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Publications (10 of 36) Show all publications
Leisner, P. & Zanella, C. (2018). Application of Assaf panel for evaluating throwing power of pulse reverse electroplating on complex geometries. Transactions of the Institute of Metal Finishing, 96(5), 258-264
Open this publication in new window or tab >>Application of Assaf panel for evaluating throwing power of pulse reverse electroplating on complex geometries
2018 (English)In: Transactions of the Institute of Metal Finishing, ISSN 0020-2967, E-ISSN 1745-9192, Vol. 96, no 5, p. 258-264Article in journal (Refereed) Published
Abstract [en]

The Assaf panel arrangement was used for evaluating pulse reverse plating processes and optimisation of the throwing power (TP) of complex three-dimensional (3D) geometries. Two different electroplating processes were investigated: an acid copper bath and a cyanide silver bath without additives. It has not been possible to establish a direct correlation factor for TP obtained with the Assaf panel and the 3D objects included in the trials. Nevertheless, the Assaf panel was found to be a useful tool for preliminary process parameter optimisation. The copper bath needs agitation to deposit coatings of good quality, whereas the silver bath obtains the best throwing power without agitation. The latter is probably due to inhibition by adsorbed cyanide.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Throwing power; pulse reverse; silver; copper
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hj:diva-41719 (URN)10.1080/00202967.2018.1507331 (DOI)000444095300006 ()2-s2.0-85053235016 (Scopus ID)
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-04Bibliographically approved
Ahmadkhaniha, D., Huang, Y., Jaskari, M., Järvenpää, A., Sohi, M. H., Zanella, C., . . . Langdon, T. G. (2018). Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg. Journal of Materials Science, 53(24), 16585-16597
Open this publication in new window or tab >>Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg
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2018 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 53, no 24, p. 16585-16597Article in journal (Refereed) Published
Abstract [en]

High-pressure torsion (HPT) processing was applied to cast pure magnesium, and the effects of the deformation on the microstructure, hardness, tensile properties and corrosion resistance were evaluated. The microstructures of the processed samples were examined by electron backscatter diffraction, and the mechanical properties were determined by Vickers hardness and tensile testing. The corrosion resistance was studied using electrochemical impedance spectroscopy in a 3.5% NaCl solution. The results show that HPT processing effectively refines the grain size of Mg from millimeters in the cast structure to a few micrometers after processing and also creates a basal texture on the surface. It was found that one or five turns of HPT produced no significant difference in the grain size of the processed Mg and the hardness was a maximum after one turn due to recovery in some grains. Measurements showed that the yield strength of the cast Mg increased by about seven times whereas the corrosion resistance was not significantly affected by the HPT processing. 

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Corrosion resistance, Electrochemical impedance spectroscopy, Grain size and shape, High pressure effects, Mechanical properties, Microstructure, Sodium chloride, Tensile testing, Torsional stress, Vickers hardness, Vickers hardness testing, 3.5% nacl solutions, Basal textures, Cast structures, Effect of high pressure, Electron back scatter diffraction, Grain size, High pressure torsions, Pure magnesium, Electrochemical corrosion
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41252 (URN)10.1007/s10853-018-2779-1 (DOI)000445912300033 ()30393393 (PubMedID)2-s2.0-85051418547 (Scopus ID)MaterialIS (Local ID)MaterialIS (Archive number)MaterialIS (OAI)
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-12-07Bibliographically approved
Maryam, E., Payandeh, M., Deflorian, F., Jarfors, A. E. .. & Zanella, C. (2018). Effect of Segregation and Surface Condition on Corrosion of Rheo-HPDC Al–Si Alloys. Metals, 8(4), Article ID 209.
Open this publication in new window or tab >>Effect of Segregation and Surface Condition on Corrosion of Rheo-HPDC Al–Si Alloys
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2018 (English)In: Metals, Vol. 8, no 4, article id 209Article in journal (Refereed) Published
Abstract [en]

Corrosion properties of two Al–Si alloys processed by Rheo-high pressure die cast (HPDC) method were examined using polarization and electrochemical impedance spectroscopy (EIS) techniques on as-cast and ground surfaces. The effects of the silicon content, transverse and longitudinal macrosegregation on the corrosion resistance of the alloys were determined. Microstructural studies revealed that samples from different positions contain different fractions of solid and liquid parts of the initial slurry. Electrochemical behavior of as-cast, ground surface, and bulk material was shown to be different due to the presence of a segregated skin layer and surface quality.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
Al–Si alloys, rheocasting, HPDC, electrochemical evaluation
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:hj:diva-39065 (URN)10.3390/met8040209 (DOI)000434882800012 ()2-s2.0-85044734700 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Funder
Knowledge Foundation, 20100280
Available from: 2018-03-28 Created: 2018-03-28 Last updated: 2018-09-19Bibliographically approved
Ahmadkhaniha, D., Eriksson, F., Leisner, P. & Zanella, C. (2018). Effect of SiC particle size and heat-treatment on microhardness and corrosion resistance of NiP electrodeposited coatings. Journal of Alloys and Compounds, 769, 1080-1087
Open this publication in new window or tab >>Effect of SiC particle size and heat-treatment on microhardness and corrosion resistance of NiP electrodeposited coatings
2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 769, p. 1080-1087Article in journal (Refereed) Published
Abstract [en]

