Quantitative Evaluation of the Interaction Between Wear and Corrosion on Mg-3Gd-1Zn Alloy in Simulated Body Fluid
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Quantitative Evaluation of the Interaction Between Wear and Corrosion on Mg-3Gd-1Zn Alloy in Simulated Body Fluid Xiaobo Zhang, Jianwei Dai, Jie Zhang, and Yunqiang Bai (Submitted May 11, 2018; in revised form October 9, 2018; published online November 26, 2018) As potential temporary implants, biodegradable magnesium (Mg) alloys will undergo fretting friction and corrosion simultaneously in human body. Aiming at illustrating the interaction between wear and corrosion of Mg alloys, wear and corrosion rates in simulated body fluid (SBF) were quantitatively evaluated on Mg3Gd-1Zn (wt.%, GZ31) alloy. Wear behaviors of the alloy in SBF were compared with those under dry sliding condition, and corrosion rates of the alloy accompanied with wear were also compared with those without wear in SBF. The characteristic parameters of wear tracks were collected by 3D surface profile. The results indicated that the friction coefficient in SBF was much lower as compared to that under dry sliding condition. Owing to the protection of Mg(OH)2 and lubrication of SBF, wear was significantly restricted, but due to the galvanic corrosion between matrix and wear debris, corrosion was seriously aggravated. Most of the mass loss was attributed to corrosion rather than wear for the wear test in SBF. Keywords
biomaterial, corrosion and wear, magnesium
1. Introduction Owing to good biodegradation, biocompatibility, mechanical and physical properties (Ref 1-3), Mg alloys have become the most promising metallic materials in orthopedic implants, the representative examples of which are bone plates and screws (Ref 4-7). Biodegradable Mg alloys play an important impermanent role in providing adequate strength in service and then degrade completely after they finish supporting or connecting tasks (Ref 8-10). Fretting and corrosion may occur at the interfaces between human bone and implants (Ref 11, 12). The keel failure caused by the aseptic loosening may be essentially owing to the wear debris and corrosion particles (Ref 12). And it is suspected that the bone screws would suffer from wear during the initial implanting process. Tribocorrosion was also detected at the contacting interfaces between the implants subject to minute relative movements according to the studies (Ref 13-16). Recent study has found that the nitinol spinal rods were sensitive to fretting corrosion on the surfaces in conjunction with titanium pedicle screws (Ref 13). In general, the fretting and corrosion behaviors are unavoidable due to the service condition in human body, which would accelerate failure of implants, including titanium alloys and stainless steels currently used in clinic (Ref 17-20). It has been indicated that periprosXiaobo Zhang, Jianwei Dai, and Yunqiang Bai, School of Materials Engineering, Nanjing Institute of Technology, Nanjing 211167, China; and Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing 211167, China; Jie Zhang, School of Materials Engineering, Nanjing Institute of Techn
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