond turning on optical quality of anodized film on 6060 (AlMgSi) alloy was investigated and compared with microstructural changes. Heat treatment of the samples was carried out either prior to forging, post-forging, or both...

Low voltage aluminium anodes. Optimization of the insert-anode bond

Energy Technology Data Exchange (ETDEWEB)

Le Guyader, Herve; Debout, Valerie; Grolleau, Anne-Marie [DCN Cherbourg, Departement 2EI, Place Bruat, BP 440, 50104 Cherbourg-Octeville (France); Pautasso, Jean-Pierre [DGA/CTA 16 bis, avenue Prieur de la Cote D' Or, 94 114 Arcueil Cedex (France)

2004-07-01

Zinc or Al/Zn/In sacrificial anodes are widely used to protect submerged marine structures from corrosion. Their Open Circuit Potential range from - 1 V vs. Ag/AgCl for Zn anodes to -1.1 V vs. Ag/AgCl for Al/Zn/In. These potentials are sufficiently electronegative as to reduce the threshold for stress corrosion cracking and/or hydrogen embrittlement, KISCC, especially in the presence of high strength alloys. In the 90's, an extensive research programme was initiated by DGA/DCN to implement a new low voltage material. Laboratory and full scale marine tests performed on industrial castings, as previously reported, led to the development of a new patented Al- 0.1%Ga alloy having a working potential of - 0.80 to - 0.83 V vs. Ag/AgCl. This alloy was also evaluated at full scale at the Naval Research Laboratory anode qualification site in Key West, Fl, and gave satisfactory results. Around 500 cylindrical AlGa anodes were then installed on a submerged marine structure replacing the classical zinc anode. A first inspection, carried out after a few months of service, showed that some of the anodes had not operated as expected, which led to further investigations. The examinations performed indicated that the problem was due to a bad metallurgical compatibility between the insert and the sacrificial materials inducing a poor bond between the anode and the plain rod insert. Progressive loss of contact between the anode and the structure to be protected was then induced by penetration of sea water and corrosion at the anode-insert interface. This phenomenon was aggravated by seawater pressure. Additional studies were therefore launched with two aims: (1) find temporary remedies for the anodes already installed on the structure; (2) correct the anode original design and/or manufacturing process to achieve the maximum performance on new anodes lots. This paper describes the various solutions investigated to improve the insert-anode bond: design of the anode, rugosity and

Studies of localized corrosion in welded aluminum alloys by the scanning reference electrode technique

Science.gov (United States)

Danford, M. D.; Nunes, A. C.

1995-01-01

Localized corrosion in welded samples of 2219-T87 Al alloy (2319 filler), 2090 Al-Li alloy (4043 and 2319 fillers), and 2195 Al-Li alloy (4043 and 2319 fillers) has been investigated using the relatively new scanning reference electrode technique. The weld beads are cathodic in all cases, leading to reduced anode/cathode ratios. A reduction in anode/cathode ratio leads to an increase in the corrosion rates of the welded metals, in agreement with results obtained in previous electrochemical and stress corrosion studies involving the overall corrosion rates of welded samples. The cathodic weld beads are bordered on both sides by strong anodic regions, with high propensity for corrosion.

Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

Science.gov (United States)

Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

2015-03-01

The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

Hydrothermal synthesis and electrochemical properties of nano-sized Co-Sn alloy anodes for lithium ion batteries

International Nuclear Information System (INIS)

He Jianchao; Zhao Hailei; Wang Jing; Wang Jie; Chen Jingbo

2010-01-01

Research highlights: → Nano-sized Co-Sn alloys were synthesized by hydrothermal route. → Li 2 O and CoSn can buffer the large volume change associated with lithiation of Sn. → A two-step reaction mechanism of CoSn 2 alloy during cycling was confirmed. - Abstract: Nano-sized Co-Sn alloys with a certain amount of Sn oxides used as potential anode materials for lithium ion batteries were synthesized by hydrothermal route. The effects of hydrothermal conditions and post annealing on the phase compositions and the electrochemical properties of synthesized powders were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) with energy dispersive spectra (EDS) analysis and galvanostatic cycling tests. Prolonging the dwelling time at the same hydrothermal temperature can increase the content of Sn oxides, which will lead to a high initial irreversible capacity loss but a better cycling stability owing to the buffer effect of irreversible product Li 2 O. Heat-treatment can increase the crystallinity and cause the presence of a certain amount of inert CoSn component, which both have positive impact on the cycling stability of Co-Sn electrode. By comparison with the lithiation/delithiation processes of metal Sn, a two-step mechanism of CoSn 2 alloy during cycling was confirmed.

The Effect of Grain Size on Mechanical Instability in Single-Phase Li-Alloy Anodes

National Research Council Canada - National Science Library

Wolfenstine, Jeff

2000-01-01

.... The results of this study suggest that decreasing the particle and/or grain size is not a practical approach to solving the mechanical instability problem of single phase Li alloys that are intended to be used as anodes in Li-ion batteries.

Effect of Silica Sol on Boric-sulfuric Acid Anodic Oxidation of LY12CZ Aluminum Alloy

Directory of Open Access Journals (Sweden)

LIU Hui-cong

2016-07-01

Full Text Available Aluminum alloy anodizing coatings were prepared for LY12CZ in the boric-sulfuric acid solution (45g/L sulfuric acid,8g/L boric acid with the addition of 10%,20%,30% (volume fractionsilica sol,with the gradient voltage of 15V. The current and voltage transients of the anodizing process were collected by data collection instrument. The surface morphologies,microstructure and chemical composition of the anodic coatings were characterized by scanning electron microscopy (SEM. The corrosion resistance was examined by neutral salt spray,electrochemical impedance spectroscopy (EIS test and titrating test. The results show that the different concentration of silica sol addition can influence the forming and dissolution of anodizing coatings,improve the compactness smoothness and corrosion resistance during the anodizing process in the boric-sulfuric acid solution.

Anodic behaviours, dissolution and passivation of iron-nickel alloys in sulphuric environment. Influence of friction

International Nuclear Information System (INIS)

Ponthiaux, Pierre

1990-01-01

This research thesis reports the study of anodic dissolution and passivation of iron-nickel alloys (10, 20 and 31 pc nickel) in a sulphuric environment, with or without friction, by using anodic polarization curves. Without friction, the three alloys have a similar behaviour as pure iron. The analysis reveals different dissolution and passivation mechanisms with pure iron, and highlights the influence of nickel content on corresponding kinetics. The influence of cyclic plane-on-plane friction has been studied for the 31 pc nickel alloy which has an unsteady austenitic structure. Fretting results in some modifications of polarization curves. These modifications are analysed with respect to fretting parameters (relative speed of antagonist surfaces, contact pressure). They reveal the specific influence of the following phenomena: material strain hardening, martensitic transformation induced by strain hardening, partial destruction of adsorbates and/or of the passive film. Modifications of polarization curves give also information on the evolution of friction characteristics with respect to speed (a phenomenon of lubrication by the electrolyte occurs) [fr

Enhancing pitting corrosion resistance of Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} high-entropy alloys by anodic treatment in sulfuric acid

Energy Technology Data Exchange (ETDEWEB)

Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Shih, H.C. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan (China)], E-mail: hcshih@mx.nthu.edu.tw

2008-12-01

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 {omega}cm{sup 2} as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 {omega}cm{sup 2}). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H{sub 2}SO{sub 4} solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe{sub 1.5}MnNi{sub 0.5} and Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} alloys optimized their surface structures and minimized their susceptibility to pitting corrosion.

Behavior of alloying elements during anodizing of Mg-Cu and Mg-W alloys in a fluoride/glycerol electrolyte

Czech Academy of Sciences Publication Activity Database

Palagonia, M. S.; Němcová, A.; Kuběna, Ivo; Šmíd, Miroslav; Gao, S.; Liu, H.; Zhong, X. L.; Haigh, S. J.; Santamaria, M.; Di Quarto, F.; Habazaki, H.; Skeldon, P.; Thomson, G.

2015-01-01

Roč. 162, č. 9 (2015), C487-C494 ISSN 0013-4651 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : alloying element * anodizing * ion beam analysis * magnesium * TEM Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 3.014, year: 2015 http://jes.ecsdl.org/content/162/9/C487.full

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

Energy Technology Data Exchange (ETDEWEB)

Garcia-Rubio, M. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain); Ocon, P. [Departamento de Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, 28049 Madrid (Spain)], E-mail: pilar.ocon@uam.es; Climent-Font, A. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid (UAM), 28049 Madrid (Spain); Smith, R.W. [Unidad de Microanalisis de Materiales, Parque Cientifico de Madrid (PCM), Campus de Cantoblanco, 28049 Madrid (Spain); Curioni, M.; Thompson, G.E.; Skeldon, P. [Corrosion and Protection Centre, School of Materials, University of Manchester, M60 1QD England (United Kingdom); Lavia, A.; Garcia, I. [Department of Surface Technologies, Engineering of Materials and Processes, Airbus Spain, Av. John Lennon s/n 28906 Getafe (Spain)

2009-09-15

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

International Nuclear Information System (INIS)

Garcia-Rubio, M.; Ocon, P.; Climent-Font, A.; Smith, R.W.; Curioni, M.; Thompson, G.E.; Skeldon, P.; Lavia, A.; Garcia, I.

2009-01-01

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.

Electrical Properties of a Thin Anodized Capacitor Made of Y-Doped Al Alloy Film

Science.gov (United States)

Onozuka, Tomotake; Sasaki, Hayato; Mikuni, Naohiro; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

2005-09-01

We have prepared an Al-Y anodized capacitor using sputter-deposited Al-Y alloy film with 5 at. % Y atoms, and evaluated the capacitor properties and the leakage current properties before and after heat treatment. In addition, the characterization of Al-Y anodized films was examined by X-ray diffraction, Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy analyses. As a result, it is revealed that the thermal stability of an Al-Y anodized capacitor is superior to that of a pure Al anodized capacitor because of its excellent passive nature, and the loss properties can be improved by increasing the heat treatment temperature in air because of the reduction of the equivalent series resistance. Furthermore, it is clarified that the cause of the short-circuited state observed at 550°C is the formation of a narrow capillary-like conduction path of metallic Al atoms as a result of the interdiffusion of Al.

Prevention of Crevice Corrosion of STS 304 Stainless Steel by a Mg-alloy Galvanic Anode

International Nuclear Information System (INIS)

Lim, U. J.; Yun, B. D.; Kim, J. J.

2006-01-01

Prevention of crevice corrosion was studied for STS 304 stainless steel using a Mg-alloy galvanic anode in solutions with various specific resistivity. The crevice corrosion and corrosion protection characteristics of the steel was investigated by the electrochemical polarization and galvanic corrosion tests. Experimental results show that the crevice corrosion of STS 304 stainless steel does not occur in solutions of high specific resistivity, but it occurs in solutions of low specific resistivity like in solutions with resistivities of 30, 60 and 115 Ω · m. With decreasing specific resistivity of the solution, the electrode potential of STS 304 stainless steel in the crevice is lowered. The potential of STS 304 stainless steel in the crevice after coupling is cathodically polarized more by decreasing specific resistivity indicating that the crevice corrosion of STS 304 stainless steel is prevented by the Mg-alloy galvanic anode

Corrosion and Discharge Behaviors of Mg-Al-Zn and Mg-Al-Zn-In Alloys as Anode Materials

Directory of Open Access Journals (Sweden)

Jiarun Li

2016-03-01

Full Text Available The Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(1%, 1.5%, 2%In alloys were prepared by melting and casting. Their microstructures were investigated via metallographic and energy-dispersive X-ray spectroscopy (EDS analysis. Moreover, hydrogen evolution and electrochemical tests were carried out in 3.5 wt% NaCl solution aiming at identifying their corrosion mechanisms and discharge behaviors. The results suggested that indium exerts an improvement on both the corrosion rate and the discharge activity of Mg-Al-Zn alloy via the effects of grain refining, β-Mg17Al12 precipitation, dissolving-reprecipitation, and self-peeling. The Mg-6%Al-3%Zn-1.5%In alloy with the highest corrosion rate at free corrosion potential did not perform desirable discharge activity indicating that the barrier effect caused by the β-Mg17Al12 phase would have been enhanced under the conditions of anodic polarization. The Mg-6%Al-3%Zn-1.0%In alloy with a relative low corrosion rate and a high discharge activity is a promising anode material for both cathodic protection and chemical power source applications.

Anodization of Zr-Nb-Cu alloy in mandelic acid - effect of solvent and anionic impurities

International Nuclear Information System (INIS)

Lavanya, A.; Raghunath Reddy, G.; Ch Anjaneyulu

2004-01-01

Anodization of zirconium-niobium-copper (ZNC) alloy in 0.1 M mandelic acid has been carried out. The effect of solvent (ethylene glycol) and added anionic impurities (sulphates, phosphates and carbonates) showed better kinetic results (formation rate, current efficiency and differential field of formation). (author)

25th anniversary article: Understanding the lithiation of silicon and other alloying anodes for lithium-ion batteries.

Science.gov (United States)

McDowell, Matthew T; Lee, Seok Woo; Nix, William D; Cui, Yi

2013-09-25

Alloying anodes such as silicon are promising electrode materials for next-generation high energy density lithium-ion batteries because of their ability to reversibly incorporate a high concentration of Li atoms. However, alloying anodes usually exhibit a short cycle life due to the extreme volumetric and structural changes that occur during lithium insertion/extraction; these transformations cause mechanical fracture and exacerbate side reactions. To solve these problems, there has recently been significant attention devoted to creating silicon nanostructures that can accommodate the lithiation-induced strain and thus exhibit high Coulombic efficiency and long cycle life. In parallel, many experiments and simulations have been conducted in an effort to understand the details of volumetric expansion, fracture, mechanical stress evolution, and structural changes in silicon nanostructures. The fundamental materials knowledge gained from these studies has provided guidance for designing optimized Si electrode structures and has also shed light on the factors that control large-volume change solid-state reactions. In this paper, we review various fundamental studies that have been conducted to understand structural and volumetric changes, stress evolution, mechanical properties, and fracture behavior of nanostructured Si anodes for lithium-ion batteries and compare the reaction process of Si to other novel anode materials. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

Science.gov (United States)

Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

2016-01-01

A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

An AC impedance study of self-discharge mechanism of nickel-metal hydride (Ni-MH) battery using Mg{sub 2}Ni-type hydrogen storage alloy anode

Energy Technology Data Exchange (ETDEWEB)

Cui, N.; Luo, J.L. [University of Alberta, Edmonton, Alberta (Canada). Department of Chemical and Materials Engineering

2000-07-01

The self-discharge mechanism during storage in open-circuit states of a Ni-MH battery using a Mg{sub 2}Ni-type hydrogen storage alloy anode was investigated by electrochemical impedance spectroscopy (EIS) and X-ray diffraction (XRD). The loss of discharge capacity for this battery can be ascribed to two causes: (i) desorption of hydrogen from the Mg{sub 1.95}Y{sub 0.05}Ni{sub 0.92}Al{sub 0.08} hydride anode; and (ii) anode surface degradation resulting from oxidation of the magnesium alloy in the electrolyte. At the higher open-circuit voltages (OCV), the former was mainly responsible for a high self-discharge rate, while the latter might dominate the loss of capacity at the lower OCV. XRD results confirmed that Mg(OH){sub 2} formed on the magnesium alloy anode after storage in an open-circuit condition for 20 days. (author)

Length-dependent corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of Ni-Ti-O nanopores anodically grown on biomedical NiTi alloy.

Science.gov (United States)

Hang, Ruiqiang; Liu, Yanlian; Bai, Long; Zhang, Xiangyu; Huang, Xiaobo; Jia, Husheng; Tang, Bin

2018-08-01

In the present work, nickel-titanium-oxygen nanopores with different length (0.55-114 μm) were anodically grown on nearly equiatomic nickel-titanium (NiTi) alloy. Length-dependent corrosion behavior, nickel ion (Ni 2+ ) release, cytocompatibility, and antibacterial ability were investigated by electrochemical, analytical chemistry, and biological methods. The results show constructing nanoporous structure on the NiTi alloy improve its corrosion resistance. However, the anodized samples release more Ni 2+ than that of the bare NiTi alloy, suggesting chemical dissolution of the nanopores rather than electrochemical corrosion governs the Ni 2+ release. In addition, the Ni 2+ release amount increases with nanopore length. The anodized samples show good cytocompatibility when the nanopore length is covers the one (1-11 μm) that the nanopores showing favorable antibacterial ability. Consequently, the nanopores with length in the range of 1-11 μm are promising as coatings of biomedical NiTi alloy for anti-infection, drug delivery, and other desirable applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy

Directory of Open Access Journals (Sweden)

Sonia C. Ferreira

2014-12-01

Full Text Available Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp produced by powder metallurgy (PM were anodized under voltage control in tartaric-sulfuric acid (TSA. In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050 anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiCnp. The current peaks and the steady-state current density recorded at each voltage step increases with the SiCnp volume fraction due to the oxidation of the SiCnp. The formation mechanism of the anodic film on Al/SiCnp composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiCnp in the anodic film.

Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy

Science.gov (United States)

Ferreira, Sonia C.; Conde, Ana; Arenas, María A.; Rocha, Luis A.; Velhinho, Alexandre

2014-01-01

Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiCnp. The current peaks and the steady-state current density recorded at each voltage step increases with the SiCnp volume fraction due to the oxidation of the SiCnp. The formation mechanism of the anodic film on Al/SiCnp composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiCnp in the anodic film. PMID:28788295

Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy.

Science.gov (United States)

Ferreira, Sonia C; Conde, Ana; Arenas, María A; Rocha, Luis A; Velhinho, Alexandre

2014-12-19

Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiC np ) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiC np on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodized under the same conditions. The processing method of the aluminum alloys influences the efficiency of the anodizing process, leading to a lower thicknesses for the unreinforced Al-PM alloy regarding the AA1050. The current density versus time response is strongly dependent on the amount of SiC np . The current peaks and the steady-state current density recorded at each voltage step increases with the SiC np volume fraction due to the oxidation of the SiC np . The formation mechanism of the anodic film on Al/SiC np composites is different from that occurring in AA1050, partly due the heterogeneous distribution of the reinforcement particles in the metallic matrix, but also to the entrapment of SiC np in the anodic film.

Directly smelted lead-tin alloys: A historical perspective

Science.gov (United States)

Dube, R. K.

2010-08-01

This paper discusses evidence related to the genesis and occurrence of mixed lead-tin ore deposit consisting of cassiterite and the secondary minerals formed from galena. These evidences belong to a very long time period ranging from pre-historic to as late as the nineteenth century a.d. This type of mixed ore deposits was smelted to prepare lead-tin alloys. The composition of the alloy depended on the composition of the starting ore mixture. A nineteenth century evidence for the production of directly smelted lead-tin alloys in southern Thailand is discussed. A unique and rather uncommon metallurgical terminology in Sanskrit language— Nāgaja—was introduced in India for the tin recovered from impure lead. This suggests that Indians developed a process for recovering tin from lead-tin alloys, which in all probability was based on the general principle of fire refining. It has been shown that in the context of India the possibility of connection between the word Nāgaja and the directly smelted lead-tin alloys cannot be ruled out.

Anodic galvanostatic polarization of AA2024-T3 aircraft alloy in conventional mineral acids

Energy Technology Data Exchange (ETDEWEB)

Kozhukharov, S., E-mail: stephko1980@abv.bg [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria); Girginov, Ch. [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria); Avramova, I. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Science, 11 “Georgi Bonchev” Str., 1113, Sofia (Bulgaria); Machkova, M. [Department of Chemical Sciences, University of Chemical Technology and Metallurgy, 8 “Kliment Okhridski” Blvd, 1756, Sofia (Bulgaria)

2016-09-01

The present study is devoted to the determination of the impact of the anodization of AA2024-T3 alloys in HCl, HNO{sub 3}, H{sub 2}SO{sub 4} or H{sub 3}PO{sub 4} on the samples’ surface morphology and properties. Subsequent systematic assessments were performed by Scanning Electron Microscopy (SEM), Energy Dispersion X-Ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS). These observations were combined with Linear Voltammetry (LVA) and Electrochemical Impedance Spectroscopy (EIS) after 48 and 168 h of exposure to a 3.5% NaCl model corrosive medium. The main result is, that completely different effects were observed in accordance to the acid used. It was established that the monoprotonic acids have a deep destructive effect due to dissolution of the alloy components, whereas the polyprotonic ones possess either indistinguishable influence, or surface film formation. - Highlights: • AA2024 was polarized anodically in 15%{sub wt} acid solutions at 15 mA cm{sup −2} for 2 h. • Four mineral acids were selected for investigation: HCl, HNO{sub 3}, H{sub 2}SO{sub 4} and H{sub 3}PO{sub 4}. • SEM, EDX and XPS were applied for morphological description. • Electrochemical characterizations were performed by EIS and linear voltammetry. • The acid used predetermines completely different interaction with the AA2024 alloy.

Processing of copper anodic-slimes for extraction of valuable metals.

Science.gov (United States)

Amer, A M

2003-01-01

This work focuses on processing of anodic slimes obtained from an Egyptian copper electrorefining plant. The anodic slimes are characterized by high concentrations of copper, lead, tin and silver. The proposed hydrometallurgical process consists of two leaching stages for the extraction of copper (H(2)SO(4)-O(2)) and silver (thiourea-Fe3+), and pyrometallurgical treatment of the remaining slimes for production of Pb-Sn soldering alloy. Factors affecting both the leaching and smelting stages were studied.

Work function of oxygen exposed lead and lead/indium alloy films

International Nuclear Information System (INIS)

Gundlach, K.H.; Hellemann, H.P.; Hoelzl, J.

1982-01-01

The effect of indium in superconducting tunnel junctions with lead/indium alloy base electrodes is investigated by measuring the vacuum work function of lead, indium, and lead/indium alloy films. It is found that the anomalous decrease of the work function of lead upon exposure to oxygen, explained by the penetration of oxygen into the inner surface of the lead film, is reversed into a slight increase in work function when some indium is added to the lead. This result indicates that the addition of indium provides a protection by suppressing the penetration of oxygen (and probably other gases) into the interior of the thin film

Carbon-shell-constrained silicon cluster derived from Al-Si alloy as long-cycling life lithium ion batteries anode

Science.gov (United States)

Su, Junming; Zhang, Congcong; Chen, Xiang; Liu, Siyang; Huang, Tao; Yu, Aishui

2018-03-01

Although silicon is the most promising anode material for Li-ion batteries, large volume expansion during lithiation and delithiation is the main obstacle limiting the commercial application of silicon anodes. There are two ways to alleviate volume expansion and prevent further pulverization of a Si anode: fabrication of a rational nanostructure possessing void spaces and uniform distribution of the conducting sites, without a good balance effect in mitigating the limiting factors and enhancing battery performance. In this paper, we propose a novel nanostructure - a carbon-shell-constrained Si cluster (Si/C shell) with both adequate void space and good distribution of electrical contact sites to guarantee homogeneous lithiation in the initial cycle. Benefiting from the ability to maintain electrical conductivity of the outer carbon shell, even after cluster fragmentation, the Si/C shell synthesized from low-cost commercial Al-Si alloy spheres can deliver 0.03% capacity loss from 100th to 1000th cycles at a current density of 1 A g-1. The Si/C shell sample with the dual functional structure mentioned above can also maintain its own nanostructure during cycling and deliver excellent rate performance. It is a concise and scalable strategy which can simplify the preparation of other alloy anode materials for Li-ion batteries.

Precipitation in a lead calcium tin anode

International Nuclear Information System (INIS)

Pérez-González, Francisco A.; Camurri, Carlos G.; Carrasco, Claudia A.; Colás, Rafael

2012-01-01

Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 °C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn 3 particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: ► The distance between precipitates in a lead alloy is recorded. ► The relationship between the distance and the cooling rate is established. ► It is found that the strengthening of the alloy depends on the distance between precipitates.

Electrically conductive anodized aluminum coatings

Science.gov (United States)

Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

2001-01-01

A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

The Incorporation of Lithium Alloying Metals into Carbon Matrices for Lithium Ion Battery Anodes

Science.gov (United States)

Hays, Kevin A.

An increased interest in renewable energies and alternative fuels has led to recognition of the necessity of wide scale adoption of the electric vehicle. Automotive manufacturers have striven to produce an electric vehicle that can match the range of their petroleum-fueled counterparts. However, the state-of-the-art lithium ion batteries used to power the current offerings still do not come close to the necessary energy density. The energy and power densities of the lithium ion batteries must be increased significantly if they are going to make electric vehicles a viable option. The chemistry of the lithium ion battery, based on lithium cobalt oxide cathodes and graphite anodes, is limited by the amount of lithium the cathode can provide and the anode will accept. While these materials have proven themselves in portable electronics over the past two decades, plausible higher energy alternatives do exist. The focus is of this study is on anode materials that could achieve a capacity of more than 3 times greater than that of graphite anodes. The lithium alloying anode materials investigated and reported herein include tin, arsenic, and gallium arsenide. These metals were synthesized with nanoscale dimensions, improving their electrochemical and mechanical properties. Each exhibits their own benefits and challenges, but all display opportunities for incorporation in lithium ion batteries. Tin is incorporated in multilayer graphene nanoshells by introducing small amounts of metal in the core and, separately, on the outside of these spheres. Electrolyte decomposition on the anode limits cycle life of the tin cores, however, tin vii oxides introduced outside of the multilayer graphene nanoshells have greatly improved long term battery performance. Arsenic is a lithium alloying metal that has largely been ignored by the research community to date. One of the first long term battery performance tests of arsenic is reported in this thesis. Anodes were made from nanoscale

Study of anodic dissolution of Fe-Ru alloy with the aid of mossbauer spectroscopy

International Nuclear Information System (INIS)

Khlystov, A.S.; Fasman, A.B.; Kil'dibekova, G.A.

1986-01-01

This paper uses Fe 57 Mossbauer spectroscopy, whereby iron compounds may be identified quantitatively and their composition and structure can be determined, for the study of the relationships of slime formation from Fe-Ru binary alloys. Both the products of dissolution and the composition and state of intermediate phases formed at various stages of anodic dissolution were studied simultaneously. It was found that the slimes formed both during chemical and during electrochemical destruction of ruthenium-iron alloys are finely dispersed systems of complex composition, analogous to those formed in the course of electrochemical dissolution of Ni-Ru alloys, which were found to contain oxide phases of ruthenium (by x-ray spectroscopy and ESCA) and of nickel (by x-ray phase analysis). The difference between the slime compositions is determined mainly by kinetic factors

Anode behaviors of aluminum antimony synthesized by mechanical alloying for lithium secondary battery

International Nuclear Information System (INIS)

Honda, H.; Sakaguchi, H.; Fukuda, Y.; Esaka, T.

2003-01-01

AlSb was synthesized as an anode active material for lithium secondary battery using mechanical alloying (MA). Electrochemical performance was examined on the electrodes of AlSb synthesized with different MA time. The first charge (lithium-insertion) capacity of the AlSb electrodes decreased with increasing the MA time. The discharge capacity on repeating charge-discharge cycle, however, did not show the same dependence. The electrode, consisting of the 20 h MA sample exhibited the longest charge-discharge life cycle, suggesting that there is the optimum degree of internal energy derived from the strain and/or the amorphization due to mechanical alloying. These results were evaluated using ex situ X-ray diffraction and differential scanning calorimetry

Surface treatment of new type aluminum lithium alloy and fatigue crack behaviors of this alloy plate bonded with Ti–6Al–4V alloy strap

International Nuclear Information System (INIS)

Sun, Zhen-Qi; Huang, Ming-Hui; Hu, Guo-Huai

2012-01-01

Highlights: ► A new generation aluminum lithium alloy which special made for Chinese commercial plane was investigated. ► Pattern of aluminum lithium alloy and Ti alloy were shown after anodization. ► Crack propagation of samples bonded with different wide Ti straps were studied in this paper. -- Abstract: Samples consisting of new aluminum lithium alloy (Al–Li alloy) plate developed by the Aluminum Company of America and Ti–6Al–4V alloy (Ti alloy) plate were investigated. Plate of 400 mm × 140 mm × 2 mm with single edge notch was anodized in phosphoric solution and Ti alloy plate of 200 mm × 20 (40) mm × 2 mm was anodized in alkali solution. Patterns of two alloys were studied at original/anodized condition. And then, aluminum alloy and Ti alloy plates were assembled into a sample with FM 94 film adhesive. Fatigue crack behaviors of the sample were investigated under condition of nominal stress σ = 36 MPa and 54 MPa, stress ratio of 0.1. Testing results show that anodization treatment modifies alloys surface topography. Ti alloy bonding to Al–Li alloy plate effectively retards crack growth than that of Al–Li alloy plate. Fatigue life of sample bonded with Ti alloy strap improves about 62.5% than that of non-strap plate.

Anodization and Optical Appearance of Sputter Deposited Al-Zr Coatings

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara

2014-01-01

of the anodized layer. The microstructure of the coating is found to influence the appearance of anodized layer owing to the presence of completely or partially dissolved second phases during anodizing process. Oxidation status of the second phase particles in the coatings affected the light absorption......Anodized Al alloy components are extensively used in various applications like architectural, decorative and automobiles for corrosion protection and/or decorative optical appearance. However, tailoring the anodized layer for specific optical appearance is limited due to variation in composition...... and microstructure of the commercial alloys, and even more difficult with recycled alloys. Sputter coating methods promise to control the chemical composition of the Al alloy surfaces and eventually modify the microstructure of the surfaces with heat treatments thus enabling the freedom on the substrate quality...

Evaluation of colloidal Pd and Pd-alloys as anode electrocatalysts for direct borohydride fuel cells applications

Energy Technology Data Exchange (ETDEWEB)

Atwan, M.H. [General Motors R and D Technical Center, Warren, MI (United States); Gyenge, E.L. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Northwood, D.O. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

2010-07-01

An evaluation was conducted to assess the use of colloidal palladium (Pd) and Pd alloys as anode electrocatalysts for direct borohydride fuel cell applications. A modified Bonneman method was used to investigate borohydride oxidation on supported Pd and Pd-alloy nano-electrocatalysts. Cyclic voltammetry (CV), rotating disk electrode (RDE) voltammetry, and single fuel cell test stations were used to determine Tafel slopes, exchange current densities, oxidation peak potentials, and fuel cell performance. The study also investigated the influence of temperature and oxidant flow and fuel flow rates on fuel cell performance. The study showed that the current density of the fuel cell increased with increases in temperature for all the investigated Pd electrocatalysts. However, the increase in current density was not as high as expected when fuel flow rates were increased. A current density of 50 mA cm{sup -2} was observed at 298 K with a Pd-Ir anode catalyst operating at a cell voltage of 0.5 V. 28 refs., 1 tab., 15 figs.

Anodizing And Sealing Aluminum In Nonchromated Solutions

Science.gov (United States)

Emmons, John R.; Kallenborn, Kelli J.

1995-01-01

Improved process for anodizing and sealing aluminum involves use of 5 volume percent sulfuric acid in water as anodizing solution, and 1.5 to 2.0 volume percent nickel acetate in water as sealing solution. Replaces process in which sulfuric acid used at concentrations of 10 to 20 percent. Improved process yields thinner coats offering resistance to corrosion, fatigue life, and alloy-to-alloy consistency equal to or superior to those of anodized coats produced with chromated solutions.

Precipitation in a lead calcium tin anode

Energy Technology Data Exchange (ETDEWEB)

Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

2012-02-15

Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

Anodic solubility and electrochemical machining of hard alloys on the base of chromium and titanium carbides

Energy Technology Data Exchange (ETDEWEB)

Davydov, A D; Klepikov, A N; Malofeeva, A N; Moroz, I I

1985-01-01

The regularities of anodic behaviour and electrochemical machining (ECM) of the samples of three materials with the following compositions: 25% of Cr/sub 3/C/sub 2/, 15% of Ni, 70% of TiC, 25% of Ni, 5% of Cr, 70% of TiC, 15% of Ni, 15% of Mo are investigated. It is shown that the electrochemical method is applicable to hard alloys machining on the base of chromium and titanium carbides, the machining of which mechanically meets serious difficulties. The alloys machining rate by a mobile cathode constitutes about 0.5 mm/min.

Three-dimensional carbon network confined antimony nanoparticle anodes for high-capacity K-ion batteries.

Science.gov (United States)

Han, Chunhua; Han, Kang; Wang, Xuanpeng; Wang, Chenyang; Li, Qi; Meng, Jiashen; Xu, Xiaoming; He, Qiu; Luo, Wen; Wu, Liming; Mai, Liqiang

2018-04-19

Antimony (Sb) represents a promising anode for K-ion batteries (KIBs) due to its high theoretical capacity and suitable working voltage. However, the large volume change that occurs in the potassiation/depotassiation process can lead to severe capacity fading. Herein, we report a high-capacity anode material by in situ confining Sb nanoparticles in a three-dimensional carbon framework (3D SbNPs@C) via a template-assisted freeze-drying treatment and subsequent carbothermic reduction. The as-prepared 3D SbNPs@C hybrid material delivers high reversible capacity and good cycling stability when used as the anode for KIBs. Furthermore, cyclic voltammetry and in situ X-ray diffraction analysis were performed to reveal the intrinsic mechanism of a K-Sb alloying reaction. Therefore, this work is of great importance to understand the electrochemical process of the Sb-based alloying reaction and will pave the way for the exploration of high performance KIB anode materials.

Selective anodic dissolution of cerium from aluminium alloys under potentiostatic conditions

International Nuclear Information System (INIS)

Gol'dshtejn, S.L.; Raspopin, S.P.; Seleznev, V.D.; Tunin, A.V.; Fedorov, V.A.

1975-01-01

A study was made of selective anodic dissolution of aluminum alloys containing cerium in concentrations from 0.5 to 10% by mass. The electropurification was carried out with the aid of a potentiostatic setup at 700 deg C in atmosphere of purified argon. Liquid aluminum served as the cathode, with chlorine half-cell as reference electrode and the melt of equimolar KCl-NaCl mixture as the electrolyte. The ''current-time'' plots are presented for selective ionization of cerium from aluminum alloys at preset potential values on the installation. For PHIsub(preset)=-2.04 v the current of potentiostatic electrolysis fades out to that of the supporting electrolyte, and the process itself proceeds at a rate that provides maximal extraction of cerium from the alloy (csub9finite)approximately equal to 0.002% by mass) at minimal ionization of the metalsolvent (Δ Msub(Al)approximately equal to 0.2). Alloys containing not less then 1% by mass of Ce exhibit a characteristic abrupt change of the attenuation coefficient apparently owing to nonlinear dependence of unbalance (ΔE) of signals at the input of the potentiostat. The ''ΔE-c'' function for Al alloy containing 0.5% by mass of Ce can be approximated by linear function. In this case the current of potentiostatic electrolysis approaches the value of the limiting diffusion current. To obtain the relationship between the magnitude of the limiting current of Ce ionization and the initial composition of the dissolving alloy, measurements were made under potentiodynamic conditions at a scanning rate of approximately equal to 500 mv/min. The results indicate that isub(intermediate) is directly proportional to csub(initial). It was shown that under the conditions employed, practically complete (csub(finite)<=0.004% by mass) extraction of the electronegative component is possible without noticeable ionization of the metal-solvent

Anodic Behavior of Alloy 22 in Calcium Chloride and in Calcium Chloride Plus Calcium Nitrate Brines

International Nuclear Information System (INIS)

Evans, K.J.; Day, S.D.; Ilevbare, G.O.; Whalen, M.T.; King, K.J.; Hust, G.A.; Wong, L.L.; Estill, J.C.; Rebak, R.B.

2003-01-01

Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl 2 ) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of the tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl 2 at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy

Carbonate fuel cell anodes

Science.gov (United States)

Donado, Rafael A.; Hrdina, Kenneth E.; Remick, Robert J.

1993-01-01

A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process for production of the lithium ferrite containing anode by slipcasting.

Electrochemical Random Signal Analysis during Localized Corrosion of Anodized 1100 Aluminum Alloy in Chloride Environments

International Nuclear Information System (INIS)

Sakairi, M.; Shimoyama, Y.; Nagasawa, D.

