Corrosion behavior of mesoporous bioglass-ceramic coated magnesium alloy under applied forces

• Degradation behavior of coated Mg alloy under applied forces was studied.
• With compressive stress larger than 25 MPa, coating lost protection in a short time.
• Apatite deposition improved the corrosion resistance under a less force.

In order to research the corrosion behavior of bioglass-ceramic coated magnesium alloys under applied forces, mesoporous 45S5 bioactive glass–ceramic (45S5 MBGC) coatings were successfully prepared on AZ31 substrates using a sol–gel dip-coating technique followed by a heat treatment at the temperature of 400 °C. In this work, corrosion behavior of the coated samples under applied forces was characterized by electrochemical tests and immersion tests in simulated body fluid. Results showed that the glass–ceramic coatings lost the protective effects to the magnesium substrate in a short time when the applied compressive stress was greater than 25 MPa, and no crystallized apatite was formed on the surface due to the high Mg2+ releasing and the peeling off of the coatings. Whereas, under low applied forces, apatite deposition and crystallization on the coating surface repaired cracks to some extent, thus improving the corrosion resistance of the coated magnesium during the long–term immersion period.

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