Electrodeposition of NiP composite coatings with nano and sub-micron sized SiC has been carried out to investigate the possibility of replacing hard chromium coatings. The composition and structure of the coatings were evaluated by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. Microhardness was measured by Vickers indentation and polarization measurements were carried out to study the corrosion behavior of the coatings. The results showed that submicron particles can be codeposited with a higher content as compared to nano sized ones. However, even if a smaller amount of the nano-sized SiC particles are incorporated in the coating, the contribution to an increasing microhardness was comparable with the submicron sized particles, which can be related to the higher density of codeposited particles. SiC particles did not change the anodic polarization behavior of NiP coatings in a 3.5% NaCl solution. Finally, the effect of heat-treatment on the coatings properties at 400 °C for 1 h was studied to investigate the contribution of particles and heat-treatment on hardness and corrosion properties. It was found that the heat-treatment doubled the microhardness and changed the anodic polarization behavior of the coatings from passive to active with respect to the as-plated conditions.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Electrodeposition, Heat-treatment, Microhardness, NiP, Polarization, SiC
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hj:diva-41502 (URN)10.1016/j.jallcom.2018.08.013 (DOI)000449481200126 ()2-s2.0-85051683091 (Scopus ID)
Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-11-22Bibliographically approved
Eslami, M., Deflorian, F., Fedel, M. & Zanella, C. (2017). Ce-based conversion coatings on Rheo-HPDC low Si content aluminium alloy. In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017: . Paper presented at Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017; Prague ; Czech Republic; 3 - 7 September 2017 (pp. 777-794). Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers
Open this publication in new window or tab >>Ce-based conversion coatings on Rheo-HPDC low Si content aluminium alloy
2017 (English)In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017, Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers , 2017, p. 777-794Conference paper, Published paper (Refereed)
Abstract [en]

Cerium-based conversion coatings have been considered as an effective alternative to hazardous and carcinogenic chromate-based coatings used in the treatment of metal surfaces such as aluminium alloys. However, there is still considerable debate over the mechanism by which these coatings are formed on different alloys and microstructure features. In the current work, Ce-based conversion coatings were deposited on Rheo-HPDC Al-Si alloys by immersion in water-based solutions of cerium nitrate. Effect of deposition parameters including immersion time and Ce(NO3)3.6H2O concentration on the corrosion resistance and the morphology of coatings was investigated. In addition in some experiments, NaCl was added to the cerium based solution in order to accelerate the deposition of the conversion coating and also to understand the coating formation mechanism. Electrochemical behaviour of the treated aluminium alloys was evaluated in the solution of 0.05 mol/L NaCl using polarization test and electrochemical impedance spectroscopy (EIS) measurements. The morphology and distribution of the cerium-based conversion coatings on the aluminium alloys were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS) and X-ray photoelectron spectroscopy (XPS). Conversion treated substrates in all solutions were shown to possess improved corrosion resistance in comparison to the untreated samples. Immersion time and Ce(NO3)3.6H2O concentration slightly affect the deposition and the passivation capability of the cerium hydroxide/oxide layers. SEM images revealed that the deposition of cerium is more favoured in some cathodic areas including iron-based intermetallics and/or eutectic silicon phase. This phenomenon helps to block the active interfaces between these cathodic sites and the aluminium matrix, which is prone to localized corrosion in chloride ion containing environments. 

