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Volume 66 (2022): Edizione 1 (January 2022)

Volume 65 (2021): Edizione 4 (December 2021)

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Volume 65 (2021): Edizione 2 (September 2021)

Volume 65 (2021): Edizione 1 (May 2021)

Volume 64 (2020): Edizione 4 (December 2020)

Volume 64 (2020): Edizione 3 (October 2020)

Volume 64 (2020): Edizione 2 (June 2020)

Volume 64 (2020): Edizione 1 (March 2020)

Volume 63 (2019): Edizione 4 (December 2019)

Volume 63 (2019): Edizione 3 (November 2019)

Volume 63 (2019): Edizione 2 (June 2019)

Volume 63 (2019): Edizione 1 (March 2019)

Volume 62 (2018): Edizione 4 (December 2018)

Volume 62 (2018): Edizione 3 (July 2018)

Volume 62 (2018): Edizione 2 (May 2018)

Volume 62 (2018): Edizione 1 (February 2018)

Volume 61 (2017): Edizione 5 (December 2017)

Volume 61 (2017): Edizione 4 (October 2017)

Volume 61 (2017): Edizione 3 (July 2017)

Volume 61 (2017): Edizione 2 (April 2017)

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Volume 60 (2016): Edizione 5 (December 2016)

Volume 60 (2016): Edizione 4 (December 2016)

Volume 60 (2016): Edizione 3 (September 2016)

Volume 60 (2016): Edizione 2 (June 2016)

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Volume 59 (2015): Edizione 4 (December 2015)

Volume 59 (2015): Edizione 3 (November 2015)

Volume 59 (2015): Edizione 2 (July 2015)

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Volume 58 (2014): Edizione 4 (December 2014)

Volume 58 (2014): Edizione 3 (November 2014)

Volume 58 (2014): Edizione 2 (June 2014)

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Volume 57 (2013): Edizione 4 (December 2013)

Volume 57 (2013): Edizione 3 (September 2013)

Volume 57 (2013): Edizione 2 (June 2013)

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Volume 56 (2012): Edizione 3 (October 2012)

Volume 56 (2012): Edizione 2 (July 2012)

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Dettagli della rivista
Formato
Rivista
eISSN
1804-1213
Pubblicato per la prima volta
03 Apr 2012
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

Volume 63 (2019): Edizione 4 (December 2019)

Dettagli della rivista
Formato
Rivista
eISSN
1804-1213
Pubblicato per la prima volta
03 Apr 2012
Periodo di pubblicazione
4 volte all'anno
Lingue
Inglese

Cerca

5 Articoli
Accesso libero

Corrosion resistance of the biodegradable ZE41 magnesium alloy treated by unconventional fluoride conversion coating

Pubblicato online: 24 Jan 2020
Pagine: 138 - 147

Astratto

Abstract

Magnesium based alloys are very promising material to be used mainly for biodegradable implants in medical applications. However, due to their very low corrosion resistance in the environment of in vivo is their use limited. Increase of the corrosion resistance of magnesium alloys in vivo can be achieved, for example, by a suitable choice of surface treatment while the biocompatibility must be ensured. Fluoride conversion coatings meet these requirements. Unconventional fluoride conversion coating was prepared on ZE41 magnesium alloy by dipping the magnesium alloy into the Na[BF4] salt melt at 450 °C for 0.5; 2 and 8 h. The morphology and thickness of the prepared fluoride conversion coatings were investigated as well as the corrosion resistance of the treated and untreated ZE41 magnesium alloy specimens. The corrosion resistance of the untreated and treated ZE41 magnesium alloy was investigated using electrochemical impedance spectroscopy in the environment of the simulated body fluids at 37 ± 2 °C. The obtained results showed a positive influence of the fluoride conversion coating on the corrosion resistance of the ZE41 magnesium alloy.

Accesso libero

Impact of corrosion product removal to depth of corrosion damage in weldment joint

Pubblicato online: 24 Jan 2020
Pagine: 148 - 152

Astratto

Abstract

Corrosion flaws in pipelines can caused severe financial losses and also can be dangerous for people. One of the most frequently damaged parts are dissimilar pipe welds. We would like to understand how corrosion process reacts on corrosion product removal. Outputs from experiment will be used for production of test specimens. For testing we chose standard dissimilar weldment used in Czech power plants. It is joint with 08Ch18N10T and 22K (GOST) steel. Joint is cut to 24 same specimens. There are exposed to flowing water solution of 5% NaCl. Half of the specimens are regularly mechanically cleaned. The joint is metallographically observed and parts with and without corrosion products are compared. Water salt solution increased pH from 7,25 to 7,86 during 31 days test and conductivity varies around 74 mS cm−1. Metallographic observation indicates that corrosion under corrosion products layer is locally speed up and causes pitting corrosion. Cleaned specimens indicate plane corrosion with lower depth. These results indicate that slag in pipeline could locally speed up corrosion depth penetration. On the other hand, solutions with abrasive particles (which can wipe out the corrosion product) will probably facilitate plane corrosion damage on pipeline walls. This test brings us another knowledge, how to simulate realistic corrosion damage for production of NDT qualification test pieces.

