Enhanced corrosion resistance and surface bioactivity of AZ31B Mg alloy by high pressure cold sprayed monolayer Ti and bilayer Ta/Ti coatings in simulated body fluid
Enhanced corrosion resistance and surface bioactivity of AZ31B Mg alloy by high pressure cold sprayed monolayer Ti and bilayer Ta/Ti coatings in simulated body fluid
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DOI：
10.1016/j.matchemphys.2020.123627
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发表时间：
2020-12-01
影响因子：
4.6
通讯作者：
Bakhsheshi-Rad, H. R.
中科院分区：
文献类型：
--
作者：
Daroonparvar, M.;Khan, M. U. Farooq;Bakhsheshi-Rad, H. R.
采用高压冷喷涂工艺在AZ31B镁合金表面成功地制备了钛涂层和Ta/Ti涂层。这些涂层(尤其是Ta/Ti涂层)具有较高的硬度，降低了AZ31BMg合金的磨损率。体外生物活性测试、无限聚焦3D测量和能谱分析结果表明，由于高压冷喷钛和Ta/Ti涂层的高度钝化和表面粗糙(岛状)，两种涂层表面的钙磷化合物的成核和生长能力都高于AZ31B镁合金表面，这进一步有利于生物固定。电化学腐蚀和浸泡试验表明，在Hank‘s平衡盐溶液中，在Ti涂层上沉积一层致密的Ta能提高Ti/AZ31B-Mg体系的耐蚀性。Ta/Ti涂层镁合金的R-ct(电荷转移电阻)和垂直条Z垂直条(f=0.01赫兹)值保持了轻微的稳定。这意味着电极/电解液界面的电化学过程在浸泡过程中可能保持非常缓慢的速度。同样，在长期的电化学腐蚀试验中，Ta/Ti涂层的开路电位(OCP)值保持不变。这一行为可能源于高压冷喷涂Ta层相当致密的结构，它显著阻碍了腐蚀性溶液对涂层内部的渗透。Ta/Ti涂层表现出最正的电势、最高的R-ct和最高的垂直条Z垂直条(f=0.01赫兹)值，这表明它是热力学上最稳定的，而且随着时间的推移，在Hank的平衡盐溶液中腐蚀最少。总之，冷喷涂Ta/Ti涂层为镁合金在生物材料领域的应用开辟了一条新的途径。
Ti and Ta/Ti coatings were successfully applied on AZ31B Mg alloy using high pressure cold spray process. These coatings (particularly Ta/Ti coating) with high hardness lowered the wear rate of AZ31BMg alloy. In-vitro bioactivity test, infinite focus 3D measurement and EDS results revealed that the calcium-phosphate (Ca-P) compounds nucleation and growth capabilities on both the coatings surface are higher than AZ31B Mg alloy surface due to the highly passivating nature and rough surface (island-like) of the high pressure cold sprayed Ti and Ta/Ti coatings, which are further conducive to the biological fixation. Electrochemical corrosion and immersion tests disclosed that a dense layer of Ta on Ti coating was able to enhance the corrosion resistance of Ti/ AZ31B Mg system in the Hank's balanced salt solution. R-ct (charge transfer resistance) and vertical bar Z vertical bar(f=0.01Hz) values for Ta/Ti coated Mg alloy have remained slightly stable. This imparted that the rate of electrochemical processes at the electrode/electrolyte interface could remain very slow in the course of immersion time. Likewise, the OCP (open circuit potential) values of Ta/Ti coating remained constant during long term electrochemical corrosion test. This behavior could originate from fairly dense structure of the high pressure cold sprayed Ta layer which considerably impeded the penetration of corrosive solution into the coating interiors. Ta/Ti coating presented the most positive potential, highest R-ct, and highest vertical bar Z vertical bar(f=0.01Hz) values, suggesting that it is the most thermodynamically stable/least to be corroded in Hank's balanced salt solution over time. In general, cold sprayed Ta/Ti coating might open a new way to broaden the utilization of Mg alloys in the field of biomaterials.