Mg-1Zn-xMn合金微弧氧化膜层的组织结构及腐蚀行为研究
发布时间：2018-09-07 07:31
【摘要】：镁合金由于弹性模量低、密度与人骨接近、生物相容性良好、可降解等优点,在生物植入材料领域展示了良好的应用前景。然而纯镁及其合金在pH值为7.4～7.6、富Cl-的复杂生理系统环境中,腐蚀速度过快,易造成氢气聚集导致植入部位的炎性反应,同时也会造成镁合金植入物过早地失去其机械完整性,达不到服役时间要求。因此,改善镁合金的耐蚀性并研究其腐蚀机理成为生物医用镁合金材料亟待解决的问题。合金化和表面处理是两种有效提高镁合金耐蚀性能的方法。本文选择Zn、Mn作为合金化元素,通过熔铸、均匀化热处理、正挤压等一系列手段制备出不同锰含量的Mg-1Zn-xMn (x=0.8, 1.0, 1.2wt%)镁合金,再采用微弧氧化工艺对镁合金进行表面陶瓷化处理。研究了 Mg-1Zn-xMn镁合金进行微弧氧化工艺处理后的微观组织及其在SBF模拟体液中的腐蚀性能,讨论了表面陶瓷膜层的组织与腐蚀性能之间的关系。得出以下主要结论:(1) Mg-1Zn-xMn合金微弧氧化陶瓷层与基体结合良好,主要相组成为MgO和Mg2Si04。陶瓷层由多孔的疏松层和致密层组成。随着微弧氧化时间延长,陶瓷层缺陷增多,出现了较大的放电微孔。陶瓷层上存在微裂纹,是由于熔融物的不均匀冷却造成的。(2)在相同微弧氧化工艺参数下,Mg-1Zn-0.8Mn合金微弧氧化陶瓷层的孔隙率最小,腐蚀电流密度也最小,其耐蚀性最佳。(3)表面陶瓷层可以显著提高合金的硬度,随微弧氧化时间增加,膜层变厚,硬度增大。微弧氧化3min (陶瓷层厚为5μm)的Mg-1Zn-1Mn合金硬度值为178HV,微弧氧化5min (陶瓷层厚为10μm)时合金硬度为274HV。微弧氧化陶瓷层可使Mg-1Zn-xMn镁合金硬度值提高3-4倍。(4)微弧氧化可以显著提高Mg-1Zn-xMn合金的耐腐蚀性。Mg-1Zn-1Mn合金的电化学腐蚀速率为0.252 mm/a,微弧氧化5min可使合金的腐蚀速率降低至0.026 mm/a,耐腐蚀性提高近10倍。(5)在37℃的SBF溶液中浸泡15天后,微弧氧化5 min的合金质量损失最小,耐蚀性能最好,腐蚀以点蚀和丝状腐蚀为主。合金表面的腐蚀产物主要由HA(Ca10(OH)2(PO4)6).MgCl2 和 Mg(OH)2 组成。
[Abstract]:Due to its low elastic modulus, close density to human bone, good biocompatibility and biodegradability, magnesium alloy has shown a good application prospect in the field of biological implant materials. However, the corrosion rate of pure magnesium and its alloys is too fast in the complex physiological system with a pH value of 7.4 ~ 7.6 and rich in Cl-, which leads to the accumulation of hydrogen and the inflammatory reaction of the implanted site. At the same time, magnesium alloy implants will lose their mechanical integrity prematurely and fail to meet the service time requirement. Therefore, improving the corrosion resistance of magnesium alloy and studying its corrosion mechanism become the urgent problem of biomedical magnesium alloy materials. Alloying and surface treatment are two effective methods to improve corrosion resistance of magnesium alloys. In this paper, Zn,Mn was chosen as alloying element. Magnesium alloys with different manganese content were prepared by melting casting, homogenizing heat treatment, forward extrusion and so on. Magnesium alloys with different manganese contents were prepared by micro-arc oxidation. The microstructure of Mg-1Zn-xMn magnesium alloy treated by micro-arc oxidation and its corrosion resistance in simulated body fluid of SBF were studied. The relationship between the microstructure and corrosion resistance of ceramic film on the surface was discussed. The main conclusions are as follows: (1) Mg-1Zn-xMn alloy ceramic coating of micro-arc oxidation binds well to the matrix, and the main phase composition is MgO and Mg2Si04.. The ceramic layer consists of porous loose layer and dense layer. With the increase of the time of micro-arc oxidation, the defects of ceramic layer increase and large discharge micropores appear. The microcracks on the ceramic layer are caused by the inhomogeneous cooling of the melt. (2) under the same process parameters of micro-arc oxidation, the porosity and corrosion current density of the ceramic layer of Mg-1Zn-0.8Mn alloy are minimum. (3) the hardness of the alloy can be improved by ceramic coating. With the increase of the time of micro-arc oxidation, the film becomes thicker and the hardness increases. The hardness of Mg-1Zn-1Mn alloy with microarc oxidation (5 渭 m ceramic layer thickness) is 178HVV, and 274HV with 5min (ceramic layer thickness 10 渭 m). (4) Micro-arc oxidation can significantly improve the corrosion resistance of Mg-1Zn-xMn alloy. The electrochemical corrosion rate of Mg-1Zn-1Mn alloy is 0.252 mm/a, 5min can reduce the corrosion rate of Mg-1Zn-xMn alloy. The corrosion resistance of 0.026 mm/a, was increased by nearly 10 times. (5) after soaking in SBF solution at 37 鈩，
