Corrosion of Al-Alloys during Dry/Wet-Repeating Atmospheres with Pure Water and NaCl Solution

Saito, S.; Hiraga, Takuya; Chiba, Makoto; Shibata, Yutaka; Takahashi, Hideaki

doi:10.3323/jcorr.63.570

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…Figure 3a, f indicates that Si-and Fe-enriched areas distribute randomly at the 4043-Al alloy surface after the immersion test and the P/C treatment. The Si-enriched areas correspond to Si phases and the Fe-enriched areas to Al 3 Fe intermetallic compounds [6]. After the 1-day immersion, the specimen surface shows preferential dissolution of Al matrix around the Si phases, while after the 7-day immersion the specimen shows preferential dissolution around both the Si phases and the Al 3 Fe intermetallic compounds.…”

Section: Resultsmentioning

confidence: 98%

“…The local cell corrosion expressed by Eq. 5 may be accelerated in the NaCl solution since the surface of local cathodes is activated by the breakdown of the oxide films on Si phases and Al 3 Fe intermetallic compounds due to the attack of Cl − ions [6]. The largest Δm value, on the 4043-Al, in the NaCl solution would be due to the higher concentration of Si in the specimen.…”

Section: Discussionmentioning

confidence: 99%

“…Aluminum alloy pipes have attracted attention because Al alloys have a thermal conductivity similar to copper, and they would be able to reduce the cost of air conditioners. However, the corrosion resistance of Al alloys is poorer than that of copper, and the corrosion behavior of pure Al and Al alloys has been studied extensively [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Corrosion of Al alloys in repeated wet-dry cycle tests with NaCl solution and pure water at 323 K

Chiba

Saito

Takahashi

et al. 2015

J Solid State Electrochem

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Corrosion of Al alloys was examined by repeated wet-dry cycle tests with 5.5 M NaCl solution and pure water at 323 K and compared with immersion test corrosion. All Al alloy specimens after the immersion tests for 7 days in the NaCl solution showed preferential dissolution of the aluminum matrix around Si phases and Al 3 Fe intermetallic compounds, and in pure water showed formation of thick amorphous hydroxide films. The corrosion rate in pure water was higher than that in the NaCl solution. In the repeated wet-dry cycle test with NaCl solutions, a 0.02-ml droplet of 5.5 M NaCl solutions was initially dripped on specimens at 323 K and left for 690 s to allow the dry up of the droplet, resulting in solid NaCl precipitation. Then, the dissolution and precipitation of NaCl were repeated 150 times by dripping 0.02-ml pure water at 690-s intervals. At the edge of the droplet, pits with 20-100-μm diameter had formed after the 150 cycles, while, at the central areas, the corrosion behavior was similar to that observed in the NaCl immersion test. In similar cycle tests with pure water, dripping of water droplet was also repeated 150 times. Here, needle-like crystalline hydroxides formed at the edge of the droplet, while thick hydroxide films formed at the central areas, like in the pure water immersion test.

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Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Corrosion of Al alloys in repeated wet-dry cycle tests with NaCl solution and pure water at 323 K

Chiba

Saito

Takahashi

et al. 2015

J Solid State Electrochem

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“…The images in Fig. show many shallow pits formed around Si rich areas (dotted line circles), which are where Si‐phases are included in the specimen, and that the number and size of the pits are larger after immersion in 0.2 kmol/m 3 NaCl solution than after immersion in 5.5 kmol/m 3 NaCl solution. This result strongly suggests that preferential dissolution of Al matrix around the Si‐phases occurs during the immersion test in the diluted and concentrated NaCl solutions; there is more corrosion at the lower C NaCl .…”

Section: Resultsmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Effect of NaCl concentration on corrosion of Al alloy during repeated wet–dry cycle tests at 323 K—comparing with corrosion in immersion tests‐

Chiba

Saito

Nagai

et al. 2015

Surface & Interface Analysis

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Corrosion of 4043-Al alloy was examined by repeated wet-dry cycle tests with NaCl solutions at 323 K, and compared with immersion test corrosion in 0.2-5.5 kmol/m 3 NaCl solutions. The Al alloy specimens after the immersion tests for 86.4 ks (1 day) or 604.8 ks (7 days) showed preferential dissolution of the aluminum matrix around Si-phase compounds, and the dissolution was more remarkable at lower NaCl concentrations. Mass loss of the specimens after the 604.8-ks immersion was also higher at lower NaCl concentrations. In the repeated wet-dry cycle tests, a 20 mm 3 droplet of 0.2-5.5 kmol/m 3 NaCl solution was initially dripped on the specimens, and left for 690 s to allow the drying up of the droplet, resulting in solid NaCl precipitation. Then, the dissolution and precipitation of NaCl were repeated a further 149 times by dripping 20-mm 3 pure water at 690-s intervals. The specimens after the 150 cycles showed different corrosion modes at the center and edge of the droplets. At the edge, 40-80 × 10 À6 pits/m 2 of 20-50 μm diameter had formed, showing more corrosion with higher NaCl concentration droplets, and at the droplet center, the corrosion showed preferential dissolution of the aluminum matrix around the Si-phases, similar to the situation in the immersion tests.

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Corrosion Morphology and Rate of Iron and Steel in NaCl Solutions during Repeated Wet-Dry Cycling Condition

et al. 2021

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Steels are widely used for structural material of bridges. Some of bridges have been used for more than half century, and degradation of bridges become severe problems, due to the atmospheric corrosion of metallic materials. Especially, atmospheric corrosion of steel is caused by cycles of wet and dry conditions, and accelerated by evaporation of raindrops containing Clions. In this study, corrosion of pure iron and steels is investigated under wet-dry cycling condition with NaCl solution by scanning electron microscopy (SEM) and 3D-optical microscopy (3D-OM). Initially 20 mm 3 of 0.02 M-NaCl solution was dropped on pure Fe, SM490Y, and SMA490AW specimens, and then, droplets of water were dropped at the same position of the specimens at 9 min intervals for 150 cycles. All specimens were covered with white, black, and reddish corrosion products at the water-dropped position, and the reddish ones became major with increasing water-dropping cycles. SEM images after corrosion product removal showed pitting corrosion on all specimens, and the corrosion was more severe at the edge areas of water-dropped position than at the center areas. 3D-OM obtained after 150 cycles showed that the deepest pit produced at the edge areas were in the order of Fe >> SM490Y = SMA490AW, and that the total volume loss at the edge areas by corrosion were in the order of Fe > SMA490AW > SM490Y. The corrosion mechanism can be explained by higher rates of O 2 supply at the edge areas and denser corrosion products on steel than on Fe.

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Corrosion of Al-Alloys during Dry/Wet-Repeating Atmospheres with Pure Water and NaCl Solution

Cited by 4 publications

References 4 publications

Corrosion of Al alloys in repeated wet-dry cycle tests with NaCl solution and pure water at 323 K

Corrosion of Al alloys in repeated wet-dry cycle tests with NaCl solution and pure water at 323 K

Effect of NaCl concentration on corrosion of Al alloy during repeated wet–dry cycle tests at 323 K—comparing with corrosion in immersion tests‐

Corrosion Morphology and Rate of Iron and Steel in NaCl Solutions during Repeated Wet-Dry Cycling Condition

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