Recobriment per conversió

El recobriment per conversió és un tractament químic o electroquímic aplicat a les peces fabricades que converteix el material que hi hagi a la superfície en una fina capa adherida d'un compost insoluble.^[1] Aquests recobriments s'apliquen habitualment per protegir la peça de la corrosió, per millorar l'adherència d'altres recobriments, per a la lubricació o amb finalitats estètiques.^[2]^[3]^[4]

Tipus

Els processos de recobriment de conversió més comuns per a peces metàl·liques amb ús industrial inclouen

Cromatge (alumini, acer)
Fosfatació (acer)
Blau (acer)
Òxid negre (acer)
Anoditzat (alumini)
Estanat (magnesi) ^[5]
Molibdat (zinc, zinc- níquel) ^[6]^[7]
Zirconat (acer, alumini, magnesi, acer galvanitzat).^[8]^[9]^[10]
Titanat (acer, alumini, magnesi).^[8]
Electròlisi de plasma (alumini, magnesi, titani) ^[11]^[12]

Substrats no metàl·lics

S'han estudiat recobriments de conversió per a substrats no metàl·lics, com per a la protecció de vidres de fluorozirconat utilitzats en optoelectrònica.^[13]

Normativa

Les especificacions militars dels EUA per als recobriments de conversió inclouen MIL-DTL-5541, MIL-DTL-81706 i MIL-DTL-5574, totes elles relacionades amb l'alumini.^[8]

Referències

↑ I. Milošev and G. S. Frankel (2018): "Review—Conversion Coatings Based on Zirconium and/or Titanium". Journal of the Electrochemical Society, volume 165, issue 3,pages C127-C144. doi:10.1149/2.0371803jes
↑ ""
↑ ""
↑ "Fastener Surface Conversion", In: FastenerData.co.uk
↑ M. A. Gonzalez-Nunez, C. A. Nunez-Lopez, P. Skeldon, G. E. Thompson, H. Karimzadeh, P. Lyon, and T.E.Wilks (1995): "A non-chromate conversion coating for magnesium alloys and magnesium-based metal matrix composites". Corrosion Science, volume 37, issue 11, pages 1763-1772. doi:10.1016/0010-938X(95)00078-X
↑ A. A. O. Magalhães, I. C. P. Margarita, O. R. Mattos (2004): "Molybdate conversion coatings on zinc surfaces". Journal of Electroanalytical Chemistry, volume 572, issue 2, pages 433-440. doi:10.1016/j.jelechem.2004.07.016
↑ J. A. Wharton, G. D. Wilcox, and K. R Baldwin (1996): "Non-Chromate Conversion Coating Treatments For Electrodeposited Zinc-Nickel Alloys". Transactions of the IMF - The International Journal of Surface Engineering and Coatings, volume 74, issue 6, pages 210-213. doi:10.1080/00202967.1996.11871128
↑ ^8,0 ^8,1 ^8,2 I. Milošev and G. S. Frankel (2018): "Review—Conversion Coatings Based on Zirconium and/or Titanium". Journal of the Electrochemical Society, volume 165, issue 3,pages C127-C144. doi:10.1149/2.0371803jes
↑ Charles E. Tomlinson (1998): "Chromate-free conversion coatings for metals". US Patent 5759244^{[Enllaç no actiu]}, filed on 1996-10-09, granted on 1998-06-02, expired on 2016-10-09.
↑ Raoling Wang (2018): "Chromium-free aluminum conversion coating agent, aluminum material, and surface conversion coating treatment method". Patent WO2018006270, filed on 2016-07-05, granted on 2018-01-11.
↑ Lishi Wang, Tao Feng, Shanwen Yu, Yihang Cheng, Zhixiang Bu and Xinbin Hu (2020): "Fluoride effect on plasma electrolytic oxidation coating formed on Mg-Al alloy in alkaline electrolytes". Materials Research Express, volume 7, issue 1, article 016412. doi:10.1088/2053-1591/ab60a7
↑ Liu Feng, Shan Dayong, Song Yingwei, Liu Xianbin, and Han Enhou (2012): "Highly corrosion-resistant ceramic coating solution prepared through magnesium alloy surface micro-arc oxidation and application thereof". Chinese patent 101994145^{[Enllaç no actiu]}, filed on 2009-08-19, granted on 2012-05-23.
↑ A. P. Rizzato, C. V. Santilli, S. H. Pulcinelli, Y. Messaddeq, and P. Hammer (2004): "XPS Study of the Corrosion Protection of Fluorozirconate Glasses Dip-Coated with SnO2 Transparent Thin Films". Journal of Sol-Gel Science and Technology, volume 32, pages 155–160. doi:10.1007/s10971-004-5781-9

Bibliografia

MIL-HDBK-205, Phosphate & Black Oxide Coating of Ferrous Metals: a standard overview on phosphate and black oxide (bluing) coatings
Surface Engineering for Wear Resistance. Prentice Hall, 1988, p. 48.
Electrofinishing. American Elsevier Publishing Company, Inc., 1965, p. 62–63. .