本文编号：2227618
[Abstract]:Due to its low elastic modulus, close density to human bone, good biocompatibility and biodegradability, magnesium alloy has shown a good application prospect in the field of biological implant materials. However, the corrosion rate of pure magnesium and its alloys is too fast in the complex physiological system with a pH value of 7.4 ~ 7.6 and rich in Cl-, which leads to the accumulation of hydrogen and the inflammatory reaction of the implanted site. At the same time, magnesium alloy implants will lose their mechanical integrity prematurely and fail to meet the service time requirement. Therefore, improving the corrosion resistance of magnesium alloy and studying its corrosion mechanism become the urgent problem of biomedical magnesium alloy materials. Alloying and surface treatment are two effective methods to improve corrosion resistance of magnesium alloys. In this paper, Zn,Mn was chosen as alloying element. Magnesium alloys with different manganese content were prepared by melting casting, homogenizing heat treatment, forward extrusion and so on. Magnesium alloys with different manganese contents were prepared by micro-arc oxidation. The microstructure of Mg-1Zn-xMn magnesium alloy treated by micro-arc oxidation and its corrosion resistance in simulated body fluid of SBF were studied. The relationship between the microstructure and corrosion resistance of ceramic film on the surface was discussed. The main conclusions are as follows: (1) Mg-1Zn-xMn alloy ceramic coating of micro-arc oxidation binds well to the matrix, and the main phase composition is MgO and Mg2Si04.. The ceramic layer consists of porous loose layer and dense layer. With the increase of the time of micro-arc oxidation, the defects of ceramic layer increase and large discharge micropores appear. The microcracks on the ceramic layer are caused by the inhomogeneous cooling of the melt. (2) under the same process parameters of micro-arc oxidation, the porosity and corrosion current density of the ceramic layer of Mg-1Zn-0.8Mn alloy are minimum. (3) the hardness of the alloy can be improved by ceramic coating. With the increase of the time of micro-arc oxidation, the film becomes thicker and the hardness increases. The hardness of Mg-1Zn-1Mn alloy with microarc oxidation (5 渭 m ceramic layer thickness) is 178HVV, and 274HV with 5min (ceramic layer thickness 10 渭 m). (4) Micro-arc oxidation can significantly improve the corrosion resistance of Mg-1Zn-xMn alloy. The electrochemical corrosion rate of Mg-1Zn-1Mn alloy is 0.252 mm/a, 5min can reduce the corrosion rate of Mg-1Zn-xMn alloy. The corrosion resistance of 0.026 mm/a, was increased by nearly 10 times. (5) after soaking in SBF solution at 37 鈩，
本文编号：2227618
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/2227618.html
