中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 30 No. 8 August 2020 |
（1. Department of Mining and Petroleum Engineering, Faculty of Engineering, Al-Azhar University, Nasr City, Cairo 11371, Egypt;
2. Department of Metallurgy, Faculty of Engineering, Cairo University, Giza 12613, Egypt）
Abstract:Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.% NaCl solution. The anodes were fabricated from pure Al, Zn and Mg metals using casting technique. Optical microscopy, SEM-EDS, XRD and electrochemical techniques were used. The results indicated that with decreasing Zn/Mg mass ratio, the grain size of α(Al) and the particle size of the precipitates decreased while the volume fraction of the precipitates increased. The anode with Zn/Mg mass ratio >4.0 exhibited the lowest corrosion rate, while the anode with Zn/Mg mass ratio <0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel (AISI 1018). Furthermore, the results showed that the anode with Zn/Mg mass ratio <0.62 exhibited a porous corrosion product compared to the other anodes.
Key words: cathodic protection; Al-Zn-Mg sacrificial anode; current capacity; passive film; precipitate; grain size
