The corrosion resistance of samples at different laser
The corrosion resistance of samples at different laser power was measured by neutral salt spray test according to Chinese standard GB/T10125-1997. Samples were immersed in 5% NaCl solution (35 °C ± 2 °C, PH = 6.8∼7.2) in salt spray sulfide corrosion experimental box (FOY/L-03) with salt spray deposition rate being 1 mL/h～2 mL/h per 80 cm2 area. The exposed area of samples was 20 mm × 20 mm, and the other area was sealed with neoprene. Observe the samples until the first corrosion point was found by eyes. Then the corrosion resistance time of coating can be obtained. Fig. 4 shows the corrosion morphologies of the Al–Si/Al2O3 coatings under neutral salt spray conditions at different laser power. It can be seen from Fig. 4 that the Al–Si/Al2O3 coatings sprayed by laser Ritonavir hybrid spraying greatly improved the corrosion resistance of magnesium alloy matrix. When the laser power was 600 W, the time of resistant to salt spray was up to 640 h. With the increasing of laser power, for example, when the laser power was 700 W, the time of resistant to salt spray further increased to 925 h. However, it decreased to 705 h when laser power continued increasing to 800 W. The corrosion resistance of the coatings was closely related to the porosity of the coatings and their composition. The surface of Al–Si/Al2O3 coatings was Al2O3, which had good chemical stability and high corrosion resistance. After the hybrid spraying of laser and plasma, the porosity of coatings decreased more significantly and coatings were denser than by plasma spraying. In particular, when the laser power was 700 W, the coatings had the lowest porosity (3.6%) and the best corrosion resistance.