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 Cf/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 × 10−5 A·cm−2 to 2.37 × 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° to 72.4° 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 Cf/Mg composites. •A SiO2 layer successfully sealed the ZrO2 coating by sol-gel method assisted by heat treatment.•The SiO2 sealing layer decreased the corrosion rate of ZrO2 coated Cf/Mg composites by nearly 10 times.•The improved electrochemical properties were attributed to the dense structure and hydrophobicity of the SiO2 layer.