Place, publisher, year, edition, pages
Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers, 2017
Keywords
Aluminum alloys, Aluminum coatings, Aluminum corrosion, Cerium compounds, Chromate coatings, Chromates, Corrosion resistance, Deposition, Electrochemical corrosion, Electrochemical impedance spectroscopy, Energy dispersive spectroscopy, Localized corrosion, Scanning electron microscopy, Silicon alloys, Sodium chloride, Solution mining, X ray photoelectron spectroscopy, Cerium-based conversion coatings, Conversion coatings, Deposition Parameters, Electrochemical behaviour, Electrochemical impedance spectroscopy measurements, Energy dispersive x-ray spectroscopy, Immersion in waters, Polarization tests, Corrosion resistant coatings
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:hj:diva-41533 (URN)2-s2.0-85052327991 (Scopus ID)
Conference
Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017; Prague ; Czech Republic; 3 - 7 September 2017
Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2018-09-21Bibliographically approved
Leisner, P., Zanella, C., Belov, I., Edström, C., Sandulache, G. & Hansal, W. E. (2017). Control of silver throwing power by pulse reverse electroplating. Transactions of the Institute of Metal Finishing, 95(1), 25-30
Open this publication in new window or tab >>Control of silver throwing power by pulse reverse electroplating
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2017 (English)In: Transactions of the Institute of Metal Finishing, ISSN 0020-2967, E-ISSN 1745-9192, Vol. 95, no 1, p. 25-30Article in journal (Refereed) Published
Abstract [en]

The influence of electroplating parameters on throwing power (TP) is studied in additive-free silver cyanide solutions under direct current and pulse reverse electroplating conditions. It is found that the best TP is obtained when no agitation of the electrolyte is applied. The most important parameters for controlling the TP are the cathodic current density, the anodic to cathodic charge ratio, and the ratio between the anodic and cathodic current densities. Guidelines for process optimisation are given.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
Agitation, Pulse reverse electrodeposition, Silver, Throwing power, Electrolytes, Electroplating, Optimization, Cathodic charge, Cathodic current density, Direct current, Process optimisation, Pulse-reverse electrodeposition, Silver cyanide, Electroplating solutions
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-35017 (URN)10.1080/00202967.2017.1260895 (DOI)000394497000007 ()2-s2.0-85009956051 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Funder
VINNOVA, 2013-01883
Available from: 2017-02-06 Created: 2017-02-06 Last updated: 2018-09-19Bibliographically approved
Eslami, M., Fedel, M., Speranza, G., Deflorian, F. & Zanella, C. (2017). Deposition and Characterization of Cerium-Based Conversion Coating on HPDC Low Si Content Aluminum Alloy. Journal of the Electrochemical Society, 164(9), C581-C590
Open this publication in new window or tab >>Deposition and Characterization of Cerium-Based Conversion Coating on HPDC Low Si Content Aluminum Alloy
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2017 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 9, p. C581-C590Article in journal (Refereed) Published
Abstract [en]

Cerium-based conversion coatings were deposited on high pressure die cast (HPDC) Al-Si alloys using an immersion method. Hydrogen peroxide and sodium chloride were added to the conversion solution to accelerate the coating formation and to understand its formation mechanism. These studies showed that the deposition of cerium hydroxide/ oxide conversion layer starts from iron-rich intermetallic particles, which are located inside the eutectic region and then the coating growth continues to cover the entire alloy surface. This phenomenon passivates the active interfaces between iron-rich intermetallic particles and/ or the eutectic silicon phase and the aluminum matrix, which are prone to localized corrosion in chloride ions containing environments. Accordingly, values of the total impedance in EIS measurements significantly increased for the treated substrates. Morphologies of the conversion coatings and the oxidation state of cerium compounds were found to be dependent on the composition of the solution and the presence of chloride ions and/ or hydrogen peroxide. Aluminum alloy with higher silicon content showed a more active surface during immersion in the conversion solution. This makes it more difficult to be treated using aggressive conversion solutions. 

Place, publisher, year, edition, pages
Electrochemical Society, 2017
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38179 (URN)10.1149/2.1511709jes (DOI)000413256400034 ()2-s2.0-85030855929 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2018-10-16Bibliographically approved
Ahmadkhaniha, D., Huang, Y., Jaskari, M., Järvenpää, A., Heydarzadeh Sohi, M., Zanella, C., . . . Langdon, T. (2017). Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg. In: : . Paper presented at 6th International Biennial Conference on Ultrafine Grained and Nano-structured Materials (UFGNSM 2017), 12th-13th November, 2017, Kish Island, Iran.
Open this publication in new window or tab >>Effect of high-pressure torsion on microstructure, mechanical properties and corrosion resistance of cast pure Mg
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2017 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

High-pressure torsion (HPT) processing was applied to cast pure Mg pieces and its effects on microstructure, hardness and tensile properties as well as corrosion resistance were evaluated. The microstructure of the processed samples was examined by electron backscatter diffraction (EBSD) and the mechanical properties were determined by microhardness and tensile tests. Corrosion resistance of the samples was studied via electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results showed that HPT refined the grain size of Mg very effectively from millimeters in the cast structure to a few micrometers homogeneously through the thickness and created a basal texture on the surface. One or five turns of HPT produced no significant difference in the grain size of the processed Mg but the hardness was a maximum after one turn. The yield strength of the cast Mg was increased by seven times whereas the corrosion resistance was not affected by the HPT processing.