2008-01-01

A new type of electrochemical random signal (electrochemical noise) analysis technique was applied to localized corrosion of anodic oxide film formed 1100 aluminum alloy in 0.5 kmol/m 3 H 3 BO 4 /0.05 kmol/m 3 Na 2 B 4 O 7 with 0.01 kmol/m 3 NaCl. The effect of anodic oxide film structure, barrier type, porous type, and composite type on galvanic corrosion resistance was also examined. Before localized corrosion started, incubation period for pitting corrosion, both current and potential slightly change as initial value with time. The incubation period of porous type anodic oxide specimens are longer than that of barrier type anodic oxide specimens. While pitting corrosion, the current and potential were changed with fluctuations and the potential and the current fluctuations show a good correlation. The records of the current and potential were processed by calculating the power spectrum density (PSD) by the Fast Fourier Transform (FFT) method. The potential and current PSD decrease with increasing frequency, and the slopes are steeper than or equal to minus one (-1). This technique allows observation of electrochemical impedance changes during localized corrosion

Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

International Nuclear Information System (INIS)

Rashvand avei, M.; Jafarian, M.; Moghanni Bavil Olyaei, H.; Gobal, F.; Hosseini, S.M.; Mahjani, M.G.

2013-01-01

The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media. - Highlights: • Decreasing the corrosion rate of tested alloys in 4 M NaOH solution specially AA6060. • Lowering the extent of anodic polarization at a current density of 50 mA cm −2 . • High inhibitor efficiency about 97% for AA6060

Study of the alloying additives and alkaline zincate solution effects on the commercial aluminum as galvanic anode for use in alkaline batteries

Energy Technology Data Exchange (ETDEWEB)

Rashvand avei, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Jafarian, M., E-mail: mjafarian@kntu.ac.ir [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Moghanni Bavil Olyaei, H. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Gobal, F. [Department of Chemistry, Sharif University of Technology, P.O. Box 11365-8516, Tehran (Iran, Islamic Republic of); Hosseini, S.M. [Jahad Organization – Science and Technology Center, Tehran (Iran, Islamic Republic of); Mahjani, M.G. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)

2013-12-16

The corrosion behavior of different grades of commercial aluminum such as AA1040, AA5083, AA6060 and AA7075 in ZnO-containing 4 M NaOH has been determined by using open circuit potential-time measurements (OCP), galvanostatic and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) reveal that ZnO produces the inhibition effect by the formation of a zinc-containing deposit layer on the surface of aluminum electrodes. Although the influence of zincating on the performance of aluminum alloys and considering the amount of alloying elements such as zinc, magnesium and manganese in AA7075 and AA5083 alloys is much more than AA6060 one, the AA6060 aluminum exhibits negligible corrosion rate. Alloying aluminum with other elements and modifying the composition of the electrolyte is a necessary condition for reducing the self-corrosion of the aluminum anodes, whereas the proportion of the amount of additive elements is sufficient and important condition. As AA6060 with a low amount of Zn and Mg, but the high value of the ratio of (Mg/Zn) content (>400) can serve as a good galvanic anode in the alkaline media. - Highlights: • Decreasing the corrosion rate of tested alloys in 4 M NaOH solution specially AA6060. • Lowering the extent of anodic polarization at a current density of 50 mA cm{sup −2}. • High inhibitor efficiency about 97% for AA6060.

Phase formation in alloy-type anode materials in the quaternary system Li-Sn-Si-C

Energy Technology Data Exchange (ETDEWEB)

Druee, Martin; Seyring, Martin [Jena Univ. (Germany). Otto Schott Inst. of Materials Research; Liang, Song-Mao; Kozlov, Artem; Schmid-Fetzer, Rainer [Clausthal Univ. of Technology, Clausthal-Zellerfeld (Germany). Inst. of Metallurgy; Song, Xiaoyan [Beijing Univ. of Technology (China). Key Lab. of Advanced Functional Materials; Rettenmayr, Markus [Jena Univ. (Germany). Otto Schott Inst. of Materials Research; Jena Univ. (Germany). Center for Energy and Environmental

2017-11-15

Investigations on the thermodynamics of alloy-type anode materials have been carried out for the quaternary Li-C-Si-Sn system. Phase equilibria and phase stabilities were characterized in the binary subsystems Li-C, Li-Si, Li-Sn. The Calphad method was first used to optimize or completely re-establish all binary subsystems containing Li. For reasons of consistency, the binary subsystem Si-C had to be revisited and its Calphad description was modified. The ternary phase diagrams were then tentatively calculated by extrapolation from the binary subsystems and confirmed by key experiments. No ternary compounds were found. In order to verify the applicability of the anode materials in real batteries, some of the materials were nanostructured by ball milling and spark plasma sintering, the corresponding nanostructures were characterized. Theoretical predictions that nanograined Li{sub 2}C{sub 2} can also be used as cathode material were verified experimentally. The methodologies worked out in the present project (e.g. nanoscale structure transmission electron microscopy analysis, glow discharge optical emission spectroscopy) were also employed in other projects and led to publications concerning other materials such as Mg alloys, carbon nanofibers and an Mn-based antiperovskite.

The aluminum anode in deep ocean environments

International Nuclear Information System (INIS)

Schreiber, C.F.

1989-01-01

Results of field and mini-plant studies are presented for A1 + 0.045% Hg + 0.1% Si + 0.45% Zn* and A1 + 0.015% In + 0.1% Si + 3% Zn** anodes in varying depths of natural seawater. Current capacity and potential information are presented. In addition to information on anode current capacity and potential, polarization curves were obtained on both aluminum alloys using potentiostatic techniques at a simulated ocean depth of 1090 ft. (332 m). These data were compared with similarly run experiments at ocean surface pressures. As a basis of comparison, zinc anodes (U.S. Mil-A-18001H) were included as a companion alloy. Information gained on zinc is sufficient to accurately represent the behavior of this alloy. Results conclude that conditions of high pressure (and low temperature) associated with the alloys under test did not alter their galvanic behavior from that noted at the ocean surface

Effect of different ions on the anodic behaviour of alloy 800 chloride solutions at high temperature

International Nuclear Information System (INIS)

Lafont, C.J.; Alvarez, M.G.

1993-01-01

The anodic behaviour and passivity breakdown of alloy 800 in sodium bicarbonate and sodium phosphate aqueous solutions were studied in the temperature range from 100 degrees C to 280 degrees C by means of electrochemical techniques. The effect of phosphate or bicarbonate additions on the pitting susceptibility and pitting morphology of the alloy in chloride solutions was also examined. Experiments were performed in the following solutions: 0.1M NaHCO 3 , at 100 degrees C, 200 degrees C, 280 degrees C; 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 , at 100 degrees C, 200 degrees C and 280 degrees C, and 0.1M NaCl with different additions of bicarbonate ion (0.02M, 0.05M and 0.1M) and phosphate ion (0.01M, 0.05M and 0.1M) at 100 degrees C and 280 degrees C. The anodic polarization curves of alloy 800 in deaerated 0.1M NaHCO 3 and 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 solutions exhibited a similar shape at all the tested temperatures. No localized or generalized corrosion was detected on the metallic surface after polarization. The results obtained in chloride plus bicarbonate and chloride plus phosphate mixtures showed that the pitting potential of alloy 800 in chloride solutions was increased by the presence of bicarbonate or phosphate ions. In those solutions where the inhibitor concentration in the mixture is equal or higher than the chloride concentration , the behaviour of the alloy is similar to the one observed in the absence of chlorides. Changes in pitting morphology were found in phosphate containing solutions, while the pits found in bicarbonate containing solutions were similar to those formed in pure chloride solutions. (author). 3 refs., 4 figs

Non-sparking anodization process of AZ91D magnesium alloy under low AC voltage

International Nuclear Information System (INIS)

Li, Weiping; Li, Wen; Zhu, Liqun; Liu, Huicong; Wang, Xiaofang

2013-01-01

Highlights: ► Four different processes appear on magnesium alloys with applied voltage increase. ► Non-sparking film formation process occurred in the range of 6–10 V AC. ► The film was composed of Mg 2 SiO 4 with a stable growth rate in 30 min. ► Film growth was a balance of electrochemical dissolution and chemical deposition. -- Abstract: Anodization is widely recognized as one of the most important surface treatments for magnesium alloys. However, since high voltage oxidation films are limited in some applications due to porosity and brittleness, it is worthwhile to explore the non-sparking oxidizing process. In this work, AZ91D was electrochemically anodized at different AC voltages in an electrolyte containing 120 g/L NaOH and 80 g/L Na 2 SiO 3 ·9H 2 O. The effects of voltage on the surface morphology, composition and reaction process, especially the non-sparking discharge anodic film formation process, were investigated. The results showed that four different processes would appear according to the applied voltage variation from 6 V to 40 V, and that the non-sparking film formation process occurred in the range of 6–10 V. The film formed on the AZ91D surface under 10 V AC was mainly composed of Mg 2 SiO 4 with a lamellar structure. The horizontal and vertical expansion of the lamellar structure resulted in the formation of a multi-layered structure with a stable, linear growth rate for 30 min. The non-sparking film formation process can be considered to be the result of a balance of electrochemical dissolution and chemical deposition reaction

Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions.

Science.gov (United States)

Ross, Alexandra P; Webster, Thomas J

2013-01-01

Current titanium-based implants are often anodized in sulfuric acid (H(2)SO(4)) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone-implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications.

Electric charging/discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons.

Science.gov (United States)

Fukuhara, Mikio; Sugawara, Kazuyuki

2014-01-01

Charging/discharging behaviors of de-alloyed and anodic oxidized Ti-Ni-Si amorphous alloy ribbons were measured as a function of current between 10 pA and 100 mA, using galvanostatic charge/discharging method. In sharp contrast to conventional electric double layer capacitor (EDLC), discharging behaviors for voltage under constant currents of 1, 10 and 100 mA after 1.8 ks charging at 100 mA show parabolic decrease, demonstrating direct electric storage without solvents. The supercapacitors, devices that store electric charge on their amorphous TiO2-x surfaces that contain many 70-nm sized cavities, show the Ragone plot which locates at lower energy density region near the 2nd cells, and RC constant of 800 s (at 1 mHz), which is 157,000 times larger than that (5 ms) in EDLC.

The influence of the deoxidization on the aluminum alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, Q.; Wu, X.; Wang, W. [Beijing Univ. of Aeronautics and Astronautics (China). Dept. of Mater. Sci. and Eng.

2000-07-01

Though the composition of the 7075 and 7050 aluminum alloys are quite similar, the anodic behaviors of the two alloys were quite different. Unlike the 7075 alloy, a chromic acid anodic film could not be formed on the 7050 alloy surface with a conventional anodizing process, unless a so-called deoxidization was employed. Therefore, the effects of the deoxidization were studied. The results showed that the deoxidization affected the 7050 quite obviously, introducing numerous number of the ''pits'' to the sample surface, and hence the film obtained was relatively thick but rather weak. In addition, the anodizing voltage also brought remarkable effect to the anodic behavior of the 7050 alloy. The test results showed that the deoxidization lowered the corrosion resistance of the 7050 alloys. By contrast, neither oxidization nor the voltage affected the anodic behavior and the corrosion resistance of the 7075 alloy very much. (orig.)

Electrochemical behavior of anodized AA6063-T6 alloys affected by matrix structures

International Nuclear Information System (INIS)

Huang, Yung-Sen; Shih, Teng-Shih; Wu, Chen-En

2013-01-01

Highlights: ► Deformation after solution treatment introduced Al matrix to have deformation bands and few Si particles. ► Dislocations remained in the matrix lift up field potential and produce AlOOH oxide in the AAO film. ► The silicon-containing particles were found to trap in the AAO film. ► The silicon particles and the Al(OOH) oxide is significantly to influence the electrochemical behavior of AAO films. - Abstract: AA 6063 alloys were cold-rolled (CR) either before or after solution treatment (S) and then different samples were artificially aged (T6) to obtain different samples (CRST6 and SCRT6). The highest dislocation density was observed in the SCRT6 sample which also showed the lowest particle count among the three samples; ST6, CRST6 and SCRT6. Subsequently, all samples were anodized in a 15 wt% sulfuric acid solution for different time spans to obtain anodic aluminum oxide (AAO) films. The anodized samples were further analyzed with X-ray Photoelectron Spectroscopy (XPS) analysis. We determined that the constituent phases in the AAO film were composed of hydrated amorphous alumina, hydrated oxide (Al(OH) 3 ) and oxyhydroxide (AlOOH) phases together with some silicon-containing particles trapped in the films on all samples. In the electrochemical test, the silicon-containing particles and hydrated Al(OH) 3 oxide that existed at the electrolyte/film (e/f) interface were found to inversely influence the corrosion resistance of the anodized samples.

Influence of the heat treatment condition of alloy AlCu4Mg1 on the microstructure and properties of anodic oxide layers

Science.gov (United States)

Morgenstern, R.; Dietrich, D.; Sieber, M.; Lampke, T.

2017-03-01

Due to their outstanding specific mechanical properties, high-strength, age-hardenable aluminum alloys offer a high potential for lightweight security-related applications. However, the use of copper-alloyed aluminum is limited because of their susceptibility to selective corrosion and their low wear resistance. These restrictions can be overcome and new applications can be opened up by the generation of protective anodic aluminum oxide layers. In contrast to the anodic oxidation of unalloyed aluminum, oxide layers produced on copper-rich alloys exhibit a significantly more complex pore structure. It is the aim of the investigation to identify the influence of microstructural parameters such as size and distribution of the strengthening precipitations on the coating microstructure. The aluminum alloy EN AW-2024 (AlCu4Mg1) in different heat treatment conditions serves as substrate material. The influence of the strengthening precipitations’ size and distribution on the development of the pore structure is investigated by the use of high-resolution scanning electron microscopy. Integral coating properties are characterized by non-destructive and light-microscopic thickness measurements and instrumented indentation tests.

Lead activity in Pb-Sb-Bi alloys

Directory of Open Access Journals (Sweden)

A. S. Kholkina

2014-11-01

Full Text Available The present work is devoted to the study of lead thermodynamic activity in the Pb-Sb-Bi alloys. The method for EMF measurements of the concentration cell: (–Pb|KCl-PbCl2¦¦KCl-PbCl2|Pb-(Sb-Bi(+ was used. The obtained concentration dependences of the galvanic cell EMF are described by linear equations. The lead activity in the ternary liquid-metal alloy demonstrates insignificant negative deviations from the behavior of ideal solutions.

Novel Lead dioxide-Graphite-Polymer composite anode for electrochemical chlorine generation

Czech Academy of Sciences Publication Activity Database

Gedam, N.; Neti, R.N.; Kormunda, M.; Šubrt, Jan; Bakardjieva, Snejana

2015-01-01

Roč. 169, JUL (2015), s. 109-116 ISSN 0013-4686 Institutional support: RVO:61388980 Keywords : beta-Lead dioxide * Graphite * Polymer composite anode * Chlorine generation * Cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions

Directory of Open Access Journals (Sweden)

Webster TJ

2013-01-01

Full Text Available Alexandra P Ross, Thomas J WebsterSchool of Engineering and Department of Orthopedics, Brown University, Providence, RI, USAAbstract: Current titanium-based implants are often anodized in sulfuric acid (H2SO4 for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study

A novel high performance composite anode with in situ growth of Fe-Ni alloy nanoparticles for intermediate solid oxide fuel cells

International Nuclear Information System (INIS)

Li, Jingcheng; Yu, Yan; Yin, Yi-Mei; Zhou, Ning; Ma, Zi-Feng

2017-01-01

Highlights: • A composite anode with endogenous Fe-Ni alloy nanoparticles has been prepared. • The redox reversibility of the anode has been confirmed by XRD. • The E_a of H_2 oxidation at the anode is much smaller than that at Ni-YSZ anode. • A ScSZ supported cell achieves MPD of 0.71 Wcm"−"2 and R_p of 0.16 Ω cm"2 at 800 °C. • The single cell shows stable output during 105 h testing at 800 °C 0.7 V in wet H_2". - Abstract: A redox reversible composite anode with Fe-Ni alloy nanoparticles in situ growth on SrLaFeO_4-type and LaFeO_3-type oxide substrates has been prepared for intermediate temperature solid oxide fuel cell (IT-SOFC) by reducing perovskite precursor La_0_._4Sr_0_._6Fe_0_._7_5Ni_0_._1Nb_0_._1_5O_3_-_δ (LSFNNb) in wet H_2 at 900 °C for 1 h. The anode has shown an excellent electrochemical catalytic activity for oxidation of hydrogen with much smaller E_a (25.1 ∼ 68.9 kJ mol"−"1) than the value (>160 kJ mol"−"1) at Ni-YSZ anode. A scandium stabilized zirconia (ScSZ) electrolyte supported SOFC with the anode achieves maximum power densities of 0.71, 0.52, 0.35, and 0.21 W cm"−"2 at 800, 750, 700 and 650 °C, respectively in wet H_2 (3% H_2O), and the corresponding R_p of 0.16, 0.21, 0.35, and 0.60 Ω cm"2 under OCV. Moreover, the single cell shows stable power output during ∼105 h operation at 800 °C under 0.7 V in wet H_2 after a initial degradation, indicating that R-LSFNNb is an excellent candidate as anode of IT-SOFC.

Non-sparking anodization process of AZ91D magnesium alloy under low AC voltage

Energy Technology Data Exchange (ETDEWEB)

Li, Weiping, E-mail: liweiping@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Wen [AVIC Beijing Aeronautical Manufacturing Technology Research Institue, Beijing 100024 (China); Zhu, Liqun; Liu, Huicong; Wang, Xiaofang [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2013-04-20

Highlights: ► Four different processes appear on magnesium alloys with applied voltage increase. ► Non-sparking film formation process occurred in the range of 6–10 V AC. ► The film was composed of Mg{sub 2}SiO{sub 4} with a stable growth rate in 30 min. ► Film growth was a balance of electrochemical dissolution and chemical deposition. -- Abstract: Anodization is widely recognized as one of the most important surface treatments for magnesium alloys. However, since high voltage oxidation films are limited in some applications due to porosity and brittleness, it is worthwhile to explore the non-sparking oxidizing process. In this work, AZ91D was electrochemically anodized at different AC voltages in an electrolyte containing 120 g/L NaOH and 80 g/L Na{sub 2}SiO{sub 3}·9H{sub 2}O. The effects of voltage on the surface morphology, composition and reaction process, especially the non-sparking discharge anodic film formation process, were investigated. The results showed that four different processes would appear according to the applied voltage variation from 6 V to 40 V, and that the non-sparking film formation process occurred in the range of 6–10 V. The film formed on the AZ91D surface under 10 V AC was mainly composed of Mg{sub 2}SiO{sub 4} with a lamellar structure. The horizontal and vertical expansion of the lamellar structure resulted in the formation of a multi-layered structure with a stable, linear growth rate for 30 min. The non-sparking film formation process can be considered to be the result of a balance of electrochemical dissolution and chemical deposition reaction.

Evaluation of shot peening on the fatigue strength of anodized Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Costa Midori Yoshikawa Pitanga

2006-01-01

Full Text Available The increasingly design requirements for modern engineering applications resulted in the development of new materials with improved mechanical properties. Low density, combined with excellent weight/strength ratio as well as corrosion resistance, make the titanium attractive for application in landing gears. Fatigue control is a fundamental parameter to be considered in the development of mechanical components. The aim of this research is to analyze the fatigue behavior of anodized Ti-6Al-4V alloy and the influence of shot peening pre treatment on the experimental data. Axial fatigue tests (R = 0.1 were performed, and a significant reduction in the fatigue strength of anodized Ti-6Al-4V was observed. The shot peening superficial treatment, which objective is to create a compressive residual stress field in the surface layers, showed efficiency to increase the fatigue life of anodized material. Experimental data were represented by S-N curves. Scanning electron microscopy technique (SEM was used to observe crack origin sites.

Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars

Directory of Open Access Journals (Sweden)

de Rincón, O.

2003-12-01

Full Text Available This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation, indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials ( < -1100 mV vs. Cu/CuSO₄ they supply to the reinforcement could lead to hydrogen embrittlement.

Este trabajo presenta la realización de varios diseños de protección catódica utilizando aleaciones de aluminio para la protección de pilotes pretensados. Los resultados obtenidos con diferentes diseños (aleación de Al/Zn/In, tipo brazalete y aluminio termorociado (3 años de evaluación y ánodos convencionales de Al/Zn/In colocados en un brazalete de acero pintado con epoxy (12 años de evaluación, indicaron que todos estos sistemas pueden ser utilizados como ánodos de sacrificio para la protección de los pilotes. Sin embargo, el sistema con aluminio termorociado no puede ser utilizado en pilotes de acero pretensado debido al potencial muy negativo alcanzado por la armadura (<-1100 mV vs Cu/CuSO₄, lo cual podría inducir a daños por hidrógeno.

INFLUENCE OF MECHANICAL ALLOYING AND LEAD CONTENT ON MICROSTRUCTURE, HARDNESS AND TRIBOLOGICAL BEHAVIOR OF 6061 ALUMINIUM ALLOYS

Directory of Open Access Journals (Sweden)

M. Paidpilli

2017-03-01

Full Text Available In the present work, one batch of prealloyed 6061Al powder was processed by mixing and another one was ball milled with varying amount of lead content (0-15 vol. %. These powders were compacted at 300MPa and sintered at 590˚C under N2. The instrumented hardness and the young’s modulus of as-sintered 6061Al-Pb alloys were examined as a function of lead content and processing route. The wear test under dry sliding condition has been performed at varying loads (10-40 N using pin-on-disc tribometer. The microstructure and worn surfaces have been investigated using SEM to evaluate the change in topographical features due to mechanical alloying and lead content. The mechanically alloyed materials showed improved wear characteristics as compared to as-mixed counterpart alloys. Delamination of 6061Al-Pb alloys decreases up to an optimum lead composition in both as-mixed and ball-milled 6061Al-Pb alloys. The results indicated minimum wear rate for as-mixed and ball-milled 6061Al alloy at 5 and 10 vol. % Pb, respectively.

Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells

Science.gov (United States)

Narayanan, Sekharipuram; Whitacre, Jay

2008-01-01

Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

A new, bright and hard aluminum surface produced by anodization

Science.gov (United States)

Hou, Fengyan; Hu, Bo; Tay, See Leng; Wang, Yuxin; Xiong, Chao; Gao, Wei

2017-07-01

Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance.

Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

Science.gov (United States)

Wang, Ximei; Zhu, Liqun; Li, Weiping; Liu, Huicong; Li, Yihong

2009-03-01

Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na 2SiO 3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg 2SiO 4 and amorphous SiO 2.

Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Wang Ximei [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)], E-mail: wangximei126@126.com; Zhu Liqun; Li Weiping; Liu Huicong; Li Yihong [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

2009-03-15

Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na{sub 2}SiO{sub 3} with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg{sub 2}SiO{sub 4} and amorphous SiO{sub 2}.

The role of anodic dissolution in the stress corrosion cracking of Al-Li-Cu alloy 2090

International Nuclear Information System (INIS)

Buchheit, R.G. Jr.; Wall, F.D.; Stoner, G.E.; Moran, J.P.

1991-01-01

The short-transverse (S-T) stress corrosion cracking (SCC) behavior of Al-Li-CU alloy 2090 was studied using a static load SCC test technique. Time to failure was measured as a function of applied potential in several different environments. Rapid SCC failures ( br, T1 applied br, matrix where potentials refer to the breakaway potentials of the subgrain boundary T 1 (Al 2 CuLi) phase and the α-Al matrix phase. E br values were measured using potentiodynamic polarization of bulk materials intended to simulate the individual phases found in the subgrain boundary region. Results strongly suggest an anodic dissolution based SCC mechanism for this alloy where selective dissolution of T 1 on the subgrain boundary is a critical step. The unusual pre-exposure embrittlement phenomenon demonstrated by Al- Li alloys is also shown to be consistent with these simple SCC criteria. 21 refs., 9 figs., 6 tabs

Excitation of anodized alumina films with a light source

DEFF Research Database (Denmark)

Aggerbeck, Martin; Canulescu, Stela; Rechendorff, K.

Optical properties of anodized aluminium alloys were determined by optical diffuse reflectance spectroscopy of such films. Samples with different concentrations of dopants were excited with a white-light source combined with an integrating sphere for fast determination of diffuse reflectance....... The UV-VIS reflectance of Ti-doped anodized aluminium films was measured over the wavelength range of 200 nm to 900 nm. Titanium doped-anodized aluminium films with 5-15 wt% Ti were characterized. Changes in the diffuse light scattering of doped anodized aluminium films, and thus optical appearance......, with doping are discussed. Using the Kubelka-Munk model on the diffuse reflectance spectra of such films, the bandgap Eg of the oxide alloys can be determined....

A novel tin-bismuth alloy electrode for anodic stripping voltammetric determination of zinc

International Nuclear Information System (INIS)

Pan, D.; Yin, T.; Qin, W.; Zhang, L.; Zhuang, J.

2012-01-01

We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5. 0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 μM concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS. (author)

Recovery of plutonium from electrorefining anode heels at Savannah River

International Nuclear Information System (INIS)

Gray, J.H.; Gray, L.W.; Karraker, D.G.

1987-03-01

In a joint effort, the Savannah River Laboratory (SRL), Savannah River Plant (SRP), and the Rocky Flats Plant (RFP) have developed two processes to recover plutonium from electrorefining anode heel residues. Aqueous dissolution of anode heel metal was demonstrated at SRL on a laboratory scale and on a larger pilot scale using either sulfamic acid or nitric acid-hydrazine-fluoride solutions. This direct anode heel metal dissolution requires the use of a geometrically favorable dissolver. The second process developed involves first diluting the plutonium in the anode heel residues by alloying with aluminum. The alloyed anode heel plutonium can then be dissolved using a nitric acid-fluoride-mercury(II) solution in large non-geometrically favorable equipment where nuclear safety is ensured by concentration control

Experimental system design of liquid lithium-lead alloy bubbler for DFLL-TBM

International Nuclear Information System (INIS)

Xie Bo; Li Junge; Xu Shaomei; Weng Kuiping

2011-01-01

The liquid lithium-lead alloy bubbler is a very important composition in the tritium unit of Chinese Dual-Functional Lithium Lead Test Blanket Module (DFLL-TBM). In order to complete the construction and run of the bubbler experimental system,overall design of the system, main circuit design and auxiliary system design have been proposed on the basis of theoretical calculations for the interaction of hydrogen isotope with lithium-lead alloy and experiment for hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle. The key of this design is gas-liquid exchange packed column, to achieve the measurement and extraction of hydrogen isotopes from liquid lithium-lead alloy. (authors)

Initial stages of AZ91 Mg alloy micro-arc anodizing: Growth mechanisms and effect on the corrosion resistance

International Nuclear Information System (INIS)

Veys-Renaux, Delphine; Rocca, Emmanuel; Martin, Julien; Henrion, Gérard

2014-01-01

Graphical abstract: - Highlights: • The dielectric breakdown occurs for a specific value of capacitance. • Before breakdown, Si is incorporated to the anodic film under MgSiO 3 form. • After breakdown, Si is incorporated to the anodic film also under Mg 2 SiO 4 form. • The presence of Mg 2 SiO 4 in the anodic film provides good corrosion resistance due to sealing of the porosities. - Abstract: In the framework of the new ecological regulations, micro-arc oxidation (MAO) appears as an alternative to usual processes in the field of corrosion protection of Mg alloys. In this work, the initial stages of anodic layer growth in KOH-based electrolytes are studied up to and beyond the initiation of the micro-arc regime. The properties of the first anodized film preceding the occurrence of the dielectric breakdown (corresponding to the start of the micro-arc regime) are mainly determined by the incorporation of additives (fluorides or silicates) in the film, as shown by in situ electrochemical measurements. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy reveal both the change of morphology and chemical state of silicate and fluoride in the anodized layer before and after the micro-arc regime. In terms of electrochemical behaviour, investigated by stationary methods and electrochemical impedance spectroscopy (EIS) in reference corrosive water, the anodic film grown in the silicate medium provides the best corrosion resistance thanks to a thick layer containing Mg 2 SiO 4 , whose degradation products seal the porosities of the coating

DC electrodeposition of NiGa alloy nanowires in AAO template

Energy Technology Data Exchange (ETDEWEB)

Maleki, K. [Nanomaterials Group, Department of Materials Engineering, Tarbiat Modares University, Iran, P.O. Box: 14115-143, Tehran (Iran, Islamic Republic of); Sanjabi, S., E-mail: sanjabi@modares.ac.ir [Nanomaterials Group, Department of Materials Engineering, Tarbiat Modares University, Iran, P.O. Box: 14115-143, Tehran (Iran, Islamic Republic of); Alemipour, Z. [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

2015-12-01

NiGa alloy nanowires were electrodeposited from an acidic sulfate bath into nanoporous anodized alumina oxide (AAO). This template was fabricated by two-step anodizing. The effects of bath composition and current density were explored on the Ga content of electrodeposited nanowires. The Ga content in the deposits was increased by increasing both Ga in the bath composition and electrodepositing current density. The NiGa alloy nanowires were synthesized for Ga content up to 2–4% without significant improving the magnetic properties. Above this threshold Ga clusters were formed and decreased the magnetic properties of the nanowires. For Ga content of the alloy above 30%, the wires were too short and incomplete. X-ray diffraction patterns reveal that the significant increase of Ga content in the nanowires, changes the FCC crystal structure of Ni to an amorphous phase. It also causes a sizeable increase in the Ga cluster size; these both lead to a significant reduction in the coercivity and the magnetization respectively. - Highlights: • NiGa alloy nanowires were electrodeposited from acidic sulphate baths into nanoporous anodized alumina oxide (AAO) template. • The Ga content was increased by increasing the Ga in the bath composition and electrodeposition current density. • The magnetic parameters such as coercivity and magnetization were not changed for the alloy nanowire with Ga content less than 4%.

Photoluminescent properties of nanoporous anodic alumina doped with manganese ions

Energy Technology Data Exchange (ETDEWEB)

Gasenkova, I.V. [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Mukhurov, N.I., E-mail: n.mukhurov@ifanbel.bas-net.by [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Zhvavyi, S.P.; Kolesnik, E.E. [State Research and Production Association ' Optic, Optoelectronic and Laser techniques”, 68 Nezavisimosti Ave., Minsk 220072 (Belarus); Stupak, A.P. [B.I.Stepanov Institute of Physics of the National Academy of Sciences of Belarus, 68 Nezavisimosti Ave., Minsk 220072 (Belarus)

2017-05-15

The results are presented of a comparative study of photoluminescent (PL) properties of unalloyed and Mn-alloyed porous anodic alumina (PAA) subjected to annealing at temperatures in the range of ГђВў{sub a}=200–1300 °ГђВЎ. The possibility of alloying of PAA with metal atoms is illustrated through an example of Mn atoms, and the effect of this impurity on the optical properties of aluminum oxide is examined. Alloying of PAA with Mn ions leads to the formation of complex defects including manganese ions and oxygen vacancies. The difference observed in the spectral dependences of the PL intensity of alloyed and unalloyed specimens is explained by the change in the valence of manganese ions in the complex defects. A decrease has been discovered in the PL intensity of the PL bands and R-lines of Mn and Cr ions in the α-phase under prolonged UV-exposure of the alloyed samples.

Crevice corrosion propagation on alloy 625 and alloy C276 in natural seawater

International Nuclear Information System (INIS)

McCafferty, E.; Bogar, F.D.; Thomas, E.D. II; Creegan, C.A.; Lucas, K.E.; Kaznoff, A.I.

1997-01-01

Chemical composition of the aqueous solution within crevices on two different Ni-Cr-Mo-Fe alloys immersed in natural seawater was determined using a semiquantitative thin-layer chromatographic method. Active crevices were found to contain concentrated amounts of dissolved Ni 2+ , Cr 3+ , Mo 3+ , and Fe 2+ ions. Propagation of crevice corrosion for the two alloys was determined from anodic polarization curves in model crevice solutions based upon stoichiometric dissolution or selective dissolution of alloy components. Both alloys 625 (UNS N06625) and C276 (UNS N10276) underwent crevice corrosion in the model crevice electrolytes. For the model crevice solution based upon selective dissolution of alloy constituents, the anodic dissolution rate for alloy 625 was higher than that for alloy C276. This trend was reversed for the model crevice solution based upon uniform dissolution of alloy constituents

Fast ion transport at solid-solid interfaces in hybrid battery anodes

Science.gov (United States)

Tu, Zhengyuan; Choudhury, Snehashis; Zachman, Michael J.; Wei, Shuya; Zhang, Kaihang; Kourkoutis, Lena F.; Archer, Lynden A.

2018-04-01

Carefully designed solid-electrolyte interphases are required for stable, reversible and efficient electrochemical energy storage in batteries. We report that hybrid battery anodes created by depositing an electrochemically active metal (for example, Sn, In or Si) on a reactive alkali metal electrode by a facile ion-exchange chemistry lead to very high exchange currents and stable long-term performance of electrochemical cells based on Li and Na electrodes. By means of direct visualization and ex situ electrodeposition studies, Sn-Li anodes are shown to be stable at 3 mA cm-2 and 3 mAh cm-2. Prototype full cells in which the hybrid anodes are paired with high-loading LiNi0.8Co0.15Al0.05O2(NCA) cathodes are also reported. As a second demonstration, we create and study Sn-Na hybrid anodes and show that they can be cycled stably for more than 1,700 hours with minimal voltage divergence. Charge storage at the hybrid anodes is reported to involve a combination of alloying and electrodeposition reactions.

The effect lead impurities on the corrosion resistance of alloy 600 and alloy 690 in high temperature water

International Nuclear Information System (INIS)

Sakai, T.; Nakagomi, N.; Kikuchi, T.; Aoki, K.; Nakayasu, F.; Yamakawa, K.

1998-01-01

Degradation of nickel-based alloy steam generator (SG) tubing caused by lead-induced corrosion has been reported recently in some PWR plants. Several laboratory studies also have shown that lead causes intergranular or transgranular stress corrosion cracking (IGSCC or TGSCC) of the tubing materials. Information from previous studies suggests two possible explanations for the mechanism of lead-induced corrosion. One is selective dissolution of tube metal elements, resulting in formation of a lead-containing nickel-depleted oxide film as observed in mildly acidic environments. The other explanation is an increase in potential, as has been observed in lead-contaminated caustic environments, although not in all volatile treatment (AVT) water such as the ammonium-hydrazine water chemistry. These observation suggest that an electrochemical reaction between metal elements and dissolved lead might be the cause of lead-induced corrosion. The present work was undertaken to clarify the lead-induced corrosion mechanism of nickel-based alloys from an electrochemical viewpoint, focusing on mildly acidic and basic environments. These are the probable pH conditions in the crevice region between the tube and tube support plate of the SG where corrosion damage could occur. Measurements of corrosion potential and electrochemical polarization of nickel-based alloys were performed to investigate the effect of lead on electrochemical behavior of the alloys. Then, constant extension rate tests (CERT) were carried out to determine the corrosion susceptibility of the alloys in a lead-contaminated environment. (J.P.N.)

Mechanism of Early Stage Corrosion for Boric-sulfuric Acid Anodized 2A97 Al-Cu-Li Alloy Under Tropical Marine Atmosphere

Directory of Open Access Journals (Sweden)

LUO Chen

2016-09-01

Full Text Available Optical microscopy(OM, scanning electron microscopy(SEM, EDX and EIS combined with ultramicrotomy were employed to investigate the micro morphology, chemical composition and electrochemical properties of anodized 2A97 Al-Cu-Li alloy before and after atmospheric corrosion. The results show that when electrolytes containing combinations of tartaric-sulfuric or boric-sulfuric acid are used to grow the films at different temperatures, boric acid addition and higher temperature allow for higher current density that speeds up the film growth. The pore geometry and structure is similar for different electrolytes. Dispersive dark rusty spots composed of O, Al, Cl, Cu are present on the boric-sulfuric acid anodized specimen after exposure in tropical marine atmosphere for 1 month. Deposition of white corrosion product is found on the specimen surface as well. Severe pitting occurs and develops deeply into the alloy substrate after elongated outdoor exposure. Corrosion propagation is associated with θ-phase particles.

Performance Enhancement of Silicon Alloy-Based Anodes Using Thermally Treated Poly(amide imide) as a Polymer Binder for High Performance Lithium-Ion Batteries.

