Fabrication Of Rare Earth Oxide Coatings On Type 304 Stainless Steel And Its Superhydrophobicity

The fabrication of superhydrophobic coatings on type 304 stainless steel is of great significance in a broad range of applications.Many organics have been used for preparation of hydrophobic coatings on stainless steel such as fluorosilane,However,organic coatings have several disadvantages in practical applications,chiefly their inherently poor mechanical durability and thermal stability.In this paper,superhydrophobic cerium oxide and lanthanum oxide coatings on type 304 stainless steel is obtained by combination of cathodic electrodeposition and long-term surface relaxation in high vacuum.The effect of fabrication process parameters including electrolyte composition,deposition time and deposition temperature on the morphology,phase composition and hydrophobic properties is studied,and the thermal stability and mechanical durability was explored.The research results show that the addition of H₂O₂ is essential to improve the hydrophobic properties of Ce O₂ coating on.With the addition of the ratio of H₂O₂ increase,the contact angle of the Ce O₂ coating surface gradually increases to 150.3°±2.2°,and the increase of the concentration of Ce Cl₃ and La Cl₃ does not improve the hydrophobic properties of the coating.And the deposition temperature have a great influence on the surface morphology and hydrophobic properties of the Ce O₂ and La₂O₃ coatings.Increasing the deposition temperature can significantly improve the morphology and hydrophobicity of the Ce O₂ coating until the deposition temperature increases to 55?.But the increase of deposition temperature is unfavorable for the preparation of La₂O₃ coating.At the deposition temperatures of 45°C and 55°C,there are many places where no coating is deposited on the surface of the substrate.And the research results show that the best deposition time is 30 min.Increasing the deposition time can not improve the hydrophobic properties of Ce O₂ and La₂O₃ coatings.The thermal stability of Ce O₂ and La₂O₃ coatings are also tested respectively.Both the Ce O₂ and La₂O₃ coatings can stay good hydrophobicity after heat treatment at 200°C for 30 minutes until the coatings were heated at250°C for 30 minutes.And the coatings can mostly recover their hydrophobic properties after the coatings being revacuumed.The La₂O₃ and Ce O₂ coatings have been tested for mechanical durability by tape tear test.For Ce O₂ coating,the contact angle remained unchanged after3 times of tearing test,and the contact angle gradually drops to 125°after tearing 10 times.For the La₂O₃ coating,the contact angle gradually decreases with the incresing times of tearing test,and finally decreases to 121°.