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Zhu, B., Seifeddine, S., Jarfors, A. E. .., Leisner, P. & Zanella, C. (2019). A study of anodising behaviour of Al-Si components produced by rheocasting. Paper presented at 15th International conference on semi-solid processing of alloys and composites, October 22nd to 24th, 2018, Shenzhen, China. Solid State Phenomena, 285, 39-44
Open this publication in new window or tab >>A study of anodising behaviour of Al-Si components produced by rheocasting
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2019 (English)In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 285, p. 39-44Article in journal (Refereed) Published
Abstract [en]

This paper aims to investigate the anodising behaviour of Al-Si components produced by rheocasting, to understand the effect of the surface liquid segregation (SLS) on the anodising response. The material investigated was EN AC 42000 Al-alloy with an addition of 150 ppm Sr. The component was rheocast and conventionally liquid cast for benchmarking. The RheoMetalTM process was used to prepare slurry and subsequently cast using a vertical pressure die casting machine. Prior to anodising, mechanical grinding was used as pre-treatment method for selected samples as comparison with components in the as-cast state. Anodising was performed on the components using a constant controlled voltage at 25 V, in 1 M H2SO4, at room temperature. The duration of anodising was varied from 30 mins to 120 mins to examine the relationship between oxide layer thickness and the anodising time. The oxide layer was investigated and characterised. The results demonstrated that the presence of the SLS layer, which was enriched with alloying elements, had a significant influence on the anodising behaviour of the cast component. The oxide layer thickness of the components produced by rheocasting and fully liquid casting was measured and compared. The relations between the oxide layer thickness and anodising time, as well as the casting methods are presented and discussed in this paper.

Place, publisher, year, edition, pages
Trans Tech Publications, 2019
Keywords
Anodising, Oxide Layer, Rheocasting
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-42630 (URN)10.4028/www.scientific.net/SSP.285.39 (DOI)2-s2.0-85059944290 (Scopus ID)
Conference
15th International conference on semi-solid processing of alloys and composites, October 22nd to 24th, 2018, Shenzhen, China
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-05-09Bibliographically approved
Gracco, A., Dandrea, M., Deflorian, F., Zanella, C., De Stefani, A., Bruno, G. & Stellini, E. (2019). Application of a molybdenum and tungsten disulfide coating to improve tribological properties of orthodontic archwires. Nanomaterials, 9(5), Article ID 753.
Open this publication in new window or tab >>Application of a molybdenum and tungsten disulfide coating to improve tribological properties of orthodontic archwires
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2019 (English)In: Nanomaterials, ISSN 2079-4991, Vol. 9, no 5, article id 753Article in journal (Refereed) Published
Abstract [en]

Coatings incorporating nanoparticles of molybdenum and tungsten disulfide (MoS2 and WS2)—known for their lubricating properties—are applied to orthodontic stainless steel wires to verify if there is an improvement in terms of tribological properties during the sliding of the wire along the bracket. To simulate in vitro sliding of the wire along the bracket and evaluate friction 0.019 × 0.025 inches orthodontic stainless steel (SS) wires were subjected to the application, by electrodeposition, of Ni, Ni + MoS2, and Ni + WS2 . The samples produced were analyzed with scanning electron microscopy and assessment of resistance to bending. Thirty-two test conditions have been analyzed, arising from the combination of four types of coatings (SS bare wires and strings with three types of coating), two types of self-ligating bracket (Damon Q, Ormco and In-Ovation R, GAC International), two bracket-wire angles (0◦ and 5◦), two environments (dry and wet). Analyses carried out on the samples show acceptable coatings incorporating MoS2 and WS2 and a resistance of coatings after a minimum bending. In “dry conditions” a statistically significant decrease in friction occurs for wires coated with MoS2 and WS2 if associated with the In-Ovation bracket. In “wet conditions” this decrease is observed only in isolated test conditions. Analysis of the wires after sliding tests show little wear of the applied coatings. Nanoparticles are acceptable and similar in their behavior. Improvements in terms of friction are obtained pairing coatings incorporating MoS2 and WS2 with the In-Ovation bracket in dry conditions. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Friction, Inorganic nanoparticles, Stainless steel archwires
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-44854 (URN)10.3390/nano9050753 (DOI)000479007900095 ()31100885 (PubMedID)2-s2.0-85067098393 (Scopus ID)GOA JTH 2019;JTHMaterialIS (Local ID)GOA JTH 2019;JTHMaterialIS (Archive number)GOA JTH 2019;JTHMaterialIS (OAI)
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-08-15Bibliographically approved
Eslami, M., Speranza, G., Fedel, M., Andersson, N.-E., Deflorian, F., Omanovic, S. & Zanella, C. (2019). Electropolymerization and possible corrosion protection effect of polypyrrole coatings on AA1050 (UNS A91050) in NaCl solutions. Corrosion, 75(7), 745-755
Open this publication in new window or tab >>Electropolymerization and possible corrosion protection effect of polypyrrole coatings on AA1050 (UNS A91050) in NaCl solutions
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2019 (English)In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 75, no 7, p. 745-755Article in journal (Refereed) Published
Abstract [en]