Science.gov (United States)

Yang, Hwi Soo; Kim, Sang-Hyung; Kannan, Aravindaraj G; Kim, Seon Kyung; Park, Cheolho; Kim, Dong-Won

2016-04-05

The development of silicon-based anodes with high capacity and good cycling stability for next-generation lithium-ion batteries is a very challenging task due to the large volume changes in the electrodes during repeated cycling, which results in capacity fading. In this work, we synthesized silicon alloy as an active anode material, which was composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. Poly(amide imide)s, (PAI)s, with different thermal treatments were used as polymer binders in the silicon alloy-based electrodes. A systematic study demonstrated that the thermal treatment of the silicon alloy electrodes at high temperature made the electrodes mechanically strong and remarkably enhanced the cycling stability compared to electrodes without thermal treatment. The silicon alloy electrode thermally treated at 400 °C initially delivered a discharge capacity of 1084 mAh g(-1) with good capacity retention and high Coulombic efficiency. This superior cycling performance was attributed to the strong adhesion of the PAI binder resulting from enhanced secondary interactions, which maintained good electrical contacts between the active materials, electronic conductors, and current collector during cycling. These findings are supported by results from X-ray photoelectron spectroscopy, scanning electron microscopy, and a surface and interfacial cutting analysis system.

Multi-metallic anodes for solid oxide fuel cell applications

International Nuclear Information System (INIS)

Restivo, T.A. Guisard; Mello-Castanho, S.R.H.; Leite, D. Will

2009-01-01

A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

Significant Corrosion Resistance in an Ultrafine-Grained Al6063 Alloy with a Bimodal Grain-Size Distribution through a Self-Anodic Protection Mechanism

Directory of Open Access Journals (Sweden)

Mahdieh Shakoori Oskooie

2016-12-01

Full Text Available The bimodal microstructures of Al6063 consisting of 15, 30, and 45 vol. % coarse-grained (CG bands within the ultrafine-grained (UFG matrix were synthesized via blending of high-energy mechanically milled powders with unmilled powders followed by hot powder extrusion. The corrosion behavior of the bimodal specimens was assessed by means of polarization, steady-state cyclic polarization and impedance tests, whereas their microstructural features and corrosion products were examined using optical microscopy (OM, scanning transmission electron microscopy (STEM, field emission scanning electron microscopy (FE-SEM, electron backscattered diffraction (EBSD, energy dispersive spectroscopy (EDS, and X-ray diffraction (XRD techniques. The bimodal Al6063 containing 15 vol. % CG phase exhibits the highest corrosion resistance among the bimodal microstructures and even superior electrochemical behavior compared with the plain UFG and CG materials in the 3.5% NaCl solution. The enhanced corrosion resistance is attributed to the optimum cathode to anode surface area ratio that gives rise to the formation of an effective galvanic couple between CG areas and the UFG matrix. The operational galvanic coupling leads to the domination of a “self-anodic protection system” on bimodal microstructure and consequently forms a uniform thick protective passive layer over it. In contrast, the 45 vol. % CG bimodal specimen shows the least corrosion resistance due to the catastrophic galvanic corrosion in UFG regions. The observed results for UFG Al6063 suggest that metallurgical tailoring of the grain structure in terms of bimodal microstructures leads to simultaneous enhancement in the electrochemical behavior and mechanical properties of passivable alloys that are usually inversely correlated. The mechanism of self-anodic protection for passivable metals with bimodal microstructures is discussed here for the first time.

Effect of heat treatment on anodic activation of aluminium by trace element indium

Energy Technology Data Exchange (ETDEWEB)

Graver, Brit [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Helvoort, Antonius T.J. van [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Nisancioglu, Kemal, E-mail: kemal.nisancioglu@material.ntnu.n [Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491 Trondheim (Norway)

2010-11-15

Research highlights: {yields} Indium segregation activates AlIn alloy surface anodically in chloride solution. {yields} Enrichment of In on Al surface can occur thermally by heat treatment at 300 {sup o}C. {yields} Increasing temperature homogenises indium in aluminium reducing anodic activation. {yields} Indium can activate AlIn surface by segregating through dealloying of aluminium. {yields} Anodic activation is caused by AlIn amalgam formation at aluminium surface. - Abstract: The presence of trace elements in Group IIIA-VA is known to activate aluminium anodically in chloride environment. The purpose of this paper is to investigate the surface segregation of trace element In by heat treatment and resulting surface activation. Model binary AlIn alloys, containing 20 and 1000 ppm by weight of In, were characterized after heat treatment at various temperatures by use of glow discharge optical emission spectroscopy, electron microscopy and electrochemical polarization. Heat treatment for 1 h at 300 {sup o}C gave significant segregation of discrete In particles (thermal segregation), which activated the surface. Indium in solid solution with aluminium, obtained by 1 h heat treatment at 600 {sup o}C, also activated by surface segregation of In on alloy containing 1000 ppm In, resulting from the selective dissolution of the aluminium component during anodic oxidation (anodic segregation). The effect of anodic segregation was reduced by decreasing indium concentration in solid solution; it had negligible effect at the 20 ppm level. The segregated particles were thought to form a liquid phase alloy with aluminium during anodic polarization, which in turn, together with the chloride in the solution destabilized the oxide.

Anode materials for lithium-ion batteries

Science.gov (United States)

Sunkara, Mahendra Kumar; Meduri, Praveen; Sumanasekera, Gamini

2014-12-30

An anode material for lithium-ion batteries is provided that comprises an elongated core structure capable of forming an alloy with lithium; and a plurality of nanostructures placed on a surface of the core structure, with each nanostructure being capable of forming an alloy with lithium and spaced at a predetermined distance from adjacent nanostructures.

Ternary equilibria in bismuth--indium--lead alloys

International Nuclear Information System (INIS)

Liao, K.C.; Johnson, D.L.; Nelson, R.C.

1975-01-01

The liquidus surface is characterized by three binary equilibria. One binary extends from the Pb--Bi peritectic to the Pb--In peritectic. The other two extend from In--Bi eutectics, merge at 50 at. percent Bi and 30 at. percent Pb, and end at the Bi--Pb eutectic. Based on analysis of ternary liquidus contours and vertical sections, it is suggested that solidification for high lead and very high indium alloys occurs from two-phase equilibria. Solidification from all other alloys occurs from three-phase equilibria. Four-phase solidification does not occur in this system

An investigation into the mechanical and tribological properties of plasma electrolytic oxidation and hard-anodized coatings on 6082 aluminum alloy

International Nuclear Information System (INIS)

Malayoglu, Ugur; Tekin, Kadir C.; Malayoglu, Ufuk; Shrestha, Suman

2011-01-01

Highlights: → Mechanical properties of PEO and anodised coatings were studied using ultra-micro hardness tester. → Elastic modulus and hardness of the PEO coating were found much higher than those of the anodised coating. → Improved sliding wear of PEO coating is due to presence of hard α and γ-Al 2 O 3 phases. - Abstract: A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2-3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed.

Group IVA Element (Si, Ge, Sn)-Based Alloying/Dealloying Anodes as Negative Electrodes for Full-Cell Lithium-Ion Batteries.

Science.gov (United States)

Liu, Dequan; Liu, Zheng Jiao; Li, Xiuwan; Xie, Wenhe; Wang, Qi; Liu, Qiming; Fu, Yujun; He, Deyan

2017-12-01

To satisfy the increasing energy demands of portable electronics, electric vehicles, and miniaturized energy storage devices, improvements to lithium-ion batteries (LIBs) are required to provide higher energy/power densities and longer cycle lives. Group IVA element (Si, Ge, Sn)-based alloying/dealloying anodes are promising candidates for use as electrodes in next-generation LIBs owing to their extremely high gravimetric and volumetric capacities, low working voltages, and natural abundances. However, due to the violent volume changes that occur during lithium-ion insertion/extraction and the formation of an unstable solid electrolyte interface, the use of Group IVA element-based anodes in commercial LIBs is still a great challenge. Evaluating the electrochemical performance of an anode in a full-cell configuration is a key step in investigating the possible application of the active material in LIBs. In this regard, the recent progress and important approaches to overcoming and alleviating the drawbacks of Group IVA element-based anode materials are reviewed, such as the severe volume variations during cycling and the relatively brittle electrode/electrolyte interface in full-cell LIBs. Finally, perspectives and future challenges in achieving the practical application of Group IVA element-based anodes in high-energy and high-power-density LIB systems are proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Sn4+ Additives on the Microstructure and Corrosion Resistance of Anodic Coating Formed on AZ31 Magnesium Alloy in Alkaline Solution

Science.gov (United States)

Salman, S. A.; Kuroda, K.; Saito, N.; Okido, M.

Magnesium is the lightest structural metal with high specific strength and good mechanical properties. However, poor corrosion resistance limits its widespread use in many applications. Magnesium is usually treated with Chromate conversion coatings. However, due to changing environmental regulations and pollution prevention requirements, a significant push exists to find new, alternative for poisonous Cr6+. Therefore, we aim to improve corrosion resistance of anodic coatings on AZ31 alloys using low cost non-chromate electrolyte. Anodizing was carried out in alkaline solutions with tin additives. The effect of tin additives on the coating film was characterized by SEM and XRD. The corrosion resistance was evaluated using anodic and cathodic polarizations and electrochemical impedance spectroscopy (EIS). Corrosion resistance property was improved with tin additives and the best anti-corrosion property was obtained with addition of 0.03 M Na2SnO3.3H2O to anodizing solution.

Fabrication of CoPd alloy nanowire arrays on an anodic aluminum oxide/Ti/Si substrate and their enhanced magnetic properties

International Nuclear Information System (INIS)

Xu Cailing; Li Hua; Xue Tong; Li Hulin

2006-01-01

An anodic aluminum oxide/Ti/Si substrate was successfully synthesized by the anodization of an aluminum film on a Ti/Si substrate and then used as a template to grow 10 nm diameter CoPd alloy nanowires. X-ray diffraction and energy-dispersed X-ray patterns indicated that Co 0.97 Pd 0.03 nanowire arrays with a preferential orientation of (0 0 2) were formed during electrodeposition. High coercivity (about 1700 Oe) and squareness (about 0.85) were obtained in the samples when the magnetic field was applied parallel to the axis of the nanowires; these values are much larger than those of pure Co nanowire arrays with the same diameters

Penetration of a magnetic field into superconducting lead and lead-indium alloys

International Nuclear Information System (INIS)

Egloff, C.; Raychaudhuri, A.K.; Rinderer, L.

1983-01-01

The temperature dependence of the magnetic field penetration depth of superconducting lead and lead-indium alloys has been studied over the temperature range between about 2 K and T/sub c/. Data are analyzed in terms of the microscopic theory. The difficulties of a unique analysis of the penetration data are pointed out and a strategy for the analysis is discussed. The penetration depth at T = 0K for pure lead is determined as 522 A. This value, though higher than the previously accepted value for lead, is nevertheless consistent with the strong coupling character of lead

Enhanced tribological behavior of anodic films containing SiC and PTFE nanoparticles on Ti6Al4V alloy

International Nuclear Information System (INIS)

Li, Songmei; Zhu, Mengqi; Liu, Jianhua; Yu, Mei; Wu, Liang; Zhang, Jindan; Liang, Hongxing

2014-01-01

Highlights: • An environmental friendly sodium tartrate (C 4 O 6 H 4 Na 2 ) electrolyte is used. • SiC and PTFE nanoparticles reduce friction coefficient of composite films. • SiC and PTFE nanoparticles demonstrate a favorable synergistic effect on improving tribological properties of composite films. • Lubricating mechanisms of SiC and PTFE nanoparticles are discussed. - Abstract: Anodic films containing SiC and polytetrafluoroethylene (PTFE) nanoparticles were successfully fabricated on Ti6Al4V alloy by using anodic oxidation method in an environmental friendly electrolyte. The morphology, structure and composition of the films were studied with the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the film contained a layered structure and have a surface full of petaloid bulges, which was totally different from the common anodic oxide film of the porous kind. The tribological properties of the films were investigated with dry friction tests in terms of the friction coefficient, wear rate and the morphology of worn surfaces. The results indicated that the SiC/PTFE composite film exhibited much better anti-wear and anti-friction performances than that of the SiC composite film, the PTFE composite film and the ordinary film without nanoparticles. The SiC/PTFE composite film has friction coefficient of 0.1 and wear rate of 20.133 mg/m, which was decreased respectively by 80% and 44.5% compared with that of the ordinary film. The lubricating mechanisms of the composite film containing SiC and PTFE nanoparticles were discussed. PTFE nanoparticles could lead to the formation of lubricating layer while SiC nanoparticles inside the lubricating layer turned sliding friction to rolling friction

The mode of stress corrosion cracking in Ni-base alloys in high temperature water containing lead

International Nuclear Information System (INIS)

Hwang, S.S.; Kim, H.P.; Lee, D.H.; Kim, U.C.; Kim, J.S.

1999-01-01

The mode of stress corrosion cracking (SCC) in Ni-base alloys in high temperature aqueous solutions containing lead was studied using C-rings and slow strain rate testing (SSRT). The lead concentration, pH and the heat treatment condition of the materials were varied. TEM work was carried out to observe the dislocation behavior in thermally treated (TT) and mill annealed (MA) materials. As a result of the C-ring test in 1M NaOH+5000 ppm lead solution, intergranular stress corrosion cracking (IGSCC) was found in Alloy 600MA, whereas transgranular stress corrosion cracking (TGSCC) was found in Alloy 600TT and Alloy 690TT. In most solutions used, the SCC resistance increased in the sequence Alloy 600MA, Alloy 600TT and Alloy 690TT. The number of cracks that was observed in alloy 690TT was less than in Alloy 600TT. However, the maximum crack length in Alloy 690TT was much longer than in Alloy 600TT. As a result of the SSRT, at a nominal strain rate of 1 x 10 -7 /s, it was found that 100 ppm lead accelerated the SCC in Alloy 600MA (0.01%C) in pH 10 at 340 C. IGSCC was found in a 100 ppm lead condition, and some TGSCC was detected on the fracture surface of Alloy 600MA cracked in the 10000 ppm lead solution. The mode of cracking for Alloy 600 and Alloy 690 changed from IGSCC to TGSCC with increasing grain boundary carbide content in the material and lead concentration in the solution. IGSCC seemed to be retarded by stress relaxation around the grain boundaries, and TGSCC in the TT materials seemed to be a result of the crack blunting at grain boundary carbides and the enhanced Ni dissolution with an increase of the lead concentration. (orig.)

Scalable Production of the Silicon-Tin Yin-Yang Hybrid Structure with Graphene Coating for High Performance Lithium-Ion Battery Anodes.

Science.gov (United States)

Jin, Yan; Tan, Yingling; Hu, Xiaozhen; Zhu, Bin; Zheng, Qinghui; Zhang, Zijiao; Zhu, Guoying; Yu, Qian; Jin, Zhong; Zhu, Jia

2017-05-10

Alloy anodes possessed of high theoretical capacity show great potential for next-generation advanced lithium-ion battery. Even though huge volume change during lithium insertion and extraction leads to severe problems, such as pulverization and an unstable solid-electrolyte interphase (SEI), various nanostructures including nanoparticles, nanowires, and porous networks can address related challenges to improve electrochemical performance. However, the complex and expensive fabrication process hinders the widespread application of nanostructured alloy anodes, which generate an urgent demand of low-cost and scalable processes to fabricate building blocks with fine controls of size, morphology, and porosity. Here, we demonstrate a scalable and low-cost process to produce a porous yin-yang hybrid composite anode with graphene coating through high energy ball-milling and selective chemical etching. With void space to buffer the expansion, the produced functional electrodes demonstrate stable cycling performance of 910 mAh g -1 over 600 cycles at a rate of 0.5C for Si-graphene "yin" particles and 750 mAh g -1 over 300 cycles at 0.2C for Sn-graphene "yang" particles. Therefore, we open up a new approach to fabricate alloy anode materials at low-cost, low-energy consumption, and large scale. This type of porous silicon or tin composite with graphene coating can also potentially play a significant role in thermoelectrics and optoelectronics applications.

Copper Antimonide Nanowire Array Lithium Ion Anodes Stabilized by Electrolyte Additives.

Science.gov (United States)

Jackson, Everett D; Prieto, Amy L

2016-11-09

Nanowires of electrochemically active electrode materials for lithium ion batteries represent a unique system that allows for intensive investigations of surface phenomena. In particular, highly ordered nanowire arrays produced by electrodeposition into anodic aluminum oxide templates can lead to new insights into a material's electrochemical performance by providing a high-surface-area electrode with negligible volume expansion induced pulverization. Here we show that for the Li-Cu x Sb ternary system, stabilizing the surface chemistry is the most critical factor for promoting long electrode life. The resulting solid electrolyte interphase is analyzed using a mix of electron microscopy, X-ray photoelectron spectroscopy, and lithium ion battery half-cell testing to provide a better understanding of the importance of electrolyte composition on this multicomponent alloy anode material.

Anodal tDCS applied during multitasking training leads to transferable performance gains.

Science.gov (United States)

Filmer, Hannah L; Lyons, Maxwell; Mattingley, Jason B; Dux, Paul E

2017-10-11

Cognitive training can lead to performance improvements that are specific to the tasks trained. Recent research has suggested that transcranial direct current stimulation (tDCS) applied during training of a simple response-selection paradigm can broaden performance benefits to an untrained task. Here we assessed the impact of combined tDCS and training on multitasking, stimulus-response mapping specificity, response-inhibition, and spatial attention performance in a cohort of healthy adults. Participants trained over four days with concurrent tDCS - anodal, cathodal, or sham - applied to the left prefrontal cortex. Immediately prior to, 1 day after, and 2 weeks after training, performance was assessed on the trained multitasking paradigm, an untrained multitasking paradigm, a go/no-go inhibition task, and a visual search task. Training combined with anodal tDCS, compared with training plus cathodal or sham stimulation, enhanced performance for the untrained multitasking paradigm and visual search tasks. By contrast, there were no training benefits for the go/no-go task. Our findings demonstrate that anodal tDCS combined with multitasking training can extend to untrained multitasking paradigms as well as spatial attention, but with no extension to the domain of response inhibition.

Nanotemplated platinum fuel cell catalysts and copper-tin lithium battery anode materials for microenergy devices

Energy Technology Data Exchange (ETDEWEB)

Rohan, J.F., E-mail: james.rohan@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Hasan, M.; Holubowitch, N. [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland)

2011-11-01

Highlights: > Anodic Aluminum oxide formation on Si substrate. > High density nanotemplated Pt catalyst on Si for integrated energy and electronics. > CuSn alloy deposition from a single, high efficiency methanesulfonate plating bath. > Nanotemplated CuSn Li anode electrodes with high capacity retention. - Abstract: Nanotemplated materials have significant potential for applications in energy conversion and storage devices due to their unique physical properties. Nanostructured materials provide additional electrode surface area beneficial for energy conversion or storage applications with short path lengths for electronic and ionic transport and thus the possibility of higher reaction rates. We report on the use of controlled growth of metal and alloy electrodeposited templated nanostructures for energy applications. Anodic aluminium oxide templates fabricated on Si for energy materials integration with electronic devices and their use for fuel cell and battery materials deposition is discussed. Nanostructured Pt anode catalysts for methanol fuel cells are shown. Templated CuSn alloy anodes that possess high capacity retention with cycling for lithium microbattery integration are also presented.

Application of EIS to In Situ Characterization of Hydrothermal Sealing of Anodized Aluminum Alloys: Comparison between Hexavalent Chromium-Based Sealing, Hot Water Sealing and Cerium-Based Sealing

OpenAIRE

Carangelo, Anna; Curioni, Michele; Acquesta, Annalisa; Monetta, Tullio; Bellucci, Francesco

2016-01-01

Chromic acid anodizing has been used for almost a century to enhance corrosion protection of aerospace alloys. For some applications,hydrothermal sealing in hexavalent chromium-containing solution is required to enhance further the corrosion resistance but, due toenvironmental concerns, the use of hexavalent chromium must be discontinued. Good progress has been made to replace chromatesduring anodizing but comparatively less effort has focused on the sealing process. In this work, for the fir...

Effect of Wetting Agents and Approaching Anodes on Lead Migration in Electrokinetic Soil Remediation

OpenAIRE

Ng, Yee-Sern; Gupta, Bhaskar Sen; Hashim, Mohd Ali

2015-01-01

This is the presentation slides for my conference paper "Effect of Wetting Agents and Approaching Anodes on Lead Migration in Electrokinetic Soil Remediation", which was presented in 5th International Conference on Chemical Engineering and Applications, Taipei on 27 August 2014.

Synthesis and application of a novel Cu/RGO@Pb alloy for lead-acid batteries

International Nuclear Information System (INIS)

Wu, Yumeng; Zhao, Ruirui; Zhou, Huawen; Zhang, Dejing; Zhao, Wei; Chen, Hongyu

2016-01-01

In this work, a novel Cu/RGO@Pb alloy was prepared successfully and tested in the simulated lead-acid battery environment. In preparing the novel alloy, Cu/RGO composite was firstly synthesized in order to increase the wettability of RGO to Pb, and then the composite was added to the molten lead to obtain the target alloy. Scanning electron microscope, energy dispersive spectrometer, X-ray diffraction as well as electrochemical measurements were employed to evaluate the performance of the obtained composite and alloy. Results show that the prepared Cu/RGO@Pb possessed higher oxygen evolution over-potential and lower hydrogen evolution over-potential than the contrast alloy, indicating this novel alloy was more suitable for using as positive grids in lead acid batteries. Moreover, the RGO additive could inhibit the formation of Pb(II) and Pb(IV) film on the surface of the alloy, which could enhance the deep-charge/discharge performance of the grids and improve the corrosion resistance.

Iron migration from the anode surface in alumina electrolysis

Energy Technology Data Exchange (ETDEWEB)

Zhuravleva, Elena N.; Drozdova, Tatiana N.; Ponomareva, Svetlana V. [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Kirik, Sergei D., E-mail: kiriksd@yandex.ru [Siberian Federal University, Krasnoyarsk, 660041 (Russian Federation); Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk, 660036 (Russian Federation)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Corrosion destruction of two-component iron-based alloys in high-temperature aluminum electrolysis in the cryolite alumina melt has been studied. Black-Right-Pointing-Pointer It was found that at the first stage oxidative polarization of iron atoms on the anode surface into Fe{sup 2+} takes place. Black-Right-Pointing-Pointer Fe{sup 2+} interacts with cryolite melt producing FeF{sub 2}. Black-Right-Pointing-Pointer FeF{sub 2} gives oxides FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Black-Right-Pointing-Pointer The participation of oxygen in the corrosion has not been observed. - Abstract: Corrosion destruction of two-component iron-based alloys used as an anode in high-temperature alumina electrolysis in the melt of NaF/KF/AlF{sub 3} electrolyte has been considered. Ni, Si, Cu, Cr, Mn, Al, Ti in the amount of up to 10% have been tested as the dopants to an anode alloys. The composition of the corrosion products has been studied using X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It has been established that the anode corrosion is induced by a surface electrochemical polarization and iron atom oxidation. Iron ions come into an exchange interaction with the fluoride components of the melted electrolyte, producing FeF{sub 2}. The last interacts with oxyfluoride species transforming into the oxide forms: FeAl{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, Fe{sub 2}O{sub 3}. Due to the low solubility, the iron oxides are accumulated in the near-electrode sheath. The only small part of iron from anode migrates to cathode that makes an production of high purity aluminum of a real task. The alloy dopants are also subjected to corrosion in accordance with electromotive series resulting corrosion tunnels on the anode surface. The oxides are final compounds which collect in the same area. The corrosion products form an anode shell which is electronic conductor at electrolysis temperature. The

Effect of friction on anodic polarization properties of metallic biomaterials.

Science.gov (United States)

Okazaki, Yoshimitsu

2002-05-01

The effect of friction on the anodic polarization properties of metallic biomaterials in a physiological saline solution was investigated. The current density during friction becomes higher than during the static condition. The fluctuation range of the current density caused by the destruction and formation of passive film was observed. For SUS316L stainless steel and Co-Cr-Mo casting alloy, the fluctuation range was observed in the passivity zone. Otherwise, for Ti alloys, the fluctuation range was observed in both the activity and passivity zones. The decrease of the corrosion potential for Ti alloys due to friction was much larger than that of SUS316L stainless steel and Co-Cr-Mo casting alloy. From this result, it was considered that in a the frictional environment, the stressing zone turned anodic and its periphery cathodic, and corrosion tended to progress more than in the static environment. The effect of wear on the anodic polarization curves also changed depending on the frictional load, potential zone and the pH of the solution. A rapid increase in current density due to corrosion starting from the frictional area was found in the Ti-6Al-4V and Ti-15Mo-5Zr-3Al alloys containing Al. However, for the new Ti-15Zr-4Nb-4Ta alloy, this rapid increase was not seen in the high-potential region. The effect of the lateral reciprocal speed was also negligible for the new Ti alloy. It was found that the new Ti-15Zr-4Nb-4Ta alloy exhibited excellent corrosion resistance under friction.

Evaluation of colloidal Ag and Ag-alloys as anode electrocatalysts for direct borohydride fuel cells

Energy Technology Data Exchange (ETDEWEB)

Atwan, Mohammed H.; Northwood, Derek O. [Mechanical, Auto, and Materials Engineering, University of Windsor, Windsor, N9B 3P4 (Canada); Gyenge, Elod L. [Chemical and Biological Engineering, The University of British Colombia, Vancouver, BC, V6T 1Z4 (Canada)

2007-10-15

In this study, colloidal silver and silver-alloys (Ag-Pt, Ag-Au, Ag-Ir, and Ag-Pd) prepared by the Boenneman technique were evaluated as anode catalysts for sodium borohydride oxidation using cyclic voltammetry (CV), chronoamperometry (CA), chronopotentiometry (CP) and rotating disk electrode (RDE) voltammetry. The CV results show that the colloidal Ag-alloys were electrochemically active towards borohydride oxidation with oxidation potentials ranging between -0.7 and 0.4 V vs. Hg/HgO (MOE). The most negative oxidation potential was recorded on Ag-Pt. CA results show that the steady state current density was highest on Ag-Pt, followed by Ag-Ir, Ag-Au, and Ag-Pd. The lowest overpotential was recorded on Ag-Ir for a current step change of 10mAcm{sup -2}. A significant temperature effect and a small rotation speed effect were found in the rotating disc voltammetry for all the investigated colloids. The highest peak current was recorded on Ag-Au, while the most negative peak potential was recorded on Ag-Ir. (author)

Solid solution lithium alloy cermet anodes

Science.gov (United States)

Richardson, Thomas J.

2013-07-09

A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

Pore development in anodic alumina in sulphuric acid and borax electrolytes

International Nuclear Information System (INIS)

Garcia-Vergara, S.J.; Skeldon, P.; Thompson, G.E.; Habakaki, H.

2007-01-01

The formation of porous anodic films on an Al-3.5 at.%W alloy is compared in sulphuric acid and borax electrolytes in order to investigate pore development processes. The findings disclose that for anodizing in sulphuric acid, the pores develop mainly due to the influences of field-induced plasticity of the film and growth stresses; in borax, field-assisted dissolution dominates. The films formed in sulphuric acid are consequently much thicker than the layer of oxidized alloy and tungsten species are retained in the film. In contrast, with borax, the films and oxidized alloy layers are of similar thickness and tungsten species are lost to the electrolyte. Efficiencies of film growth are also significantly different, about 65% in sulphuric acid and about 52% in borax. The retention of tungsten species during anodizing in sulphuric acid is due to the localization of tungsten in the inner regions of the barrier layer and cell walls, with a layer of anodic alumina separating the tungsten-containing regions from the electrolyte. For borax, the tungsten is distributed more uniformly through the film material, enabling loss of tungsten species to the electrolyte from the pore base

Determination of new time-temperature-transformation diagrams for lead-calcium alloys

Energy Technology Data Exchange (ETDEWEB)

Rossi, F.; Lambertin, M. [Arts et Metiers Paristech, LaBoMaP, ENSAM, Rue porte de Paris, 71250 Cluny (France); Delfaut-Durut, L. [CEA, centre de Valduc [SEMP, LECM], 21120 Is-sur-Tille (France); Maitre, A. [SPCTS, UFR Sciences et techniques, 87060 Limoges (France); Vilasi, M. [LCSM, Universite Nancy I, 54506 Vandoeuvre les Nancy (France)

2008-12-01

The Pb-Ca is an age hardening alloy that allows for an increase in the hardness compared to pure lead. The hardening is obtained after different successive ageing transformations. In addition, this hardening is followed by an overageing which induces a softening. The ageing and overageing transformation mechanisms are now well identified in lead-calcium alloys. In this paper, we propose to represent the domain of stability of each transformation via time-temperature-transformation diagrams for a calcium concentration from 600 to 1280 ppm and in a range of temperatures from -20 to 180 C. These diagrams are constructed with the data obtained by in situ ageing with metallographic observations, hardness and electrical resistance measurements. The specificities of lead-calcium such as its fast ageing at ambient temperature and its overageing over time required the design of specific devices to be able to identify the characteristics of these alloys. (author)

Porous carbon-free SnSb anodes for high-performance Na-ion batteries

Science.gov (United States)

Choi, Jeong-Hee; Ha, Choong-Wan; Choi, Hae-Young; Seong, Jae-Wook; Park, Cheol-Min; Lee, Sang-Min

2018-05-01

A simple melt-spinning/chemical-etching process is developed to create porous carbon-free SnSb anodes. Sodium ion batteries (SIBs) incorporating these anodes exhibit excellent electrochemical performances by accomodating large volume changes during repeated cycling. The porous carbon-free SnSb anode produced by the melt-spinning/chemical-etching process shows a high reversible capacity of 481 mAh g-1, high ICE of 80%, stable cyclability with a high capacity retention of 99% after 100 cycles, and a fast rate capability of 327 mAh g-1 at 4C-rate. Ex-situ X-ray diffraction and high resolution-transmission electron microscopy analyses demonstrate that the synthesized porous carbon-free SnSb anodes involve the highly reversible reaction with sodium through the conversion and recombination reactions during sodiation/desodiation process. The novel and simple melt-spinning/chemical-etching synthetic process represents a technological breakthrough in the commercialization of Na alloy-able anodes for SIBs.

Effects of dissolved calcium and magnesium ions on lead-induced stress corrosion cracking susceptibility of nuclear steam generator tubing alloy in high temperature crevice solutions

International Nuclear Information System (INIS)

Lu, B.T.; Tian, L.P.; Zhu, R.K.; Luo, J.L.; Lu, Y.C.

2011-01-01

The effects of Ca 2+ and Mg 2+ ions on the stress corrosion cracking (SCC) susceptibility of UNS N08800 are investigated using constant extension rate tensile (CERT) tests at 300 o C in simulated crevice chemistries. The presence of lead contamination in the crevice chemistries increases significantly the SCC susceptibility of the alloy. The lead-assisted SCC (PbSCC) susceptibility is reduced markedly by the addition of Ca 2+ and Mg 2+ ions into the solution and this mitigating effect is enhanced by increasing the total concentration of Ca 2+ + Mg 2+ . The CERT test results are consistent with the types of fracture surfaces shown by Scanning Electron Microscopy (SEM). There is a reasonable correlation between the SCC susceptibility and the donor densities in the anodic films in accord with the role of lead-induced passivity degradation in PbSCC.

Heat conduction in superconducting lead thallium alloys

International Nuclear Information System (INIS)

Ho, J.L.N.

1975-01-01

The heat conduction of six strong coupling superconducting Pb--Tl alloy specimens (1 to 20 percent wt Tl) was investigated with the emphasis on the effects of impurities upon the phonon thermal conductivity. All the specimens were annealed at 275 0 C for one week. Results show that the superconducting state phonon thermal conductivity of Pb--Tl is in reasonably good agreement with BRT theory. The strong coupling superconductivity of lead alloys can be handled by scaling the gap parameter using a constant factor. The results presented also show that the phonon thermal conductivity at low temperatures of well annealed lead-thallium alloys can be analyzed in terms of phonon scattering by the grain boundaries, point defects, conduction electrons, and other phonons. The phonon-dislocation scattering was found to be unimportant. The phonon relaxation rate due to point defects is in reasonably good agreement with the Klemens theory for the long range strain field scattering introduced by the thallium impurities. At low temperatures, the normal state phonon thermal conductivity showed an increase in the phonon-electron relaxation rate as the thallium concentration increases. The increase of the phonon-electron relaxation rate is attributed to the change of the Fermi surface caused by the presence of thallium impurity. The effect of the strong electron-phonon coupling character upon the phonon-electron relaxation rate has also been considered in terms of the electron-phonon enhancement factor found in the specific heat measurements

Modified surface morphology of a novel Ti-24Nb-4Zr-7.9Sn titanium alloy via anodic oxidation for enhanced interfacial biocompatibility and osseointegration.

Science.gov (United States)

Li, Xiang; Chen, Tao; Hu, Jing; Li, Shujun; Zou, Qin; Li, Yunfeng; Jiang, Nan; Li, Hui; Li, Jihua

2016-08-01

The Ti-24Nb-4Zr-7.9Sn titanium alloy (Ti2448) has shown potential for use in biomedical implants, because this alloy possesses several important mechanical properties, such as a high fracture strength, low elastic modulus, and good corrosion resistance. In this study, we aimed to produce a hierarchical nanostructure on the surface of Ti2448 to endow this alloy with favorable biological properties. The chemical composition of Ti2448 (64.0wt% Ti, 23.9wt% Nb, 3.9wt% Zr, and 8.1wt% Sn) gives this material electrochemical properties that lead to the generation of topographical features under standard anodic oxidation. We characterized the surface properties of pure Ti (Ti), nanotube-Ti (NT), Ti2448, and nanotube-Ti2448 (NTi2448) based on surface morphology (scanning electron microscopy and atomic force microscopy), chemical and phase compositions (X-ray diffraction and X-ray photoelectron spectroscopy), and wettability (water contact angle). We evaluated the biocompatibility and osteointegration of implant surfaces by observing the behavior of bone marrow stromal cells (BMSCs) cultured on the surfaces in vitro and conducting histological analysis after in vivo implantation of the modified materials. Our results showed that a hierarchical structure with a nanoscale bone-like layer was achieved along with nanotube formation on the Ti2448 surface. The surface characterization data suggested the superior biocompatibility of the NTi2448 surface in comparison with the Ti, NT, and Ti2448 surfaces. Moreover, the NTi2448 surface showed better biocompatibility for BMSCs in vitro and better osteointegration in vivo. Based on these results, we conclude that anodic oxidation facilitated the formation of a nanoscale bone-like structure and nanotubes on Ti2448. Unlike the modified titanium surfaces developed to date, the NTi2448 surface, which presents both mechanical compatibility and bioactivity, offers excellent biocompatibility and osteointegration, suggesting its potential for

Materials for innovative lead alloy cooled nuclear systems: Overview

International Nuclear Information System (INIS)

Mueller, Georg; Weisenburger, Alfons; Fetzer, Renate; Heinzel, Annette; Jianu, Adrian

2015-01-01

One of the most challenging issues for all future innovative nuclear systems including Gen IV reactors are materials. The selection of the structural materials determines the design which has to consider the properties and the availability of the materials. Beside general requirements for material properties that are common for all fast reactor types specific issues arise from coolant compatibility. The high solubility of steel alloying elements in liquid Pb-alloys at reactor relevant temperatures is clearly detrimental. Therefore, all steels that are considered as structural materials have to be protected by dissolution barriers. The most common barriers for steels under consideration are oxide scales that form in situ during operation. However, increasing the temperature above 500 deg. C will result either in dissolution attack or in enhanced oxidation. For higher temperatures additional barriers like alumina forming surface alloys are discussed and investigated. Mechanical loads like creep stress and fretting will act on the steels. These mechanical loads will interact with the coolant and can increase the negative effects. For a LFR (Lead Fast Reactor) Demonstrator and MYHRRA (ADS) austenitic steels (316L) are selected for most in core components. The 15-15Ti is the choice for the fuel cladding of MYHRRA and a Pb cooled demonstrator. For an industrial LFR (Lead Fast Reactor) the ferritic martensitic steel T91 was selected as fuel clad material due to its improved irradiation resistance. T91 is in both designs the material to be used for the heat exchanger. Surface alloying with alumina forming alloys is considered to assure material functionality at higher temperatures and is therefore selected for fuel cladding of the ELFR and the heat exchanger tubes. This presentation will give an overview on the selected materials for innovative Pb alloy cooled nuclear systems considering, beside pure compatibility, the influence of mechanical interaction like creep and

Carbon Anode Materials

Science.gov (United States)

Ogumi, Zempachi; Wang, Hongyu

Accompanying the impressive progress of human society, energy storage technologies become evermore urgent. Among the broad categories of energy sources, batteries or cells are the devices that successfully convert chemical energy into electrical energy. Lithium-based batteries stand out in the big family of batteries mainly because of their high-energy density, which comes from the fact that lithium is the most electropositive as well as the lightest metal. However, lithium dendrite growth after repeated charge-discharge cycles easily will lead to short-circuit of the cells and an explosion hazard. Substituting lithium metal for alloys with aluminum, silicon, zinc, and so forth could solve the dendrite growth problem.1 Nevertheless, the lithium storage capacity of alloys drops down quickly after merely several charge-discharge cycles because the big volume change causes great stress in alloy crystal lattice, and thus gives rise to cracking and crumbling of the alloy particles. Alternatively, Sony Corporation succeeded in discovering the highly reversible, low-voltage anode, carbonaceous material and commercialized the C/LiCoO2 rocking chair cells in the early 1990s.2 Figure 3.1 schematically shows the charge-discharge process for reversible lithium storage in carbon. By the application of a lithiated carbon in place of a lithium metal electrode, any lithium metal plating process and the conditions for the growth of irregular dendritic lithium could be considerably eliminated, which shows promise for reducing the chances of shorting and overheating of the batteries. This kind of lithium-ion battery, which possessed a working voltage as high as 3.6 V and gravimetric energy densities between 120 and 150 Wh/kg, rapidly found applications in high-performance portable electronic devices. Thus the research on reversible lithium storage in carbonaceous materials became very popular in the battery community worldwide.

