生物医用可降解镁基大块非晶合金的制备及其表面微弧氧化改性
发布时间：2018-08-08 14:33
【摘要】：金属镁及其合金由于优异的生物相容性,与自然骨相近的密度和力学性能,在众多材料中脱颖而出成为最具潜力的可降解金属骨移植材料。但是由于其腐蚀速率过快,往往在植入初期就无法保证自身结构的完整性,限制了该材料的临床应用。合金化和表面改性是两种较为有效的降低镁合金腐蚀速率的方法,研究者对此做了大量研究,虽取得了一定进展却仍不尽如人意。近年来,镁基大块非晶合金的出现为寻求合适腐蚀速率的镁基可降解金属医用材料打开了一扇新的大门。它们的单相结构、化学均匀性和无晶界等特点可以有效减弱电偶腐蚀效应,使其耐蚀性优于同成分的晶态合金。本文设计并制备了MgZnCa和MgZnCaSi两种体系的块体非晶合金,并结合微弧氧化技术对其表面进行了改性处理,以改善非晶合金表面的生物活性和进一步提高其耐蚀性能。通过铜模喷铸法成功制备出临界铸造尺寸为5 mm的Mg_(65.2)Zn_(28.8)Ca_6非晶合金,以硅酸钠(Na_2SiO_3·9H_2O),四硼酸钠(Na2B4O7·10H2O)和氢氧化钠(NaOH)为电解液,采用恒压模式对非晶合金进行微弧氧化处理。测试发现:涂层由MgO,CaO,MgSiO_3和Zn_2SiO_4相构成。涂层表面多孔内部致密并未发现有因热应力造成的微裂纹生成。与未经处理的非晶合金样品相比,涂层使基体的耐蚀性明显提高,腐蚀电位和极化电阻分别增加了101 mV和3.246×10~5Ω。模拟体液浸泡实验发现羟基基磷灰石(HA)可以在多孔的涂层表面快速而自发的形成,证实了该涂层具有优良的生物活性。在MgZnCa三元非晶合金体系的基础上添加微量的Si元素,设计并制备出四元非晶合金体系Mg_(66)Zn_(29-x)Ca_5Si_x(at.%,x=0,0.25,0.5,0.75,1)。测试发现:当Si含量为0.5%时,合金的耐蚀性能有所提升,同时玻璃形成能力,室温压缩强度俱佳。为进一步改善镁基非晶合金表面的生物活性,我们采用甘油磷酸钙(Ca-Gp),氢氧化钠(NaOH),磷酸二氢钙(Ca(H_2PO_4)2·H_2O),氟化氢铵(NH_4HF_2)和乙二胺四乙酸二钠(EDTA-2Na)组成的弱碱性电解液体系,在Mg_(66)Zn_(28.5)Ca_5Si_(0.5)非晶合金表面制备了含Ca、P的微弧氧化陶瓷涂层。使用控制变量法,研究了微弧氧化电压、时间以及电解液中的NaOH浓度对膜层结构以及性能的影响。电化学测试表明,Ca、P涂层的腐蚀电流密度只有基体的六分之一,极化电阻提升了一个数量级。之前制备的含硅涂层可以将极化电阻提升两个数量级,显然Ca、P涂层的耐蚀性不如含Si涂层,但其诱导生成的羟基磷灰石数量和结晶性均优于含Si涂层,显示出优异的生物活性。
[Abstract]:Due to their excellent biocompatibility, density and mechanical properties similar to those of natural bone, magnesium and its alloys have become the most promising biodegradable bone graft materials. However, due to its rapid corrosion rate, the integrity of its own structure can not be guaranteed at the early stage of implantation, which limits the clinical application of the material. Alloying and surface modification are two effective methods to reduce the corrosion rate of magnesium alloys. In recent years, the appearance of Mg-based bulk amorphous alloys has opened a new door for magnesium based degradable metal medical materials with appropriate corrosion rate. Their single phase structure, chemical homogeneity and grain boundary characteristics can effectively weaken the galvanic corrosion effect and make their corrosion resistance better than that of the same composition crystalline alloys. In this paper, bulk amorphous alloys of MgZnCa and MgZnCaSi systems were designed and prepared. The surface of amorphous alloys was modified by micro-arc oxidation in order to improve the surface bioactivity and corrosion resistance of amorphous alloys. Mg _ (65.2) Zn _ (28.8) Ca_6 amorphous alloy with critical casting size of 5 mm was successfully prepared by copper mold spray casting. The amorphous alloy was treated by microarc oxidation in constant pressure mode with sodium silicate (Na_2SiO_3 9H_2O), sodium tetraborate (Na2B4O7 10H2O) and sodium hydroxide (NaOH) as electrolyte. It is found that the coating consists of MgO / Cao / MgSiOS _ 3 and Zn_2SiO_4 phase. No microcracks due to thermal stress were found in the porous interior of the coating surface. Compared with the untreated amorphous alloy samples, the corrosion resistance of the coating is obviously improved, the corrosion potential and polarization resistance are increased by 101mV and 3.246 脳 10 ~ (5) 惟, respectively. Simulated body fluid immersion experiments showed that hydroxyapatite (HA) could form on the surface of porous coating rapidly and spontaneously, which proved that the coating had excellent biological activity. A quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x (at 0.250.50.55) was designed and prepared on the basis of adding trace Si on the basis of MgZnCa ternary amorphous alloy system, and a quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x was designed and prepared. It is found that the corrosion resistance of the alloy is improved when Si content is 0.5 and the glass forming ability and compression strength at room temperature are all good. In order to further improve the surface biological activity of Mg-based amorphous alloys, a weakly basic electrolyte system composed of calcium glycerophosphate (Ca-Gp), sodium hydroxide (NaOH), calcium dihydrogen phosphate (Ca (H_2PO_4) 2H 2O), ammonium hydroxide (NH_4HF_2) and ethylenediamine tetraacetate disodium (EDTA-2Na) was used. Microarc oxidation ceramic coatings containing CaOP were prepared on Mg66 Zn28.5 Ca5Si0.5 amorphous alloy. The effects of microarc oxidation voltage, time and concentration of NaOH in electrolyte on the structure and properties of the film were studied by the method of controlling variables. Electrochemical measurements show that the corrosion current density of the coating is only 1/6 of that of the substrate, and the polarization resistance is increased by an order of magnitude. The silicon coating prepared before can increase the polarization resistance by two orders of magnitude. Obviously, the corrosion resistance of CaOP coating is not as good as that of Si-containing coating, but the amount of hydroxyapatite induced by the coating is better than that of Si-containing coating, which shows excellent bioactivity.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8;TG174.4
