Effect of sealing treatment on corrosion behavior of plasma sprayed ZrO2 coated Cf/Mg composites

To improve the corrosion resistance of plasma sprayed ZrO2 coated C-f/Mg composites, the pores on the ZrO2 coating were sealed with the SiO2 coating prepared by sol-gel technology. The surface porosity of the ZrO2 coating was reduced by 65.47% after the SiO2 sealing treatment. The electrochemical results demonstrated that the corrosion potential was significantly improved by 44.61% after the SiO2 sealing treatment. The corrosion current density was degraded from 1.94 x 10(-5) A.cm(-2) to 2.37 x 10(-6) A.cm(-2), and the corrosion rate was even reduced by nearly 10 times. Besides, the contact angle of the corrosive solution on the coating was raised from 45.3 degrees to 72.4 degrees after the sealing treatment. The good corrosion resistance after the sealing treatment is ascribed to the dense structure and the improved hydrophobicity of the SiO2 sealing layer, which provide an effective barrier to block the penetration of corrosive solution for C-f/Mg composites.