Pengaruh Rapat Arus Anodizing terhadap Nilai Kekerasan pada Plat Aluminium Paduan Aa Seri 2024-t3

OpenAIRE

Fajar Nugroho

2015-01-01

Aluminum alloy AA 2024-T3 is widely applied in the aircraft industry because it has good mechanical properties such as; light weight, good conductivity and the corrosion resistance. However Aluminium 2024-T3 susceptible to wearing. One method to improve the wear resistance o f AA 2024-T3 is the anodizing process. The aims of this research to study the effect of current density and anodizing time against the hardness of aluminum alloy AA 2024-T3. The process of anodizing was carried out using ...

Aluminum anode for aluminum-air battery - Part II: Influence of In addition on the electrochemical characteristics of Al-Zn alloy in alkaline solution

Science.gov (United States)

Park, In-Jun; Choi, Seok-Ryul; Kim, Jung-Gu

2017-07-01

Effects of Zn and In additions on the aluminum anode for Al-air battery in alkaline solution are examined by the self-corrosion rate, cell voltage, current-voltage characteristics, anodic polarization, discharge performance and AC impedance measurements. The passivation behavior of Zn-added anode during anodic polarization decreases the discharge performance of Al-air battery. The addition of In to Al-Zn anode reduces the formation of Zn passivation film by repeated adsorption and desorption behavior of In ion onto anode surface. The attenuated Zn passive layer by In ion attack leads to the improvement of discharge performance of Al-air battery.

Neutronic design for a 100MWth Small modular natural circulation lead or lead-alloy cooled fast reactors core

International Nuclear Information System (INIS)

Chen, C.; Chen, H.; Zhang, H.; Chen, Z.; Zeng, Q.

2015-01-01

Lead or lead-alloy cooled fast reactor with good fuel proliferation and nuclear waste transmutation capability, as well as high security and economy, is a great potential for the development of fourth-generation nuclear energy systems. Small natural circulation reactor is an important technical route lead cooled fast reactors industrial applications, which has been chosen as one of the three reference technical for solution lead or lead-alloy cooled fast reactors by GIF lead-cooled fast reactor steering committee. The School of Nuclear Science and Technology of USTC proposed a small 100MW th natural circulation lead cooled fast reactor concept called SNCLFR-100 based realistic technology. This article describes the SNCLFR-100 reactor of the overall technical program, core physics calculation and analysis. The results show that: SNCLFR-100 with good neutronic and safety performance and relevant design parameters meet the security requirements with feasibility. (author)

The effect of zinc on the aluminum anode of the aluminum-air battery

Science.gov (United States)

Tang, Yougen; Lu, Lingbin; Roesky, Herbert W.; Wang, Laiwen; Huang, Baiyun

Aluminum is an ideal material for batteries, due to its excellent electrochemical performance. Herein, the effect of zinc on the aluminum anode of the aluminum-air battery, as an additive for aluminum alloy and electrolytes, has been studied. The results show that zinc can decrease the anodic polarization, restrain the hydrogen evolution and increase the anodic utilization rate.

Development of new anodes for rechargeable lithium batteries

Energy Technology Data Exchange (ETDEWEB)

Sandi, G. [Argonne National Laboratory, Argonne, IL (United States)

2001-10-01

Lithium ion batteries have been introduced in the early 1990s by Sony Corporation. Ever since their introduction carbonaceous materials have received considerable attention for use as anodes because of their potential safety and reliability advantages. Natural graphite, cokes, carbon fibres, non-graphitizable carbon, and pyrolytic carbon have been used as sources for carbon materials. Recently metal alloys and metal oxides have been studied as alternatives to carbon as negative electrodes in lithium-ion cells. This paper reviews the performance of some of the carbonaceous materials used in lithium-ion batteries as well as some of the new metallic alloys of aluminum, silica, selenium, lead, bismuth, antimony and arsenic, as alternatives to carbon as negative electrodes in lithium-ion batteries. It is concluded that while some of these materials are promising, practical applications will continue to be limited until after the volume expansion and the irreversibility problems are resolved. 50 refs., 5 figs.

Influence of the cooling rate on the ageing of lead-calcium alloys

Energy Technology Data Exchange (ETDEWEB)

Rossi, F.; Lambertin, M. [LaBoMaP, Arts et Metiers ParisTech, Rue porte de Paris, 71250 Cluny (France); Delfaut-Durut, L. [CEA, centre de Valduc [SEMP, LECM], 21120 Is-sur-Tille (France); Maitre, A. [SPCTS, UFR Sciences et Techniques, 87060 Limoges (France); Vilasi, M. [LCSM, Universite Nancy I, 54506 Vandoeuvre les Nancy (France)

2009-03-01

Cast lead-calcium alloys were known to be sensitive to experimental parameters, which cause large variations on the ageing and overageing behaviour. From the study of these parameters, the quenching rate was the only significant parameter. A critical cooling rate was defined based on hardness, electrical resistivity and metallographical observations. The inconsistencies in the literature noticed on the evolutions of lead-calcium alloys can now be explained by whether or not this critical cooling rate was respected. (author)

Fabrication of lithium/C-103 alloy heat pipes for sharp leading edge cooling

Science.gov (United States)

Ai, Bangcheng; Chen, Siyuan; Yu, Jijun; Lu, Qin; Han, Hantao; Hu, Longfei

2018-05-01

In this study, lithium/C-103 alloys heat pipes are proposed for sharp leading edge cooling. Three models of lithium/C-103 alloy heat pipes were fabricated. And their startup properties were tested by radiant heat tests and aerothermal tests. It is found that the startup temperature of lithium heat pipe was about 860 °C. At 1000 °C radiant heat tests, the operating temperature of lithium/C-103 alloy heat pipe is lower than 860 °C. Thus, startup failure occurs. At 1100 °C radiant heat tests and aerothermal tests, the operating temperature of lithium/C-103 alloy heat pipe is higher than 860 °C, and the heat pipe starts up successfully. The startup of lithium/C-103 alloy heat pipe decreases the leading edge temperature effectively, which endows itself good ablation resistance. After radiant heat tests and aerothermal tests, all the heat pipe models are severely oxidized because of the C-103 poor oxidation resistance. Therefore, protective coatings are required for further applications of lithium/C-103 alloy heat pipes.

An Environmentally Friendly, Cost-Effective Determination of Lead in Environmental Samples Using Anodic Stripping Voltammetry

Science.gov (United States)

Goldcamp, Michael J.; Underwood, Melinda N.; Cloud, Joshua L.; Harshman, Sean

2008-01-01

Contamination of the environment with heavy metals such as lead presents many health risks. Simple, effective, and field-portable methods for the measurement of toxic metals in environmental samples are vital tools for evaluating the risks that these contaminants pose. This article describes the use of new developments in anodic stripping…

Lead-free bearing alloys for engine applications

Science.gov (United States)

Ratke, Lorenz; Ågren, John; Ludwig, Andreas; Tonn, Babette; Gránásy, László; Mathiesen, Ragnvald; Arnberg, Lars; Anger, Gerd; Reifenhäuser, Bernd; Lauer, Michael; Garen, Rune; Gust, Edgar

2005-10-01

Recent developments to reduce the fuel consumption, emission and air pollution, size and weight of engines for automotive, truck, ship propulsion and electrical power generation lead to temperature and load conditions within the engines that cannot be borne by conventional bearings. Presently, only costly multilayer bearings with electroplated or sputtered surface coatings can cope with the load/speed combinations required. Ecological considerations in recent years led to a ban by the European Commission on the use of lead in cars a problem for the standard bronze-lead bearing material. This MAP project is therefore developing an aluminium-based lead-free bearing material with sufficient hardness, wear and friction properties and good corrosion resistance. Only alloys made of components immiscible in the molten state can meet the demanding requirements. Space experimentation plays a crucial role in optimising the cast microstructure for such applications.

A low sludge generated anode by hybrid solar electrocoagulation for the removal of lead

Science.gov (United States)

Hussin, F.; Aroua, M. K.

2017-06-01

In this work, perforated zinc is proposed as a new anode for lead removal by hybrid solar electrocoagulation. The characteristics of the sludge were investigated to understand the behaviour of lead removal during electrocoagulation. Sludge products formed were characterised using X-ray diffraction (XRD), X-ray fluorescence (XRF) and Field Emission Scanning Electron Microscopy (FESEM). In addition, the pH variation during electrocoagulation and effects on the sludge products were examined. At optimum conditions showed that the perforated zinc electrode produced better performance with high removal efficiency, low sludge volume index and less energy consumption.

Safety considerations of lithium lead alloy as a fusion reactor breeding material

International Nuclear Information System (INIS)

Jeppson, D.W.; Muhlestein, L.D.

1985-01-01

Test results and conclusions are presented for lithium lead alloy interactions with various gas atmospheres, concrete and potential reactor coolants. The reactions are characterized to evaluate the potential of volatilizing and transporting radioactive species associated with the liquid breeder under postulated fusion reactor accident conditions. The safety concerns identified for lithium lead alloy reactions with the above materials are compared to those previously identified for a reference fusion breeder material, liquid lithium. Conclusions made from this comparison are also included

Nano-composite of PtRu alloy electrocatalyst and electronically conducting polymer for use as the anode in a direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Jongho Choi; Kyungwon Park; Hyekyung Lee; Youngmin Kim; Jaesuk Lee; Yungeun Sung [Kwangju Inst. of Science and Technology, Dept. of Materials Science and Engineering, Gwangju (Korea)

2003-08-15

Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly(N-vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH{sub 3}OH/{sub 0.5} M H{sub 2}SO{sub 4} solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes. (Author)

Copper-Silver Alloy Depositions Using Thermionic Vacuum ARC (TVA)

International Nuclear Information System (INIS)

Akan, T.

2004-01-01

TVA is a plasma source generating pure metal vapor plasma and consists of a heated cathode emitting thermo electrons and an anode containing material to be evaporated. We used Cu and Ag pieces as anode materials and produced their alloys by electron bombarding. Cu-Ag alloys in various mass ratios were prepared by using the TVA and the TVA discharges were generated in the vapors of these alloys. The volt-ampere characteristics of the TVA discharges generated in the vapors of these alloys were investigated with respect to the ratio of Ag in the Cu-Ag alloy. Cu-Ag alloy thin films with various mass ratios were deposited onto the glass substrates by using their TVA discharges. The ratios of Cu and Ag in the thin Cu-Ag alloy films were found using scanning electron microscope-energy dispersive xray (SEM-EDX) microanalyses

Etching Behavior of Aluminum Alloy Extrusions

Science.gov (United States)

Zhu, Hanliang

2014-11-01

The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

Surface characterization and cytotoxicity response of biodegradable magnesium alloys

International Nuclear Information System (INIS)

Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem

2015-01-01

Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys

Surface characterization and cytotoxicity response of biodegradable magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Pompa, Luis; Rahman, Zia Ur; Munoz, Edgar; Haider, Waseem, E-mail: haiderw@utpa.edu

2015-04-01

Magnesium alloys have raised an immense amount of interest to many researchers because of their evolution as a new kind of third generation materials. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium alloys experience a natural phenomenon to biodegrade in aqueous solutions due to its corrosion activity, which is excellent for orthopedic and cardiovascular applications. However, a major concern with such alloys is fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of biodegradable implants. In this investigation, three different grades of magnesium alloys: AZ31B, AZ91E and ZK60A were studied for their corrosion resistance and biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter are used to study surface morphology, chemistry, roughness and wettability, respectively. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium based bio-assay, MTS. - Highlights: • Micro-textured features formed after the anodization of magnesium alloys. • Contact angle increased and surface free energy decreased by anodization. • Corrosion rate increased for anodized surfaces compared to untreated samples. • Cell viability was greater than 75% implying the cytocompatibility of Mg alloys.

Effects of anodic passivation on the constitution, stability and resistance to corrosion of passive film formed on an Fe-24Mn-4Al-5Cr alloy

International Nuclear Information System (INIS)

Zhang, Y.S.; Zhu, X.M.; Liu, M.; Che, R.X.

2004-01-01

The effects of anodic aging time and potential on the corrosion resistance, stability and constitution of the passive film formed on an Fe-24Mn-4Al-5Cr alloy in 50% HNO 3 solution were studied by using combined electrochemical measurements and Auger electron spectroscopic (AES)/X-ray photoelectron spectroscopic (XPS) analysis. In the anodic passive region, prolonged anodic aging time or increased passivating potential can induce better protective and stable properties of the passive film and better resistance to corrosion. With increasing aging time from 15 min to 5 h, the time required for the potential decay from the passive to active state increases from about 300 up to above 12,000 s, and the corrosion resistance in 1 mol l -1 Na 2 SO 4 solution of Fe-24Mn-4Al-5Cr alloy, characterized by polarization curves, is superior to that of Fe-13% Cr-0.1% C stainless steel. AES and XPS analyses of the aging passive film show that these improvements of properties are related to modifications of the passive layer with time. The increase of resistance to corrosion is attributed to Al 2 O 3 and Cr 2 O 3 enrichment and oxides of Fe and Mn depletion in the passive film and a thickening of the effective barrier layer of oxides

Research progress of aluminium alloy endplates for PEMFCs

Energy Technology Data Exchange (ETDEWEB)

Fu, Yu.; Hou, Junbo [Fuel Cell system and Engineering Laboratory, Dalian Institute of Chemical and Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Hou, Ming; Yan, Xiqiang; Luo, Xiaokuan; Shao, Zhigang; Yi, Baolian [Fuel Cell system and Engineering Laboratory, Dalian Institute of Chemical and Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2007-04-15

The endplate is a crucial component in a proton exchange membrane fuel cell (PEMFC) stack. It can provide the necessary rigidity and strength for the stack. An aluminium alloy is one of the ideal materials for PEMFC endplates because of its low density and high rigidity. But it does not meet the requirements of corrosion resistance and electrical insulation in PEMFC environments. In this work, methods of sealing treatments and the conditions of aluminium alloy anodization were investigated. Corrosion resistances of the samples prepared by different technologies were evaluated in simulated PEMFC environments. The results showed that the corrosion resistance of the samples sealed by epoxy resin was greatly improved compared with those sealed in boiling water, and the samples anodized at a constant current density performed better than those anodized at a constant voltage. By insulation measurements, all of the samples showed good electrical insulation. The aluminium alloy endplate anodized at a constant current density and sealed with thermosetting bisphenol-A epoxy resin exhibited promising potential for practical applications by assembling it in a PEMFC stack and applying a life test. (author)

Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion Transport

KAUST Repository

Choudhury, Snehashis; Tu, Zhengyuan; Stalin, Sanjuna; Vu, Duylinh; Fawole, Kristen; Gunceler, Deniz; Sundararaman, Ravishankar; Archer, Lynden A.

2017-01-01

Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes.

Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion Transport

KAUST Repository

Choudhury, Snehashis

2017-08-17

Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes.

In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

International Nuclear Information System (INIS)

Bertram, F.; Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

2014-01-01

We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

Synthesis, characterization and electrochemical performances of new antimony-containing graphite compounds used as anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Dailly, A.; Willmann, P.; Billaud, D.

2002-01-01

Graphite intercalation intercalated with metal alloys able to alloy reversibly lithium constitute a large set of new anodic materials for lithium-ion batteries of significantly improved reversible capacities. Especially, graphite intercalated with cesium-antimony alloys can be used as materials for anodes in lithium-ion batteries. Electrochemical insertion of lithium in such chemically modified precursors shows that lithium both intercalates in the empty van der Waals spaces of graphite and alloys reversibly with antimony. The total electrochemical reversible capacities, measured between 0 and 2 V vs Li + /Li, close to 700 mAh g -1 have been currently obtained

A Dealloying Synthetic Strategy for Nanoporous Bismuth-Antimony Anodes for Sodium Ion Batteries.

Science.gov (United States)

Gao, Hui; Niu, Jiazheng; Zhang, Chi; Peng, Zhangquan; Zhang, Zhonghua

2018-04-24

Metal-based anodes have recently aroused much attention in sodium ion batteries (SIBs) owing to their high theoretical capacities and low sodiation potentials. However, their progresses are prevented by the inferior cycling performance caused by severe volumetric change and pulverization during the (de)sodiation process. To address this issue, herein an alloying strategy was proposed and nanoporous bismuth (Bi)-antimony (Sb) alloys were fabricated by dealloying of ternary Mg-based precursors. As an anode for SIBs, the nanoporous Bi 2 Sb 6 alloy exhibits an ultralong cycling performance (10 000 cycles) at 1 A/g corresponding to a capacity decay of merely 0.0072% per cycle, due to the porous structure, alloying effect and proper Bi/Sb atomic ratio. More importantly, a (de)sodiation mechanism ((Bi,Sb) ↔ Na(Bi,Sb) ↔ Na 3 (Bi,Sb)) is identified for the discharge/charge processes of Bi-Sb alloys by using operando X-ray diffraction and density functional theory calculations.

A Technique for Dynamic Corrosion Testing in Liquid Lead Alloys

Energy Technology Data Exchange (ETDEWEB)

Loewen, Eric Paul; Davis, Cliff Bybee; Mac Donald, Philip Elsworth

2001-04-01

An experimental apparatus for the investigation of the flow-assisted dissolution and precipitation (corrosion) of potential fuel cladding and structural materials to be used in liquid lead alloy cooled reactors has been designed. This experimental project is part of a larger research effort between Idaho National Engineering and Environmental Laboratory (INEEL) and Massachusetts Institute of Technology to investigate the suitability of lead, lead-bismuth, and other lead alloys for cooling fast reactors designed to produce low-cost electricity as well as for actinide burning. The INEEL forced convection corrosion cell consists of a small heated vessel with a shroud and gas flow system. The gas flow rates, heat input, and shroud and vessel dimensions have been adjusted so that a controlled coolant flow rate, temperature, and oxygen potential are created within the downcomer located between the shroud and vessel wall. The ATHENA computer code was used to design the experimental apparatus and estimate the fluid conditions. The corrosion cell will test steel that is commercially available in the U. S. to temperatures above 650oC.

Effect of nickel content on the anodic dissolution and passivation of ...

Indian Academy of Sciences (India)

The effect of systematic increase of Ni on the anodic dissolution and passivation of Zn–Ni alloys in various concentrations of KOH solution (0.1–1 M) was investigated. The anodic dissolution and passivation behaviour for each pure Zn and Ni in the same studied solutions was also investigated, and the obtained data were ...

Synthesis of uniform nano-structured lead oxide by sonochemical method and its application as cathode and anode of lead-acid batteries

International Nuclear Information System (INIS)

Karami, Hassan; Karimi, Mohammad Ali; Haghdar, Saeed

2008-01-01

This paper discusses the results of a research aimed at investigating the synthesis of nano-structured lead oxide through reaction of lead nitrate solution and sodium carbonate solution by the sonochemical method. At the first, lead carbonate was obtained in a synthesized solution and then, after filtration, it was calcinated at the temperature of 320 deg. C so that nano-structured lead oxide can be produced. The effects of different parameters on particle size and morphology of final lead oxide powder were optimized by a 'one at a time' method. The prepared lead oxide powder was characterized by scanning electron microscopy (SEM), transmission electron spectroscopy (TEM) and X-ray diffraction (XRD). Under optimum conditions, uniformed and homogeneous nano-structured lead oxide powder with more spongy morphology and particle size of 20-40 nm was obtained. The synthesized lead oxide, as anode and cathode of lead-acid batteries, showed an excellent discharge capacity (140 mA h/g)

Sample preparation technique for transmission electron microscopy anodized Al-Li-SiC metal matrix composite

International Nuclear Information System (INIS)

Shahid, M.; Thomson, G.E.

1997-01-01

Along with improved mechanical properties, metal matrix composites (MMC) have a disadvantage of enhanced corrosion susceptibility in aggressive environments. Recent studies on corrosion behaviour of an Al-alloy 8090/SiC MMC, revealed considerably high corrosion rates of the MMC in near neutral solutions containing chloride ions. Anodizing is one of the potential surface treatment for the MMC to provide protective coating against corrosion. The surface and cross section of the anodized MMC can easily be observed using scanning electron microscope. The anodizing behaviour of the MMC can be understood further if the anodized cross section in examined under transmission electron microscope (TEM). However, it is relatively difficult to prepare small (3 mm diameter) electron transparent specimens of the MMC supporting an anodic film. In the present study a technique has been developed for preparing thin electron transparent specimens of the anodized MMC. This technique employed conventional ion beam thinning process but the preparation of small discs was a problem. A MMMC consisting of Al-alloy 8090 with 20 % (by weight) SiC particulate with an average size of 5 Mu m, was anodized and observed in TEM after preparing the samples using the above mentioned techniques. (author)

Lead migration from toys by anodic stripping voltammetry using a bismuth film electrode.

Science.gov (United States)

Leal, M Fernanda C; Catarino, Rita I L; Pimenta, Adriana M; Souto, M Renata S; Afonso, Christelle S; Fernandes, Ana F Q

2016-09-02

Metals may be released from toys via saliva during mouthing, via sweat during dermal contact, or via gastric and intestinal fluids after partial or whole ingestion. In this study, we determined the lead migration from toys bought on the Portuguese market for children below 3 years of age. The lead migration was performed according to the European Committee for Standardization EN 71-3, which proposes a 2-hour migration test that simulates human gastric conditions. The voltammetric determination of migrated lead was performed by anodic stripping voltammetry (ASV) at a bismuth film electrode (BiFE). For all the analyzed toys, the values of migrated lead did not exceed the limits imposed by the European Committee for Standardization EN 71-3 (90 mg kg -1 ) and by the EU Directive 2009/48/EC (13.5 mg kg -1 ) on the safety of toys.

Analyses of alloys for quelatometry, part one, alloys with copper, lead and zinc

International Nuclear Information System (INIS)

Clavijo Diaz, Alfonso

1995-01-01

A chemical-mathematic model and experimental method based on the acid base balances is developed for the analysis of metallic ions, isolated or in mixtures. The theoretical titling curves, including chelones-forming agents and metallo-chromic indicator were worked on a personal computer. This chelometric method was applied to the quantitative determination of copper, zinc and lead ions in alloys

Hydrogen extraction from liquid lithium-lead alloy by gas-liquid contact method

International Nuclear Information System (INIS)

Xie Bo; Weng Kuiping; Hou Jianping; Yang Guangling; Zeng Jun

2013-01-01

Hydrogen extraction experiment from liquid lithium-lead alloy by gas-liquid contact method has been carried out in own liquid lithium-lead bubbler (LLLB). Experimental results show that, He is more suitable than Ar as carrier gas in the filler tower. The higher temperature the tower is, the greater hydrogen content the tower exports. Influence of carrier gas flow rate on the hydrogen content in the export is jagged, no obvious rule. Although the difference between experimental results and literature data, but it is feasible that hydrogen isotopes extraction experiment from liquid lithium-lead by gas-liquid contact method, and the higher extraction efficiency increases with the growth of the residence time of the alloy in tower. (authors)

Corrosion mechanism of Al, Al–Zn and Al–Zn–Sn alloys in 3 wt.% NaCl solution

International Nuclear Information System (INIS)

Khireche, S.; Boughrara, D.; Kadri, A.; Hamadou, L.; Benbrahim, N.

2014-01-01

Highlights: • We elaborate Al–5Zn–xSn sacrificial anodes (x = 0.1%, 0.2% and 0.4%). • Increasing Sn amount does activate Al alloys. • The anode dissolution in NaCl initiates at precipitations where Sn is enriched. • Sn enhances uniform attack on the surface of the Al alloy. • Al–Zn–Sn anodes perform better than the Al–Zn anode. - Abstract: The effect of zinc and tin addition to pure aluminum was investigated in 3 wt.% NaCl solution. The corrosion behavior of the elaborated samples (Al, Al–Zn and Al–Zn–Sn) was studied by open circuit potential, Tafel plot and electrochemical impedance spectroscopy. For the microstructure characterization, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy were used. The aluminum activation increases in the following order: Al < Al–5Zn < Al–5Zn–0.1Sn < Al–5Zn–0.2Sn < Al–5Zn–0.4Sn. The impedance measurements and the microscopic observations confirmed the great activity of Al–Zn and Al–Zn–Sn compared to pure Al. The segregation at the grain boundaries leads to intergranular corrosion

Porous-Nickel-Scaffolded Tin-Antimony Anodes with Enhanced Electrochemical Properties for Li/Na-Ion Batteries.

Science.gov (United States)

Li, Jiachen; Pu, Jun; Liu, Ziqiang; Wang, Jian; Wu, Wenlu; Zhang, Huigang; Ma, Haixia

2017-08-02

The energy and power densities of rechargeable batteries urgently need to be increased to meet the ever-increasing demands of consumer electronics and electric vehicles. Alloy anodes are among the most promising candidates for next-generation high-capacity battery materials. However, the high capacities of alloy anodes usually suffer from some serious difficulties related to the volume changes of active materials. Porous supports and nanostructured alloy materials have been explored to address these issues. However, these approaches seemingly increase the active material-based properties and actually decrease the electrode-based capacity because of the oversized pores and heavy mass of mechanical supports. In this study, we developed an ultralight porous nickel to scaffold with high-capacity SnSb alloy anodes. The porous-nickel-supported SnSb alloy demonstrates a high specific capacity and good cyclability for both Li-ion and Na-ion batteries. Its capacity retains 580 mA h g -1 at 2 A g -1 after 100 cycles in Li-ion batteries. For a Na-ion battery, the composite electrode can even deliver a capacity of 275 mA h g -1 at 1 A g -1 after 1000 cycles. This study demonstrates that combining the scaffolding function of ultralight porous nickel and the high capacity of the SnSb alloy can significantly enhance the electrochemical performances of Li/Na-ion batteries.

A Comparative Electrochemical Study of AZ31 and AZ91 Magnesium Alloy

Directory of Open Access Journals (Sweden)

S. A. Salman

2010-01-01

Full Text Available A comparative study has been carried out on AZ31 and AZ91 magnesium alloys in order to understand the electrochemical behavior in both alkaline and chloride containing solutions. The open circuit potential (OCP was examined in 1 M NaOH and 3.5 mass % NaCl solutions. AZ31 magnesium alloy shows several potential drops throughout the immersion in 1 M NaOH solution, though AZ91 does not show this phenomenon. The specimens were anodized at a constant potential of 3 V for 30 minutes at 298 K in 1 M NaOH solution. The anticorrosion behavior of the anodized specimens was better than those of nonanodized specimens. The anodized AZ91 has better corrosion resistance compared to nonanodized specimen and anodized AZ31 magnesium alloy.

Neutronic design for a 100MW{sub th} Small modular natural circulation lead or lead-alloy cooled fast reactors core

Energy Technology Data Exchange (ETDEWEB)

Chen, C.; Chen, H.; Zhang, H.; Chen, Z.; Zeng, Q., E-mail: shchshch@ustc.edu.cn, E-mail: hlchen1@ustc.edu.cn, E-mail: kulah@mail.ustc.edu.cn, E-mail: zchen214@mail.ustc.edu.cn, E-mail: zengqin@ustc.edu.cn [Univ. of Science and Technology of China, School of Nuclear Science and Technology, Hefei, Anhui (China)

2015-07-01

Lead or lead-alloy cooled fast reactor with good fuel proliferation and nuclear waste transmutation capability, as well as high security and economy, is a great potential for the development of fourth-generation nuclear energy systems. Small natural circulation reactor is an important technical route lead cooled fast reactors industrial applications, which has been chosen as one of the three reference technical for solution lead or lead-alloy cooled fast reactors by GIF lead-cooled fast reactor steering committee. The School of Nuclear Science and Technology of USTC proposed a small 100MW{sub th} natural circulation lead cooled fast reactor concept called SNCLFR-100 based realistic technology. This article describes the SNCLFR-100 reactor of the overall technical program, core physics calculation and analysis. The results show that: SNCLFR-100 with good neutronic and safety performance and relevant design parameters meet the security requirements with feasibility. (author)

Electroplating on titanium alloy

Science.gov (United States)

Lowery, J. R.

1971-01-01

Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

A review of refractory materials for vapor-anode AMTEC cells

Science.gov (United States)

King, Jeffrey C.; El-Genk, M. S.

2000-01-01

Recently, refractory alloys have been considered as structural materials for vapor-anode Alkali Metal Thermal-to-Electric Conversion (AMTEC) cells, for extended (7-15 years) space missions. This paper reviewed the existing database for refractory metals and alloys of potential use as structural materials for vapor-anode sodium AMTEC cells. In addition to requiring that the vapor pressure of the material be below 10-9 torr (133 nPa) at a typical hot side temperature of 1200 K, other screening considerations were: (a) low thermal conductivity, low thermal radiation emissivity, and low linear thermal expansion coefficient; (b) low ductile-to-brittle transition temperature, high yield and rupture strengths and high strength-to-density ratio; and (c) good compatibility with the sodium AMTEC operating environment, including high corrosion resistance to sodium in both the liquid and vapor phases. Nb-1Zr (niobium-1% zirconium) alloy is recommended for the hot end structures of the cell. The niobium alloy C-103, which contains the oxygen gettering elements zirconium and hafnium as well as titanium, is recommended for the colder cell structure. This alloy is stronger and less thermally conductive than Nb-1Zr, and its use in the cell wall reduces parasitic heat losses by conduction to the condenser. The molybdenum alloy Mo-44.5Re (molybdenum-44.5% rhenium) is also recommended as a possible alternative for both structures if known problems with oxygen pick up and embrittlement of the niobium alloys proves to be intractable. .

Electrocatalysis on bimetallic and alloy surfaces

NARCIS (Netherlands)

Koper, M.T.M.

2004-01-01

Bimetallic surfaces and alloys are well known to have unique catalytic properties for many important chemical transformations [1]. In electrocatalysis, bimetallic and alloy catalysts have been a particularly active area of research in relation to low-temperature fuel cells [2]. On the anode side,

The mineralogical characterization of tellurium in copper anodes

Science.gov (United States)

Chen, T. T.; Dutrizac, J. E.

1993-12-01

A mineralogical study of a «normal» commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copper Smelting and Refining Company was carried out to identify the tellurium carriers and their relative abundances. In all the anodes, the major tellurium carrier is the Cu2Se-Cu2Te phase which occurs as a constituent of complex inclusions at the copper grain boundaries. In tellurium-rich anodes, the molar tellurium content of the Cu2Se-Cu2Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu2Se-Cu2Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of the grain-boundary inclusions. About 1 pct of the tellurium content of silver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the total tellurium content of the anodes occurs in solid solution in the copper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.

Selection and characterization of lead alloys for use in the SDC EM Calorimeter

International Nuclear Information System (INIS)

Nasiatka, J.

1993-01-01

Lead, because of it's density and ductility, has been used by man for centuries for many things ranging from building materials, to piping; from electrical connections, to radiation shielding, and batteries. However, despite it's extensive and varied use, not much is really known about it's exact physical and structural properties except in a very rudimentary way. The SDC cast lead EM Calorimeter needs to take full advantage of all the properties that the lead alloy has to offer. Hence, a very thorough and detailed understanding of the properties of the lead-absorber structure must be obtained and controlled, so that the integrity of the calorimeter is not compromised. This paper will attempt to detail a series of ongoing experiments used to characterize and define the properties of the Calcium-Tin-Lead alloys for use in the SDC cast lead electromagnetic calorimeter

Electroless formation of hybrid lithium anodes for fast interfacial ion transport

Energy Technology Data Exchange (ETDEWEB)

Choudhury, Snehashis; Stalin, Sanjuna; Vu, Duylinh; Fawole, Kristen; Archer, Lynden A. [School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY (United States); Tu, Zhengyuan [Department of Material Science and Engineering, Cornell University, Ithaca, NY (United States); Gunceler, Deniz [Department of Physics, Cornell University, Ithaca, NY (United States); Sundararaman, Ravishankar [Material Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY (United States)

2017-10-09

Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

International Nuclear Information System (INIS)

Abd-Elnaiem, Alaa M.; Mebed, A.M.; El-Said, Waleed Ahmed; Abdel-Rahim, M.A.

2014-01-01

Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes

Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

Energy Technology Data Exchange (ETDEWEB)

Abd-Elnaiem, Alaa M., E-mail: alaa.abd-elnaiem@science.au.edu.eg [KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mebed, A.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Department of Physics, Faculty of Science, Al-Jouf University, Sakaka 2014 (Saudi Arabia); El-Said, Waleed Ahmed [Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Abdel-Rahim, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

2014-11-03

Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes.

Au-Ge based Candidate Alloys for High-Temperature Lead-Free Solder Alternatives

DEFF Research Database (Denmark)

Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

2009-01-01

Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure and microhard......Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The influence of the low melting point metals namely In, Sb and Sn to the Au-Ge eutectic with respect to the microstructure...... was primarily strengthened by the refined (Ge) dispersed phase. The distribution of phases played a relatively more crucial role in determining the ductility of the bulk solder alloy. In the present work it was found that among the low melting point metals, the addition of Sb to the Au-Ge eutectic would...

Diffusivity, activity and solubility of oxygen in liquid lead and lead-bismuth eutectic alloy by electrochemical methods

International Nuclear Information System (INIS)

Ganesan, Rajesh; Gnanasekaran, T.; Srinivasa, Raman S.

2006-01-01

The diffusivity of oxygen in liquid lead and lead-bismuth eutectic (LBE) alloy was measured by a potentiostatic method and is given by log(D O Pb /cm 2 s -1 )=-2.554-2384/T(+/-0.070), 818-1061K, and log(D O LBE /cm 2 s -1 )=-0.813-3612/T(+/-0.091), 811-980K. The activity of oxygen in lead and LBE was determined by coulometric titration experiments. Using the measured data, the standard free energy of dissolution of oxygen in liquid lead and LBE was derived and is given byG O(Pb) xs =-121349+16.906T(+/-560)J(gatomO) -1 ,815-1090K,G O(LBE) xs = -127398+27.938T(+/-717)J(gatomO) -1 ,812-1012K.Using the above data, the Gibbs energy of formation of PbO(s) and equilibrium oxygen pressures measured over the oxygen-saturated LBE alloy, the solubility of oxygen in liquid lead and LBE were derived. The solubility of oxygen in liquid lead and LBE are given by log(S/at.%O)=-5100/T+4.32 (+/-0.04), 815-1090K and log(S/at.%O)=-4287/T+3.53 (+/-0.06), 812-1012K respectively.

Effect of Solution Temperature for Al Alloy Anodizing on Cavitation Characteristics

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Jun [Kunsan National University, Kunsan (Korea, Republic of); Lee, Jung Hyung; Kim, Seong Jong [Mokpo National Maritime University, Haeyangdaehak-ro 91, Mokpo (Korea, Republic of)

2015-06-15

The commercialization of aluminum had been delayed than other metals because of its high oxygen affinity. Anodizing is a process in which oxide film is formed on the surface of a valve metal in an electrolyte solution by anodic oxidation reaction. Aluminum has thin oxide film on surface but the oxide film is inhomogeneous having a thickness only in the range of several nanometers. Anodizing process increases the thickness of the oxide film significantly. In this study, porous type oxide film was produced on the surface of aluminum in sulfuric acid as a function of electrolyte temperature, and the optimum condition were determined for anodizing film to exhibit excellent cavitation resistance in seawater environment. The result revealed that the oxide film formed at 10 ℃ represented the highest cavitation resistance, while the oxide film formed at 15 ℃ showed the lowest resistance to cavitation in spite of its high hardness.

