M.C. Reboul, M.C. Delatte and J.M. Pieraerts
Electrochemical results:
M.C. Reboul, M.C. Delatte and J.M. Pieraerts
Hydral‐2 aluminium anodes are industrially produced by the vertical semi‐continuous casting process. The results of a comparative study, conducted on large offshore anodes, of the…
Abstract
Hydral‐2 aluminium anodes are industrially produced by the vertical semi‐continuous casting process. The results of a comparative study, conducted on large offshore anodes, of the chemical and electrochemical homogenieties of fixed mould cast anodes and semi‐continuous cast anodes are detailed. The effects that alloy solidification after casting have upon grain structure and upon contact between insert and alloy are discussed. We report the preliminary results of field tests at Pechiney's test facility in Vlissengen, Holland. These trials were conducted in the North Sea with full‐size production anodes.
R. Souchet, F. Dalard, J.J. Rameau and M. Reboul
Introduction The competitive complexation of Sn(II) hydroxycomplexes and Sn(II) complexes with organic acids present in fruit juices, has been studied, in a first stage, by the…
Abstract
Introduction The competitive complexation of Sn(II) hydroxycomplexes and Sn(II) complexes with organic acids present in fruit juices, has been studied, in a first stage, by the experimental method of titration. This method allows to compare the complexing power of different organic acids. Applied to tartaric and acetic acids it shows that tartaric acid is more complexing towards tin than acetic acid.
J. Mathiyarasu, L.C. Nehru, P. Subramanian, N. Palaniswamy and N.S. Rengaswamy
Aluminium alloys are being employed very widely as galvanic anodes for cathodic protection. Aluminium‐zinc‐mercury and aluminium‐zinc‐indium are the popular alloys that are used…
Abstract
Aluminium alloys are being employed very widely as galvanic anodes for cathodic protection. Aluminium‐zinc‐mercury and aluminium‐zinc‐indium are the popular alloys that are used as anodes. In general, the alloying ingredients activate aluminium and maintain uniform dissolution. In the present investigation, the role of addition of gallium in the ternary alloy of aluminium‐zinc‐indium has been studied by making use of polarisation studies, capacity measurements and galvanic current measurements.
Mansoureh Parsa, Seyed Mohammad Ali Hosseini, Zahra Hassani and Effat Jamalizadeh
The purpose of this paper was to study the corrosion resistance of water-based sol-gel coatings containing titania nanoparticles doped with organic inhibitors for corrosion…
Abstract
Purpose
The purpose of this paper was to study the corrosion resistance of water-based sol-gel coatings containing titania nanoparticles doped with organic inhibitors for corrosion protection of AA2024 alloy.
Design/methodology/approach
The coatings were obtained using tetraethylorthosilicate, 3-glycidoxypropyltrimethoxysilane, titanium (IV) tetrapropoxide and poly(ethylene imine) polymer as cross-linking agents. As corrosions inhibitors, 2-mercaptobenzoxazole and salicylaldoxime were incorporated into the sol-gel for the improvement of the corrosion resistance. The corrosion protection performance of coatings was studied using the potentiodynamic scan and the electrochemical impedance spectroscopy (EIS) methods. Atomic force microscopy was used to investigate surface morphology of the coatings.
Findings
The results indicated that doping the sol-gel coatings with inhibitors leads to improvement of the corrosion protection. The comparison of doped coatings confirmed that corrosion protection performance of the sol-gel coatings doped with 2-mercaptobenzoxazole was better than for the sol-gel coatings doped with salicylaldoxime. Also the EIS results verified self-healing effects for the sol-gel coatings doped with 2-mercaptobenzoxazole.
Originality/value
This paper indicates 2-mercaptobenzoxazole and salicylaldoxime can be added as corrosion inhibitors to sol-gel coatings to improve their corrosion protective properties for AA2024 alloy.