Accesso libero

Anticorrosion coatings based on novel acrylate binders containing MeO nanoparticles

Pubblicato online: 24 Jan 2020
Pagine: 153 - 158

Astratto

Abstract

Water based paints are increasingly attracting interest mainly with a view to reducing air pollution with volatile organic compounds (VOC). However, the protective properties of water-based paints are inferior to those of solvent-based paints and so new ways to increase the resistance of water-based systems are sought. The present contribution describes the preparation and testing of environmentally friendly anti-corrosion paints based on novel water-based self-crosslinking acrylate latexes containing appropriate pigments and ZnO or MgO nanoparticles at a concentration of 1.5 % (with respect to the monomers) compared to the same systems free from the nanoparticles. Both the effect of the MeO nanoparticles and the effects of the pigment species and particle shapes on the paint film properties were examined. The MeO nanoparticles were found to improve all the properties tested. The latexes with MgO exhibited the highest resistance to flash corrosion while the latexes with ZnO exhibited the highest anticorrosion resistance. Furthermore, the systems with the calcium-aluminium polyphosphosilicate based pigment were superior to all the remaining systems in this respect. It is concluded that binders with nanoparticles can be used as a basis for anticorrosion coatings provided that a suitable pigment is selected.

Accesso libero

Evaluation of selected properties of coatings in respect of risk elimination of surface damage of stamped parts

Pubblicato online: 24 Jan 2020
Pagine: 159 - 166

Astratto

Abstract

For achieving a long service life of stamping dies for new types of steel sheets intended for the automotive industry, the tribosystem must be optimally designed. One of the possible solutions is its optimization by coatings. More modern coating technologies for stamping dies include PVD (physical vapor deposition) and CVD (chemical vapor deposition) methods. The properties of PVD TiCN and DLC (diamond-like carbon) coatings deposited on ledeburitic high-alloy Cr–Mo–V steel were analyzed by standard tests (coating adhesion by both the scratch and Rockwell C tests, microhardness by Vickers method and coating thickness by Calotest) and developed tribo-meter of the “friction jaw-roller” type at drawing double-sided hot-dip galvanized steel sheet. The obtained results showed better tribological behavior of the DLC coating.

Accesso libero

Characterization of selected properties of WC–WB–Co and WC–FeCrAl coatings applied by HVOF technology

Pubblicato online: 24 Jan 2020
Pagine: 167 - 173

Astratto

Abstract

The paper presents results of the research focused on the characterization of two types of coatings – WC–FeCrAl and WC–WB–Co. The properties of the WC–FeCrAl coating (Co and Ni free) were compared against the WC–WB–Co coating to see if it could be used as an environmentally more suitable substitute for conventional Co and Ni containing powders. The coatings were applied by HVOF technology. The influence of thermal cyclic stress on the hardness, adhesion of coatings and their corrosion resistance was determined. A change in the phase composition of coatings after thermal cyclic loading was also determined.

5 Articoli
Accesso libero

Corrosion resistance of the biodegradable ZE41 magnesium alloy treated by unconventional fluoride conversion coating

Pubblicato online: 24 Jan 2020
Pagine: 138 - 147

Astratto

Abstract

Magnesium based alloys are very promising material to be used mainly for biodegradable implants in medical applications. However, due to their very low corrosion resistance in the environment of in vivo is their use limited. Increase of the corrosion resistance of magnesium alloys in vivo can be achieved, for example, by a suitable choice of surface treatment while the biocompatibility must be ensured. Fluoride conversion coatings meet these requirements. Unconventional fluoride conversion coating was prepared on ZE41 magnesium alloy by dipping the magnesium alloy into the Na[BF4] salt melt at 450 °C for 0.5; 2 and 8 h. The morphology and thickness of the prepared fluoride conversion coatings were investigated as well as the corrosion resistance of the treated and untreated ZE41 magnesium alloy specimens. The corrosion resistance of the untreated and treated ZE41 magnesium alloy was investigated using electrochemical impedance spectroscopy in the environment of the simulated body fluids at 37 ± 2 °C. The obtained results showed a positive influence of the fluoride conversion coating on the corrosion resistance of the ZE41 magnesium alloy.