Enhanced Electrochemical Performance of Electrospun Ag/Hollow Glassy Carbon Nanofibers as Free-standing Li-ion Battery Anode

International Nuclear Information System (INIS)

Shilpa; Sharma, Ashutosh

2015-01-01

Silver with a high theoretical capacity for lithium storage is an attractive alloy based anode for Li-ion batteries, but large volume changes associated with AgLi x alloy formation leads to electrode cracking, pulverization and rapid capacity fading. A buffer matrix, like the electrospun hollow carbon nanofibers, can reduce this problem to a great extent. Herein, we demonstrate the facile synthesis of a free-standing, binder free Ag-C hybrid electrode through co-axial electrospinning, where well dispersed Ag nanoparticles are embedded in hollow carbon nanofibers. Using this approach, the long cycle life of carbon is complemented with the high lithium storage capacity of Ag, resulting in a high performance anode. The Ag-C composite electrode delivers a capacity of 739 mAh g −1 (>conventional graphite anodes) at 50 mA g −1 , with ∼85% capacity retention after 100 cycles. In addition, the Ag-C composite nanofibers are highly porous and exhibit a large accessible surface area (∼726.9 m 2 g −1 ) with an average pore diameter of ∼6.07 nm. The encapsulation of Ag in the hollow interiors not only provides additional lithium storage sites but also enhances the electronic conductivity, which combined with the reduced lithium diffusion path lengths in the nanofibers result in faster charge-discharge kinetics and hence a high rate performance

Spectra of luminescence due to microdischarges on an aluminum valve anode

International Nuclear Information System (INIS)

Sizikov, A.M.; Vol'f, V.G.; Bugaenko, L.T.

1995-01-01

The spectrum of visible and near-UV luminescence due to a microdischarge on an AMg-6 aluminum alloy was studied under conditions of valve anodization in solutions of sodium carbonate and other electrolytes. It was shown that emission spectra exhibit lines that characterize anodic (aluminum and magnesium) and electrolytic (sodium) components. The dependence of the temperature of the microdischarge on the electrolyte concentration and composition is discussed

SnSe2 2D Anodes for Advanced Sodium Ion Batteries

KAUST Repository

Zhang, Fan

2016-08-22

A simple synthesis method to prepare pure SnSe2 nanosheet anodes for Na ion batteries is reported. The SnSe2 2D sheets achieve a stable and reversible specific capacity of 515 mA h g-1 after 100 cycles, with excellent rate performance. The sodiation and desodiation process in this anode material is shown to occur via a combination of conversion and alloying reactions.

Effect of aluminum coatings on corrosion properties of AZ31 magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Chiu Liuho; Lin Hsingan; Chen Chunchin; Yang Chihfu [Dept. of materials engineering, Tatung Univ., Taipei (Taiwan); Chang Chiahua; Wu Jenchin [Physical chemistry section, chemical systems research div., Chung-Shan Inst. of Science and Technology, Tao-Yuan (Taiwan)

2003-07-01

This investigation aimed to increase the corrosion resistance of an AZ31 magnesium alloy by an aluminum arc spray coating and a post-treatment consisted of hot pressing and anodizing. It was found that the aluminum arc spraying alone was incapable of protection against corrosion due to the high amount of pores present in the coating layer. In order to solve the problem, densification of the Al arc-sprayed layer was carried out by hot pressing the coated AZ31 Mg alloy plate under an appropriate range of temperature, time and pressure. After hot pressing the Al coated AZ31 Mg alloy plate exhibited a much improved corrosion resistance. A final anodizing treatment applied to the AZ31 alloy with the dense Al coating further improved its resisting to corrosion. The results showed that, by adopting the Al arc spraying, hot pressing and anodizing process, the corrosion current density of the AZ31 alloy in a 3.5 wt% NaCl solution was from 2.1 x 10{sup -6} A/cm{sup 2} (original AZ31) to 3.7 x 10{sup -7} A/cm{sup 2} (after the surface treatment), which value is close to that of an anodized aluminum plate. (orig.)

Study of localized corrosion in aluminum alloys by the scanning reference electrode technique

Science.gov (United States)

Danford, M. D.

1995-01-01

Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more frequent and of greater strength in the 2195 Al-Li alloy than in the 2219-T87 Al alloy, indicating a greater tendency toward pitting for the latter. However, the overall corrosion rates are about the same for these two alloys, as determined using the polarization resistance technique. In the welded 2195 Al-Li alloy, the weld bean is entirely cathodic, with rather strongly anodic heat affected zones (HAZ) bordering both sides, indicating a high probability of corrosion in the HAZ parallel to the weld bead.

Si/C composite lithium-ion battery anodes synthesized using silicon nanoparticles from porous silicon

International Nuclear Information System (INIS)

Park, Jung-Bae; Lee, Kwan-Hee; Jeon, Young-Jun; Lim, Sung-Hwan; Lee, Sung-Man

2014-01-01

The synthesis of Si nanoparticles by ultrasonication processing of porous Si powder and a novel method for preparing a high-capacity Si/C composite using this technique is reported. The porous Si powder is prepared by selectively etching the silicide phase of a Ti 24 Si 76 alloy consisting of Si and silicide phases. The particle size of the nanocrystalline Si is determined by the crystallite size of the Si and silicide phases in the alloy powder. Ultrasonication of the porous Si obtained from the mechanically alloyed Ti 24 Si 76 alloy generates nanocrystalline Si particles of size about 5 nm. Growth of the Si and silicide phases in the alloy is induced by annealing of the mechanically alloyed sample, with a consequent increase in the size of the Si particles obtained after ultrasonication. Application of the ultrasonication process to the fabrication of Si/C composite anode materials generates nanometer-scale Si particles in situ that are distributed in the matrix. Analysis of the phases obtained and evaluation of the distribution of the nanometer-scale Si particles in the composites via XRD/TEM measurements show that the nanometer-scale Si particles are effectively synthesized and uniformly distributed in the carbon matrix, leading to enhanced electrochemical performance of the Si/C composites

Surface treatments for aluminium alloys

Science.gov (United States)

Ardelean, M.; Lascău, S.; Ardelean, E.; Josan, A.

2018-01-01

Typically, in contact with the atmosphere, the aluminium surface is covered with an aluminium oxide layer, with a thickness of less than 1-2μm. Due to its low thickness, high porosity and low mechanical strength, this layer does not protect the metal from corrosion. Anodizing for protective and decorative purposes is the most common method of superficial oxidation processes and is carried out through anodic oxidation. The oxide films, resulted from anodizing, are porous, have a thickness of 20-50μm, and are heat-resistant, stable to water vapour and other corrosion agents. Hard anodizing complies with the same obtains principles as well as decorative and protective anodization. The difference is in that hard anodizing is achieved at low temperatures and high intensity of electric current. In the paper are presented the results of decorative and hard anodization for specimens made from several aluminium alloys in terms of the appearance of the specimens and of the thickness of the anodized.

Anodic stripping voltammetry of mercury, zinc, cadmium, and lead in a rice farm ecosystem

International Nuclear Information System (INIS)

Del Mundo, F.R.; Vicente-Beckett, V.A.

1990-01-01

Analytical procedures based on differential pulse anodic stripping voltammetry were developed and applied to the analysis of some trace metals in a rice farm ecosystem. A gold wire served as working electrode for the analysis of mercury in 0.1M HNO 3 ; a hanging mercury drop electrode was used for the simultaneous analyses of zinc, cadmium, and lead in 0.1M sodium acetate buffer (pH 4.5). Mercury was pre-concentrated for five minutes at + 0.20 V vs SCE. The area of the anodic stripping peaks varied linearly over the concentration range 3x10 -10 -2x10 -8 M Hg(II); the limit of detection was 0.06 ppb or 3x10 -10 M Hg(II). The simultaneous analytical method involved pre-electrolysis at -1.2 V vs SCE for ten minutes. The heights of the individual anodic stripping peaks varied linearly with concentration in a mixture of the ions over the concentration range 0.020-0.10 ppm for each ion; the limits of detection were 0.004 ppm, 0.01 ppm, and 0.01 ppm for Cd, Pb, Zn, respectively. The developed procedures were used to determine the baseline levels of these metals in soil, water, and rice plant samples from a one-hectare traditional rice farm in San Pedro, Laguna. (auth.). 26 refs.; 4 tabs.; 6 figs

An Analysis of Mechanical Properties of Anodized Aluminum Film at High Stress

Science.gov (United States)

Zhao, Xixi; Wei, Guoying; Yu, Yundan; Guo, Yuemei; Zhang, Ao

2015-10-01

In this paper, a new environmental-friendly electrolyte containing sulfuric acid and tartaric acid has been used as the substitute of chromic acid for anodization. The work discussed the influence of anodizing voltages on the fatigue life of anodized Al 2024-T3 by performing fatigue tests with 0.1 stress ratio (R) at 320 MPa. Meanwhile the fatigue cycles to failure, yield strength, tensile strength and fracture surface of anodic films at different conditions were investigated. The results showed that the fatigue life of anodized and sealed specimens reduced a lot compared to aluminum alloy, which can be attributed to the crack sites initiated at the oxide layer. The fracture surface analyses also revealed that the number of crack initiation sites enlarged with the increase of anodizing voltage.

Electrolytic production of metals using a resistant anode

Science.gov (United States)

Tarcy, G.P.; Gavasto, T.M.; Ray, S.P.

1986-11-04

An electrolytic process is described comprising evolving oxygen on an anode in a molten salt, the anode comprising an alloy comprising a first metal and a second metal, both metals forming oxides, the oxide of the first metal being more resistant than the second metal to attack by the molten salt, the oxide of the second metal being more resistant than the first metal to the diffusion of oxygen. The electrode may also be formed of CuAlO[sub 2] and/or Cu[sub 2]O. 2 figs.

Novel Non-Carbonate Based Electrolytes for Silicon Anodes

Energy Technology Data Exchange (ETDEWEB)

Zhu, Ye [Wildcat Discovery Technologies, San Diego, CA (United States); Yang, Johnny [Wildcat Discovery Technologies, San Diego, CA (United States); Cheng, Gang [Wildcat Discovery Technologies, San Diego, CA (United States); Carroll, Kyler [Wildcat Discovery Technologies, San Diego, CA (United States); Clemons, Owen [Wildcat Discovery Technologies, San Diego, CA (United States); Strand, Diedre [Wildcat Discovery Technologies, San Diego, CA (United States)

2016-09-09

Substantial improvement in the energy density of rechargeable lithium batteries is required to meet the future needs for electric and plug-in electric vehicles (EV and PHEV). Present day lithium ion battery technology is based on shuttling lithium between graphitic carbon and inorganic oxides. Non-graphitic anodes, such as silicon can provide significant improvements in energy density but are currently limited in cycle life due to reactivity with the electrolyte. Wildcat/3M proposes the development of non-carbonate electrolyte formulations tailored for silicon alloy anodes. Combining these electrolytes with 3M’s anode and an NMC cathode will enable up to a 20% increase in the volumetric cell energy density, while still meeting the PHEV/EV cell level cycle/calendar life goals.

The learning machine in quantitative chemical analysis : Part I. Anodic Stripping Voltammetry of Cadmium, Lead and Thallium

NARCIS (Netherlands)

Bos, M.; Jasink, G.

1978-01-01

The linear learning machine method was applied to the determination of cadmium, lead and thallium down to 10-8 M by anodic stripping voltammetry at a hanging mercury drop electrode. With a total of three trained multicategory classifiers, concentrations of Cd, Pb and Tl could be predicted with an

Electrochemical performance and stability of Ni1-xCox-based cermet anode for direct methane-fuelled solid oxide fuel cells

Directory of Open Access Journals (Sweden)

Nicharee Wongsawatgul

2017-01-01

Full Text Available Carbon deposition on Ni-based anode is well-known as a major barrier for the practical use and commercialization of hydrocarbon-fuelled solid oxide fuel cells (SOFCs. In this work, Co alloying in Ni-YSZ was studied as an alternative anode material for using CH4 as a fuel. The Ni-YSZ and Ni-Co alloyed-YSZ were prepared by the traditional impregnation method without further mixing processes. After sintering and reduction in H2 atmosphere, the introduced Co can completely dissolved into the Ni lattice and changed the morphology with an increase in the Ni-YSZ grain size and showed a better uniform microstructure. The Co alloying also enhanced the electrochemical performance under CH4 fuel by reducing the resistance and anodic overvoltage. Moreover, the Co addition enhanced the stability of the cell with CH4 a constant load current of 80 mA for 60 h. This performance related to the carbon deposition on the anode surface. The Co alloying showed a high efficiency to suppress the carbon deposition and improved the electrochemical performance of an SOFC cell operating under CH4 fuel.

Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Jensen, Flemming; Bordo, Kirill

2014-01-01

Multiple-pass friction stir processing (FSP) was employed to impregnate Ti, Y and Ce oxide powders into the surface of an Aluminium alloy. The FSP processed surface composite was subsequently anodized with an aim to develop optical effects in the anodized layer owing to the presence of incorporated...... oxide particles which will influence the scattering of light. This paper presents the investigations on relation between microstructure of the FSP zone and optical appearance of the anodized layer due to incorporation of metal oxide particles and modification of the oxide particles due to the anodizing...

Handbook on Lead-bismuth Eutectic Alloy and Lead Properties, Materials Compatibility, Thermal-hydraulics and Technologies - 2015 Edition

International Nuclear Information System (INIS)

Fazio, Concetta; Sobolev, V.P.; Aerts, A.; Gavrilov, S.; Lambrinou, K.; Schuurmans, P.; Gessi, A.; Agostini, P.; Ciampichetti, A.; Martinelli, L.; Gosse, S.; Balbaud-Celerier, F.; Courouau, J.L.; Terlain, A.; Li, N.; Glasbrenner, H.; Neuhausen, J.; Heinitz, S.; Zanini, L.; Dai, Y.; Jolkkonen, M.; Kurata, Y.; Obara, T.; Thiolliere, N.; Martin-Munoz, F.J.; Heinzel, A.; Weisenburger, A.; Mueller, G.; Schumacher, G.; Jianu, A.; Pacio, J.; Marocco, L.; Stieglitz, R.; Wetzel, T.; Daubner, M.; Litfin, K.; Vogt, J.B.; Proriol-Serre, I.; Gorse, D.; Eckert, S.; Stefani, F.; Buchenau, D.; Wondrak, T.; Hwang, I.S.

2015-01-01

Heavy liquid metals such as lead or lead-bismuth have been proposed and investigated as coolants for fast reactors since the 1950's. More recently, there has been renewed interest worldwide in the use of these materials to support the development of systems for the transmutation of radioactive waste. Heavy liquid metals are also under evaluation as a reactor core coolant and accelerator-driven system neutron spallation source. Several national and international R and D programmes are ongoing for the development of liquid lead-alloy technology and the design of liquid lead-alloy-cooled reactor systems. In 2007, a first edition of the handbook was published to provide deeper insight into the properties and experimental results in relation to lead and lead-bismuth eutectic technology and to establish a common database. This handbook remains a reference in the field and is a valuable tool for designers and researchers with an interest in heavy liquid metals. The 2015 edition includes updated data resulting from various national and international R and D programmes and contains new experimental data to help understand some important phenomena such as liquid metal embrittlement and turbulent heat transfer in a fuel bundle. The handbook provides an overview of liquid lead and lead-bismuth eutectic properties, materials compatibility and testing issues, key aspects of thermal-hydraulics and existing facilities, as well as perspectives for future R and D. (authors)

X-ray fluorescence determination of Sn, Sb, Pb in lead-based bearing alloys using a solution technique

Science.gov (United States)

Tian, Lunfu; Wang, Lili; Gao, Wei; Weng, Xiaodong; Liu, Jianhui; Zou, Deshuang; Dai, Yichun; Huang, Shuke

2018-03-01

For the quantitative analysis of the principal elements in lead-antimony-tin alloys, directly X-ray fluorescence (XRF) method using solid metal disks introduces considerable errors due to the microstructure inhomogeneity. To solve this problem, an aqueous solution XRF method is proposed for determining major amounts of Sb, Sn, Pb in lead-based bearing alloys. The alloy samples were dissolved by a mixture of nitric acid and tartaric acid to eliminated the effects of microstructure of these alloys on the XRF analysis. Rh Compton scattering was used as internal standard for Sb and Sn, and Bi was added as internal standard for Pb, to correct for matrix effects, instrumental and operational variations. High-purity lead, antimony and tin were used to prepare synthetic standards. Using these standards, calibration curves were constructed for the three elements after optimizing the spectrometer parameters. The method has been successfully applied to the analysis of lead-based bearing alloys and is more rapid than classical titration methods normally used. The determination results are consistent with certified values or those obtained by titrations.

Electrochemical reduction of oxygen on lead-silver alloys in an alkaline medium

International Nuclear Information System (INIS)

Seliverstov, S.D.; Arkhangel'skaya, Z.P.; Lyzlov, N.Y.

1986-01-01

The use of lead-silver alloys as materials for the gas-absorbing electrode in sealed silver-cadmium alkaline storage batteries is desirable primarily from the stanpoint of saving the costly silver. The authors studied reduction of oxygen with the aim of optimizing the composition of the Pb-Ag alloy and of the porous structure of the electrodes. The alloys were made in a muffle furnace in corundum crucibles under a layer of VI-2 flux. Curves are shown which represent the dependence of the ionization current of molecular oxygen on smooth partially immersed electrodes made from alloys differing in composition on the length of the part of the electrode withdrawn from the solution. It is shown that decrease of the corrosion resistance of the alloy in the porous electrode causes partial loss of its mechanical strength. Worsening of the electric contact between the particles of active material is also possible. An alloy of the composition (mass %) 60 Pb-40 Ag is the most suitable from the practical standpoint

Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Jensen, Flemming; Canulescu, Stela

2014-01-01

Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO2, Y2O3 and CeO2) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical...... dark to greyish white. This is attributed to the localized microstructural and morphological differences around the metal oxide particles incorporated into the anodic alumina matrix. The metal oxide particles in the FSP zone electrochemically shadowed the underlying Al matrix and modified the local...

The Influence of the Electrolyte Nature and PEO Process Parameters on Properties of Anodized Ti-15Mo Alloy Intended for Biomedical Applications

Directory of Open Access Journals (Sweden)

Oksana Banakh

2018-05-01

Full Text Available Plasma electrolytic oxidation (PEO of Ti-15Mo alloys conducted in electrolytes containing Ca and P compounds can be an efficient process with which to obtain bioactive coatings. This paper reports on the influence of the nature of the electrolyte, its concentration, and PEO process parameters on the properties of anodized layers on Ti-15Mo. A wide range of Ca- and P-containing alkaline and acidic solutions was employed to incorporate Ca and P ions into the anodized layer. The efficiency of the incorporation was evaluated by the Ca/P ratio in the coating as compared to that in the electrolyte. It was found that alkaline solutions are not suitable electrolytes for the formation of good quality, uniform PEO coatings. Only acidic electrolytes are appropriate for obtaining well-adherent homogeneous layers on Ti-15Mo. However, the maximum Ca/P ratios reached in the coatings were rather low (close to 1. The variation of electrical signal (negative-to-positive current ratio, frequency and time of electrolysis do not result in a substantial change of this value. The processing time, however, did influence the coating thickness. Despite their low Ca/P ratio, the anodized layers demonstrate good biological activity, comparable to pure microrough titanium.

Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

Science.gov (United States)

Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

2014-02-01

The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing

International Nuclear Information System (INIS)

Huan, Z; Fratila-Apachitei, L E; Apachitei, I; Duszczyk, J

2014-01-01

The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel–titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO 2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces. (paper)

Synthesis and characterization of hybrid micro/nano-structured NiTi surfaces by a combination of etching and anodizing.

Science.gov (United States)

Huan, Z; Fratila-Apachitei, L E; Apachitei, I; Duszczyk, J

2014-02-07

The purpose of this study was to generate hybrid micro/nano-structures on biomedical nickel-titanium alloy (NiTi). To achieve this, NiTi surfaces were firstly electrochemically etched and then anodized in fluoride-containing electrolyte. With the etching process, the NiTi surface was micro-roughened through the formation of micropits uniformly distributed over the entire surface. Following the subsequent anodizing process, self-organized nanotube structures enriched in TiO2 could be superimposed on the etched surface under specific conditions. Furthermore, the anodizing treatment significantly reduced water contact angles and increased the surface free energy compared to the surfaces prior to anodizing. The results of this study show for the first time that it is possible to create hybrid micro/nano-structures on biomedical NiTi alloys by combining electrochemical etching and anodizing under controlled conditions. These novel structures are expected to significantly enhance the surface biofunctionality of the material when compared to conventional implant devices with either micro- or nano-structured surfaces.

Anodic behavior of mechanically alloyed Cu–Ni–Fe and Cu–Ni–Fe–O electrodes for aluminum electrolysis in low-temperature KF-AlF3 electrolyte

International Nuclear Information System (INIS)

Goupil, G.; Helle, S.; Davis, B.; Guay, D.; Roué, L.

2013-01-01

A comparative study on the anodic behavior of Cu 65 Ni 20 Fe 15 and (Cu 65 Ni 20 Fe 15 ) 98.6 O 1.4 materials during the electrolysis of aluminum was conducted. Both materials were prepared in powder form by ball milling and subsequently consolidated to form dense pellets that were used as anodes. The electrochemical characterization was performed at 700 °C in a potassium cryolite-based electrolyte, and the composition-morphology of the oxide scales formed on both anodes were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction measurements. On Cu 65 Ni 20 Fe 15 , a thick (170 μm) and porous oxide scale is formed after 15 min of electrolysis that readily dissolves (or spalls) before a denser oxide layer is formed after a longer electrolysis time (1 and 5 h). In comparison, a thin (2 μm) and dense oxide layer mainly composed of NiFe 2 O 4 is observed on a (Cu 65 Ni 20 Fe 15 ) 98.6 O 1.4 electrode after 15 min of electrolysis. The thickness of this oxide layer increases to 10 and 30 μm after 1 h and 5 h of electrolysis. However, the outward diffusion of Cu to form CuO x at the surface of the electrode is not totally hampered by the presence of NiFe 2 O 4 and a porous Cu-depleted region is formed at the oxide/alloy interface. As a result, electrolyte penetration occurs in the scale, which favors the progressive formation of an iron fluoride layer at the oxide/alloy interface

Hydrogen extraction from liquid lithium-lead alloy by bubbling with rotational jet nozzle

International Nuclear Information System (INIS)

Xie Bo; Yang Tongzai; Guan Rui; Weng Kuiping

2010-01-01

The technology of tritium extraction from lithium-lead alloy has been simulated, hydrogen extraction from lithium-lead alloy by bubbling with rotational jet nozzle being used to simulate tritium in the study based on the introduction of fluid dynamics to establish algebraic model. The results show that the higher than lithium-lead melting temperature, the higher cumulative hydrogen extraction efficiency, and gas holdup of bubble column is little affected by the impeller diameter. Gas holdup when using small aperture is slightly higher when using large aperture only at a high helium flow rate, but the smaller the aperture, the greater the bubble surface area, and a marked increase in intensity of flow circulation for liquid lithium-lead with the increase of helium flow rate, hydrogen extraction rate increases too. Moreover, influence of the jet rotational velocity on hydrogen extraction is limited. (authors)

Increasing Wear Resistance of Titanium Alloys by Anode Plasma Electrolytic Saturation with Interstitial Elements

Science.gov (United States)

Belkin, P. N.; Kusmanov, S. A.; Dyakov, I. G.; Silkin, S. A.; Smirnov, A. A.

2017-05-01

In our previous studies, we have shown that anode plasma electrolytic saturation of titanium alloys with nitrogen and carbon can improve their tribological properties. Obtained structure containing oxide layer and solid solution of diffused element in titanium promotes the enhancement of running-in ability and the decrease in the wear rate in some special cases. In this paper, further investigations are reported regarding the tribological properties of alpha- and beta-titanium alloys in wear test against hardened steel (50 HRC) disk using pin-on-disk geometry and balls of Al2O3 (6.25 mm in diameter) or bearing steel (9.6 mm in diameter) with ball-on-plate one and normal load from 5 to 209 N. Reproducible results were obtained under testing samples treated by means of the plasma electrolytic nitriding (PEN) with the mechanical removal of the oxide layer. Friction coefficient of nitrided samples is 0.5-0.9 which is somewhat higher than that for untreated one (0.48-0.75) during dry sliding against Al2O3 ball. An increase in the sliding speed results in the polishing of nitrided samples and reduction of their wear rate by 60 times. This result is obtained for 5 min at 850 °C using PEN in electrolyte containing 5 wt.% ammonia and 10 wt.% ammonium chloride followed by quenching in solution. Optical microscope was employed to assist in the evaluation of the wear behavior. Sizes of wear tracks were measured by profilometer TR200.

Electrochemical performance of Sn-Sb-Cu film anodes prepared by layer-by-layer electrodeposition

International Nuclear Information System (INIS)

Jiang Qianlei; Xue Ruisheng; Jia Mengqiu

2012-01-01

A novel layer-by-layer electrodeposition and heat-treatment approach was attempted to obtain Sn-Sb-Cu film anode for lithium ion batteries. The preparation of Sn-Sb-Cu anodes started with galvanostatic electrochemically depositing antimony and tin sequentially on the substrate of copper foil collector. Sn-Sb and Cu-Sb alloys were formed when heated. The SEM analysis showed that the crystalline grains become bigger and the surface of the Sn-Sb-Cu anode becomes more denser after annealing. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis showed the antimony, tin and copper were alloyed to form SnSb and Cu 2 Sb after heat treatment. The X-ray photoelectron spectroscopy (XPS) analysis showed the surface of the Sn-Sb-Cu electrode was covered by a thin oxide layer. Electrochemical measurements showed that the annealed Sn-Sb-Cu anode has high reversible capacity and good capacity retention. It exhibited a reversible capacity of about 962 mAh/g in the initial cycle, which still remained 715 mAh/g after 30 cycles.

Corrosion Prevention of Steel Reinforcement in 7.5% NaCl Solution using Pure Magnesium Anode

Science.gov (United States)

Iyer Murthy, Yogesh; Gandhi, Sumit; Kumar, Abhishek

2018-03-01

The current work investigates the performance of pure Magnesium on corrosion prevention of steel reinforcements by way of sacrificial anoding. Two set of six steel reinforcements were tested for half-cell potential, weight loss, anode efficiency and tensile strength for each of the sacrificial anodes in a high chloride atmosphere of 7.5% NaCl in tap water. Significant reduction in weight of anode was observed during the initial 12 days. The reduction in weight of steel reinforcements tied with anodes was found to be negligible, while that of reinforcements without anodes was significantly higher. Five distinct zones of corrosion were observed during the test. The tensile strength of steel cathodically protected by Mg alloy anodes was found less affected. It could be concluded that pure Mg anode provides an effective way of corrosion mitigation.

Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells

Directory of Open Access Journals (Sweden)

Hong J.H.

2015-06-01

Full Text Available With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2, as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA, has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC, referred to as process control agents (PCAs, were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC/dimethylcarbonate (DMC/ethylene methyl carbonate (EMC (volume ratio of 1:1:1.

QUANTIFICATION OF LEAD AND CADMIUM IN POULTRY AND BIRD GAME MEAT BY SQUARE WAVE ANODIC STRIPPING VOLTAMMETRY

OpenAIRE

2011-01-01

Abstract A Square Wave Anodic Stripping Voltammetric method for the analysis of lead and cadmium in chicken muscle and liver was developed and validated, and the results of a monitoring study relative to chicken and pigeon meat are reported. The voltammetric method allows the analysis of lead and cadmium at the same time in samples after acid digestion. The use of perchloric acid for digestion and of acetate buffer in the supporting electrolyte have been found suitable to reduce ma...

Differential pulse anodic stripping voltametry for ultratrace determination of cadmium and lead in Antarctic snow

International Nuclear Information System (INIS)

Scarponi, G.; Barbante, C.; Cescon, P.

1994-01-01

Differential pulse anodic stripping voltametry has sufficient sensitivity to be used for direct determination of heavy metals in Antarctic snow, thus avoiding long and contamination-prone enrichment procedures. A result of particular concern to global change studies can be drawn from these preliminary data: lead concentration in Antarctic snow decreased rapidly during the 1980s from about 10-15 pg/g to 2-4 pg/g in 1991. (authors). 16 refs., 3 figs., 1 tab

Development of quantitative analysis for cadmium, lead and chromium in aluminum alloys by using x-ray fluorescence spectrometry

International Nuclear Information System (INIS)

Yamashita, Satoshi; Kurusu, Kazuhiko; Kudou, Aiko

2009-01-01

A highly reliable quantitative analysis for cadmium, lead and chromium in aluminum alloys was developed. Standard samples were made by doping cadmium, lead and chromium into several aluminum alloys, and the composition of standard samples were determined by inductively coupled plasma optical emission spectrometry and gravimetric method. The calibration curves for these standard samples by using WD-XRF and ED-XRF exhibited linear correlation. Slope of calibration curves for Al-Cu alloy and Al-Zn-Mg alloy were smaller than other alloy's one, because of the effect by coexistent elements. Then, all calibration curves agreed with each other by performing correction with α-coefficient method. (author)

Reducing Staphylococcus aureus growth on Ti alloy nanostructured surfaces through the addition of Sn.

Science.gov (United States)

Verissimo, Nathália C; Geilich, Benjamin M; Oliveira, Haroldo G; Caram, Rubens; Webster, Thomas J

2015-12-01

β-type Ti alloys containing Nb are exciting materials for numerous orthopedic and dental applications due to their exceptional mechanical properties. To improve their cytocompatibility properties (such as increasing bone growth and decreasing infection), the surfaces of such materials can be optimized by adding elements and/or nanotexturing through anodization. Because of the increasing prevalence of orthopedic implant infections, the objective of this in vitro study was to add Sn and create unique nanoscale surface features on β-type Ti alloys. Nanotubes and nanofeatures on Ti-35Nb and Ti-35Nb-4Sn alloys were created by anodization in a HF-based electrolyte and then heat treated in a furnace to promote amorphous structures and phases such as anatase, a mixture of anatase-rutile, and rutile. Samples were characterized by SEM, which indicated different morphologies dependent on the oxide content and method of modification. XPS experiments identified the oxide content which resulted in a phase transformation in the oxide layer formed onto Ti-35Nb and Ti-35Nb-4Sn alloys. Most importantly, regardless of the resulting nanostructures (nanotubes or nanofeatures) and crystalline phase, this study showed for the first time that adding Sn to β-type Ti alloys strongly decreased the adhesion of Staphylococcus aureus (S. aureus; a bacteria which commonly infects orthopedic implants leading to their failure). Thus, this study demonstrated that β-type Ti alloys with Nb and Sn have great promise to improve numerous orthopedic applications where infection may be a concern. © 2015 Wiley Periodicals, Inc.

Electrochemical synthesis of SnCo alloy shells on orderly rod-shaped Cu current collectors as anode materials for lithium-ion batteries with enhanced performance

Energy Technology Data Exchange (ETDEWEB)

Zhan, Fangwei; Zhang, Hui, E-mail: meszhanghui@zju.edu.cn; Qi, Yue; Wang, Jiazheng; Du, Ning; Yang, Deren

2013-09-05

Highlights: •Nanostructured SnCo/Cu electrodes have been successfully fabricated. •A simple electrodeposition approach was employed. •The Cu arrays offer large surface area and improve electronic/ionic conductivity. •The electrodes show improved performance as anode for Li-ion batteries. •The improved performance was attributed to the nanostructured current collectors. -- Abstract: In this article, we report a two-step electrodeposition method for the synthesis of Cu/SnCo core–shell rod-shaped arrays as anodes of lithium-ion batteries. Firstly, the arrayed Cu nanorods with diameters of 200 nm were fabricated on a Cu foil through an electrodeposition method with alumina oxide membrane (AAO) as the template. Secondly, the SnCo alloy shells were subsequently electrodeposited on the surface of the rod-shaped Cu arrays to form the hybrid nanostructures. These hybrid electrodes delivered the enhanced cyclic performance and high rate capability serving as the anode materials for lithium-ion batteries. The improved electrochemical performance might be attributed to the large surface-to-volume area, sufficient buffering space, and high electronic conductivity associated with these 3-dimensional (3D) nanostructures.

Ballistic transport of spin waves incident from cobalt leads across cobalt–gadolinium alloy nanojunctions

International Nuclear Information System (INIS)

Ashokan, V.; Abou Ghantous, M.; Ghader, D.; Khater, A.

2014-01-01

Calculations are presented for the scattering and ballistic transport of spin waves (SW) incident from cobalt leads, on ultrathin ferrimagnetic cobalt–gadolinium ‥Co][Co (1−c) Gd (c) ] ℓ [Co‥ nanojunction systems. The nanojunction [Co (1−c) Gd (c) ] ℓ itself is a randomly disordered alloy of thickness ℓ hcp lattice planes between matching hcp planes of the Co leads, at known stable concentrations c≤0.5 for this alloy system. To compute the spin dynamics, and the SW scattering and ballistic transport, this alloy nanojunction is modeled in the virtual crystal approximation (VCA), valid in particular at the length scale of the nanojunction for submicroscopic SW wavelengths. The phase field matching theory (PFMT) is applied to compute the localized and resonant magnons on the nanojunction. These magnons, characteristic of the embedded nanostructure, propagate in its symmetry plane with spin precession amplitudes that decay or match the spin wave states in the semi-infinite leads. The eigenvectors of these magnon modes are calculated for certain cases to illustrate the spin precession configurations on the nanojunction. The VCA-PFMT approach is also used to calculate the reflection and transmission spectra for the spin waves incident from the Co leads on the nanojunction. The results demonstrate resonance assisted maxima for the ballistic SW transmission spectra due to interactions between the incident spin waves and the nanojunction magnon modes. These properties are general for variable nanojunction thicknesses and alloy stable concentrations c≤0.5. In particular, the positions of the resonance assisted maxima of spin wave transmission can be modified with nanojunction thickness and alloy concentration. - Highlights: • Model is presented for spin wave scattering at CoGd disordered alloy nanojunctions. • Computations yield the localized and resonant magnon modes on the nanojunctions. • The spin waves ballistic reflection and transmission

The effect of zinc (Zn) content to cell potential value and efficiency aluminium sacrificial anode in 0.2 M sulphuric acid environment

Science.gov (United States)

Akranata, Ahmad Ridho; Sulistijono, Awali, Jatmoko

2018-04-01

Sacrificial anode is sacirifial component that used to protect steel from corrosion. Generally, the component are made of aluminium and zinc in water environment. Sacrificial anode change the protected metal structure become cathodic with giving current. The advantages of aluminium is corrosion resistance, non toxicity and easy forming. Zinc generally used for coating in steel to prevent steel from corrosion. This research was conducted to analyze the effect of zinc content to the value of cell potential and efficiency aluminium sacrificial anode with sand casting method in 0.2 M sulphuric acid environment. The sacrificial anode fabrication made with alloying aluminium and zinc metals with variation composition of alloy with pure Al, Al-3Zn, Al-6Zn, and Al-9Zn with open die sand casting process. The component installed with ASTM A36 steel. After the research has been done the result showed that addition of zinc content increase the cell potential, protection efficiency, and anode efficiency from steel plate. Cell potential value measurement and weight loss measurement showed that addition of zinc content increase the cell potential value into more positive that can protected the ASTM A36 steel more efficiently that showed in weight loss measurement where the protection efficiency and anodic efficiency of Al-9Zn sacrificial anode is better than protection efficiency and anodic efficiency of pure Al. The highest protection efficiency gotten by Al-9Zn alloy

On the increasing of adhesive strength of nanotube layers on beta titanium alloys for medical applications

Energy Technology Data Exchange (ETDEWEB)

Fojt, Jaroslav, E-mail: fojtj@vscht.cz; Filip, Vladimir; Joska, Ludek

2015-11-15

Graphical abstract: - Highlights: • The nanostructured surface on Ti–36Nb–6Ta alloy was prepared by anodic oxidation. • The nanotubes properties were modified by electrochemical process parameters. • The composition and mechanical properties of the anodized surface were investigated. • The adhesive strength of the nanostructures was over 30 MPa. - Abstract: The nanostructuring of titanium and its alloys surfaces is used inter alia for increasing the medical implants osseointegration. Many papers about this topic were published. However, in most cases there were no informations about nanostructures adhesion to the surface, which is crucial from the application point of view. The aim of this study was to prepare nanostructures on titanium beta alloy and optimized its adhesion to the alloy surface. Nanotubes were formed by anodic polarization in electrolyte containing fluoride ions. The composition of the nanotubes was described by X-ray photoelectron spectroscopy. Nanostructures adhesion was tested by pull-of method. The nanotubes on the Ti–36Nb–6Ta beta alloy surface were prepared by anodization. The nanostructures properties were modified by electrochemical process parameters. The adhesion of the nanotubes prepared in this work was satisfactory for implantological applications.

