Effect of Al2O3 content on the electrochemical corrosion performance of alumina ceramic coating

       

Effect of Al2O3 content on the electrochemical corrosion performance of alumina ceramic coating

Corrosion resistance is often used to characterize the ability of a material to resist environmental corrosion. The better the corrosion resistance, the longer the service life of the material. Therefore, in addition to studying the mechanical properties of the coating, the resistance

 

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Corrosion is also one of the important properties of the coating. From the previous research, we can see that with the change of Al2O3 content, the various properties of composite ceramics change significantly, which shows that Al2O3 content has a significant impact on the mechanical properties of composite ceramic coatings, so it is necessary to study its corrosion resistance of the coating. The impact of sex.

For all samples, the self-corrosion potential of substrate preheating is more positive than that without substrate preheating. This is because the substrate preheating enhances the bonding force and hardness of the ceramic coating, so the substrate preheating is more conducive to the improvement of the corrosion resistance of the coating. . It is worth noting that with the increase of Al2O3 content, the self-corrosion potential of composite ceramic coatings continues to increase. This is because the porosity of the composite ceramic coating decreases and the bonding force increases, so its self-corrosion potential also increases, indicating that the addition of Al2O3 can significantly reduce the corrosion thermodynamic tendency of the ceramic coating, thereby improving the corrosion resistance of the ceramic composite coating Sex [32]. But when the mass fraction of Al2O3 continues to increase to 80%, the self-corrosion potential of the composite ceramic coating drops again. This is because the bonding force and hardness of the coating decrease at this time, especially the porosity increases, which will cause the corrosive medium to enter the inside of the coating along the pores, corrode the metal substrate, and cause the coating to fall off and fail and reduce the corrosion resistance. In addition, since the excessive Al2O3 at this time leads to the formation of new phases, these non-equilibrium phases will also cause chemical corrosion.

For all samples, the self-corrosion potential of substrate preheating is more positive than that without substrate preheating. This is because the substrate preheating enhances the bonding force and hardness of the ceramic coating, so the substrate preheating is more conducive to the improvement of the corrosion resistance of the coating. . It is worth noting that with the increase of Al2O3 content, the self-corrosion potential of composite ceramic coatings continues to increase. This is because the porosity of the composite ceramic coating decreases and the bonding force increases, so its self-corrosion potential also increases, indicating that the addition of Al2O3 can significantly reduce the corrosion thermodynamic tendency of the ceramic coating, thereby improving the corrosion resistance of the ceramic composite coating Sex [32]. But when the mass fraction of Al2O3 continues to increase to 80%, the self-corrosion potential of the composite ceramic coating drops again. This is because the bonding force and hardness of the coating decrease at this time, especially the porosity increases, which will cause the corrosive medium to enter the inside of the coating along the pores, corrode the metal substrate, and cause the coating to fall off and fail and reduce the corrosion resistance. In addition, since the excessive Al2O3 at this time leads to the formation of new phases, these non-equilibrium phases will also cause chemical corrosion.