Long-term atmospheric pre-corrosion fatigue properties of epoxy primer-coated 7075-T6 aluminum alloy structures

2019 ◽  
Vol 129 ◽  
pp. 105225 ◽  
Author(s):  
Sheng Zhang ◽  
Teng Zhang ◽  
Yuting He ◽  
Xu Du ◽  
Binlin Ma ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Fatigue ◽  
Fatigue Properties ◽  
Epoxy Primer

scholarly journals Long-Term Atmospheric Aging and Corrosion of Epoxy Primer-Coated Aluminum Alloy in Coastal Environments

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 237
Author(s):  
Tianyu Zhang ◽  
Teng Zhang ◽  
Yuting He ◽  
Sheng Zhang ◽  
Binlin Ma ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Electrochemical Impedance ◽  
Synergistic Effects ◽  
Fractal Dimensions ◽  
Weather Conditions ◽  
X Ray ◽  
Epoxy Primer ◽  
Atmospheric Exposure ◽  
Effects Of Aging

Aircraft are subjected to extreme weather conditions in coastal areas. This study reports long-term atmospheric exposure tests carried out on an epoxy primer-coated aluminum alloy in a coastal environment for 7, 12, and 20 years. The micromorphology and characteristics of the section and surface, the products of corrosion, electrochemical impedance, and molecular structure of the coated specimens were examined through a spectrophotometer, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectrometer (XPS). The results showed that the angles of contact of the specimens with different numbers of years of atmospheric exposure satisfied the normal distribution. Their fractal dimensions increased with an increase in the duration of exposure. Intergranular corrosion and exfoliation corrosion appeared in the specimens after 20 years, where the product of corrosion was Al(OH)3. The impedances and thermal properties of the epoxy coatings were influenced by the synergistic effects of aging and post-curing. The impedances of the coatings decreased greatly after long-term atmospheric exposure. After 20 years of corrosion, the specimen showed the characteristics of the substrate being corroded. The mechanism of corrosion and the electrochemical equivalent circuit were also analyzed.

scholarly journals Corrosion Fatigue Characteristics of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1046
Author(s):  
Balachander Gnanasekaran ◽  
Jie Song ◽  
Vijay Vasudevan ◽  
Yao Fu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Corrosion Properties ◽  
Powder Bed ◽  
Fatigue Characteristics

Laser powder bed fusion (LPBF) has been increasingly used in the fabrication of dense metallic structures. However, the corrosion related properties of LPBF alloys, in particular environment-assisted cracking, such as corrosion fatigue properties, are not well understood. In this study, the corrosion and corrosion fatigue characteristics of LPBF 316L stainless steels (SS) in 3.5 wt.% NaCl solution have been investigated using an electrochemical method, high cycle fatigue, and fatigue crack propagation testing. The LPBF 316L SSs demonstrated significantly improved corrosion properties compared to conventionally manufactured 316L, as reflected by the increased pitting and repassivation potentials, as well as retarded crack initiation. However, the printing parameters did not strongly affect the pitting potentials. LPBF samples also demonstrated enhanced capabilities of repassivation during the fatigue crack propagation. The unique microstructural features introduced during the printing process are discussed. The improved corrosion and corrosion fatigue properties are attributed to the presence of columnar/cellular subgrains formed by dislocation networks that serve as high diffusion paths to transport anti-corrosion elements.

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