Plant-scale anodic dissolution of unirradiated IFR fuel pins

International Nuclear Information System (INIS)

Gay, E.C.; Tomczuk, Z.; Miller, W.E.

1993-01-01

This report discusses anodic dissolution which is a major operation in the pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor (IFR), an advanced reactor design developed at Argonne National Laboratory. This process involves electrorefining the heavy metals (uranium and plutonium) from chopped, steel-clad fuel segments. The heavy metals are electrotransported from anodic dissolution baskets to solid and liquid cathodes in a molten salt electrolyte (LiCl-KCI) at 500 degrees C. Uranium is recovered on a solid cathode mandrel, while a uranium-plutonium mixture is recovered in a liquid cadmium cathode. The anode configuration consists of four baskets mounted on an anode shaft. These baskets provide parallel circuits in the electrolyte and salt flow through the chopped fuelbed as the baskets are rotated. The baskets for the engineering-scale tests were sized to contain up to 2.5 kg of heavy metal. Anodic dissolution of 10 kg batches of chopped, steel-clad simulated tuel (U-10% Zr and U-Zr-Fs alloy) was demonstrated

An insight into the passivation of cupronickel alloys in chloride ...

Indian Academy of Sciences (India)

Unknown

surface of the alloy C was seen under scanning electron microscope at different magnifications. ... oxygen evolution for alloy C. The reverse scan revealed an inverted anodic peak at. 458 mV followed .... Scanning electron microscope picture.

New High-Energy Nanofiber Anode Materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiangwu [North Carolina State Univ., Raleigh, NC (United States); Fedkiw, Peter [North Carolina State Univ., Raleigh, NC (United States); Khan, Saad [North Carolina State Univ., Raleigh, NC (United States); Huang, Alex [North Carolina State Univ., Raleigh, NC (United States); Fan, Jiang [North Carolina State Univ., Raleigh, NC (United States)

2013-11-15

The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

Anodic behavior of stainless-steel substrate in organic electrolyte solutions containing different lithium salts

International Nuclear Information System (INIS)

Furukawa, Kazuki; Yoshimoto, Nobuko; Egashira, Minato; Morita, Masayuki

2014-01-01

Highlights: • We investigated anodic behavior of stainless-steel in organic electrolytes for advanced capacitor. • Anion of the electrolyte affected the anodic stability of the alloy. • Anodic passivation occurs in LiPF 6 solution but pitting or active dissolution proceeds in other electrolyte solutions. • Fluoride source in the solution contributes to forming a stable surface layer on the stainless steel. - Abstract: The anodic behavior of austenitic stainless-steel, SUS304, as a current collector of positive electrode in lithium-ion battery/capacitor has been investigated in organic electrolyte solutions based on a mixed alkyl carbonate solvent with different lithium salts. Stable passivation characteristics were observed for the stainless-steel in the LiPF 6 solution, but pitting corrosion or active dissolution proceeded in the solutions containing other anions, BF 4 - , (CF 3 SO 2 ) 2 N - (TFSA - ) and ClO 4 - . The mass ratios of the dissolved metal species in the solutions of LiTFSA and LiClO 4 were equivalent to that of the alloy composition, which suggests that no preferential dissolution occurs during the anodic polarization in these electrolyte solutions. An HF component formed by decomposition of PF 6 - with the contaminate water will act as an F - source for the formation of a surface fluoride layer, that will contribute to the anodic stability of SUS304 in the LiPF 6 solution. The anodic corrosion in the LiTFSA solution was suppressed in part by mixing the PF 6 salt or adding HF in the electrolyte

The corrosion behaviour and structure of amorphous and thermally treated Fe-B-Si alloys

International Nuclear Information System (INIS)

Raicheff, R.; Zaprianova, V.; Petrova, E.

2003-01-01

The corrosion behaviour of magnetic amorphous alloys Fe 78 B 13 Si 9 , Fe 81 B 13 Si 4 C 2 and Fe 67 Co 18 Bi 4 S 1 obtained by rapid quenching from the melts are investigated in a model corrosive environment of 1N H 2 SO 4 . The structure of the alloys, is, characterized by DTA, SEM, TEM, X-ray and electron diffraction techniques. The dissolution kinetics of the,alloys is studied using gravimetric and electrochemical polarization measurements. It is established that the corrosion rate of the amorphous Fe 67 Co 18 Bt 4 S 1 alloy is up to 50 times lower than that of Fe 78 Bi 3 Si 9 alloy and the addition of cobalt leads to a considerable reduction of the rates of both partial corrosion reactions, while the addition of carbon results only in a moderate decrease (2-3 times) of the corrosion rate. It is also shown that the crystallization of the amorphous Fe 78 B 13 Si 9 alloy (at 700 o C for 3 h) leads to formation of multiphase structure consisting of crystalline phases α-Fe and Fe 3 (B,Si). After crystallization an increase of the rate of both hydrogen evolution and anodic dissolution reactions is observed which results in a considerable (an order of magnitude) increase of the corrosion rate of the alloy. (Original)

Metal oxides and lithium alloys as anode materials for lithium-ion batteries

CSIR Research Space (South Africa)

Kebede, M

2016-07-01

Full Text Available -generation anode materials for lithium–ion batteries with high prospect of replacing graphite. Most of these anode materials have higher specific capacities between the range of 600-1000 mA h g(sup-1) compared with 340 mA h g(sup-1) of graphite. These high...

Precipitation hardened nickel-base alloys for sour gas environments

International Nuclear Information System (INIS)

Igarashi, M.; Mukai, S.; Kudo, T.; Okada, Y.; Ikeda, A.

1987-01-01

SCC (Stress Corrosion Cracking) in sour gas environments of γ'(gamma prime: Ni/sub 3/(Ti and/or Al)) and γ''(gamma double prime: Ni/sub 3/Nb) precipitation hardened nickel-base alloys has been studied using the SSRT (Slow Strain Rate Tensile) test, anodic polarization measurement and transmission electron microscopy (TEM). The γ'-type alloy containing Ti was more susceptible to SCC in the SSRT tests up to 350 0 F(450 K) than the γ''-type alloy containing Nb. The susceptibility to SCC was related to their deformation structures in terms of stress localization and sensitivity to pitting corrosion in H/sub 2/S solutions. TEM observation showed the γ'-type alloy deformed by the superlattice dislocations in coplanar structures. This mode of deformation induced the stress localization to some boundaries such as grain boundary and as a result the susceptibility to SCC of the γ'-type alloy was increased. On the other hand, the γ''-type alloy deformed by the massive dislocation not in coplanar structures so that it was less susceptible to SCC in terms of the stress localization. The anodic polarization measurement suggested the γ'-type alloy was more susceptible to pitting corrosion compared with the γ''-type alloy

Multi-metallic anodes for solid oxide fuel cell applications; Anodos multi-metalicos para aplicacoes em celulas a combustivel de oxido solido

Energy Technology Data Exchange (ETDEWEB)

Restivo, T.A. Guisard; Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia dos Materiais; Leite, D. Will [Instituto de Pesquisas e Estudos Industriais (IPEI/FEI), Sao Bernardo do Campo, SP (Brazil). Fac. de Engenharia Industrial

2009-07-01

A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

Trace analysis of lead and cadmium in seafoods by differential pulse anodic stripping voltametry

International Nuclear Information System (INIS)

Sumera, F.C.; Verceluz, F.P.; Kapauan, P.A.

1979-01-01

A method for the simultaneous determination of cadmium and lead in seafoods is described. The sample is dry ashed in a muffle furnace elevating the temperature gradually up to 500 0 C. The ashed sample is treated with concentrated nitric acid, dried on a heating plate and returned to the muffle furnace for further heating. The treated ash is then dissolved in 1 N HCL acetate buffer and citric acid are added and the pH adjusted to 3.6-4. The resulting solution is analyzed for lead and cadmium by differential pulse anodic stripping voltametry (DPASV) using a wax-impregnated graphite thin film electrode. The average recoveries of 0.4 of cadmium and lead added to 5 fish samples were 97% and 99% respectively. The standard deviations, on a homogenized shark sample for lead and cadmium analysis were 6.7 ppb and 12.3 ppb, respectively, and the relative standard deviations were 21.0% and 15.5% respectively. Studies on instrumental parameters involved in the DPASV step of analysis and methods of measuring peak current signals were also made. (author)

Influence of electrical parameters on morphology of nanostructured TiO2 layers developed by electrochemical anodization

Directory of Open Access Journals (Sweden)

Strnad Gabriela

2017-01-01

Full Text Available Ti6Al4V alloy micro rough surfaces with TiO2 self-organized nanostructured layers were synthesized using electrochemical anodization in phosphate/fluoride electrolyte, at different end potentials (5V, 10V, 15V, and 20 V. The current – time characteristics were recorded, and the link between current evolution and the morphology of developing oxide layers was investigated. On flat surfaces of Ti6Al4V alloy we developed TiO2 layers with different morphologies (random pores, nanopores of 25…50 nm, and highly organized nanotubes of 50…100 nm in diameter depending on electrical parameters of anodization process. In our anodization cell, in optimized conditions, we are able to superimpose nanostructured oxide layers (nanotubular or nanoporous over micro structured surfaces of titanium based materials used for biomedical implants.

Factors Influencing Plasma Electrolytic Oxidation(PEO) Coatings on Magnesium Alloys: A Review

Energy Technology Data Exchange (ETDEWEB)

Shim, Gunchoo [KISTI ReSEAT Program, Daejon (Korea, Republic of)

2017-05-15

Magnesium alloys, which possess excellent specific strength and castability, are highly susceptible to corrosion. Although anodizing is widely used to resolve this problem, it requires toxic electrolytes and produces relatively thin and weak surface coatings. Recently, plasma electrolytic oxidation (PEO) has emerged as an alternative to anodizing. Although it is derived from conventional anodizing, it uses eco-friendly electrolytes and forms thicker, denser, and harder coatings on the surface of magnesium alloys. However, PEO is a complex process involving physical, chemical, and electrochemical reactions, and it is influenced by various factors such as the alloy substrate composition, electrolyte/additive composition, and the electrical variables including the mode of power supply, applied voltage/current density, frequency, and duty cycle. In this article, the detailed effects of these parameters on the microstructure and properties of the PEO coatings are reviewed, and methods of improving the coatings are proposed.

Morphology and performances of the anodic oxide films on Ti6Al4V alloy formed in alkaline-silicate electrolyte with aminopropyl silane addition under low potential

International Nuclear Information System (INIS)

Chen, Jiali; Wang, Jinwei; Yuan, Hongye

2013-01-01

Oxide films on Ti6Al4V alloy are prepared using sodium hydroxide–sodium silicate as the base electrolyte with addition of aminopropyl trimethoxysilane (APS) as additive by potentiostatic anodizing under 10 V. APS is incorporated into the films during anodizing and the surface morphology of the oxide films is changed from particle stacked to honeycomb-like porous surfaces as shown by scanning electron microscopy (SEM) with Energy Disperse Spectroscopy (EDX). The surface roughness and aminopropyl existence on the oxide films result in their differences in wettability as tested by the surface profile topography and contact angle measurements. The anti-abrasive ability of the anodic films is improved with the addition of APS due to its toughening effects and serving as lubricants in the ceramic oxide films as measured by ball-on-disk friction test. Also, potentiodynamic corrosion test proves that their anticorrosive ability in 3.5 wt.% NaCl is greatly improved as reflected by their much lower corrosion current (I corr ) and higher corrosion potential (E corr ) than those of the substrate.

Morphology and performances of the anodic oxide films on Ti6Al4V alloy formed in alkaline-silicate electrolyte with aminopropyl silane addition under low potential

Energy Technology Data Exchange (ETDEWEB)

Chen, Jiali; Wang, Jinwei, E-mail: wangjw@ustb.edu.cn; Yuan, Hongye

2013-11-01

Oxide films on Ti6Al4V alloy are prepared using sodium hydroxide–sodium silicate as the base electrolyte with addition of aminopropyl trimethoxysilane (APS) as additive by potentiostatic anodizing under 10 V. APS is incorporated into the films during anodizing and the surface morphology of the oxide films is changed from particle stacked to honeycomb-like porous surfaces as shown by scanning electron microscopy (SEM) with Energy Disperse Spectroscopy (EDX). The surface roughness and aminopropyl existence on the oxide films result in their differences in wettability as tested by the surface profile topography and contact angle measurements. The anti-abrasive ability of the anodic films is improved with the addition of APS due to its toughening effects and serving as lubricants in the ceramic oxide films as measured by ball-on-disk friction test. Also, potentiodynamic corrosion test proves that their anticorrosive ability in 3.5 wt.% NaCl is greatly improved as reflected by their much lower corrosion current (I{sub corr}) and higher corrosion potential (E{sub corr}) than those of the substrate.

A STUDY ABOUT CELL ACTIVITY ON ANODIZED Ti-6Al-4V BY MEANS OF PULSED CURRENT

Directory of Open Access Journals (Sweden)

LUANA M. R. VASCONCELLOS

2017-05-01

Full Text Available Titanium and some of its alloys exhibit excellent anti-corrosive and biocompatibility properties due to rapid formation of a passive film on their surfaces when exposed to the atmosphere. However, such materials presentpoor osteoindutive properties. Surfaces modified via anodization are being proposed in this study to promote a chemical interaction between implants and bone cells. For this purpose, samples in Ti-6Al-4V alloy discs were anodized in a phosphoric acid solution using pulsed current for being applied in orthopaedic implants. The pulsed current is based on duty cycle (DC, which was supplied by a square wave pulse rectifier at 100 Hz and maximum tension of 30 V. A scanning electron microscope was used to obtain images of the anodized surfaces, thus revealing the presence of uniformly distributed pores over the entire surface, measuring approximately 2 m in diameter. Osteogenic cells grown on the surface of the control and anodized samples were assayed for cytotoxicity and mineralized matrix formation. The anodized surfaces presented a higher rate of viable cells after 10 days, as well as a higher amount of nodules (p = 0.05. In conclusion, these results suggest that the nanotopography promoted by anodization using pulsed current induces beneficial modulatory effects on osteoblastic cells.

Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium.

Science.gov (United States)

Amin Yavari, S; Chai, Y C; Böttger, A J; Wauthle, R; Schrooten, J; Weinans, H; Zadpoor, A A

2015-06-01

Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20V anodizing time: 30min to 3h) are used for anodizing porous titanium structures that were later heat treated at 500°C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500°C improve the cell culture response of porous titanium

Anodic oxidation of benzoquinone using diamond anode.

Science.gov (United States)

Panizza, Marco

2014-01-01

The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5-2 A), BQ concentration (1-2 g dm(-3)), temperature (20-45 °C) and flow rate (100-300 dm(3) h(-1)) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature.

Studies on black anodic coatings for spacecraft thermal control applications

Energy Technology Data Exchange (ETDEWEB)

Uma Rani, R.; Subba Rao, Y.; Sharma, A.K. [ISRO Satellite Centre, Bangalore (India). Thermal Systems Group

2011-10-15

An inorganic black colouring process using nickel sulphate and sodium sulphide was investigated on anodized aluminium alloy 6061 to provide a flat absorber black coating for spacecraft thermal control applications. Influence of colouring process parameters (concentration, pH) on the physico-optical properties of black anodic film was investigated. The nature of black anodic film was evaluated by the measurement of film thickness, micro hardness and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy studies confirmed the presence of nickel and sulphur in the black anodic coating. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion resistance of the coating. The environmental tests, namely, humidity, corrosion resistance, thermal cycling and thermo vacuum performance tests were used to evaluate the space worthiness of the coating. Optical properties of the film were measured before and after each environmental test to ascertain its stability in harsh space environment. The black anodic films provide higher thermal emittance ({proportional_to} 0.90) and solar absorptance ({proportional_to} 0.96) and their high stability during the environmental tests indicated their suitability for space and allied applications. (orig.)

Elaboration, physical and electrochemical characterizations of CO tolerant PEMFC anode materials. Study of platinum-molybdenum and platinum-tungsten alloys and composites; Elaborations et caracterisations electrochimiques et physiques de materiaux d'anode de PEMFC peu sensibles a l'empoisonnement par CO: etude d'alliages et de composites a base de platine-molybdene et de platine-tungstene

Energy Technology Data Exchange (ETDEWEB)

Peyrelade, E.

2005-06-15

PEMFC development is hindered by the CO poisoning ability of the anode platinum catalyst. It has been previously shown that the oxidation potential of carbon monoxide adsorbed on the platinum atoms can be lowered using specific Pt based catalysts, either metallic alloys or composites. The objective is then to realize a catalyst for which the CO oxidation is compatible with the working potential of a PEMFC anode. In our approach, to enhance the CO tolerance of platinum based catalyst supported on carbon, we studied platinum-tungsten and platinum-molybdenum alloys and platinum-metal oxide materials (Pt-WO{sub x} and Pt-MoO{sub x}). The platinum based alloys demonstrate a small effect of the second metal towards the oxidation of carbon monoxide. The platinum composites show a better tolerance to carbon monoxide. Electrochemical studies on both Pt-MoO{sub x} and Pt-WO{sub x} demonstrate the ability of the metal-oxides to promote the ability of Pt to oxidize CO at low potentials. However, chrono-amperometric tests reveal a bigger influence of the tungsten oxide. Complex chemistry reactions on the molybdenum oxide surface make it more difficult to observe. (author)

Removal of lead from the industrial and synthetic Cu-Pb-Fe alloy with argon barbotage

Directory of Open Access Journals (Sweden)

B. Oleksiak

2012-01-01

Full Text Available Results of research on removal of lead from synthetic and industrial Cu-Pb-Fe alloy with argon barbotage are presented. For examinations was taken a synthetic alloy and industrial alloy coming “Glogow II” Copperworks. As basic research equipment was used a pipe resistance furnace enabling heating of samples up to 1 473 K. Examinations were made in 2 test series. The 1 series was performed on the synthetic alloy, while in 2 series was used an industrial alloy. All series were conducted at 1 473 K and with gas fl ow 5,55•10-6, 6,94•10-6, 8,33•10-6, 9,72•10-6 m3•s-1.

Improved Anode for a Direct Methanol Fuel Cell

Science.gov (United States)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

Study and understanding of the ageing mechanisms in lead-calcium alloys

International Nuclear Information System (INIS)

Rossi, F.

2006-12-01

The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

Pt -based anode catalysts for direct ethanol fuel cells

International Nuclear Information System (INIS)

Hoyos, Bibian; Sanchez, Carlos; Gonzalez, Javier

2007-01-01

In this work it is studied the electro-catalytic behavior of pure platinum and platinum-based alloys with Ru, Sn, Ir, and Os supported on carbon to the ethanol electro-oxidation in aims to develop anodic catalysts for direct ethanol fuel cells, additionally, porous electrodes and membrane electrode assemblies were built for proton exchange membrane fuel cells in which the electrodes were tested. Catalysts characterization was made by cyclic voltammetry whereas the fuel cells behavior tests were made by current-potential polarization curves. in general, all alloys show a lower on-set reaction potential and a higher catalytic activity than pure platinum. However, in the high over potential zone, pure platinum has higher catalytic activity than the alloys. In agreement with these results, the alloys studied here could be useful in fuel cells operating on moderated and low current

Preparation of nickel-based amorphous alloys with finely dispersed lead and lead-bismuth particles and their superconducting properties

International Nuclear Information System (INIS)

Inoue, A.; Oguchi, M.; Harakawa, Y.; Masumoto, T.; Matsuzaki, K.

1986-01-01

The application of the melt-quenching technique to Ni-Si-B-Pb, Ni-P-B-Pb, Ni-Si-B-Pb-Bi and Ni-P-B-Pb-Bi alloys containing immiscible elements such as lead and bismuth has been tried and it has been found to result in the formation of a new type of material consisting of fine fcc Pb or hcp epsilon(Pb-Bi) + bct X(Pb-Bi) particles dispersed uniformly in the nickel-based amorphous matrix. The particle size and interparticle distance were 1 to 3 and 1 to 4 μm, respectively, for the lead phase, and less than 0.2 to 0.5 μm and 0.2 to 1.0 μm for the Pb-Bi phase. The uniform dispersion of such fine particles into the amorphous matrix was achieved in the composition range below about 6 at% Pb and 7 at% (Pb+Bi). Additionally, these amorphous alloys have been found to exhibit a superconductivity by the proximity effect of fcc Pb or epsilon(Pb-Bi) superconducting particles. The transition temperature Tsub(c) was in the range 6.8 to 7.5 K for the Ni-Si (or P)-B-Pb alloys and 8.6 to 8.8 K for the Ni-Si (or P)-B-Pb-Bi alloys. The upper critical field Hsub(c2) and the critical current density Jsub(c) for (Nisub(0.8)Psub(0.1)Bsub(0.1)) 95 Pb 3 Bi 2 at 4.2 K were, respectively, about 1.6 T and of the order of 7 x 10 7 Am -2 at zero applied field. (author)

Lithium based alloy-thionyl chloride cells for applications at temperatures to 200 C

Science.gov (United States)

Kane, P.; Marincic, N.; Epstein, J.; Lindsey, A.

A long-life lithium battery for industrial applications at temperatures up to 200 C was developed by combining Li-based alloy anodes with oxyhalide electrolytes. Cathodes were fabricated by rolling the blend of polycarbonomonofluoride, a conductive carbon additive, and a binder, while anodes were fabricated as those used in oxyhalide cells, incorporating a modified anode current collector designed to prevent the formation of 'lithium islands' at the end of discharge; nonwoven glass fiber separators were pretreated to remove excessive binders and lubricants. Various active electrode surface areas were combined with a corresponding thickness of electrodes and separators, matched in capacity. Tests of the high-rate electrode structure, using Li-Mg alloy anode in conjunction with thionyl chloride electrolyte, have demonstrated that the battery with this anode can be used under abusive conditions such as short circuit and external heating (at 175 C). Raising the operating temperature to 200 C did require some modifications of regular cell hardware.

Carbon monoxide tolerant anodes for proton exchange membrane (PEM) fuel cells. 1. Catalyst development approach

Energy Technology Data Exchange (ETDEWEB)

Holleck, G L; Pasquariello, D M; Clauson, S L

1998-07-01

PEM fuel cells are highly attractive for distributed power and cogeneration systems. They are efficient and function virtually without noise or pollution. To be competitive PEM fuel cells must operate on fuel mixtures obtained by reforming of widely available natural gas or liquid hydrocarbons. Reformed fuel gas mixtures invariably contain CO, a strong poison for Pt. Therefore CO tolerant anode catalysts are essential for wide spread PEMFC introduction. It is the objective to develop effective CO tolerant fuel cell catalysts based on multi-component platinum-transition metal alloys. Towards this goal the authors have developed a novel approach for the synthesis and performance evaluation of multifunctional ternary alloy fuel cell catalysts. The alloys are prepared as well-defined thin films on standard TFE-bonded carbon substrates via a dc magnetron sputtering technique. The anodes are laminated to Nafion membranes and the electrochemical performance is measured in a representative fuel cell configuration with H{sub 2} and H{sub 2}/CO gas mixtures. The multi-target sputtering technique permits one to reproducibly synthesize true alloy films of controlled composition. The deposit morphology and electrode structure are determined by the standardized TFE bonded carbon substrate. The thin catalyst layer is concentrated at the electrode ionomer interface where it can be fully utilized in a representative fuel cell configuration. Thus, a true comparative fuel cell catalyst evaluation is possible. The effectiveness of this approach will be demonstrated with Pt, Pt-Ru and Pt-Ru-X catalyzed anodes.

Formation of Sn-M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

Science.gov (United States)

Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

2016-10-01

A direct current arc-discharge method was applied to prepare the Sn-M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn-M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn-Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g-1/366.6 mA h g-1) and optimal cycle stability (a specific reversible capacity of 240 mA h g-1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.

Effect of CrO3 Sealing Time on Anodized A12024-T3

Science.gov (United States)

Korda, Akhmad A.; Hidayat, R. Z.

2016-08-01

The effect of CrO3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO3 sealing was conducted in CrO3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO3 sealing were compared. The highest hardness is achieved by CrO3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration.

Effect of CrO_3 Sealing Time on Anodized A12024-T3

International Nuclear Information System (INIS)

Korda, Akhmad A; Hidayat, R Z

2016-01-01

The effect of CrO_3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO_3 sealing was conducted in CrO_3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO_3 sealing were compared. The highest hardness is achieved by CrO_3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO_3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration. (paper)

Formation of Sn–M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

International Nuclear Information System (INIS)

Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

2016-01-01

A direct current arc-discharge method was applied to prepare the Sn–M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn–M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn–Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g −1 /366.6 mA h g −1 ) and optimal cycle stability (a specific reversible capacity of 240 mA h g −1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process. - Graphical abstract: The growth mechanism and electrochemical performance of Sn-based alloy nanoparticles. - Highlights: • Thermodynamic analyses of oxides on Sn-M nanoparticles surface. • The relationship between chemical components and electrochemical responses. • Sn-Fe nanoparticles show excellent electrode performance.

Formation of Sn–M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Gao, Song [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Huang, Hao, E-mail: huanghao@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Cao, Guozhong, E-mail: gzcao@u.washington.edu [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Department of Materials Science and Engineering, University of Washington, Seattle, WA 98195 (United States)

2016-10-15

A direct current arc-discharge method was applied to prepare the Sn–M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn–M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn–Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g{sup −1}/366.6 mA h g{sup −1}) and optimal cycle stability (a specific reversible capacity of 240 mA h g{sup −1} maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process. - Graphical abstract: The growth mechanism and electrochemical performance of Sn-based alloy nanoparticles. - Highlights: • Thermodynamic analyses of oxides on Sn-M nanoparticles surface. • The relationship between chemical components and electrochemical responses. • Sn-Fe nanoparticles show excellent electrode performance.

Aluminum as anode for energy storage and conversion: a review

Science.gov (United States)

Li, Qingfeng; Bjerrum, Niels J.

Aluminum has long attracted attention as a potential battery anode because of its high theoretical voltage and specific energy. The protective oxide layer on the aluminum surface is however detrimental to the battery performance, contributing to failure to achieve the reversible potential and causing the delayed activation of the anode. By developing aluminum alloys as anodes and solution additives to electrolytes, a variety of aluminum batteries have been extensively investigated for various applications. From molten salt and other non-aqueous electrolytes, aluminum can be electrodeposited and therefore be suitable for developing rechargable batteries. Considerable efforts have been made to develop secondary aluminum batteries of high power density. In the present paper, these research activities are reviewed, including aqueous electrolyte primary batteries, aluminum-air batteries and molten salt secondary batteries.

Complex anticorrosion coating for ZK30 magnesium alloy

International Nuclear Information System (INIS)

Lamaka, S.V.; Knoernschild, G.; Snihirova, D.V.; Taryba, M.G.; Zheludkevich, M.L.; Ferreira, M.G.S.

2009-01-01

This work aims at developing a new complex anticorrosion protection system for ZK30 magnesium alloy. This protective coating is based on an anodic oxide layer loaded with corrosion inhibitors in its pores, which is then sealed with a sol-gel hybrid polymer. The porous oxide layer is produced by spark anodizing. The sol-gel film shows good adhesion to the oxide layer as it penetrates through the pores of the anodized layer forming an additional transient oxide-sol-gel interlayer. The thickness of this complex protective coating is about 3.7-7.0 μm. A blank oxide-sol-gel coating system or one doped with Ce 3+ ions proved to be effective corrosion protection for the magnesium alloy preventing corrosion attack after exposure for a relatively long duration in an aggressive NaCl solution. The structure and the thickness of the anodized layer and the sol-gel film were characterized by scanning electron microscopy (SEM). The corrosion behaviour of the ZK30 substrates pre-treated with the complex coating was tested by electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET), and scanning ion-selective electrode techniques (SIET).

Stable anodes for lithium ion batteries made of self-organized mesoporous silicon

International Nuclear Information System (INIS)

Wolter, Sascha J; Köntges, Marc; Brendel, Rolf; Bahnemann, Detlef

2016-01-01

Alloy-forming compounds, such as electrodes for lithium ion batteries, stand out in terms of their theoretical specific charge capacity while still lacking in mechanical stability due to significant volume changes during operation. Herein, we examine the approach of combining low structural dimensions of the active material with built-in expansion volumes and assess their benefit for silicon anodes in lithium ion batteries. Consequently, self-organized mesoporous silicon is prepared as a suitable anode material for lithium ion batteries without any pre-structuring methods. The anodes are made by employing electrochemical etching methods in a scalable process and are characterized by ellipsometry. Thermally evaporated copper is utilized as the current collector. A sheet of freestanding silicon in contact with copper is used as an anode material with a thickness of 3 μm. After an initialization phase, electrochemical characterization reveals an anode stability of more than 160 cycles with a specific charge capacity of 730 mAh/g. The mechanical stability of the anode is examined by taking SEM measurements of the used electrode material. (paper)

Superconducting Properties of Lead-Bismuth Films Controlled by Ferromagnetic Nanowire Arrays

Science.gov (United States)

Ye, Zuxin; Lyuksyutov, Igor F.; Wu, Wenhao; Naugle, Donald G.

2011-03-01

Superconducting properties of lead-bismuth (82% Pb and 18% Bi) alloy films deposited on ferromagnetic nanowire arrays have been investigated. Ferromagnetic Co or Ni nanowires are first electroplated into the columnar pores of anodic aluminum oxide (AAO) membranes. Superconducting Pb 82 Bi 18 films are then quench-condensed onto the polished surface of the AAO membranes filled with magnetic nanowires. A strong dependence of the Pb 82 Bi 18 superconducting properties on the ratio of the superconducting film thickness to the magnetic nanowire diameter and the material variety was observed.

Electrochemical characterization of anode passivation mechanisms in copper electrorefining

Science.gov (United States)

Moats, Michael Scott

Anode passivation can decrease productivity and quality while increasing costs in modern copper electrorefineries. This investigation utilized electrochemical techniques to characterize the passivation behavior of anode samples from ten different operating companies. It is believed that this collection of anodes is the most diverse set ever to be assembled to study the effect of anode composition on passivation. Chronopotentiometry was the main electrochemical technique, employing a current density of 3820 A m-2. From statistical analysis of the passivation characteristics, increasing selenium, tellurium, silver, lead and nickel were shown to accelerate passivation. Arsenic was the only anode impurity that inhibited passivation. Oxygen was shown to accelerate passivation when increased from 500 to 1500 ppm, but further increases did not adversely affect passivation. Nine electrolyte variables were also examined. Increasing the copper, sulfuric acid or sulfate concentration of the electrolyte accelerated passivation. Arsenic in the electrolyte had no effect on passivation. Chloride and optimal concentrations of thiourea and glue delayed passivation. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy provided complementary information. Analysis of the electrochemical results led to the development of a unified passivation mechanism. Anode passivation results from the formation of inhibiting films. Careful examination of the potential details, especially those found in the oscillations just prior to passivation, demonstrated the importance of slimes, copper sulfate and copper oxide. Slimes confine dissolution to their pores and inhibit diffusion. This can lead to copper sulfate precipitation, which blocks more of the surface area. Copper oxide forms because of the resulting increase in potential at the interface between the copper sulfate and anode. Ultimate passivation occurs when the anode potential is high enough to stabilize the oxide film in

A circulating loop tester for liquid alloyed metal of lead-bismuth

International Nuclear Information System (INIS)

Kitano, Teruaki; Ono, Mikinori; Kamata, Kinya

2002-01-01

Mitsui Engineering and Shipbuilding Co., Ltd. (MES) had focused to merits of this lead-bismuth alloy, to actively carry out many works on this field such as an experience of development of heat exchanger at industrial level of intercourse with IPPE (Institute of Physics and Power Engineering) in Russia with an experience of using results for 80 years on coolant for nuclear reactor. Before about 20 years, MES developed a heat exchanger for installation at a lead-zinc separation process in a refinery in Japan under cooperation of the Mitsui Metal and Mine Co., Ltd., to deliver it for a power generation system at the Hachinohe refinery. As the heat exchanger aims at control of cooling in the separation process, it also contributes to power generation of about 4,300 kW, and now it continues to separate and contribute to self-power generation in the refinery. The heat exchanger is filled with the liquid alloyed metal of lead-bismuth for an intermediate thermal medium in its casing. The metal has some merits such as inactivity to air and water, high boiling point (1,700 centigrade), almost no volume change at its coagulation, and its minus reactivity coefficient. However, the metal has some problems to be solved, such as its steel corrosion, its purification, and control technology. To grow up lead-bismuth technology to a nuclear energy technology in Japan, the lead-bismuth circulating loop tester was produced on May, 2001, to establish application technology on this system to nuclear energy technology in Japan. (G.K.)

Nanosized Hydroxyapatite Precipitation on the Ti—30Ta—xHf Alloys.

Science.gov (United States)

Lee, Kang; Jang, Jae- In; Han-Cheol, Choe

2017-04-01

In this study, we prepared hydroxyapatite (HAp) layer on the alkali treated Ti–30Ta–xHf alloys using electrochemical deposition method. Ti–30Ta–xHf alloys was anodized in 5 M NaOH solution at 0.3 A for 10 min. Alkali treated Ti–30Ta–xHf surface formed by anodization step which acted as templates and anchorage for growth of the HAp during subsequent pulsed electrochemical deposition process at 85 °C. The phase and morphologies of deposited HAp layer were affected by the Hf contents of Ti–30Ta–xHf alloys. The nano-scale rod-like HAp layer was formed on untreated Ti–30Ta–xHf alloys with partially low crystallinity. In the case of alkali treated Ti–30Ta–xHf, nano-sized needle-like layers were transferred to nano-flake surface and denser morphology as Hf content increased.

Solution synthesis of lead seeded germanium nanowires and branched nanowire networks and their application as Li-ion battery anodes

Science.gov (United States)

Flynn, Grace; Palaniappan, Kumaranand; Sheehan, Martin; Kennedy, Tadhg; Ryan, Kevin M.

2017-06-01

Herein, we report the high density growth of lead seeded germanium nanowires (NWs) and their development into branched nanowire networks suitable for application as lithium ion battery anodes. The synthesis of the NWs from lead seeds occurs simultaneously in both the liquid zone (solution-liquid-solid (SLS) growth) and solvent rich vapor zone (vapor-liquid-solid (VLS) growth) of a high boiling point solvent growth system. The reaction is sufficiently versatile to allow for the growth of NWs directly from either an evaporated catalyst layer or from pre-defined nanoparticle seeds and can be extended to allowing extensive branched nanowire formation in a secondary reaction where these seeds are coated onto existing wires. The NWs are characterized using TEM, SEM, XRD and DF-STEM. Electrochemical analysis was carried out on both the single crystal Pb-Ge NWs and the branched Pb-Ge NWs to assess their suitability for use as anodes in a Li-ion battery. Differential capacity plots show both the germanium wires and the lead seeds cycle lithium and contribute to the specific capacity that is approximately 900 mAh g-1 for the single crystal wires, rising to approximately 1100 mAh g-1 for the branched nanowire networks.

Auger electron spectroscopy and Rutherford backscattering studies of copper in 2024-T3 aluminum following electrochemical anodization in phosphoric acid

Science.gov (United States)

Solomon, J. S.

1981-05-01

The effects of the electrochemical anodization of dioxidized 2024-T3 aluminum on copper were characterized by Auger electron spectroscopy and Rutherford backscattering. Anodization was performed in phosphoric acid at constant potential. Data is presented which shows that constant potential anodization of 2024-T3 is more efficient than aluminum in terms of oxide growth rates for short anodization times. However the maximum anodic oxide thickness achievable on the alloy is less than the pure metal. Copper is shown to be enriched at the oxide metal interface because of its diffusion from the bulk during anodization. The presence of copper at the oxide-metal interface is shown to affect oxide morphology.