Accesso libero

Impact of corrosion product removal to depth of corrosion damage in weldment joint

Pubblicato online: 24 Jan 2020
Pagine: 148 - 152

Astratto

Abstract

Corrosion flaws in pipelines can caused severe financial losses and also can be dangerous for people. One of the most frequently damaged parts are dissimilar pipe welds. We would like to understand how corrosion process reacts on corrosion product removal. Outputs from experiment will be used for production of test specimens. For testing we chose standard dissimilar weldment used in Czech power plants. It is joint with 08Ch18N10T and 22K (GOST) steel. Joint is cut to 24 same specimens. There are exposed to flowing water solution of 5% NaCl. Half of the specimens are regularly mechanically cleaned. The joint is metallographically observed and parts with and without corrosion products are compared. Water salt solution increased pH from 7,25 to 7,86 during 31 days test and conductivity varies around 74 mS cm−1. Metallographic observation indicates that corrosion under corrosion products layer is locally speed up and causes pitting corrosion. Cleaned specimens indicate plane corrosion with lower depth. These results indicate that slag in pipeline could locally speed up corrosion depth penetration. On the other hand, solutions with abrasive particles (which can wipe out the corrosion product) will probably facilitate plane corrosion damage on pipeline walls. This test brings us another knowledge, how to simulate realistic corrosion damage for production of NDT qualification test pieces.

Accesso libero

Anticorrosion coatings based on novel acrylate binders containing MeO nanoparticles

Pubblicato online: 24 Jan 2020
Pagine: 153 - 158

Astratto

Abstract

Water based paints are increasingly attracting interest mainly with a view to reducing air pollution with volatile organic compounds (VOC). However, the protective properties of water-based paints are inferior to those of solvent-based paints and so new ways to increase the resistance of water-based systems are sought. The present contribution describes the preparation and testing of environmentally friendly anti-corrosion paints based on novel water-based self-crosslinking acrylate latexes containing appropriate pigments and ZnO or MgO nanoparticles at a concentration of 1.5 % (with respect to the monomers) compared to the same systems free from the nanoparticles. Both the effect of the MeO nanoparticles and the effects of the pigment species and particle shapes on the paint film properties were examined. The MeO nanoparticles were found to improve all the properties tested. The latexes with MgO exhibited the highest resistance to flash corrosion while the latexes with ZnO exhibited the highest anticorrosion resistance. Furthermore, the systems with the calcium-aluminium polyphosphosilicate based pigment were superior to all the remaining systems in this respect. It is concluded that binders with nanoparticles can be used as a basis for anticorrosion coatings provided that a suitable pigment is selected.

Accesso libero

Evaluation of selected properties of coatings in respect of risk elimination of surface damage of stamped parts

Pubblicato online: 24 Jan 2020
Pagine: 159 - 166

Astratto

Abstract

For achieving a long service life of stamping dies for new types of steel sheets intended for the automotive industry, the tribosystem must be optimally designed. One of the possible solutions is its optimization by coatings. More modern coating technologies for stamping dies include PVD (physical vapor deposition) and CVD (chemical vapor deposition) methods. The properties of PVD TiCN and DLC (diamond-like carbon) coatings deposited on ledeburitic high-alloy Cr–Mo–V steel were analyzed by standard tests (coating adhesion by both the scratch and Rockwell C tests, microhardness by Vickers method and coating thickness by Calotest) and developed tribo-meter of the “friction jaw-roller” type at drawing double-sided hot-dip galvanized steel sheet. The obtained results showed better tribological behavior of the DLC coating.

Accesso libero

Characterization of selected properties of WC–WB–Co and WC–FeCrAl coatings applied by HVOF technology

Pubblicato online: 24 Jan 2020
Pagine: 167 - 173

Astratto

Abstract

The paper presents results of the research focused on the characterization of two types of coatings – WC–FeCrAl and WC–WB–Co. The properties of the WC–FeCrAl coating (Co and Ni free) were compared against the WC–WB–Co coating to see if it could be used as an environmentally more suitable substitute for conventional Co and Ni containing powders. The coatings were applied by HVOF technology. The influence of thermal cyclic stress on the hardness, adhesion of coatings and their corrosion resistance was determined. A change in the phase composition of coatings after thermal cyclic loading was also determined.

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