Improvement of corrosion resistance of carbon steel using chemical vapor deposition from the mixture of Mo(CO)₆ and Cr(CO)₆ with an ArF-excimer laser

Abstract

The corrosion resistance of carbon steel has been improved by the deposition from the mixture of Mo(CO)₆ and Cr(CO)₆ as well as from each carbonyl alone with an ArF-excimer laser (193 nm). The corrosion resistance attained by coating with the films from the mixture is higher than from Mo(CO)₆ alone, while lower than from Cr(CO)₆ alone. While the corrosion resistance increases with beam intensity monotonically over the range 4–25 MW cm⁻² for the deposition from Cr(CO)₆ alone, it tends to decrease slightly above 15 MW cm⁻² for the deposition from Mo(CO)₆ alone and from the mixture. SEM (Scanning Electron Microscope) photographs show that the films from each carbonyl and their mixture consist of small grains that are more densely packed at higher beam intensities. The comparison of the film thickness evaluated from sputtering time to remove the films with that from direct observation with SEM suggests that the density of the film increases with beam intensity. In the films deposited from the mixture, molybdenum is preferentially incorporated from the gas phase.