Preparation of corrosion resistant film on aluminum alloy by steam coating

摘要

The novel control method of corrosion protection for Al alloys using steam is proposed in this presentation. The preparation method of anticorrosive film on the Al alloys by means of a simple, environmentally-friendly, and inexpensive method reported here were attained by chemicals-free steam process. Al-Mg-Si and Al-Zn-Mg alloys were used as the substrate. The ultrasonic ally cleaned samples were set in a Teflon-lined autoclave with 20 ml of uhrapure water as a resource of steam. The autoclave was heated to a temperature of 373 to 453 K and held at the temperature for up to 24 h, and was subsequently cooled naturally to room temperature, resulting in the formation of anticorrosive films on the Al alloys. The resultant films were characterized by XRD, XPS, SEM and electrochemical measurements. XRD patterns indicated that the film formed on two types of Al alloys by steam coating was mainly composed of crystal AlOOH. The corrosion resistance of the film was investigated using electrochemical measurements. The potentiodynamic polarization curves of the film coated and uncoated samples after immersion in the 5 wt% NaCl aqueous solution for 30 min revealed that the corrosion current density, j_(corr), of the film coated sample decreased by more than two orders of magnitude as compared to the uncoated sample, indicating that the corrosion resistance of the Al alloys were improved by the formation of the film via steam coating.