Conversion Coatings Produced on AZ61 Magnesium Alloy by Low-Voltage Process

Directory of Open Access Journals (Sweden)

Nowak M.

2016-03-01

Full Text Available The resultes of anodic oxide conversion coatings on wrought AZ61 magnesium alloy production are describe. The studies were conducted in a solution containing: KOH (80 g/l and KF (300 g/l using anodic current densities of 3, 5 and 10 A/dm2 and different process durations. The obtained coatings were examined under a microscope and corrosion tests were performed by electrochemical method. Based on these results, it was found that the low-voltage process produces coatings conferring improved corrosion resistance to the tested magnesium alloy.

An experimental study of aluminium electrowinning using a nickel-based hydrogen diffusion anode

International Nuclear Information System (INIS)

Namboothiri, Sankar; Taylor, Mark P.; Chen, John J.J.; Hyland, Margaret M.; Cooksey, Mark A.

2011-01-01

Research highlights: → Measurable depolarisation of the anode potential and formation of water vapour. → Metallic aluminium was found on the spent cathode. → HF emissions can be minimised by conducting the electrolysis at 750 o C. → The nickel based anode surface corroded during electrolysis. → Its application is constrained by the material limitation of the porous anode. - Abstract: Laboratory scale electrolysis experiments were conducted to investigate the electrowinning of aluminium using hydrogen diffusion anodes. A potassium-based electrolyte (KF-AlF 3 -Al 2 O 3 ), porous nickel alloy anode and molybdenum disk cathode were used in experiments at 750 o C. Hydrogen gas was supplied to the anode/electrolyte interface through the porous anode. Experiments were conducted in potentiostatic, galvanostatic and galvanodynamic modes. There was a measurable depolarisation of the anode potential and also anode reaction of hydrogen and oxygen ions in the bath to form water vapour was confirmed by the water vapour condensate found at the electrolysis exit gas pipe. Metallic aluminium was found on the spent cathode. The experiments conducted in the galvanodynamic mode suggested that the rate limiter for hydrogen oxidation was the availability of surface hydrogen at the anode/electrolyte interface. The anode surface corroded during electrolysis and impurities were found both in the molten bath and on the cathode.

LEVIS active anode lithium ion source development on PBFA-II

International Nuclear Information System (INIS)

Renk, T.J.; Tisone, G.C.; Adams, R.G.; Clark, B.F.; Reyes, C.; Bailey, J.E.; Filuk, A.B.; Desjarlais, M.P.; Johnson, D.J.; Carlson, A.L.; Lake, P.

1993-01-01

Experiments are ongoing on the PBFA-II Accelerator (10 MV typical, 50 ns) to optimize an active lithium ion source in a 15-cm focusing Applied-B ion diode using the LEVIS (Laser Evaporation Ion Source) process. Two laser pulses impinge on a thin (500 nm) Li or Li-bearing alloy on an insulating substrate. A Nd:YAG laser beam (1 μm, 8 ns, 0.1--0.2 J/cm 2 ) creates a thin (∼1 mm) Li vapor, which is then ionized by a 30--60 mJ/cm 2 dye laser tuned to the first resonant transition of Li (670.8 nm). In order to achieve a high-purity Li beam on PBFA-II with LEVIS, it has proven necessary to clean the anode surface in some way. The principal technique has been DC-heating of the anode to temperatures of 150--200 C for typically 5 hours, and for as long as 13 hours, prior to machine firing. Use of a LiAg alloy and YAG energy densities of 200 mJ/cm 2 have yielded beams of Li purity greater than 90%. They authors also plan to test a diode configuration that deposits Li in-situ on the anode surface just prior to the machine shot, as an alternative to DC-heating

Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium

Energy Technology Data Exchange (ETDEWEB)

Amin Yavari, S., E-mail: s.aminyavari@tudelft.nl [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Chai, Y.C. [Prometheus, Division of Skeletal Tissue Engineering, Bus 813, O& N1, Herestraat 49, KU Leuven, 3000 Leuven (Belgium); Tissue Engineering Laboratory, Skeletal Biology and Engineering Research Center, Bus 813, O& N1, Herestraat 49, KU Leuven, 3000 Leuven (Belgium); Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Böttger, A.J. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Wauthle, R. [KU Leuven, Department of Mechanical Engineering, Section Production Engineering, Machine Design and Automation (PMA), Celestijnenlaan 300B, 3001 Leuven (Belgium); 3D Systems — LayerWise NV, Grauwmeer 14, 3001 Leuven (Belgium); Schrooten, J. [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 — PB2450, B-3001 Heverlee (Belgium); Weinans, H. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Orthopedics and Dept. Rheumatology, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht (Netherlands); Zadpoor, A.A. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands)

2015-06-01

Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20 V anodizing time: 30 min to 3 h) are used for anodizing porous titanium structures that were later heat treated at 500 °C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55 nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500 °C improve the cell culture response of porous titanium

Corrosion of aluminum alloys as a function of alloy composition

International Nuclear Information System (INIS)

Johnson, A.B. Jr.

1969-10-01

A study was initiated which included nineteen aluminum alloys. Tests were conducted in high purity water at 360 0 C and flow tests (approx. 20 ft/sec) in reactor process water at 130 0 C (TF-18 loop tests). High-silicon alloys and AlSi failed completely in the 360 0 C tests. However, coupling of AlSi to 8001 aluminum suppressed the failure. The alloy compositions containing iron and nickel survived tht 360 0 C autoclave exposures. Corrosion rates varied widely as a function of alloy composition, but in directions which were predictable from previous high-temperature autoclave experience. In the TF-18 loop flow tests, corrosion penetrations were similar on all of the alloys and on high-purity aluminum after 105 days. However, certain alloys established relatively low linear corrosion rates: Al-0.9 Ni-0.5 Fe-0.1 Zr, Al-1.0 Ni-0.15 Fe-11.5 Si-0.8 Mg, Al-1.2 Ni-1.8 Fe, and Al-7.0 Ni-4.8 Fe. Electrical polarity measurements between AlSi and 8001 alloys in reactor process water at temperatures up to 150 0 C indicated that AlSi was anodic to 8001 in the static autoclave system above approx. 50 0 C

Hydrogen traps in the oxide/alloy interface region of Zr-Nb alloys

International Nuclear Information System (INIS)

Khatamian, D.

1995-03-01

In this study the 1 H( 15 N,αγ) 12 C nuclear reaction has been used to measure hydrogen profiles of anodically oxidized Zr-Nb specimens containing various amounts of niobium. The profiles have been correlated with oxygen profiles, obtained using a Scanning Auger Microprobe (SAM), and with X-ray diffraction patterns. In addition, unoxidized Zr-2.5Nb (Zr-2.5 wt% Nb) samples were implanted with oxygen and hydrogen to study the interaction between these two species when dissolved in the alloy. All the anodically oxidized specimens, except the pure Zr and the single-phase β-Zr (Zr-20Nb) samples, displayed hydrogen peaks beneath the oxide layer. These results, in conjunction with the results from the implanted specimens, indicate that the hydrogen moves under the influence of a stress gradient to the sub-oxide region, where the metal lattice has been expanded due to superficial oxide growth. The results show that dissolved oxygen sites in Zr-2.5Nb alloy do not trap hydrogen. (author). 16 refs., 6 figs

Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

Science.gov (United States)

Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

2007-12-01

The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

Anodization Mechanism on SiC Nanoparticle Reinforced Al Matrix Composites Produced by Power Metallurgy

OpenAIRE

Ferreira, Sonia C.; Conde, Ana; Arenas, Mar?a A.; Rocha, Luis A.; Velhinho, Alexandre

2014-01-01

Specimens of aluminum-based composites reinforced by silicon carbide nanoparticles (Al/SiCnp) produced by powder metallurgy (PM) were anodized under voltage control in tartaric-sulfuric acid (TSA). In this work, the influence of the amount of SiCnp on the film growth during anodizing was investigated. The current density versus time response and the morphology of the porous alumina film formed at the composite surface are compared to those concerning a commercial aluminum alloy (AA1050) anodi...

Fabrication of porous anodic alumina using normal anodization and pulse anodization

Science.gov (United States)

Chin, I. K.; Yam, F. K.; Hassan, Z.

2015-05-01

This article reports on the fabrication of porous anodic alumina (PAA) by two-step anodizing the low purity commercial aluminum sheets at room temperature. Different variations of the second-step anodization were conducted: normal anodization (NA) with direct current potential difference; pulse anodization (PA) alternate between potential differences of 10 V and 0 V; hybrid pulse anodization (HPA) alternate between potential differences of 10 V and -2 V. The method influenced the film homogeneity of the PAA and the most homogeneous structure was obtained via PA. The morphological properties are further elucidated using measured current-transient profiles. The absent of current rise profile in PA indicates the anodization temperature and dissolution of the PAA structure were greatly reduced by alternating potential differences.

Wetting behaviour of lead-free Sn-based alloys on Cu and Ni substrates

International Nuclear Information System (INIS)

Amore, S.; Ricci, E.; Borzone, G.; Novakovic, R.

2008-01-01

The present work was carried out in the framework of the study of new lead-free solder alloys for technical applications in electronic devices. In the focus of this characterisation the wetting behaviour of several Sn-rich alloys belonging to the In-Sn, Au-Sn and Cu-Sn systems has been studied by measuring the contact angle variations on Cu and Ni substrates as a function of time and temperature. The interface between the alloy and the substrate has been analysed by the use of optical microscopy and scanning electron microscopy combined with energy-dispersive X-ray spectrometry in order to study the reaction between the alloy and the solid substrate and the possible formation of different compounds at the interface. A remarkable effect of the two different substrates on the behaviour of the contact angle as a function of temperature and on the morphology of the interface between the liquid solder and the solid substrate was observed for the In-Sn and Cu-Sn, while the Au-Sn system shows a very similar wetting behaviour on Cu and Ni

Stress corrosion cracking of nickel alloys in bicarbonate and chloride solutions

International Nuclear Information System (INIS)

Ares, A. E.; Carranza, R. M.; Giordano, C. M.; Zadorozne, N. S.; Rebak, R.B.

2013-01-01

Alloy 22 is one of the candidates for the manufacture of high level radioactive waste containers. These containers provide services in natural environments characterized by multi-ionics solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate at temperatures above 60°C and applied potentials around +400 mVSCE are necessary in order to produce cracking, . This susceptibility may be associated to the instability of the passive film formed and to the formation of an anodic current peak in the polarization curves in these media. Until now, it is unclear the role played by each alloying element (Ni, Cr or Mo) in the SCC susceptibility of Alloy 22 in these media The aim of this work is to evaluate the SCC susceptibility of nickel-based alloys in media containing bicarbonate and chloride ions, at high temperature. Slow Strain Rate Testing (SSRT) was conducted to samples of different alloys: 22 (Ni-Cr-Mo), 600 (Ni-Cr-Fe), 800H (Ni-Fe-Cr) y 201 (99.5% Ni).This tests were conducted in 1.1 mol/L NaHCO 3 +1.5 mol/L NaCl a 90°C and different applied potentials (+200mVSCE,+300 mVSCE, +400 mVSCE). These results were complemented with those obtained in a previous work, where we studied the anodic electrochemical behavior of nickel base alloys under the same conditions. It was found that alloy 22 showed a current peak in a potential range between +200 mVSCE and +300 mVSCE when immersed in bicarbonate ions containing solutions. This peak was attributed to the presence of chromium in the alloys. The SSRT showed that only alloy 22 has a clear indication of stress corrosion cracking. The current results suggested that the presence of an anodic peak in the polarization curves was not a sufficient condition for cracking. (author)

The effect of alloyed nitrogen or dissolved nitrate ions on the anodic behaviour of austenitic stainless steel in hydrochloric acid

International Nuclear Information System (INIS)

Shahrabi, T.

2004-01-01

The anodic behaviour of high purity stainless steels, based on a 316L composition, has been studied at room temperature in HCl solutions from 1 to 6 M. For all acid concentrations, the presence of 0.22% nitrogen has little or no effect on the active dissolution kinetics at low over-potentials. The effect on the critical current density for passivation is also small for low HCl concentrations ( 4.5 M), no passivation occurs and again nitrogen has little effect. However, for HCl concentrations around 4 M nitrogen reversibly impedes active dissolution at a few hundred mA cm -2 . The effect does not appear to be an oxide passivation, but is more likely to be due to surface enrichment of nitrogen atoms. Implications for localized corrosion are discussed. An effect similar to that of nitrogen alloying is reproduced on a nitrogen free alloy by adding 2 M NaNO 3 to a 4M HCl solution. This effect is distinct from the passivation of salt-covered surfaces and may be preferable to the latter as an explanation of the increase in pitting potential by nitrate additions to NaCl solutions. Passivation under a salt film is retained to explain the passivation of growing pits above the inhibition potential. (authors)

Research on high-temperature compression and creep behavior of porous Cu–Ni–Cr alloy for molten carbonate fuel cell anodes

Directory of Open Access Journals (Sweden)

Li W.

2015-06-01

Full Text Available The effect of porosity on high temperature compression and creep behavior of porous Cu alloy for the new molten carbonate fuel cell anodes was examined. Optical microscopy and scanning electron microscopy were used to investigate and analyze the details of the microstructure and surface deformation. Compression creep tests were utilized to evaluate the mechanical properties of the alloy at 650 °C. The compression strength, elastic modulus, and yield stress all increased with the decrease in porosity. Under the same creep stress, the materials with higher porosity exhibited inferior creep resistance and higher steadystate creep rate. The creep behavior has been classified in terms of two stages. The first stage relates to grain rearrangement which results from the destruction of large pores by the applied load. In the second stage, small pores are collapsed by a subsequent sintering process under the load. The main deformation mechanism consists in that several deformation bands generate sequentially under the perpendicular loading, and in these deformation bands the pores are deformed by flattering and collapsing sequentially. On the other hand, the shape of a pore has a severe influence on the creep resistance of the material, i.e. every increase of pore size corresponds to a decrease in creep resistance.

Finite Element-Assisted Assessment of the Thermo-cyclic Characteristics of Leads Soldered with SnAgCu(+Bi,In) Alloys

Science.gov (United States)

Lis, Adrian; Nakanishi, Kohei; Matsuda, Tomoki; Sano, Tomokazu; Minagawa, Madoka; Okamoto, Masahide; Hirose, Akio

2017-07-01

Solder joints between leads and printed circuit boards in thin small outline packages were produced with conventional Sn1.0Ag0.7Cu (SAC107) and Sn3.0Ag0.7Cu (SAC305) solders as well as various solder alloys with gradually increasing amounts of Bi (up to 3.0 wt.%) and In (up to 1.0 wt.%) within the SAC107 base solder. The reliability of soldered leads in temperature cycle (TC) tests improved most with solder alloys containing both Bi (1.6 wt.%) and In (0.5 wt.%). Microindentation and electron probe microanalysis mappings revealed that the effect originates from a combination of solution and precipitation strengthening of the initial SAC alloy. The distribution of inelastic strain accumulation (ISA), as a measure for degradation, was determined in the solder joints by finite element calculations. It was shown that defects in the solder proximal to the lead (60-75 μm), which was underpinned by similar cracking characteristics along the lead-solder interface. The ISA was confirmed to be lower in SAC+Bi/In alloys owing to their enhanced elasto-plastic properties. Moreover, the addition of a thin Cu coating on the leads could improve the joint reliability, as suggested by the calculation of the ISA and the acceleration factor.

Review on recent progress of nanostructured anode materials for Li-ion batteries

KAUST Repository

Goriparti, Subrahmanyam

2014-07-01

This review highlights the recent research advances in active nanostructured anode materials for the next generation of Li-ion batteries (LIBs). In fact, in order to address both energy and power demands of secondary LIBs for future energy storage applications, it is required the development of innovative kinds of electrodes. Nanostructured materials based on carbon, metal/semiconductor, metal oxides and metal phosphides/nitrides/sulfides show a variety of admirable properties for LIBs applications such as high surface area, low diffusion distance, high electrical and ionic conductivity. Therefore, nanosized active materials are extremely promising for bridging the gap towards the realization of the next generation of LIBs with high reversible capacities, increased power capability, long cycling stability and free from safety concerns. In this review, anode materials are classified, depending on their electrochemical reaction with lithium, into three groups: intercalation/de-intercalation, alloy/de-alloy and conversion materials. Furthermore, the effect of nanoscale size and morphology on the electrochemical performance is presented. Synthesis of the nanostructures, lithium battery performance and electrode reaction mechanisms are also discussed. To conclude, the main aim of this review is to provide an organic outline of the wide range of recent research progresses and perspectives on nanosized active anode materials for future LIBs.

Review on recent progress of nanostructured anode materials for Li-ion batteries

KAUST Repository

Goriparti, Subrahmanyam; Miele, Ermanno; De Angelis, Francesco; Di Fabrizio, Enzo M.; Proietti Zaccaria, Remo; Capiglia, Claudio

2014-01-01

This review highlights the recent research advances in active nanostructured anode materials for the next generation of Li-ion batteries (LIBs). In fact, in order to address both energy and power demands of secondary LIBs for future energy storage applications, it is required the development of innovative kinds of electrodes. Nanostructured materials based on carbon, metal/semiconductor, metal oxides and metal phosphides/nitrides/sulfides show a variety of admirable properties for LIBs applications such as high surface area, low diffusion distance, high electrical and ionic conductivity. Therefore, nanosized active materials are extremely promising for bridging the gap towards the realization of the next generation of LIBs with high reversible capacities, increased power capability, long cycling stability and free from safety concerns. In this review, anode materials are classified, depending on their electrochemical reaction with lithium, into three groups: intercalation/de-intercalation, alloy/de-alloy and conversion materials. Furthermore, the effect of nanoscale size and morphology on the electrochemical performance is presented. Synthesis of the nanostructures, lithium battery performance and electrode reaction mechanisms are also discussed. To conclude, the main aim of this review is to provide an organic outline of the wide range of recent research progresses and perspectives on nanosized active anode materials for future LIBs.

Effect of Processing Parameters on Pore Structure and Thickness of Anodic Aluminum Oxide (AAO) Tubular Membranes

OpenAIRE

Belwalkar, A.; Grasing, E.; Van Geertruyden, W.; Huang, Z.; Misiolek, W.Z.

2008-01-01

Nanoporous anodic aluminum oxide (AAO) tubular membranes were fabricated from aluminum alloy tubes in sulfuric and oxalic acid electrolytes using a two-step anodization process. The membranes were investigated for characteristics such as pore size, interpore distance and thickness by varying applied voltage and electrolyte concentration. Morphology of the membranes was examined using light optical and scanning electron microscopy and characterized using ImageJ software. Results showed that me...

Application of Anodization Process for Cast Aluminium Surface Properties Enhancement

Directory of Open Access Journals (Sweden)

Włodarczyk-Fligier A.

2016-09-01

Full Text Available An huge interest is observed in last years in metal matrix composite, mostly light metal based, which have found their applications in many industry branches, among others in the aircraft industry, automotive-, and armaments ones, as well as in electrical engineering and electronics, where one of the most important issue is related to the corrosion resistance, especially on the surface layer of the used aluminium alloys. This elaboration presents the influence of ceramic phase on the corrosion resistance, quality of the surface layer its thickness and structure of an anodic layer formed on aluminium alloys. As test materials it was applied the aluminium alloys Al-Si-Cu and Al-Cu-Mg, for which heat treatment processes and corrosion tests were carried out. It was presented herein grindability test results and metallographic examination, as well. Hardness of the treated alloys with those ones subjected to corrosion process were compared.

Investigation of electrochemical behaviour and structure of oxide films on Ni60Nb40 alloy in amorphous and crystalline states

International Nuclear Information System (INIS)

Tomashov, N.D.; Skvortsova, I.B.; Gorodetskij, A.E.; Bogomolov, D.B.

1987-01-01

Electrochemical properties of Ni 60 Nb 40 alloy in amorphous and crystalline states as well as structure of oxide films forming during anode polarization in electrolytes on the surface of this alloy in both its states are investigated. It is stated that increased passive ability of Ni 60 Nb 40 alloys in amorphous state and high efficiency of chlorine evolution (2 n NaCl+HCl up to pH=0) anode process in comparison with crystalline state are defined by increased homogeneity and uniformity of passive films forming on amorphous alloy and their increased electron conductivity, that is in direct dependence on different structure of passive films forming on alloys in amorphous and crystalline states

High temperature cathodic charging of hydrogen in zirconium alloys and iron and nickel base alloys

International Nuclear Information System (INIS)

John, J.T.; De, P.K.; Gadiyar, H.S.

1990-01-01

These investigations lead to the development of a new technique for charging hydrogen into metals and alloys. In this technique a mixture of sulfates and bisulfates of sodium and potassium is kept saturated with water at 250-300degC in an open pyrex glass beaker and electrolysed using platinum anode and the material to be charged as the cathode. Most of the studies were carried out on Zr alloys. It is shown that because of the high hydrogen flux available at the surface and the high diffusivity of hydrogen in metals at these temperatures the materials pick up hydrogen faster and more uniformly than the conventional electrolytic charging at room temperature and high temperature autoclaving in LiOH solutions. Chemical analysis, metallographic examination and XRD studies confirm this. This technique has been used to charge hydrogen into many iron and nickel base austentic alloys, which are very resistant to hydrogen pick up and to H-embrittlement. Since this involved a novel method of electrolysing water, the hydrogen/deuterium isotopic ratio has been studied. At this temperatures the D/H ratio in the evolved hydrogen gas was found to be closer to the value in the liquid water, which means a smaller separation factor. This confirm the earlier observation that separation factor decreases with increase of temperature. (author). 16 refs., 21 fi gs., 6 tabs

X-ray thickness measurement of aluminum alloys

International Nuclear Information System (INIS)

Albert, J.J.

1976-01-01

The theory of x-ray thickness gauging is extended to reveal the conditions under which a fixed anode voltage is ideal. A mathematical model of an alloy and computations reveal that two voltages can be used to measure the aluminum alloys with an error of roughly 1 percent, determined by the tolerance on manganese content rather than the large errors ordinarily a consequence of the tolerances on copper and zinc content. Implementation is discussed

Studies of Modified Hydrogen Storage Intermetallic Compounds Used as Fuel Cell Anodes

Directory of Open Access Journals (Sweden)

Rui F. M. Lobo

2011-12-01

Full Text Available The possibility of substituting Pt/C with the hydrogen storage alloy MlNi3.6Co0.85Al0.3Mn0.3 as the anode active material of a proton exchange membrane fuel cell system has been analyzed. The electrochemical properties indicate that a much more electrochemically active anode is obtained by impregnating the active material loaded anode in a Nafion proton conducting polymer. Such performance improvement might result from the increase of three-phase boundary sites or length in the gas diffusion electrode where the electrochemical reaction occurs. The experimental data revealed that the membrane electrode assembly (MEA shows better results when the anode active material, MlNi3.6Co0.85Al0.3Mn0.3, is treated with a hot alkaline KBH4 solution, and then chemically coated with 3 wt.% Pd. The MEA with the aforesaid modification presents an enhanced surface capability for hydrogen adsorption, and has been studied by molecular beam-thermal desorption spectrometry.

Nanotube morphology changes for Ti-Zr alloys as Zr content increases

International Nuclear Information System (INIS)

Kim, Won-Gi; Choe, Han-Cheol; Ko, Yeong-Mu; Brantley, William A.

2009-01-01

Nanotube morphology changes in Ti-Zr alloys as Zr content increases have been investigated. Ti-Zr (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting and heat treated for 24 h at 1000 o C in an argon atmosphere. TiO 2 nanotubes were formed on the Ti-Zr alloys by anodization in H 3 PO 4 containing 0.5 wt.% NaF. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Samples were embedded in epoxy resin, leaving an area of 10 mm 2 exposed to the electrolyte. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The Ti-Zr alloy microstructures observed by OM and FE-SEM changed from a lamellar structure to a needle-like structure with increasing Zr content. The microstructures also changed from β phase to increasing amounts of α phase as the Zr content increased. The number of large nanotubes formed by anodization decreased, and the number of small nanotubes increased, as the Zr content increased. The mean inner diameter ranged from approximately 150 to 200 nm with a tube-wall thickness of about 20 nm. The interspace between the nanotubes was approximately 60, 70, 100 and 130 nm for Zr contents of 10, 20, 30 and 40 wt.%, respectively.

Nanostructured silicon anodes for lithium ion rechargeable batteries.

Science.gov (United States)

Teki, Ranganath; Datta, Moni K; Krishnan, Rahul; Parker, Thomas C; Lu, Toh-Ming; Kumta, Prashant N; Koratkar, Nikhil

2009-10-01

Rechargeable lithium ion batteries are integral to today's information-rich, mobile society. Currently they are one of the most popular types of battery used in portable electronics because of their high energy density and flexible design. Despite their increasing use at the present time, there is great continued commercial interest in developing new and improved electrode materials for lithium ion batteries that would lead to dramatically higher energy capacity and longer cycle life. Silicon is one of the most promising anode materials because it has the highest known theoretical charge capacity and is the second most abundant element on earth. However, silicon anodes have limited applications because of the huge volume change associated with the insertion and extraction of lithium. This causes cracking and pulverization of the anode, which leads to a loss of electrical contact and eventual fading of capacity. Nanostructured silicon anodes, as compared to the previously tested silicon film anodes, can help overcome the above issues. As arrays of silicon nanowires or nanorods, which help accommodate the volume changes, or as nanoscale compliant layers, which increase the stress resilience of silicon films, nanoengineered silicon anodes show potential to enable a new generation of lithium ion batteries with significantly higher reversible charge capacity and longer cycle life.

Pb3O4 type antimony oxides MSb2O4 (M = Co, Ni) as anode for Li-ion batteries

International Nuclear Information System (INIS)

Jibin, A.K.; Reddy, M.V.; Subba Rao, G.V.; Varadaraju, U.V.; Chowdari, B.V.R.

2012-01-01

Graphical abstract: Isostructural Pb 3 O 4 type MSb 2 O 4 (M = Co, Ni) compounds were investigated as possible anodes for lithium ion batteries. The reversible capacity is due to electrochemically active Sb and the transition metal and Li 2 O form an inactive matrix which buffers volume variations associated with alloying-de-alloying of antimony. Highlights: ► Isostructural MSb 2 O 4 (M = Co, Ni) were studied as anode for LIBs for first time. ► Li/MSb 2 O 4 (M = Co, Ni) cells displayed reversibility due to electrochemically active Sb. ► CoSb 2 O 4 showed good reversibility compared to NiSb 2 O 4 . - Abstract: Polycrystalline samples of isostructural MSb 2 O 4 (M = Co, Ni) have been prepared by solid state synthesis and lithium-storage is investigated as possible anode materials for lithium-ion batteries. The reaction mechanism of lithium with MSb 2 O 4 (M = Co, Ni) is explored by galvanostatic cycling, cyclic voltammogram and ex situ studies. Both CoSb 2 O 4 and NiSb 2 O 4 exhibit similar electrochemical behavior and show reversible capacity of 490 and 412 mAh g −1 respectively in the first cycle. Reversible alloying de-alloying of Li x Sb takes place in an amorphous matrix of M (Co, Ni) and Li 2 O during electrochemical cycling.

Improvement of Corrosion Resistance of Aluminum Alloy with Wettability Controlled Porous Oxide films

Energy Technology Data Exchange (ETDEWEB)

Sakairi, M.; Goyal, V. [Hokkaido University, Sapporo (Japan)

2016-08-15

The combined process of porous type anodizing and desiccation treatment was applied to improve wettability of A1050 aluminum alloy. The water contact angles of anodized samples were increaseds considerably with desiccation treatment. However, there was no considerable effect of polishing and anodizing time on water contact angle. The corrosion behavior with the treatments was investigated electrochemically. The corrosion resistance of the samples in 3.5 mass% NaCl solutions increased with higher contact angle. Anodized and desiccated samples showed better corrosion resistance than un-desiccated samples around rest potential region.

Improvement of Corrosion Resistance of Aluminum Alloy with Wettability Controlled Porous Oxide films

International Nuclear Information System (INIS)

Sakairi, M.; Goyal, V.

2016-01-01

The combined process of porous type anodizing and desiccation treatment was applied to improve wettability of A1050 aluminum alloy. The water contact angles of anodized samples were increaseds considerably with desiccation treatment. However, there was no considerable effect of polishing and anodizing time on water contact angle. The corrosion behavior with the treatments was investigated electrochemically. The corrosion resistance of the samples in 3.5 mass% NaCl solutions increased with higher contact angle. Anodized and desiccated samples showed better corrosion resistance than un-desiccated samples around rest potential region.

Airborne concentrations of toxic metals resulting from the use of low melting point lead alloys to construct radiotherapy shielding

International Nuclear Information System (INIS)

McCullough, E.C.; Senjem, D.H.

1981-01-01

Determinations of airborne concentrations of lead, cadmium, bismuth, and tin were made above vessels containing a fusible lead alloy (158 0 F melting point) commonly used for construction of radiotherapy blocks. Fume concentrations were determined by collection on a membrane filter and analysis by atomic absorption spectrophotometry. Samples were obtained for alloy temperatures of 200 0 , 400 0 , and 600 0 F. In all instances, concentrations were much lower than the applicable occupational limits for continuous exposure. The results of this study indicate that the use of a vented hood as a means of reducing air concentrations of toxic metals above and near vessels containing low temperature melting point lead allows commonly used in construction of radiotherapy shields appears unjustifiable. However, proper handling procedures should be observed to avoid entry into the body via alternate pathways (e.g., ingestion or skin absorption). Transmission data of a non-cadmium containing lead alloy with a melting point of 203 0 F was ascertained and is reported on

Electrochemical studies of calcium-lithium alloys in thionyl chloride electrolyte systems

Science.gov (United States)

Gupta, V. K.; Fritts, D. H.

The corrosion of the calcium anode in the calcium thionyl chloride cell has been a persistent problem, which has kept this otherwise attractive couple from use. Investigations of cells with anodes made from calcium/calcium-lithium alloys are reported. These anodes were chosen in hopes of obtaining synergistic results, namely a stable anode surface film vs. pure calcium, and a higher melting point than lithium anodes. Results indicate that some degree of synergism does exist, but that the surface film is not sufficiently stable to protect the anode from continuous corrosion. It is concluded that the stability problem is one of a mechanical shedding of the film which occurs independent of lithium content. Also, a change in the electrolyte salt is the most promising approach to the calcium corrosion problem.

Effect of thermal aging on corrosion resistance of C-22 alloy in chloride solutions

International Nuclear Information System (INIS)

Carranza, Ricardo M.; Rodriguez, Martin A.

2007-01-01

Alloy 22 (N06022) belongs to the Ni-Cr-Mo family and it is highly resistant to localized corrosion. The anodic behavior of mill annealed (MA) and thermally aged (10 hours at 760 C degrees) Alloy 22 was studied in chloride solutions with different pH values at 90 C degrees. Thermal aging leads to a microstructure of full grain boundary precipitation of topologically closed packed (TCP) phases. Electrochemical tests included monitoring of open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. Assessment of general and localized (crevice) corrosion was performed. Re passivation potentials were obtained from cyclic potentiodynamic polarization tests. Results indicate that MA and TCP material show similar general corrosion rates and crevice corrosion resistance in the tested environments. MA and TCP specimens suffered general corrosion in an active state when tested in low pH chloride solutions. The grain structure of the alloy was revealed for MA material, while TCP material suffered a preferential attack at grain boundaries. (author)

Combined micro-droplet and thin-film-assisted pre-concentration of lead traces for on-line monitoring using anodic stripping voltammetry.

Science.gov (United States)

Belostotsky, Inessa; Gridin, Vladimir V; Schechter, Israel; Yarnitzky, Chaim N

2003-02-01

An improved analytical method for airborne lead traces is reported. It is based on using a Venturi scrubber sampling device for simultaneous thin-film stripping and droplet entrapment of aerosol influxes. At least threefold enhancement of the lead-trace pre-concentration is achieved. The sampled traces are analyzed by square-wave anodic stripping voltammetry. The method was tested by a series of pilot experiments. These were performed using contaminant-controlled air intakes. Reproducible calibration plots were obtained. The data were validated by traditional analysis using filter sampling. LODs are comparable with the conventional techniques. The method was successfully applied to on-line and in situ environmental monitoring of lead.

Combined micro-droplet and thin-film-assisted pre-concentration of lead traces for on-line monitoring using anodic stripping voltammetry

Energy Technology Data Exchange (ETDEWEB)

Belostotsky, Inessa; Gridin, Vladimir V.; Schechter, Israel; Yarnitzky, Chaim N. [Department of Chemistry, Technion Israel Institute of Technology, 32000, Haifa (Israel)

2003-02-01

An improved analytical method for airborne lead traces is reported. It is based on using a Venturi scrubber sampling device for simultaneous thin-film stripping and droplet entrapment of aerosol influxes. At least threefold enhancement of the lead-trace pre-concentration is achieved. The sampled traces are analyzed by square-wave anodic stripping voltammetry. The method was tested by a series of pilot experiments. These were performed using contaminant-controlled air intakes. Reproducible calibration plots were obtained. The data were validated by traditional analysis using filter sampling. LODs are comparable with the conventional techniques. The method was successfully applied to on-line and in situ environmental monitoring of lead. (orig.)

Influence of anodization parameters in the TiO2 nanotubes formation on Ti-7.5Mo alloy surface for biomedical application

International Nuclear Information System (INIS)

Escada, Ana Lúcia; Nakazato, Roberto Zenhei; Claro, Ana Paula Rosifini Alves

2017-01-01

In this study, the effects of the parameters such as applied potential difference, time and annealing temperature in the titania nanotubes formation were evaluated. The morphology of the nanotubes was evaluated by using Field Emission Gun - Scanning Electron Microscope (FEG-SEM), Atomic Force Microscope (AFM), contact angle and X-rays diffraction (XRD). Self-organized nano-structures were formed on the Ti-7.5Mo alloy surface from the same electrolyte (glycerol/NH4F) for all conditions. It was observed that the potential influenced the diameter while the length was changed according to the anodization time length. The presence of the phases anatase and rutile was altered by annealing temperature. Results showed that 20V-48h-450 deg C was the better than other conditions for application as biomaterial. (author)

In-Operando Raman Characterization of Carbon Deposition on SOFC Anodes

KAUST Repository

Maher, R. C.; Duboviks, V.; Offer, G.; Cohen, L. F.; Brandon, N. P.

2013-01-01

Carbon formation within nickel-based solid oxide fuel cell (SOFC) anodes exposed to carbonaceous fuels typically leads to reduced operational lifetimes and performance, and can eventually lead to catastrophic failure through cracking and delamination. In-situ Raman spectroscopy has been shown to be a powerful characterization tool for the investigation of the dynamics of physical processes occurring within operational SOFCs in real time. Here we investigate the dynamics of carbon formation on a variety of nickel-based SOFC anodes as a function of temperature, fuel and electrical loading using Raman spectroscopy. We show that the rate of carbon formation throughout the SOFC anode can be significantly reduced through a careful consideration of the SOFC anode material, design and operational conditions. © The Electrochemical Society.

In-Operando Raman Characterization of Carbon Deposition on SOFC Anodes

KAUST Repository

Maher, R. C.

2013-10-06

Carbon formation within nickel-based solid oxide fuel cell (SOFC) anodes exposed to carbonaceous fuels typically leads to reduced operational lifetimes and performance, and can eventually lead to catastrophic failure through cracking and delamination. In-situ Raman spectroscopy has been shown to be a powerful characterization tool for the investigation of the dynamics of physical processes occurring within operational SOFCs in real time. Here we investigate the dynamics of carbon formation on a variety of nickel-based SOFC anodes as a function of temperature, fuel and electrical loading using Raman spectroscopy. We show that the rate of carbon formation throughout the SOFC anode can be significantly reduced through a careful consideration of the SOFC anode material, design and operational conditions. © The Electrochemical Society.

Exploring Cu2O/Cu cermet as a partially inert anode to produce aluminum in a sustainable way

International Nuclear Information System (INIS)

Feng, Li-Chao; Xie, Ning; Shao, Wen-Zhu; Zhen, Liang; Ivanov, V.V.