Enllaços externs

Henkel Surface Technologies: propietari actual de Parco-Lubrite (un procés de fosfatació de manganès) i altres recobriments Parkerizing per prevenir l'oxidació. (Parco és una marca comercial registrada de Henkel Surface Technologies.)
Coral Chemical Company: propietari actual de Coral Eco Treat (procés de recobriment de conversió de vanadi)
Parker Rust-Proof de Cleveland: l'últim que queda dels quatre titulars de llicències originals de la botiga de treball de Parker Chemical, actualment ofereix serveis de fosfatació

[milo20182-1] I. Milošev and G. S. Frankel (2018): "Review—Conversion Coatings Based on Zirconium and/or Titanium". Journal of the Electrochemical Society, volume 165, issue 3,pages C127-C144. doi:10.1149/2.0371803jes

[rit-2] ""

[mate-3] ""

[fast-4] "Fastener Surface Conversion", In: FastenerData.co.uk

[gonz1995-5] M. A. Gonzalez-Nunez, C. A. Nunez-Lopez, P. Skeldon, G. E. Thompson, H. Karimzadeh, P. Lyon, and T.E.Wilks (1995): "A non-chromate conversion coating for magnesium alloys and magnesium-based metal matrix composites". Corrosion Science, volume 37, issue 11, pages 1763-1772. doi:10.1016/0010-938X(95)00078-X

[maga2004-6] A. A. O. Magalhães, I. C. P. Margarita, O. R. Mattos (2004): "Molybdate conversion coatings on zinc surfaces". Journal of Electroanalytical Chemistry, volume 572, issue 2, pages 433-440. doi:10.1016/j.jelechem.2004.07.016

[whar1996-7] J. A. Wharton, G. D. Wilcox, and K. R Baldwin (1996): "Non-Chromate Conversion Coating Treatments For Electrodeposited Zinc-Nickel Alloys". Transactions of the IMF - The International Journal of Surface Engineering and Coatings, volume 74, issue 6, pages 210-213. doi:10.1080/00202967.1996.11871128

[milo2018-8] 8,0 ^8,1 ^8,2 I. Milošev and G. S. Frankel (2018): "Review—Conversion Coatings Based on Zirconium and/or Titanium". Journal of the Electrochemical Society, volume 165, issue 3,pages C127-C144. doi:10.1149/2.0371803jes

[tom1998-9] Charles E. Tomlinson (1998): "Chromate-free conversion coatings for metals". US Patent 5759244^{[Enllaç no actiu]}, filed on 1996-10-09, granted on 1998-06-02, expired on 2016-10-09.

[wang2018-10] Raoling Wang (2018): "Chromium-free aluminum conversion coating agent, aluminum material, and surface conversion coating treatment method". Patent WO2018006270, filed on 2016-07-05, granted on 2018-01-11.

[wang2020-11] Lishi Wang, Tao Feng, Shanwen Yu, Yihang Cheng, Zhixiang Bu and Xinbin Hu (2020): "Fluoride effect on plasma electrolytic oxidation coating formed on Mg-Al alloy in alkaline electrolytes". Materials Research Express, volume 7, issue 1, article 016412. doi:10.1088/2053-1591/ab60a7

[feng2012-12] Liu Feng, Shan Dayong, Song Yingwei, Liu Xianbin, and Han Enhou (2012): "Highly corrosion-resistant ceramic coating solution prepared through magnesium alloy surface micro-arc oxidation and application thereof". Chinese patent 101994145^{[Enllaç no actiu]}, filed on 2009-08-19, granted on 2012-05-23.

[rizz2004-13] A. P. Rizzato, C. V. Santilli, S. H. Pulcinelli, Y. Messaddeq, and P. Hammer (2004): "XPS Study of the Corrosion Protection of Fluorozirconate Glasses Dip-Coated with SnO2 Transparent Thin Films". Journal of Sol-Gel Science and Technology, volume 32, pages 155–160. doi:10.1007/s10971-004-5781-9

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