生物活性鍍層與摩擦攪拌效應改善生物可降解性鎂合金抗腐蝕能力之研究

鎂合金為廣泛使用之輕金屬材料，具有生物可降解性並且其彈性模數與人體骨組織相近，可減緩應力遮蔽效應，鎂亦為人體重要的微量元素，因此已被廣泛研究並應用於生醫材料領域。然而鎂合金活性大，在生理環境下容易發生腐蝕，因此改善鎂合金的抗腐蝕性已成為應用上的重要指標。本實驗探討並比較表面披覆生物活性陶瓷鍍層與經過摩擦攪拌改質處理對Mg-Al-Zn、Mg-Li合金在林格氏液及Kokubo模擬體液兩種生理環境下之電化學抗腐蝕特性。實驗結果顯示，不同鎂合金經表面FHA鍍層披覆與摩擦攪拌改質後皆會對於生理體液環境中的腐蝕結果產生影響。其中表面經水熱法披覆FHA鍍層處理的鎂合金擁有最佳的抗腐蝕效果，FHA鍍層有效包覆鎂合金表面形成良好的屏蔽，隔絕鎂合金與生理體液的直接接觸，達到保護效果。影響鎂合金加速腐蝕的原因為鎂合金發生腐蝕的過程中往往伴隨著析氫反應，氫的產生加速鎂合金基材的消耗，表面生成的Mg(OH)2對腐蝕環境中的鎂合金起保護作用，Mg(OH)2層是穩定的，但膜層緻密度影響其抗腐蝕性；在含有Cl離子的生理體液中，氯離子加速整個腐蝕過程，部分被溶解的Mg(OH)2使內部的鎂合金暴露在水溶液中，同時鎂離子與溶液中的氫氧根離子形成新的Mg(OH)2沉積在表層，在這反覆的反應下Mg(OH)2結構變的疏鬆加速鎂合金的腐蝕速度。

關鍵字

鎂合金； FSP ；鍍層；生物活性陶瓷；電化學試驗；腐蝕阻抗

並列摘要

Besides the light-weight and low density, Mg-based alloys are superior in other properties such as strength-to-weight ratio, structural stability and recyclability. Some Mg alloys have also received attentions as the biodegradable metallic implants for biomedical applications. However, Mg alloys are notably characterized by low corrosion resistance in the physiological systems. The purpose of this study is to improve the biodegradation of Mg alloys by the friction stir process (FSP) and forming a surface protective coating. A calcium phosphate compound was used as the coating because of its excellent bioactivity. Thus, a F-doped HA (FHA) coating was synthesized and coated on AZ91, LZ91 and LAZ931 substrates by the hydrothermal process. Surface morphologies, phase compositions and electrochemical performances of FHA coatings on Mg alloys were studied herein. Hydrothermal synthesized FHA coatings and FSP modified Mg alloy substrates were characterized by Grazing-incidence X-ray diffraction (GI-XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The electrochemical properties of uncoated and FHA-coated AZ91, LZ91 and LAZ931 alloys were performed by the electro-polarization tests in the Ringer’s solution and Kokubo’s simulated body fluid (SBF) solution. Through the electrochemical measurements and immersion tests, we can see that the degradation and and corrosion resistance of Mg alloy were significantly increased with the deposition of the hydrothermal FHA coating.

並列關鍵字

Mg alloys ； friction stir process (FSP) ； coating ； bioactive ceramics ； electrochemical test ； corrosion resistance

參考文獻

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生物活性鍍層與摩擦攪拌效應改善生物可降解性鎂合金抗腐蝕能力之研究

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