Studies on degradation performance of Mg-4.0Zn-1.5Sr alloy with coated of the laser surface processing combining alkaline treatment

The surface modification of biomaterial Mg-4.0Zn-1.5Sr alloy has been done by means of laser surface processing combining alkaline treatment process, as well as the degradation performance of Mg-4.0Zn-1.5Sr alloy with and without coatings in Hank's solution has been analyzed comparatively. The results indicate that the optimal parameters of laser surface processing are that the power is 3 kW, the current 200 A, the width 1mm, the defocus amount 135 mm and the scanning speed 1mm/s. The optimal parameters of alkaline treatment are that the solution is NaOH, the concentration 0.5 mol/L, the temperature 80 °C and the time 12 h. There are only two phases of Mg (OH)₂ and magnesium matrix, and the surface generated most of Mg (OH)₂ which can improve the corrosion resistance of the alloy after laser combining alkaline treatment, as well as the corrosion rate is almost the stable, which is much smaller than both of uncoated and laser surface processing. The study of the electrochemical corrosion behavior shows that the corrosion potential of the alloy with coated of laser combining alkaline treatment is improved 0.1277 V than that of laser treatment, and the corrosion current is decreased 470.2 muA than laser treatment. The corrosion resistant ability of Mg-4.0Zn-1.5Sr alloy is greatly improved by means of laser combining alkaline treatment.