Keywords
Corrosion resistance, Grain size, Hardness, High-pressure torsion, Mg, Tensile strength, Texture
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:hj:diva-38704 (URN)
Conference
6th International Biennial Conference on Ultrafine Grained and Nano-structured Materials (UFGNSM 2017), 12th-13th November, 2017, Kish Island, Iran
Available from: 2018-02-02 Created: 2018-02-02 Last updated: 2018-09-19Bibliographically approved
Zhu, B., Fedel, M., Andersson, N.-E., Leisner, P., Deflorian, F. & Zanella, C. (2017). Effect of Si content and morphology on corrosion resistance of anodized cast Al-Si alloys. Journal of the Electrochemical Society, 164(7), C435-C441
Open this publication in new window or tab >>Effect of Si content and morphology on corrosion resistance of anodized cast Al-Si alloys
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2017 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 7, p. C435-C441Article in journal (Refereed) Published
Abstract [en]

This paper investigates the influence of Si content and Si particle morphology on the corrosion protection of anodized oxide layers on Al-Si alloys. Two Al alloys with low Si concentrations (2.43 wt-% and 5.45 wt-%, respectively) were studied and compared with 6082-T6 via electrochemical impedance spectroscopy (EIS) in 3 wt-% NaCl solution prior to oxide layer sealing. Si particles were also modified by the addition of Sr to study the influence of Si particle morphology on the corrosion protection of the oxide layer. The EIS showed that the corrosion protection provided by the oxide layer on Al-Si alloys is significantly affected by the presence of Si particles. Si particles make the oxide layer locally thinner and more defective in the eutectic region, thereby increasing the ease of substrate corrosion attack. However, the addition of Sr can improve the corrosion protection of anodized Al-Si alloys significantly. Furthermore, it was proved that higher Si level influences negatively the anodized oxide corrosion protection due to the higher amount of cracks and defects, but Sr modification is efficient in preventing this negative effect.

Place, publisher, year, edition, pages
The Electrochemical Society, 2017
Keywords
cast Al-Si alloys, anodising, EIS, 3D tomography
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-35095 (URN)10.1149/2.1631707jes (DOI)000404397300077 ()2-s2.0-85020855659 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Note

Part of licentiate thesis in its submitted form.

Available from: 2017-02-17 Created: 2017-02-17 Last updated: 2017-09-13Bibliographically approved
Ahmadkhaniha, D., Pinate, S., Leisner, P. & Zanella, C. (2017). Electrodeposition of Ni high P composite coatings containing nano and submicro ceramic particles. In: : . Paper presented at EUROCORR 2017, | 20th International Corrosion Congress & Process Safety CongressAnnual Congress of the European Federation of Corrosion 2017, September 3–7, 2017, Czech Republic (pp. 721-729). European Federation of Corrosion
Open this publication in new window or tab >>Electrodeposition of Ni high P composite coatings containing nano and submicro ceramic particles
2017 (English)Conference paper, Published paper (Other academic)
Abstract [en]

In this study, electrodeposition of Ni-P composite coatings has been carried out to investigate the possibility of replacing hard chromium coatings. Therefore, electrodeposition of Ni-P based composite coating with different SiC particle size (50 nm, 100 nm and 500 nm) or B4C (500 nm) was performed. The coating’s composition was evaluated by energy dispersive spectroscopy (EDS), microhardness of the coatings was measured by Vickers indentor and polarization measurements were carried out to study the corrosion behavior of the coatings. The results showed that B4C particles can codeposit in higher percent respect to SiC ones. Ceramic particles increased microhardness of Ni-P coatings to 700HV0.01. The polarization behavior of all the coatings in 3.5% NaCl was similar in as plated state proving that particles did not hindered the passive behaviour. Finally, the effect of heat-treatment (at 400 ºC for 1 hour) on the coating’s properties was studied to compare the contribution of particles and heat-treatment on mechanical and corrosion properties of the coatings. Heat-treatment increased the coating’s microhardness and changed the anodic polarization behavior of the coatings respect to the as plated conditions.

Place, publisher, year, edition, pages
European Federation of Corrosion, 2017
Keywords
Ni-P electrodeposition, SiC, B4C, Microhardness, Polarization
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hj:diva-38729 (URN)2-s2.0-85052306013 (Scopus ID)
Conference
EUROCORR 2017, | 20th International Corrosion Congress & Process Safety CongressAnnual Congress of the European Federation of Corrosion 2017, September 3–7, 2017, Czech Republic
Available from: 2018-02-02 Created: 2018-02-02 Last updated: 2018-09-21Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2924-137X

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