| LAI Yong-lai,LI Wang,JIN Hua-lan,PENG Wen-yi,GUO Hong-min,YANG Xiang-jie.Corrosion Behavior of Corrosion Resistant Film on AZ91D Magnesium Alloys[J],49(12):235-243 |
| Corrosion Behavior of Corrosion Resistant Film on AZ91D Magnesium Alloys |
| Received:April 28, 2020 Revised:June 08, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.12.027 |
| KeyWord:AZ91D semi-solid film corrosion morphology fractal theory |
| Author | Institution |
| LAI Yong-lai |
School of Mechanical and Electronic Engineering, Nanchang , China |
| LI Wang |
School of Materials Science and Engineering, Nanchang University, Nanchang , China |
| JIN Hua-lan |
School of Materials Science and Engineering, Nanchang University, Nanchang , China |
| PENG Wen-yi |
School of Materials Science and Engineering, Nanchang University, Nanchang , China |
| GUO Hong-min |
School of Materials Science and Engineering, Nanchang University, Nanchang , China |
| YANG Xiang-jie |
School of Mechanical and Electronic Engineering, Nanchang , China |
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| Abstract: |
| The work aims to obtain AZ91D magnesium alloys with better corrosion resistance. The corrosion characteristics of as-cast, semi-solid, film-forming as-cast and film-forming semi-solid AZ91D in simulated normal saline (0.9%NaCl) and simulated seawater (3.5%NaCl) were studied, and the fractal theory was introduced to characterize the corrosion degree and uniformity. Through NaCl solution corrosion and electrochemical corrosion of AZ91D in different states, the corrosion morphologies were analyzed by SEM and energy spectrum (EDS). Meanwhile, fractal theory was introduced to calculate and analyze the corrosion morphologies of AZ91D in various states. At the same corrosion time, more corrosion zones appeared on AZ91D in each state in the simulated seawater. The corrosion of film forming state and semi-solid state firstly appeared at the crack of film structure. In electrochemical experiments, as the concentration of electrolyte increased to 3.5%, the corrosion potential of unformed film casting and semi-solid state decreased from –1.4111 V and –1.4323 V to –1.5066 V and –1.5089 V, and the current density increased from 6.270×10–10 A/m2 and 9.847×10–10 A/m2 to 4.863×10–9 A/m2 and 8.396×10–9 A/m2. The corrosion potential in the as-cast and semi-solid state decreased from –1.3884 V and –1.3430 V to –1.4856 V and –1.4331 V, and the current density decreased from 5.854×10–10 A/m2 and 8.592×10–10 A/m2 to 2.050×10–11 A/m2 and 1.189×10–11 A/m2. In the fractal calculation, with the increase of the concentration of corrosion solution or the corrosion time, the corrosion tendency and corrosion rate of as-cast and semi-solid AZ91D increase, and the corrosion tendency of the film increases, but the corrosion rate decreases. At the same time, the DH fractal dimension of different AZ91D increases with the increase of the corrosion degree, and Δvalue increases as the corrosion uniformity decreases. |
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