Comparisons of Air and Water Oxidation on the Passive Properties of Chromium

Cr 2 O 3 films and coatings have widespread applications in the surface engineering of key industrial materials like irons and steels. The reason is that it can easily form and effectively prevent corrosion of metallic matrix in a lot of natural environments. However, the nature of the coating strongly depends on its formation conditions, which have a great influence on its protectiveness, and the relationship between the passivity of Cr 2 O 3 and its integrity, uniformity, and stability is still rarely understood. In this work, three different oxidation methods are employed to prepare chromium oxide. The effects of each oxidation method on the surface structure, phase component, and electrochemical performance are comprehensively investigated. The results show that the main component of different films is Cr 2 O 3 , and oxide films prepared in a water plasma environment have relatively higher compact structure, fewer defects, and more positive corrosion-resistant potential, suggesting that lower oxidative partial pressure of film growth condition would be beneficial to obtain better passive performance.