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Mohamed Yacine Debili, Nacira Sassane and Noureddine Boukhris
This paper aims to investigate ternary Al-Co-Ti alloy system with various Co compositions. Structural characterization of AlxCoy-2Ti2 alloys were performed by means of light…
Abstract
Purpose
This paper aims to investigate ternary Al-Co-Ti alloy system with various Co compositions. Structural characterization of AlxCoy-2Ti2 alloys were performed by means of light microscopy, scanning electron microscopy, X-ray diffraction and electrochemical test. The effect of the addition of 5, 10, 15, 20, 25, 30 per cent Co and 2 per cent Ti on the structural evolution shows that both intermetallic compounds formation and structure morphology are related to corrosion resistance at the as-elaborated state as after subsequent heat treatment at 500°C during short time. According to the microstructural characterizations, the authors can notice that the substitution of Co has an important effect on the corrosion resistance and plays a role for the formation of the passive film.
Design/methodology/approach
The alloys in this study were obtained by a high-frequency induction fusion. Powders from Al, Co and Ti (99.999 per cent) in proportions defined according to the composition aimed of alloy have been used. The total mass of the sample to be elaborated lies between 8 and 10 g. Cold compaction was achieved for mixed powder intended for high fusion frequency (HF). For electrochemical tests, the sample was cut by a diamond wheel to obtain a square section of dimensions 1 cm2. Afterward, this sample was connected with a Cu electrical wire. The last stage is the envelope in an acrylic resin realized in a plastic mold. The used electrolyte is a salt environment of 3.5 per cent NaCl (35 g of NaCl by liter of distilled water at room temperature [25 ± 1°C], aerated and with moderated agitation V = 250 r.min−1). This mold is kept in ambient air for 10 min to allow the resin to solidify.
Findings
The aim of this work is to establish the influence of the addition of Co and Ti on structural change and related corrosion behavior improvement in Al. Particular attention is accorded to Al-15 per cent Co-2 per cent Ti alloy.
Originality/value
Among the studied alloys with different Co contents, a precise composition of 15 per cent Co and 2 per cent Ti appears to have interesting electrochemical characteristics regarding the corrosion potential, the corrosion current and particularly the corrosion rate, which is very small when compared to that of other alloys, as well in the as-solidified state than after heat treatment. This composition is located halfway between the stainless steel 304 and the Al-Fe and Al-Co-Ce alloys.
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Qi Gongtai and Qiu Yubin
The purpose of this paper is to consider the effect of heat treatment on alloying element distribution and the electrochemical properties of Al‐5Zn‐0.03In anodes.
Abstract
Purpose
The purpose of this paper is to consider the effect of heat treatment on alloying element distribution and the electrochemical properties of Al‐5Zn‐0.03In anodes.
Design/methodology/approach
The Al‐5Zn‐0.03In alloy anodes are treated at 510°C for 10 h, then cooled in water. Electron probe microanalysis of JXA‐8800 and EDAX quantitative energy dispersive X‐ray analysis is used to examine the microstructure of the anodes before and after heat treatment, and the electrochemical properties of the anodes are tested.
Findings
By heat treatment, the solubility of Zn in aluminum is increased while the solubilities of Fe and Si are changed only slightly. The quantity of the Al‐Zn intermetallic compounds is evidently decreased and the Al‐Fe‐Si intermetallic compound is preserved. Strip segregation along grain boundaries is changed to spherical particulates. The attack of aluminum anodes initiates and propagates in grain boundaries and interdendritic zones, which are enriched in In and Zn, so the current efficiency of the aluminum anodes is related to the degree of corrosion taking place at grain boundaries and the extent of exfoliation of grains. The greater the extent of Al‐Zn metallic compounds that are present at grain boundaries, the more sensitive to grain boundary corrosion is the alloy and the greater the degree of desquamation of grains, the lower is the current efficiency of the aluminum anode.
Originality/value
The results of this paper clarify the role of water‐quenching affect on the microstructure and electrochemical properties of Al‐Zn‐In anodes.
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Zhishuo Liu, Yao Dongxin, Zhao Kuan and Wang Chun Fang
There is a certain error in the satellite positioning of the vehicle. The error will cause the drift point of the positioning point, which makes the vehicle trajectory shift to…
Abstract
Purpose
There is a certain error in the satellite positioning of the vehicle. The error will cause the drift point of the positioning point, which makes the vehicle trajectory shift to the real road. This paper aims to solve this problem.
