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Obayi CS, Tolouei R, Mostavan A, Paternoster C, Turgeon S, Okorie BA, Obikwelu DO, Mantovani D. Effect of grain sizes on mechanical properties and biodegradation behavior of pure iron for cardiovascular stent application. BIOMATTER 2016; 6:e959874. [PMID: 25482336 PMCID: PMC5055204 DOI: 10.4161/21592527.2014.959874] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pure iron has been demonstrated as a potential candidate for biodegradable metal stents due to its appropriate biocompatibility, suitable mechanical properties and uniform biodegradation behavior. The competing parameters that control the safety and the performance of BMS include proper strength-ductility combination, biocompatibility along with matching rate of corrosion with healing rate of arteries. Being a micrometre-scale biomedical device, the mentioned variables have been found to be governed by the average grain size of the bulk material. Thermo-mechanical processing techniques of the cold rolling and annealing were used to grain-refine the pure iron. Pure Fe samples were unidirectionally cold rolled and then isochronally annealed at different temperatures with the intention of inducing different ranges of grain size. The effect of thermo-mechanical treatment on mechanical properties and corrosion rates of the samples were investigated, correspondingly. Mechanical properties of pure Fe samples improved significantly with decrease in grain size while the corrosion rate decreased marginally with decrease in the average grain sizes. These findings could lead to the optimization of the properties to attain an adequate biodegradation-strength-ductility balance.
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Affiliation(s)
- Camillus Sunday Obayi
- a Department of Metallurgical & Materials Engineering , University of Nigeria , Nsukka , Nigeria.,b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
| | - Ranna Tolouei
- b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
| | - Afghany Mostavan
- b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
| | - Carlo Paternoster
- b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
| | - Stephane Turgeon
- b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
| | - Boniface Adeleh Okorie
- a Department of Metallurgical & Materials Engineering , University of Nigeria , Nsukka , Nigeria
| | - Daniel Oray Obikwelu
- a Department of Metallurgical & Materials Engineering , University of Nigeria , Nsukka , Nigeria
| | - Diego Mantovani
- b Laboratory for Biomaterials and Bioengineering (CRC-I), Department of Materials Engineering & CHU de Quebec Research Centre, Laval University , Quebec City , Canada
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Grogan J, Leen S, McHugh P. Influence of statistical size effects on the plastic deformation of coronary stents. J Mech Behav Biomed Mater 2013; 20:61-76. [DOI: 10.1016/j.jmbbm.2012.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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van Dorp D, Sattler J, den Otter J, Kelly J. Electrochemistry of anodic etching of 4H and 6H–SiC in fluoride solution of pH 3. Electrochim Acta 2009. [DOI: 10.1016/j.electacta.2009.05.086] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Harewood FJ, McHugh PE. Modeling of Size Dependent Failure in Cardiovascular Stent Struts under Tension and Bending. Ann Biomed Eng 2007; 35:1539-53. [PMID: 17503185 DOI: 10.1007/s10439-007-9326-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 05/02/2007] [Indexed: 11/25/2022]
Abstract
Cardiovascular stents are cylindrical mesh-like metallic structures that are used to treat atherosclerosis. The thickness of stent struts are typically in the range of 50-150 microm. At this microscopic size scale, the tensile failure strain has been shown to be size dependent. Micromechanically representative computational models have captured this size effect in tension. In this paper polycrystalline models incorporating material fracture are used to investigate size effects for realistic stent strut geometries and loading modes. The specific loading a stent undergoes during deployment is uniquely captured and the implications for stent design are considered. Fracture analysis is also performed, identifying trends in terms of strut thickness and loading type. The results show, in addition to the size effect in tension, further size effects in different loading conditions. The results of the loading analyses are combined to produce a tension and bending failure graph. This design safety diagram is presented as a tool to predict failure of stent struts. This study is particularly significant given the current interest in producing smaller stents.
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Affiliation(s)
- F J Harewood
- Department of Mechanical and Biomedical Engineering, National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
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