Formation behavior of phosphoric acid-based chemical conversion coating containing alkaline earth metals on magnesium alloy

Akinori Nakamura, Satoshi Oue, Hiroki Koga, Hiroaki Nakano

Research output: Contribution to journalArticle

Abstract

The phosphate coating for Mg alloy was performed in the unagitated solutions containing 1 g·dm-3 of Mg, Ca, Sr and Ba as alkali-earth metal and 50 g·dm-3 of H3PO4 of pH 3 and 40°C for 3 min, and the structure and formation behavior of the phosphate films were investigated. The X-ray diffraction patterns of phosphate films broadened regardless of the kinds of alkali-earth metal, which was a characteristic of an amorphous structure. XPS analysis revealed that the valence of P in the phosphate films was pentavalent. The pH in the vicinity of the Mg alloy during the phosphate coating, as measured using an Sb microelectrode, was approximately 10.4, 11.4, 10.7, 12.0 in the solutions containing Mg, Ca, Sr and Ba, respectively, which shows that the phosphoric acid dissociates to the third stage during the phosphate coating and the phosphate films composed of M3(PO4)2 containing alkali-earth metal (M) are formed. The phosphate coating were successively performed in the two kinds of solutions containing different alkali-earth metals and the cross section was analyzed, as a result, it was suggested that the new phosphate films were formed at the interface between Mg alloy substrate and phosphate films and the previously formed phosphate films were boosted up in films.

Original languageEnglish
Pages (from-to)684-690
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume80
Issue number11
DOIs
Publication statusPublished - Jan 1 2016

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Alkaline Earth Metals
Alkaline earth metals
alkaline earth metals
phosphoric acid
Phosphoric acid
magnesium alloys
Magnesium alloys
phosphates
Phosphates
Phosphate coatings
coatings
Coatings
Alkalies
Metals
Earth (planet)
alkalies
metals
Microelectrodes
Diffraction patterns
X ray photoelectron spectroscopy

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

Cite this

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title = "Formation behavior of phosphoric acid-based chemical conversion coating containing alkaline earth metals on magnesium alloy",
abstract = "The phosphate coating for Mg alloy was performed in the unagitated solutions containing 1 g·dm-3 of Mg, Ca, Sr and Ba as alkali-earth metal and 50 g·dm-3 of H3PO4 of pH 3 and 40°C for 3 min, and the structure and formation behavior of the phosphate films were investigated. The X-ray diffraction patterns of phosphate films broadened regardless of the kinds of alkali-earth metal, which was a characteristic of an amorphous structure. XPS analysis revealed that the valence of P in the phosphate films was pentavalent. The pH in the vicinity of the Mg alloy during the phosphate coating, as measured using an Sb microelectrode, was approximately 10.4, 11.4, 10.7, 12.0 in the solutions containing Mg, Ca, Sr and Ba, respectively, which shows that the phosphoric acid dissociates to the third stage during the phosphate coating and the phosphate films composed of M3(PO4)2 containing alkali-earth metal (M) are formed. The phosphate coating were successively performed in the two kinds of solutions containing different alkali-earth metals and the cross section was analyzed, as a result, it was suggested that the new phosphate films were formed at the interface between Mg alloy substrate and phosphate films and the previously formed phosphate films were boosted up in films.",
author = "Akinori Nakamura and Satoshi Oue and Hiroki Koga and Hiroaki Nakano",
year = "2016",
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T1 - Formation behavior of phosphoric acid-based chemical conversion coating containing alkaline earth metals on magnesium alloy

AU - Nakamura, Akinori

AU - Oue, Satoshi

AU - Koga, Hiroki

AU - Nakano, Hiroaki

PY - 2016/1/1

Y1 - 2016/1/1

N2 - The phosphate coating for Mg alloy was performed in the unagitated solutions containing 1 g·dm-3 of Mg, Ca, Sr and Ba as alkali-earth metal and 50 g·dm-3 of H3PO4 of pH 3 and 40°C for 3 min, and the structure and formation behavior of the phosphate films were investigated. The X-ray diffraction patterns of phosphate films broadened regardless of the kinds of alkali-earth metal, which was a characteristic of an amorphous structure. XPS analysis revealed that the valence of P in the phosphate films was pentavalent. The pH in the vicinity of the Mg alloy during the phosphate coating, as measured using an Sb microelectrode, was approximately 10.4, 11.4, 10.7, 12.0 in the solutions containing Mg, Ca, Sr and Ba, respectively, which shows that the phosphoric acid dissociates to the third stage during the phosphate coating and the phosphate films composed of M3(PO4)2 containing alkali-earth metal (M) are formed. The phosphate coating were successively performed in the two kinds of solutions containing different alkali-earth metals and the cross section was analyzed, as a result, it was suggested that the new phosphate films were formed at the interface between Mg alloy substrate and phosphate films and the previously formed phosphate films were boosted up in films.

AB - The phosphate coating for Mg alloy was performed in the unagitated solutions containing 1 g·dm-3 of Mg, Ca, Sr and Ba as alkali-earth metal and 50 g·dm-3 of H3PO4 of pH 3 and 40°C for 3 min, and the structure and formation behavior of the phosphate films were investigated. The X-ray diffraction patterns of phosphate films broadened regardless of the kinds of alkali-earth metal, which was a characteristic of an amorphous structure. XPS analysis revealed that the valence of P in the phosphate films was pentavalent. The pH in the vicinity of the Mg alloy during the phosphate coating, as measured using an Sb microelectrode, was approximately 10.4, 11.4, 10.7, 12.0 in the solutions containing Mg, Ca, Sr and Ba, respectively, which shows that the phosphoric acid dissociates to the third stage during the phosphate coating and the phosphate films composed of M3(PO4)2 containing alkali-earth metal (M) are formed. The phosphate coating were successively performed in the two kinds of solutions containing different alkali-earth metals and the cross section was analyzed, as a result, it was suggested that the new phosphate films were formed at the interface between Mg alloy substrate and phosphate films and the previously formed phosphate films were boosted up in films.

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