2014-01-01

Highlights: • Cu 2 O/Cu cermet was used as a candidate partially inert anode material to produce aluminum alloys. • The thermal corrosion behavior of Cu 2 O/Cu was investigated in molten salt at 960 °C. • The corrosion rate is largely governed by the geometrical structures of Cu in the prepared samples. • The corrosion rate increases with decreasing sizes and increasing filling contents of Cu phase. • The corrosion rate was 1.8–9 cm/y and the Cu contents is less than 6.2 wt.% in the produced aluminum. - Abstract: As an energy-intensive process, aluminum production by the Hall–Héroult method accounts for significant emissions of CO 2 and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Héroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu 2 O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu 2 O/Cu was investigated in Na 3 AlF 6 –CaF 2 –Al 2 O 3 electrolyte at 960 °C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu 2 O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling content of Cu phase. The calculated corrosion rate

Cermet anode compositions with high content alloy phase

Science.gov (United States)

Marschman, Steven C.; Davis, Norman C.

1989-01-01

Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M.P.; Hihn, J.Y., E-mail: jean-yves.hihn@univ-fcomte.fr

2015-11-15

Graphical abstract: Result of an etching step in ultrasound presence on intermetallic particles on a 2024 aluminum alloy. - Highlights: • Etching step prior to anodization on 2024 aluminum alloy. • Etching rate measurement and hydroxide film characterization by GDOES and SEM. • Various etching parameters (temperature, presence or absence of ultrasound). • Improvement of corrosion resistance show by electrochemical tests. - Abstract: Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

International Nuclear Information System (INIS)

Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M.P.; Hihn, J.Y.

2015-01-01

Graphical abstract: Result of an etching step in ultrasound presence on intermetallic particles on a 2024 aluminum alloy. - Highlights: • Etching step prior to anodization on 2024 aluminum alloy. • Etching rate measurement and hydroxide film characterization by GDOES and SEM. • Various etching parameters (temperature, presence or absence of ultrasound). • Improvement of corrosion resistance show by electrochemical tests. - Abstract: Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

Electrochemical migration of lead-free solder alloys in Na2SO4 environment

DEFF Research Database (Denmark)

Medgyes, Balint; Ádám, Sándor; Tar, Lajos

2017-01-01

The effect of sulphate ion concentration on electrochemical migration of lead-free solder alloys was investigated with the use of water drop tests, by applying an in-situ optical and electrical inspection system. According to the Mean-Time-To-Failure (MTTF) values it was found that in the case of...

Corrosion of high-density sintered tungsten alloys

International Nuclear Information System (INIS)

Batten, J.J.; Moore, B.T.

1989-01-01

In comparative corrosion tests, the corrosion resistance of an Australian tungsten alloy (95% W, 3.5% Ni, 1.5% Fe) was found to be superior to three other tungsten alloys and, under certain conditions, even more corrosion-resistant than pure tungsten. Corrosion resistance was evaluated after immersion in both distilled water and 5% sodium chloride solutions, and in cyclic humidity and salt mist environments. For all but the Australian alloy, the rate of corrosion in sodium chloride solution was markedly less than that in distilated water. In all cases, alloys containing copper had the greatest corrosion rates. Corrosion mechanisms were investigated using a scanning electron microscope, analysis of corrosion products and galvanic corrosion studies. For the alloys, corrosion was attributed primarily to a galvanic reaction. Whether the tungsten or binder phase of the alloy became anodic, and thus was attacked preferentially, depended upon alloy composition and corrosion environment. 16 refs., 4 tabs., 4 figs

Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

International Nuclear Information System (INIS)

Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

2000-01-01

The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

Fabrication of electrodeposited Co-Pt nano-arrays embedded in an anodic aluminum oxide/Ti/Si substrate

Energy Technology Data Exchange (ETDEWEB)

Lim, S.K. [School of Advanced Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Jeong, G.H. [School of Advanced Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Park, I.S. [School of Advanced Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Na, S.M. [Advanced Materials and Process Research for IT, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)]. E-mail: nsmv2k@skku.edu; Suh, S.J. [School of Advanced Science and Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Advanced Materials and Process Research for IT, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

2007-03-15

An anodic aluminum oxide (AAO) template, which is filled with the Co-Pt alloys, is a promising material for high-density magnetic recording media due to its high magnetic anisotropy and high coercivity. The porous AAO templates were fabricated by the two-step anodizing of 1-{mu}m-thick Al thin film evaporated on top of the titanium layer with the thickness of 250 nm. The AAO template with pore size of approximately 60 nm and aspect ratio of 10 was obtained at voltage of 40 V, temperature of 5 deg. C, oxalic acid of 0.3 M and widening time of 55 min. Then the thickness of barrier is less than 20 nm. The Co-Pt alloy electrodeposited at pulsed current density, pH of 4 and room temperature was successfully filled in the AAO template with pore size of 80 nm and aspect ratio of 3. Then the Co-Pt alloy with Pt concentration of 45 at% was uniformly filled in the template and the coercivity of 1100 Oe was observed by VSM.

Fabrication of electrodeposited Co-Pt nano-arrays embedded in an anodic aluminum oxide/Ti/Si substrate

Science.gov (United States)

Lim, S. K.; Jeong, G. H.; Park, I. S.; Na, S. M.; Suh, S. J.

An anodic aluminum oxide (AAO) template, which is filled with the Co-Pt alloys, is a promising material for high-density magnetic recording media due to its high magnetic anisotropy and high coercivity. The porous AAO templates were fabricated by the two-step anodizing of 1-μm-thick Al thin film evaporated on top of the titanium layer with the thickness of 250 nm. The AAO template with pore size of approximately 60 nm and aspect ratio of 10 was obtained at voltage of 40 V, temperature of 5 °C, oxalic acid of 0.3 M and widening time of 55 min. Then the thickness of barrier is less than 20 nm. The Co-Pt alloy electrodeposited at pulsed current density, pH of 4 and room temperature was successfully filled in the AAO template with pore size of 80 nm and aspect ratio of 3. Then the Co-Pt alloy with Pt concentration of 45 at% was uniformly filled in the template and the coercivity of 1100 Oe was observed by VSM.

Fabrication of electrodeposited Co-Pt nano-arrays embedded in an anodic aluminum oxide/Ti/Si substrate

International Nuclear Information System (INIS)

Lim, S.K.; Jeong, G.H.; Park, I.S.; Na, S.M.; Suh, S.J.

2007-01-01

An anodic aluminum oxide (AAO) template, which is filled with the Co-Pt alloys, is a promising material for high-density magnetic recording media due to its high magnetic anisotropy and high coercivity. The porous AAO templates were fabricated by the two-step anodizing of 1-μm-thick Al thin film evaporated on top of the titanium layer with the thickness of 250 nm. The AAO template with pore size of approximately 60 nm and aspect ratio of 10 was obtained at voltage of 40 V, temperature of 5 deg. C, oxalic acid of 0.3 M and widening time of 55 min. Then the thickness of barrier is less than 20 nm. The Co-Pt alloy electrodeposited at pulsed current density, pH of 4 and room temperature was successfully filled in the AAO template with pore size of 80 nm and aspect ratio of 3. Then the Co-Pt alloy with Pt concentration of 45 at% was uniformly filled in the template and the coercivity of 1100 Oe was observed by VSM

Electroplated reticulated vitreous carbon current collectors for lead-acid batteries: opportunities and challenges

Science.gov (United States)

Gyenge, Elod; Jung, Joey; Mahato, Basanta

Reticulated, open-cell structures based on vitreous carbon substrates electroplated with a Pb-Sn (1 wt.%) alloy were investigated as current collectors for lead-acid batteries. Scanning and backscattered electron microscopy, cyclic voltammetry, anodic polarization and flooded 2 V single-cell battery testing was employed to characterize the performance of the proposed collectors. A battery equipped with pasted electroplated reticulated vitreous carbon (RVC) electrodes of 137 cm 2 geometric area, at the time of manuscript submission, completed 500 cycles and over 1500 h of continuous operation. The cycling involved discharges at 63 A kg PAM-1 corresponding to a nominal 0.75 h rate and a positive active mass (PAM) utilization efficiency of 21%. The charging protocol was composed of two voltage limited (i.e. 2.6 V/cell), constant current steps of 35 and 9.5 A kg PAM-1, respectively, with a total duration of about 2 h. The charge factor was 1.05-1.15. The observed cycling behavior in conjunction with the versatility of electrodeposition to produce application-dependent optimized lead alloy coating thickness and composition shows promise for the development of lead-acid batteries using electroplated reticulated vitreous carbon collectors.

Characterization of the corrosion resistance of biologically active solutions: The effects of anodizing and welding

Science.gov (United States)

Walsh, Daniel W.

1991-01-01

An understanding of fabrication processes, metallurgy, electrochemistry, and microbiology is crucial to the resolution of microbiologically influenced corrosion (MIC) problems. The object of this effort was to use AC impedance spectroscopy to characterize the corrosion resistance of Type II anodized aluminum alloy 2219-T87 in sterile and biologically active media and to examine the corrosion resistance of 316L, alloy 2219-T87, and titanium alloy 6-4 in the welded and unwelded conditions. The latter materials were immersed in sterile and biologically active media and corrosion currents were measured using the polarization resistance (DC) technique.

Interfacial Reaction of Sn-Ag-Cu Lead-Free Solder Alloy on Cu: A Review

Directory of Open Access Journals (Sweden)

Liu Mei Lee

2013-01-01

Full Text Available This paper reviews the function and importance of Sn-Ag-Cu solder alloys in electronics industry and the interfacial reaction of Sn-Ag-Cu/Cu solder joint at various solder forms and solder reflow conditions. The Sn-Ag-Cu solder alloys are examined in bulk and in thin film. It then examines the effect of soldering conditions to the formation of intermetallic compounds such as Cu substrate selection, structural phases, morphology evolution, the growth kinetics, temperature and time is also discussed. Sn-Ag-Cu lead-free solder alloys are the most promising candidate for the replacement of Sn-Pb solders in modern microelectronic technology. Sn-Ag-Cu solders could possibly be considered and adapted in miniaturization technologies. Therefore, this paper should be of great interest to a large selection of electronics interconnect materials, reliability, processes, and assembly community.

Effect of Nitric and Oxalic Acid Addition on Hard Anodizing of AlCu4Mg1 in Sulphuric Acid

Directory of Open Access Journals (Sweden)

Maximilian Sieber

2018-02-01

Full Text Available The anodic oxidation process is an established means for the improvement of the wear and corrosion resistance of high-strength aluminum alloys. For high-strength aluminum-copper alloys of the 2000 series, both the current efficiency of the anodic oxidation process and the hardness of the oxide coatings are significantly reduced in comparison to unalloyed substrates. With regard to this challenge, recent investigations have indicated a beneficial effect of nitric acid addition to the commonly used sulphuric acid electrolytes both in terms of coating properties and process efficiency. The present work investigates the anodic oxidation of the AlCu4Mg1 alloy in a sulphuric acid electrolyte with additions of nitric acid as well as oxalic acid as a reference in a full-factorial design of experiments (DOE. The effect of the electrolyte composition on process efficiency, coating thickness and hardness is established by using response functions. A mechanism for the participation of the nitric acid additive during the oxide formation is proposed. The statistical significance of the results is assessed by an analysis of variance (ANOVA. Eventually, scratch testing is applied in order to evaluate the failure mechanisms and the abrasion resistance of the obtained conversion coatings.

Application of Box-Behnken designs in parameters optimization of differential pulse anodic stripping voltammetry for lead(II) determination in two electrolytes.

Science.gov (United States)

Yu, Xiao-Lan; He, Yong

2017-06-05

Box-Behnken design was advantageous to parameters optimization of differential pulse anodic stripping voltammetry (DPASV) for the analysis of lead(II) with its high efficiency and accuracy. Five Box-Behnken designs were designed and conducted in the electrolyte of 0.1 mol/L acetate buffer and 0.1 mol/L HCl without the removal of oxygen. Significant parameters and interactions in each electrolyte were found (P-value Box-Behnken designs in parameters optimization of DPASV for lead(II) determination regardless of the electrolyte kinds.

Electrochemical Degradation of Phenol and Resorcinol Molecules through the Dissolution of Sacrificial Anodes of Macro-Corrosion Galvanic Cells

Directory of Open Access Journals (Sweden)

Boguslaw Pierozynski

2018-06-01

Full Text Available This paper reports on the processes of phenol and resorcinol electrodegradation carried-out through continuous anodic dissolution of aluminum alloy and carbon steel sacrificial anodes for artificially aerated Cu-Al alloy and Cu-Fe-based galvanic (macro-corrosion cells and synthetically prepared wastewater solutions. Electrochemical experiments were carried-out by means of a laboratory size, PMMA (Poly-methyl methacrylate-made electrolyser unit, where significant degrees of phenol (10–89% and resorcinol (13–37% decomposition were obtained and visualized through the respective chemical/spectroscopy analyses. In addition, quantitative determination of phenol, as well as resorcinol (and possible electrodegradation products for the selected experimental conditions was performed by means of instrumental high-performance liquid chromatography/mass spectrometry analysis.

Electrochemical formation of a Pt/Zn alloy and its use as a catalyst for oxygen reduction reaction in fuel cells.

Science.gov (United States)

Sode, Aya; Li, Winton; Yang, Yanguo; Wong, Phillip C; Gyenge, Elod; Mitchell, Keith A R; Bizzotto, Dan

2006-05-04

The characterization of an electrochemically created Pt/Zn alloy by Auger electron spectroscopy is presented indicating the formation of the alloy, the oxidation of the alloy, and the room temperature diffusion of the Zn into the Pt regions. The Pt/Zn alloy is stable up to 1.2 V/RHE and can only be removed with the oxidation of the base Pt metal either electrochemically or in aqua regia. The Pt/Zn alloy was tested for its effectiveness toward oxygen reduction. Kinetics of the oxygen reduction reaction (ORR) were measured using a rotating disk electrode (RDE), and a 30 mV anodic shift in the potential of ORR was found when comparing the Pt/Zn alloy to Pt. The Tafel slope was slightly smaller than that measured for the pure Pt electrode. A simple procedure for electrochemically modifying a Pt-containing gas diffusion electrode (GDE) with Zn was developed. The Zn-treated GDE was pressed with an untreated GDE anode, and the created membrane electrode assembly was tested. Fuel cell testing under two operating conditions (similar anode and cathode inlet pressures, and a larger cathode inlet pressure) indicated that the 30 mV shift observed on the RDE was also evident in the fuel cell tests. The high stability of the Pt/Zn alloy in acidic environments has a potential benefit for fuel cell applications.

Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

Energy Technology Data Exchange (ETDEWEB)

Ge, Jisheng [Iowa State Univ., Ames, IA (United States)

1996-01-08

This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

Phase transformations of high-purity PbI{sub 2} nanoparticles synthesized from lead-acid accumulator anodes

Energy Technology Data Exchange (ETDEWEB)

Malevu, T.D., E-mail: malevutd@ufs.ac.za; Ocaya, R.O.; Tshabalala, K.G.

2016-09-01

High-purity hexagonal lead iodide nanoparticles have been synthesized from a depleted sealed lead acid battery anode. The synthesized product was found to consist of the rare 6R polytype form of PbI{sub 2} that is thought to have good potential in photovoltaic applications. We investigate the effects of annealing time and post-melting temperature on the structure and optical properties using 1.5418 Å CuKα radiation. Photoluminescence measurements were done under 150 W/221 nm wavelength xenon excitation. Phase transformation was observed through XRD peaks when annealing time increased from 0.5–5 h. The nanoparticle grain size and inter-planar distance appeared to be independent of annealing time. PL measurements show three broad peaks in a range of 400 nm to 700 nm that are attributed to excitonic, donor–acceptor pair and luminescence bands from the deep levels.

Effect of hydrogen on aluminium and aluminium alloys: A review

DEFF Research Database (Denmark)

Ambat, Rajan; Dwarakadasa, E.S.

1996-01-01

Susceptibility of aluminium and its alloys towards hydrogen embrittlement has been well established. Still a lot of confusion exists on the question of transport of hydrogen and its possible role in stress corrosion cracking. This paper reviews some of the fundamental properties of hydrogen...... in aluminium and its alloys and its effect on mechanical properties. The importance of hydrogen embrittlement over anodic dissolution to explain the stress corrosion cracking mechanism of these alloys is also examined in considerable detail. The various experimental findings concerning the link between...

Influence of anodization parameters in the TiO{sub 2} nanotubes formation on Ti-7.5Mo alloy surface for biomedical application

Energy Technology Data Exchange (ETDEWEB)

Escada, Ana Lúcia; Nakazato, Roberto Zenhei; Claro, Ana Paula Rosifini Alves, E-mail: analuciaescada@uol.com.br [Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Guaratinguetá, SP (Brazil). Departamento de Materiais e Tecnologia

2017-10-15

In this study, the effects of the parameters such as applied potential difference, time and annealing temperature in the titania nanotubes formation were evaluated. The morphology of the nanotubes was evaluated by using Field Emission Gun - Scanning Electron Microscope (FEG-SEM), Atomic Force Microscope (AFM), contact angle and X-rays diffraction (XRD). Self-organized nano-structures were formed on the Ti-7.5Mo alloy surface from the same electrolyte (glycerol/NH4F) for all conditions. It was observed that the potential influenced the diameter while the length was changed according to the anodization time length. The presence of the phases anatase and rutile was altered by annealing temperature. Results showed that 20V-48h-450 deg C was the better than other conditions for application as biomaterial. (author)

Stress corrosion cracking of an aluminum alloy used in external fixation devices.

Science.gov (United States)

Cartner, Jacob L; Haggard, Warren O; Ong, Joo L; Bumgardner, Joel D

2008-08-01

Treatment for compound and/or comminuted fractures is frequently accomplished via external fixation. To achieve stability, the compositions of external fixators generally include aluminum alloy components due to their high strength-to-weight ratios. These alloys are particularly susceptible to corrosion in chloride environments. There have been several clinical cases of fixator failure in which corrosion was cited as a potential mechanism. The aim of this study was to evaluate the effects of physiological environments on the corrosion susceptibility of aluminum 7075-T6, since it is used in orthopedic external fixation devices. Electrochemical corrosion curves and alternate immersion stress corrosion cracking tests indicated aluminum 7075-T6 is susceptible to corrosive attack when placed in physiological environments. Pit initiated stress corrosion cracking was the primary form of alloy corrosion, and subsequent fracture, in this study. Anodization of the alloy provided a protective layer, but also caused a decrease in passivity ranges. These data suggest that once the anodization layer is disrupted, accelerated corrosion processes occur. (c) 2007 Wiley Periodicals, Inc.

On the use of lead/tin alloys as target material for the production of spallation neutrons

International Nuclear Information System (INIS)

Atchison, F.; Baumann, P.; Brys, T.; Daum, M.; Egorov, A.; Fierlinger, P.; Fuchs, P.; Henneck, R.; Joray, St.; Keil, R.; Kirch, K.; Krutova, R.; Kuehne, G.; Lebedev, V.T.; Obermeier, H.; Orlova, D.N.; Perret, Ch.; Pichlmaier, A.; Richard, Ph.; Serebrov, A.; Thies, S.

2005-01-01

We have examined the suitability of lead (Pb)/tin (Sn) alloys with atomic ratios between 4:1 and 12:1 for use as a spallation target material for the PSI spallation ultracold neutron source. The measured corrosion rate with distilled water, R c -5 cm/year, is more than a factor of 80, less than for normal Pb; this corrosion rate is satisfactory. Microscopic investigations of the surface after the exposure to water revealed no visual changes. Small angle neutron scattering showed that the alloy is mechanically stable under thermal cycling. An experimental simulation of a water-cooled spallation neutron target made of Pb/Sn pebbles with a filling factor of 60% was investigated; the pulsed proton beam was simulated using hot and cold water in the target 'cooling' circuit. With realistic operational parameters for the cooling circuit, serious deformation of the PbSn pebbles occurred which finally blocked the cooling circuit. The Pb/Sn alloys solve the corrosion problem but its mechanical properties are inadequate leading to too short a lifetime to be practical in the PSI spallation source

EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

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Leszek A. Dobrzański

2011-09-01

Full Text Available In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current, based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electrochemical corrosion process of the investigated alloys: value of the corrosion potential Ecorr (mV, polarization resistance RP (kohm.cm2, corrosion current density icorr (10-6A/cm2, corrosion rate Vcorr (mm/year as well the mass loss Vc (g/m2<.

Investigation of models to predict the corrosion of steels in flowing liquid lead alloys

International Nuclear Information System (INIS)

Balbaud-Celerier, F.; Barbier, F.

2001-01-01

Corrosion of steels exposed to flowing liquid lead alloys can be affected by hydrodynamic parameters. The rotating cylinder system is of interest for the practical evaluation of the fluid velocity effect on corrosion and for the prediction of the corrosion behavior in other geometries. Models developed in aqueous medium are tested in the case of liquid metal environments. It is shown that equations established for the rotating cylinder and the pipe flow geometry can be used effectively in liquid lead alloys (Pb-17Li) assuming the corrosion process is mass transfer controlled and the diffusion coefficient of dissolved species is known. The corrosion rate of martensitic steels in Pb-17Li is shown to be independent of the geometry when plotted as a function of the mass transfer coefficient. Predictions about the corrosion of steel in liquid Pb-Bi are performed but experiments are needed to validate the results obtained by modeling

Yolk-shell structured Sb@C anodes for high energy Na-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Song, Junhua; Yan, Pengfei; Luo, Langli; Qi, Xingguo; Rong, Xiaohui; Zheng, Jianming; Xiao, Biwei; Feng, Shuo; Wang, Chongmin; Hu, Yong-Sheng; Lin, Yuehe; Sprenkle, Vincent L.; Li, Xiaolin

2017-10-01

Despite great advances in sodium-ion battery developments, the search for high energy and stable anode materials remains a challenge. Alloy or conversion-typed anode materials are attractive candidates of high specific capacity and low voltage potential, yet their applications are hampered by the large volume expansion and hence poor electrochemical reversibility and fast capacity fade. Here, we use antimony (Sb) as an example to demonstrate the use of yolk-shell structured anodes for high energy Na-ion batteries. The Sb@C yolk-shell structure prepared by controlled reduction and selective removal of Sb2O3 from carbon coated Sb2O3 nanoparticles can accommodate the Sb swelling upon sodiation and improve the structural/electrical integrity against pulverization. It delivers a high specific capacity of ~554 mAh•g-1, good rate capability (315 mhA•g-1 at 10C rate) and long cyclability (92% capacity retention over 200 cycles). Full-cells of O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 cathodes and Sb@C-hard carbon composite anodes demonstrate a high specific energy of ~130 Wh•kg-1 (based on the total mass of cathode and anode) in the voltage range of 2.0-4.0 V, ~1.5 times energy of full-cells with similar design using hard carbon anodes.

The electrochemical properties of melt-spun Al-Si-Cu alloys

International Nuclear Information System (INIS)

Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing; Sun Zhanbo; Song Xiaoping; Yang Sen; Wang Liqun

2011-01-01

Highlights: → Non-equilibrium Al 75-X Si 25 Cu X alloys exhibit high lithiation storages. → The lithiation mechanism is different from melt-spun Al-Si-Mn system. → The structural evolution is mitigated in the non-equilibrium alloys. → Volume variation is alleviated due to the co-existence of Al 2 Cu, α-Si and α-Al. - Abstract: Melt spinning was used to prepare Al 75-X Si 25 Cu X (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, α-Si and Al 2 Cu co-existed in the alloys. Nano-scaled α-Al grains, as the matrix, formed in the as-quenched ribbons. The Al 74 Si 25 Cu 1 and Al 71 Si 25 Cu 4 anodes exhibited initial discharge specific capacities of 1539 mAh g -1 , 1324 mAh g -1 and reversible capacities above 472 mAh g -1 , 508 mAh g -1 at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled α-Al, α-Si, and Al 2 Cu for the present alloys.

Surface characterization of a corroded bronze-leaded alloy in a salt spray cabinet

International Nuclear Information System (INIS)

Cura D'Ars de Figueiredo Junior, Joao; Freitas Cunha Lins, Vanessa de; Bellis, Vito Modesto de

2007-01-01

The corrosion products of a TM 23 bronze-leaded alloy (Cu 72%, Pb 15%, Zn 8% and Sn 5%) were obtained in a salt spray cabinet after exposition during 120 h and 1000 h. The products obtained were studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The major products of bronze-leaded corrosion were oxides and basic salts of Cu, CuCl 2 .3Cu(OH) 2 , and Pb, Pb(OH)Cl. The results can be attributed to a kinetic control of the corrosion reactions

Lag-Lead Compensator for Shape Memory Alloy in Gripping Manipulation

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Made Andik Setiawan

2010-12-01

Full Text Available Shape Memory Alloy (SMA is emerging actuator for micro and nano application, on the other hand the developing controller in such area needs much further considerations.This paper is to present the evaluation of close-loop controller responses of the TiNi SMA spring based gripper by introduced lag, lead and lag-lead compensator. A SMA spring has a diameter of 50 mm wire and 350 gram hanging mass. Driving the SMA actuator is used pulse width modulation (PWM signal and responses tested by varying frequencies and duty-cycles. The implemented frequencies in this study are 12, 25, 125, 250 and 1150 Hz. Lab-View and DAQ-Card is used as a controller, interfacer and data recorder of the system. The gripper fabricated consists of two fingers and the total angular displacement of the gripper is 300. The experimental result of the SMA open-loop response are presented and discussed. For advanced application, the close-loop controller is implemented and studied. The close-loop controllers employed are lag, lead and lag-lead compensator. The SMA response indicated that the rise-time and the steady-state error of the cloop-loop are shorter and lower than open-loop controller. The tuning, response and program of the lag, lead and lag-lead compensator are presented and discussed in this paper.

Medium-Power Lead-Alloy Fast Reactor Balance-of-Plant Options

International Nuclear Information System (INIS)

Dostal, Vaclav; Hejzlar, Pavel; Todreas, Neil E.; Buongiorno, Jacopo

2004-01-01

Proper selection of the power conversion cycle is a very important step in the design of a nuclear reactor. Due to the higher core outlet temperature (∼550 deg. C) compared to that of light water reactors (∼300 deg. C), a wide portfolio of power cycles is available for the lead alloy fast reactor (LFR). Comparison of the following cycles for the LFR was performed: superheated steam (direct and indirect), supercritical steam, helium Brayton, and supercritical CO 2 (S-CO 2 ) recompression. Heat transfer from primary to secondary coolant was first analyzed and then the steam generators or heat exchangers were designed. The direct generation of steam in the lead alloy coolant was also evaluated. The resulting temperatures of the secondary fluids are in the range of 530-545 deg. C, dictated by the fixed space available for the heat exchangers in the reactor vessel. For the direct steam generation situation, the temperature is 312 deg. C. Optimization of each power cycle was carried out, yielding net plant efficiency of around 40% for the superheated steam cycle while the supercritical steam and S-CO 2 cycles achieved net plant efficiency of 41%. The cycles were then compared based on their net plant efficiency and potential for low capital cost. The superheated steam cycle is a very good candidate cycle given its reasonably high net plant efficiency and ease of implementation based on the extensive knowledge and operating experience with this cycle. Although the supercritical steam cycle net plant efficiency is slightly better than that of the superheated steam cycle, its high complexity and high pressure result in higher capital cost, negatively affecting plant economics. The helium Brayton cycle achieves low net plant efficiency due to the low lead alloy core outlet temperature, and therefore, even though it is a simpler cycle than the steam cycles, its performance is mediocre in this application. The prime candidate, however, appears to be the S-CO 2

Structure of anodized Al–Zr sputter deposited coatings and effect on optical appearance

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara

2014-01-01

The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al–Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result...... in the evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550°C for 4 h in order...... parameters and their influence on the interaction of light is investigated and the results in general are applicable to discolouration of anodized layer on recycled aluminium alloys due to intermetallics. © 2014 Elsevier B.V. All rights reserved....

Effect of Aluminum Coating on the Surface Properties of Ti-(~49 at. pct) Ni Alloy

Science.gov (United States)

Sinha, Arijit; Khan, Gobinda Gopal; Mondal, Bholanath; Majumdar, Jyotsna Dutta; Chattopadhyay, Partha Protim

2015-08-01

Stable porous layer of mixed Al2O3 and TiO2 has been formed on the Ti-(~49 at. pct) Ni alloy surface with an aim to suppress leaching of Ni from the alloy surface in contact with bio-fluid and to enhance the process of osseointegration. Aluminum coating on the Ni-Ti alloy surface prior to the anodization treatment has resulted in enhancement of depth and uniformity of pores. Thermal oxidation of the anodized aluminum-coated Ni-Ti samples has exhibited the formation of Al2O3 and TiO2 phases with dense porous structure. The nanoindentation and nanoscratch measurements have indicated a remarkable improvement in the hardness, wear resistance, and adhesiveness of the porous aluminum-coated Ni-Ti sample after thermal oxidation.

The corrosion and passivity of sputtered Mg–Ti alloys

International Nuclear Information System (INIS)

Song, Guang-Ling; Unocic, Kinga A.; Meyer, Harry; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

2016-01-01

Highlights: • A supersaturated single phase Mg–Ti alloy can be obtained by magnetron sputtering. • The anodic dissolution of Mg–Ti alloy is inhibited by Ti addition. • The alloy becomes passive when Ti content is high and the alloy has become Ti based. • The formation of a continuous thin passive film is responsible for the passivation of the alloy. - Abstract: This study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. The surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy.

Nonequilibrium self-organization in alloys under irradiation leading to the formation of nano composites

CERN Document Server

Enrique, R A; Averback, R S; Bellon, P

2003-01-01

Alloys under irradiation are continuously driven away from equilibrium: Every time an external particle interacts with the atoms in the solid, a perturbation very localized in space and time is produced. Under this external forcing, phase and microstructural evolution depends ultimately on the dynamical interaction between the external perturbation and the internal recovery kinetics of the alloy. We consider the nonequilibrium steady state of an immiscible binary alloy subject to mixing by heavy-ion irradiation. It has been found that the range of the forced atomic relocations taking place during collision cascades plays an important role on the final microstructure: when this range is large enough, it can lead to the spontaneous formation of compositional patterns at the nanometer scale. These results were rationalized in the framework of a continuum model solved by deriving a nonequilibrium thermodynamic potential. Here we derive the nonequilibrium structure factor by including the role of fluctuations. In ...

Experimental Studies of the Effects of Anode Composition and Process Parameters on Anode Slime Adhesion and Cathode Copper Purity by Performing Copper Electrorefining in a Pilot-Scale Cell

Science.gov (United States)

Zeng, Weizhi; Wang, Shijie; Free, Michael L.

2016-10-01

Copper electrorefining tests were conducted in a pilot-scale cell under commercial tankhouse environment to study the effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity. Three different types of anodes (high, mid, and low impurity levels) were used in the tests and were analyzed under SEM/EDS. The harvested copper cathodes were weighed and analyzed for impurities concentrations using DC Arc. The adhered slimes and released slimes were collected, weighed, and analyzed for compositions using ICP. It was shown that the lead-to-arsenic ratio in the anodes affects the sintering and coalescence of slime particles. High current density condition can improve anode slime adhesion and cathode purity by intensifying slime particles' coalescence and dissolving part of the particles. Wide cathode blanks can raise the anodic current densities significantly and result in massive release of large slime particle aggregates, which are not likely to contaminate the cathode copper. Low flow rate can cause anode passivation and increase local temperatures in front of the anode, which leads to very intense sintering and coalescence of slime particles. The results and analyses of the tests present potential solutions for industrial copper electrorefining process.

Microstructure and wear behaviour of aluminium alloys containing embedded nanoscaled lead dispersoids

International Nuclear Information System (INIS)

Bhattacharya, Victoria; Chattopadhyay, K.

2004-01-01

We report the early stage friction and wear characteristics of aluminium containing nanosized lead dispersions. The nanocomposite was produced by rapid solidification. The experimental results indicate a significant decrease in friction and wear rate in comparison to its coarse grained counterparts. We show that the observed results suggest an adhesive type of wear mechanism. However, increase in hardness due to refinement of the aluminium grains cannot quantitatively rationalize the results. We explore and discuss the role of nanoscaled lead particles and the mass transport between the sample and counterface via mechanical alloying, in the formation of tribolayers affecting the tribological properties. The plane view and cross-sectional transmission electron microscopy reveals significant elongation as well as coarsening of the lead particles during the process of wear. We attempt to understand these results in the framework of moving dislocations and their assistance to the mass transport among the dispersed lead particles

Medium-Power Lead-Alloy Reactors: Missions for This Reactor Technology

International Nuclear Information System (INIS)

Todreas, Neil E.; MacDonald, Philip E.; Hejzlar, Pavel; Buongiorno, Jacopo; Loewen, Eric P.

2004-01-01

A multiyear project at the Idaho National Engineering and Environmental Laboratory and the Massachusetts Institute of Technology investigated the potential of medium-power lead-alloy-cooled technology to perform two missions: (1) the production of low-cost electricity and (2) the burning of actinides from light water reactor (LWR) spent fuel. The goal of achieving a high power level to enhance economic performance simultaneously with adoption of passive decay heat removal and modularity capabilities resulted in designs in the range of 600-800 MW(thermal), which we classify as a medium power level compared to the lower [∼100 MW(thermal)] and higher [2800 MW(thermal)] power ratings of other lead-alloy-cooled designs. The plant design that was developed shows promise of achieving all the Generation-IV goals for future nuclear energy systems: sustainable energy generation, low overnight capital cost, a very low likelihood and degree of core damage during any conceivable accident, and a proliferation-resistant fuel cycle. The reactor and fuel cycle designs that evolved to achieve these missions and goals resulted from study of the following key trade-offs: waste reduction versus reactor safety, waste reduction versus cost, and cost versus proliferation resistance. Secondary trade-offs that were also considered were monolithic versus modular design, active versus passive safety systems, forced versus natural circulation, alternative power conversion cycles, and lead versus lead-bismuth coolant.These studies led to a selection of a common modular design with forced convection cooling, passive decay heat removal, and a supercritical CO 2 power cycle for all our reactor concepts. However, the concepts adopt different core designs to optimize the achievement of the two missions. For the low-cost electricity production mission, a design approach based on fueling with low enriched uranium operating without costly reprocessing in a once-through cycle was pursued to achieve a

Pseudo-stir bar hollow fiber solid/liquid phase microextraction combined with anodic stripping voltammetry for determination of lead and cadmium in water samples

Directory of Open Access Journals (Sweden)

Zarrin Es’haghi

2014-11-01

Full Text Available A new procedure is presented for the determination of low concentrations of lead and cadmium in water samples. Ligand assisted pseudo-stir bar hollow fiber solid/liquid phase microextraction using sol–gel sorbent reinforced with carbon nanotubes was combined with differential pulse anodic stripping voltammetry for simultaneous determination of cadmium and lead in tap water, and Darongar river water samples. In the present work, differential pulse anodic stripping voltammetry (DPASV using a hanging mercury drop electrode (HMDE was used in order to determine the ultra trace level of lead and cadmium ions in real samples. This method is based on accumulation of lead and cadmium ions on the electrode using different ligands; Quinolin-8-ol, 5,7-diiodo quinoline-8-ol, 4,5-diphenyl-1H-imidazole-2(3H-one and 2-{[2-(2-Hydroxy-ethylamino-ethylamino]-methyl}-phenol as the complexing agent. The optimized conditions were obtained. The relationship between the peak current versus concentration was linear over the range of 0.05–500 ng mL−1 for Cd (II and Pb (II. The limits of detection for lead and cadmium were 0.015 ng mL−1 and 0.012 ng mL−1, respectively. Under the optimized conditions, the pre-concentration factors are 2440 and 3710 for Cd (II and Pb (II in 5 mL of water sample, respectively.

Synthesis and electrochemical performances of amorphous carbon-coated Sn-Sb particles as anode material for lithium-ion batteries

International Nuclear Information System (INIS)

Wang Zhong; Tian Wenhuai; Liu Xiaohe; Yang Rong; Li Xingguo

2007-01-01

The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use. - Graphical abstract: The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles

Three-Dimensional Porous Si and SiO2 with In Situ Decorated Carbon Nanotubes As Anode Materials for Li-ion Batteries.

Science.gov (United States)

Su, Junming; Zhao, Jiayue; Li, Liangyu; Zhang, Congcong; Chen, Chunguang; Huang, Tao; Yu, Aishui