A strain-mediated corrosion model for bioabsorbable metallic stents

Galvin, Emmet; O’Brien, Dónal; Cummins, Christy; Donald, Bryan J. Mac; Lally, Caitríona

doi:10.1016/j.actbio.2017.04.020

Cited by 34 publications

(14 citation statements)

References 31 publications

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“…The morphology of Si particles and its distribution play essential roles in the electrochemical properties of Al-Si alloy. The cathodic behavior of Si within the Al-rich matrix contributes to the occurrence of localized corrosion, with the formation of microgalvanic couples [2,3], which also leads to poor mechanical behavior, such as in stent applications [4]. The reduction in the area ratio of noble Si particles (cathode) to less-noble eutectic Al phase (anode) around Si particles largely improves pitting corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evaluation and Corrosion Resistance of Semisolid Cast A356 Alloy Processed by Equal Channel Angular Pressing

Gebril

Omar

Mohamed

et al. 2019

Metals

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As-cast and semisolid casting using a cooling slope A356 alloy were processed by equal channel angular pressing (ECAP) for Si and grain refinement. The ECAP was conducted at room temperature in a mold, with a channel angle of 120°, and this resulted in a significant size reduction of grain and Si particles from 170.5 and 4.22 to 23.12 and 0.71 µm, respectively, after six passes of heat-treated cooling slope casting, using the ECAP process. The hardness increased with ECAP processing, from 61 HV, for the as-cast alloy, to 134 Hv, after six passes of heat-treated cooling slope casting. The corrosion resistance of the alloy improved, from 0.042 to 0.0012 mmy−1, after the ECAP process. In this work both the strength and corrosion resistance of the ECAPed A356 alloys were improved with the application of the cooling slope process than without (i.e., from the as-cast condition).

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Section: Introductionmentioning

confidence: 99%

Microstructural Evaluation and Corrosion Resistance of Semisolid Cast A356 Alloy Processed by Equal Channel Angular Pressing

Gebril

Omar

Mohamed

et al. 2019

Metals

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“…Silicon particles with small sizes will make the re-passive process much easy (Fadavi & Tahamtan 2010). The refining of Al-Si-Mg alloy microstructure lead to improvement of mechanical and electrochemical properties due to the refining of the essentially component of eutectic phase from flake shape to fine Si particles morphology (Galvin et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Effect of Equal Channel Angular Pressing Processing Routes on Corrosion Resistance and Hardness of Heat Treated A356 Alloy

Gebril

Omar²,

Othman³

et al. 2019

JSM

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Equal channel angular pressing (ECAP) via routes A and Bc was used to process heat treated A356 alloy. The samples produced a range of microstructures in order to investigate the effect of straining on its corrosion behavior in 3.5 wt. % NaCl solution and hardness. The ECAP was conducted at room temperature in a mold with channel angle of 120°. The results show that brittle coarse silicon particles were effectively fragmented into smaller size in the Al-rich matrix after the processing. The hardness and corrosion resistance test showed improvement after T5 and T6 heat treatment, preferably to T6 due to wholly changed in silicon particles morphology than T5. The hardness increased with ECAP processing from 60.66 Hv to 1133.47, 124.91 Hv after three passes route Bc and four passes route A, respectively. The evaluation of corrosion resistance of the alloy showed improvement from 0.0424 to 0.00173, 0.00149 mmy -1 after three passes route Bc and four passes route A, respectively. In this research, both strength and corrosion resistance are improved by ECAP processing of A356 alloy using both routes. ABSTRAKDalam kajian ini, kaedah penekanan sudut saluran sama melalui laluan A dan Bc telah digunakan untuk memproses aloi A356 yang dirawat dengan rawatan haba. Sampel dengan pelbagai jenis mikrostruktur telah disediakan untuk mengkaji kesan terikan terhadap kekerasan dan sifat kakisan aloi A356 dalam larutan NaCl 3.5%. Kaedah ECAP dijalankan pada suhu bilik dengan menggunakan acuan yang mempunyai sudut saluran 120°. Keputusan kajian menunjukkan bahawa selepas pemprosesan, partikel silikon kasar dan rapuh bersepai menjadi partikel bersaiz kecil dalam matriks kaya Al. Ujian kekerasan dan ujian ketahanan kakisan menunjukkan bahawa sifat mekanik aloi A356 bertambah baik selepas rawatan haba T5 dan T6, terutamanya T6, disebabkan perubahan morfologi partikel silikon yang begitu ketara. Kekerasan aloi A356 masing-masing meningkat daripada 60.66 Hv kepada1133.47 Hv dan 124.91 Hv selepas pemprosesan ECAP melalui laluan Bc tiga kali dan laluan A empat kali. Keputusan penilaian menunjukkan bahawa ketahanan kakisan aloi masing-masing meningkat daripada 0.0424 kepada 0.00173 dan 0.00149 mmy -1 selepas pemprosesan ECAP melalui laluan Bc tiga kali dan laluan A empat kali. Oleh itu, dapat disimpulkan bahawa kekuatan dan ketahanan kakisan aloi A356 meningkat dengan menggunakan kaedah pemprosesan ECAP melalui kedua-dua laluan.

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“…The cathodic behaviour of Si within the Al-rich matrix contributes to the occurrence of localized corrosion with the formation of micro-galvanic couples (Davis 2001), which in turn contributes to poor mechanical behavior such as in the stent applications (Galvin et al 2017). A reduction in the area ratio of noble Si particles (cathode) to less-noble eutectic Al phase (anode) around Si particles significantly improve pitting corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Refinement and Corrosion Resistance Improvement of Heat-Treated A356 Alloy Processed by Equal Channel Angular Pressing

Gebril¹,

Omar²,

Othman³

et al. 2019

JSM

View full text Add to dashboard Cite

The microstructure refinement, hardness and corrosion resistance of heat-treated A356 aluminium alloy processed by equal-channel angular pressing (ECAP) were investigated. ECAP was carried out at room temperature using a mold, with a channel angle of 120° via route A. Results of the investigation confirm that the flaky coarse silicon particles were effectively fragmented from 4.22 to 0.761 µm and the grain size reduced from 171 to 40 µm after four passes of heattreated as-cast using ECAP process. ECAP processing increases the hardness of heat-treated as-cast alloy from 61 Hv to 125 HV after four passes. Heat-treated A356 alloy shows enhanced corrosion resistance from 0.0424 to 0.00149 mmy-1 , after four passes. In this research, ECAP processing has been shown to improve the hardness and corrosion resistance of as-cast A356 alloy.

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A strain-mediated corrosion model for bioabsorbable metallic stents

Cited by 34 publications

References 31 publications

Microstructural Evaluation and Corrosion Resistance of Semisolid Cast A356 Alloy Processed by Equal Channel Angular Pressing

Microstructural Evaluation and Corrosion Resistance of Semisolid Cast A356 Alloy Processed by Equal Channel Angular Pressing

Effect of Equal Channel Angular Pressing Processing Routes on Corrosion Resistance and Hardness of Heat Treated A356 Alloy

Microstructural Refinement and Corrosion Resistance Improvement of Heat-Treated A356 Alloy Processed by Equal Channel Angular Pressing

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