本文编号：2172090
[Abstract]:Due to their excellent biocompatibility, density and mechanical properties similar to those of natural bone, magnesium and its alloys have become the most promising biodegradable bone graft materials. However, due to its rapid corrosion rate, the integrity of its own structure can not be guaranteed at the early stage of implantation, which limits the clinical application of the material. Alloying and surface modification are two effective methods to reduce the corrosion rate of magnesium alloys. In recent years, the appearance of Mg-based bulk amorphous alloys has opened a new door for magnesium based degradable metal medical materials with appropriate corrosion rate. Their single phase structure, chemical homogeneity and grain boundary characteristics can effectively weaken the galvanic corrosion effect and make their corrosion resistance better than that of the same composition crystalline alloys. In this paper, bulk amorphous alloys of MgZnCa and MgZnCaSi systems were designed and prepared. The surface of amorphous alloys was modified by micro-arc oxidation in order to improve the surface bioactivity and corrosion resistance of amorphous alloys. Mg _ (65.2) Zn _ (28.8) Ca_6 amorphous alloy with critical casting size of 5 mm was successfully prepared by copper mold spray casting. The amorphous alloy was treated by microarc oxidation in constant pressure mode with sodium silicate (Na_2SiO_3 9H_2O), sodium tetraborate (Na2B4O7 10H2O) and sodium hydroxide (NaOH) as electrolyte. It is found that the coating consists of MgO / Cao / MgSiOS _ 3 and Zn_2SiO_4 phase. No microcracks due to thermal stress were found in the porous interior of the coating surface. Compared with the untreated amorphous alloy samples, the corrosion resistance of the coating is obviously improved, the corrosion potential and polarization resistance are increased by 101mV and 3.246 脳 10 ~ (5) 惟, respectively. Simulated body fluid immersion experiments showed that hydroxyapatite (HA) could form on the surface of porous coating rapidly and spontaneously, which proved that the coating had excellent biological activity. A quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x (at 0.250.50.55) was designed and prepared on the basis of adding trace Si on the basis of MgZnCa ternary amorphous alloy system, and a quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x was designed and prepared. It is found that the corrosion resistance of the alloy is improved when Si content is 0.5 and the glass forming ability and compression strength at room temperature are all good. In order to further improve the surface biological activity of Mg-based amorphous alloys, a weakly basic electrolyte system composed of calcium glycerophosphate (Ca-Gp), sodium hydroxide (NaOH), calcium dihydrogen phosphate (Ca (H_2PO_4) 2H 2O), ammonium hydroxide (NH_4HF_2) and ethylenediamine tetraacetate disodium (EDTA-2Na) was used. Microarc oxidation ceramic coatings containing CaOP were prepared on Mg66 Zn28.5 Ca5Si0.5 amorphous alloy. The effects of microarc oxidation voltage, time and concentration of NaOH in electrolyte on the structure and properties of the film were studied by the method of controlling variables. Electrochemical measurements show that the corrosion current density of the coating is only 1/6 of that of the substrate, and the polarization resistance is increased by an order of magnitude. The silicon coating prepared before can increase the polarization resistance by two orders of magnitude. Obviously, the corrosion resistance of CaOP coating is not as good as that of Si-containing coating, but the amount of hydroxyapatite induced by the coating is better than that of Si-containing coating, which shows excellent bioactivity.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8;TG174.4
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