Effect of solution chemistry on the electropolymerization and the electrochemical properties of polypyrrole coatings on aluminum is studied by means of electrochemical techniques, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy. It is shown that the protection effect of the coating in long-term exposures and when exposed to more concentrated NaCl solutions depends on the chemistry of electropolymerization electrolyte. The results show that nitrate anions passivate the aluminum substrate during the electropolymerization process. The resulting coating is less prone to blistering in a NaCl solution and probably due to its higher electrochemical activity presents a higher anodic protection effect. The galvanic interaction of polypyrrole coating with aluminum in a NaCl solution is directly observed using focused ion beam-assisted SEM.

Place, publisher, year, edition, pages
National Association of Corrosion Engineers International, 2019
Keywords
Aluminum, Conductive polymer, Corrosion protection, Galvanic interaction, Passivation, Polypyrrole, Aluminum coatings, Aluminum corrosion, Anodic protection, Electrolytes, Electropolymerization, Galvanic corrosion, Ion beams, Polypyrroles, Scanning electron microscopy, Sodium chloride, X ray photoelectron spectroscopy, Aluminum substrate, Electrochemical activities, Electrochemical techniques, Long term exposure, Polypyrrole coatings, Solution chemistry, Corrosion resistant coatings
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-45537 (URN)10.5006/3124 (DOI)000474438600005 ()2-s2.0-85069675948 (Scopus ID)HOA JTH 2019;JTHMaterialIS (Local ID)HOA JTH 2019;JTHMaterialIS (Archive number)HOA JTH 2019;JTHMaterialIS (OAI)
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-13Bibliographically approved
Zhu, B. & Zanella, C. (2019). Hardness and corrosion behaviour of anodised Al-Si produced by rheocasting. Materials & design, 173, Article ID 107764.
Open this publication in new window or tab >>Hardness and corrosion behaviour of anodised Al-Si produced by rheocasting
2019 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 173, article id 107764Article in journal (Refereed) Published
Abstract [en]

The anodised layer of Al-Si alloys produced by rheocasting was studied and compared to anodised traditional liquid casting in this paper. The anodising was performed in 1.0 M H2SO4 solution at room temperature on the as-cast substrates, and anodising voltage and time were optimised as process parameters. This study focuses on understanding the effect of the surface liquid segregation (SLS) layer by rheocasting on the hardness and corrosion protection of the oxide layer. The hardness depends on the anodising parameters and varies along the oxide thickness. The corrosion protection given by the oxide layer was evaluated by electrochemical impedance spectroscopy (EIS) in 3 wt-% NaCl solution, and the results revealed that the longitudinal macrosegregation influences the corrosion protection, with the near-to-vent region showing lower corrosion protection due to a higher eutectic fraction. A comparison between liquid and rheocast samples indicated that the presence of SLS layer by the transverse macrosegregation does not have a significant impact on the corrosion resistance of the oxide layer. Moreover, it was found that an increase of the oxide layer thickness by longer anodising time or higher applied voltage decreases both the hardness and corrosion resistance of the oxide layer.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Rheocasting, Anodising, Al oxide layer, Corrosion protection, Surface layer segregation
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-43433 (URN)10.1016/j.matdes.2019.107764 (DOI)000465533900004 ()2-s2.0-85063813035 (Scopus ID)GOA JTH 2019 (Local ID)GOA JTH 2019 (Archive number)GOA JTH 2019 (OAI)
Funder
Knowledge Foundation, 20100280; 20170066
Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-06-03Bibliographically approved
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: 2019-04-26Bibliographically 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)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2019-02-18Bibliographically 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: 2019-04-26Bibliographically 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
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2924-137X

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