MAO ceramic coatings were prepared on AZ61 magnesium alloy for various processing times ranging from 5 to 60 min, in an electrolyte solution based on silicate-fluoride. The mechanical, electrochemical and, microstructural properties and the phase compositions of the coating layers were investigated. In this work, unlike previous studies, coatings with high amounts of the Mag2SiO4 phase were formed which contained small amounts of MgO and MgF2 at a processing condition of 30 min. A microstructural analysis revealed that the porosity of the coatings was reduced considerably with an increase in the processing time, together with a change in the pore geometry from an irregular to a spherical shape. Potentiodynamic polarization and mechanical testing results showed that the coatings acquired after a processing time of 30 min were superior to all of the others.

1. Introduction
 2. Experimental Method
  2.1 Specimen and coating process
  2.2 Phase composition and microstructure
  2.3 Hardness and wear test
  2.4 Electrochemical tests
 3. Results and Discussions
  3.1 Microstructure
  3.2 Phase analysis
  3.3 Hardness and wear loss
  3.4 Potentiodynamic polarization
 4. Conclusions
 Acknowledgment
 References

• Zeeshan Ur Rehman(School of Materials Science and Engineering, Changwon National University, Changwon 641-773, South Korea)
• Yeong Seung Jeong(School of Materials Science and Engineering, Changwon National University, Changwon 641-773, South Korea)
• Bon Heun K(School of Materials Science and Engineering, Changwon National University, Changwon 641-773, South K) Corresponding author