Effect of biologically relevant ions on the corrosion products formed on alloy AZ31B: An improved understanding of magnesium corrosion
Effect of biologically relevant ions on the corrosion products formed on alloy AZ31B: An improved understanding of magnesium corrosion
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DOI：
10.1016/j.actbio.2013.03.026
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发表时间：
2013-11-01
影响因子：
9.7
通讯作者：
Yun, Yeoheung
中科院分区：
文献类型：
--
作者：
Jang, Yongseok;Collins, Boyce;Yun, Yeoheung
模拟人体血浆的模拟生理溶液已被用于研究可生物降解金属的体外腐蚀。然而，不同溶液的腐蚀和腐蚀产物形成是不同的，具有不同的响应，因此，仅根据这些研究预测体内降解行为是不可行的。本文报道了生理相关的盐及其浓度对镁合金（AZ 31 B）的腐蚀行为和随后的腐蚀产物形成的作用。采用浸泡试验方法，研究了3种不同浓度的Ca 2+、HPO 42-、HCO 3-对AZ 31 B镁合金在浸泡1、3、10 d后的腐蚀情况。使用X射线计算机断层扫描和扫描电子显微镜进行样品的延时形态表征。通过电子色散X射线光谱和X射线衍射确定了表面腐蚀产物的化学组成。结果表明：（1）当溶液中只有Cl-和OH-时，腐蚀产物层中不存在钙离子;（2）当溶液中存在HPO_（42-）和Cl-时，磷酸盐的存在诱导形成致密的无定形磷酸镁腐蚀产物层;（3）当HPO_（42-）和Ca ~（2+）同时存在时，在镁合金表面沉积了磷酸八钙和羟基磷灰石（HAp（该涂层限制了局部腐蚀并提高了总体耐腐蚀性）;（4）HCO 3-的加入加速了总体腐蚀速率，其随着碳酸氢盐浓度的增加而增加;（5）当HCO 3-、Ca 2+和HPO 42-一起存在时，由于在表面上形成不溶性HAp，腐蚀速率降低。(C)2013 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Simulated physiological solutions mimicking human plasma have been utilized to study the in vitro corrosion of biodegradable metals. However, corrosion and corrosion product formation are different for different solutions with varied responses and, hence, the prediction of in vivo degradation behavior is not feasible based on these studies alone. This paper reports the role of physiologically relevant salts and their concentrations on the corrosion behavior of a magnesium alloy (AZ31B) and subsequent corrosion production formation. Immersion tests were performed for three different concentrations of Ca2+, HPO42-, HCO3- to identify the effect of each ion on the corrosion of AZ31B assessed at 1,3 and 10 days. Time-lapse morphological characterization of the samples was performed using X-ray computed tomography and scanning electron microscopy. The chemical composition of the surface corrosion products was determined by electron dispersive X-ray spectroscopy and X-ray diffraction. The results show that: (1) calcium is not present in the corrosion product layer when only Cl- and OH- anions are available; (2) the presence of phosphate induces formation of a densely packed amorphous magnesium phosphate corrosion product layer when HPO42- and Cl- are present in solution; (3) octacalcium phosphate and hydroxyapatite (HAp) are deposited on the surface of the magnesium alloy when HPO42- and Ca2+ are present together in NaCl solution (this coating limits localized corrosion and increases general corrosion resistance); (4) addition of HCO3- accelerates the overall corrosion rate, which increases with increasing bicarbonate concentration; (5) the corrosion rate decreases due to the formation of insoluble HAp on the surface when HCO3-, Ca2+, and HPO42- are present together. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.