Effect of sodium aluminate on MAO oxide properties onto AZ31 magnesium alloy

M. Bestetti, A. Da Forno

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Oxide films were produced on AZ31 magnesium alloy by microarc oxidation (MAO) in an alkaline phosphate solution at different concentrations of NaAlO2. Surface and cross-section morphologies were assessed by scanning electron microscopy and phase composition by X-ray diffraction. The corrosion resistance was evaluated in a diluted Harrison solution using anodic polarisation tests. The results show that the properties of the oxides are affected by the NaAlO2 concentration. The thickness of the coatings increases with aluminate concentration from 5 μm in aluminate free electrolyte to 12 μm in electrolyte containing 60 g dm-3 after anodising (5 min; 135 V). The coating consists of two layers: an outer layer with high concentration of aluminium and an inner magnesium rich layer. Increased corrosion resistance was found in the samples anodised in a solution containing 30 g dm-3 NaAlO2.

Original languageEnglish
Pages (from-to)74-79
Number of pages6
JournalTransactions of the Institute of Metal Finishing
Issue number2
Publication statusPublished - Mar 2013
Externally publishedYes


  • Corrosion resistance
  • Magnesium alloys
  • Microarc oxidation
  • Sodium aluminate

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Mechanics of Materials
  • Metals and Alloys
  • Surfaces, Coatings and Films

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