Design/methodology/approach
The key technology to solve the problem is map matching (MM). The low sampling frequency of the vehicle is far from the distance between adjacent points, which weakens the correlation between the points, making MM more difficult. In this paper, an MM algorithm based on priority rules is designed for vehicle trajectory characteristics at low sampling frequencies.
Findings
The experimental results show that the MM based on priority rule algorithm can effectively match the trajectory data of low sampling frequency with the actual road, and the matching accuracy is better than other similar algorithms, the processing speed reaches 73 per second.
Research limitations/implications
In the algorithm verification of this paper, although the algorithm design and experimental verification are considered considering the diversity of GPS data sampling frequency, the experimental data used are still a single source.
Originality/value
Based on the GPS trajectory data of the Ministry of Transport, the experimental results show that the accuracy of the priority-based weight-based algorithm is higher. The accuracy of this algorithm is over 98.1 per cent, which is better than other similar algorithms.
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Jeena Joseph, Sathyabhama A. and Surya Sridhar
With aims to increase the aerodynamic efficiency of aerodynamic surfaces, study on flow control over these surfaces has gained importance. With the addition of flow control…
Abstract
Purpose
With aims to increase the aerodynamic efficiency of aerodynamic surfaces, study on flow control over these surfaces has gained importance. With the addition of flow control devices such as synthetic jets and vortex generators, the flow characteristics can be modified over the surface and, at the same time, enhance the performance of the body. One such flow control device is the tubercle. Inspired by the humpback whale’s flippers, these leading-edge serrations have improved the aerodynamic efficiency and the lift characteristics of airfoils and wings. This paper aims to discusses in detail the flow physics associated with tubercles and their effect on swept wings.
Design/methodology/approach
This study involves a series of experimental and numerical analyses that have been performed on four different wing configurations, with four different sweep angles corresponding to 0°, 10°, 20° and 30° at a low Reynolds number corresponding to Rec=100,000.
Findings
Results indicate that the effect of tubercles diminishes with an increase in wing sweep. A significant performance enhancement was observed in the stall and post-stall regions. The addition of tubercles led to a smooth post-stall lift characteristic compared to the sudden loss in the lift with regular wings. Among the four different wings under observation, it was found that tubercles were most effective on the 0° configuration (no sweep), showing a 10.8% increment in maximum lift and a 38.5% increase in the average lift generated in the post-stall region. Tubercles were least effective on 30° configuration. Furthermore, with an increase in wing sweep, co-rotating vortices were distinctly observed rather than counter-rotating vortices.
Originality/value
While extensive numerical and experimental studies have been performed on straight wings with tubercles, studies on the tubercle effect on swept wings at low Reynolds number are minimal and mainly experimental in nature. This study uses numerical methods to explore the complex flow physics associated with tubercles and their implementation on swept wings. This study can be used as an introductory study to implement passive flow control devices in the low Reynolds number regime.
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Aleksandr Georgievich Tyurin, Dmitriy Andreevich Manannikov, Vladimir Pavlovich Parshukov, Anna Valeryevna Antonova and Pavel Anatolyevich Nikolaychuk
The purpose of this study is to develop a method of thermodynamic and kinetic evaluation of corrosion properties of alloys.
Abstract
Purpose
The purpose of this study is to develop a method of thermodynamic and kinetic evaluation of corrosion properties of alloys.
Design/methodology/approach
Method of estimation of corrosion-electrochemical behaviour of multicomponent alloys is proposed. The method takes into account both thermodynamic and kinetic data and is based on mutual construction of equilibrium and polarization potential – pH diagrams. The usage of the proposed method is illustrated in the example of the structural steel 20KT.
Findings
Passivation of steel 20KT is determined by formation of oxide film based on magnetite (Fe3O4); silicon, manganese and copper oxides as well as manganese sulphides can be locally included into the inner side of the passivation layer. An experimental potential – pH diagram of steel 20KT is constructed. Interpreting the results of polarization measurements revealed good agreement between equilibrium and polarization potential – pH diagrams.
Originality/value
It is shown in the example of structural steel 20KT that for interpretation of experimental potential – pH diagrams, one should compare them with corresponding equilibrium diagrams for multicomponent alloys rather than with Pourbaix diagrams for pure metals. The corrosion properties of steel 20KT are estimated using equilibrium and polarization potential – pH diagrams.