本文關(guān)鍵詞： Mg-Zn-Y-Nd-xCu 合金 熱 擠壓 力學(xué) 性能 降解性能 抗菌性能　出處：《鄭州大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：生物鎂合金具有良好的生物相容性、可降解性能及與人體密質(zhì)骨相近的彈性模量,能夠有效避免“應(yīng)力遮擋效應(yīng)”,具有非常廣闊的應(yīng)用前景。然而鎂及其合金的力學(xué)性能和耐蝕性能比較差,不能滿足醫(yī)用金屬材料的要求,且不具備抗菌作用,容易引發(fā)術(shù)后感染。本文在Mg-Zn-Y-Nd合金中添加具有抗菌作用的Cu元素,使合金具備抗菌性能,然后通過擠壓加工處理,細化晶粒、改善合金的組織,從而提高合金的力學(xué)性能和耐蝕性能。采用OM、SEMEDS、XRD來分析合金的顯微組織和物相組成;通過顯微硬度、室溫拉伸實驗測試合金的力學(xué)性能;通過電化學(xué)實驗、失重分析、析氫分析來測試腐蝕性能;最后通過體外抗菌實驗分析合金的抗菌性能。鑄態(tài)Mg-Zn-Y-Nd-xCu合金的晶粒粗大,組織不均勻,存在一定程度的枝晶偏析。隨著Cu含量的增加,合金中第二相數(shù)量逐漸增多,并逐漸相互連接成網(wǎng)狀結(jié)構(gòu)。經(jīng)過擠壓加工后,合金的晶粒得到明顯細化,組織變?yōu)榈容S晶,第二相顆粒大部分固溶進基體,剩余部分彌散分布在晶粒內(nèi)部。隨著Cu含量的增加,擠壓態(tài)Mg-Zn-Y-Nd-xCu合金的晶粒逐漸變小,晶粒尺寸由0.1wt.%Cu時的18μm減小到0.5wt.%Cu時的3μm。Cu加入以后合金中形成了CuMg2相,鑄態(tài)Mg-Zn-Y-Nd-xCu合金的顯微組織由鎂基體和第二相(MgZn,CuMg2,Mg12YZn,Mg41Nd5)組成。經(jīng)過擠壓加工以后,只在擠壓態(tài)Mg-Zn-Y-Nd-0.5Cu合金中檢測到CuMg2二元相的存在,主要是因為含0.1wt.%Cu和0.3wt.%Cu的合金在熱擠壓過程中,Cu元素全部或者大部分固溶進入基體,導(dǎo)致含Cu第二相的體積分數(shù)大大減少,因此,沒有檢測出CuMg2相的存在。鑄態(tài)Mg-Zn-Y-Nd-xCu合金中CuMg2相的存在降低了鎂合金的力學(xué)性能。經(jīng)過擠壓加工,合金的抗拉強度和伸長率都得到明顯的提高,其中擠壓態(tài)Mg-Zn-Y-Nd-0.1Cu合金的抗拉強度能夠達到325MPa。隨著Cu含量的增加,擠壓態(tài)合金的力學(xué)性能逐漸降低。由于Cu的加入,合金中形成了CuMg2相,在腐蝕過程中該相和鎂基體形成原電池,增加了鎂合金基體的電偶腐蝕,降低了鎂合金的耐蝕性能。經(jīng)過擠壓加工以后,合金的晶粒得到明顯細化,組織比較均勻,并且第二相顆粒大部分固溶進入基體中,擠壓態(tài)合金的耐蝕性能優(yōu)于鑄態(tài)合金。隨著Cu含量的增加,擠壓態(tài)合金的耐蝕性能逐漸降低。通過抗菌實驗可知,擠壓態(tài)Mg-Zn-Y-Nd合金本身則不具有抗菌作用,擠壓態(tài)Mg-Zn-Y-Nd-xCu合金對大腸桿菌和金黃色葡萄球菌的抗菌率均在99%以上,符合Ⅰ級抗菌材料的要求,具有強烈的抗菌作用。隨著Cu含量的增加,擠壓態(tài)合金的抗菌性能逐漸增加。通過對Mg-Zn-Y-Nd-xCu合金進行擠壓加工,以期獲得合金在有限的服役期內(nèi),能夠保持機械性能的穩(wěn)定性,同時在降解過程中釋放的Cu離子又具有很好的抗菌效果,為鎂合金作為醫(yī)用材料的臨床應(yīng)用提供理論依據(jù)。
[Abstract]:Magnesium alloys have good biocompatibility, biodegradability and elastic modulus similar to those of human dense bone. It can effectively avoid the "stress shielding effect", and has a very broad application prospect. However, the mechanical properties and corrosion resistance of magnesium and its alloys are relatively poor, which can not meet the requirements of medical metal materials, and have no antimicrobial effect. It is easy to cause postoperative infection. In this paper, the antibacterial Cu element is added to the Mg-Zn-Y-Nd alloy to make the alloy have antibacterial properties, and then through extrusion processing, the grain size is refined and the microstructure of the alloy is improved. In order to improve the mechanical properties and corrosion resistance of the alloy, the microstructure and phase composition of the alloy were analyzed by OMSEMEDS XRD, the mechanical properties of the alloy were tested by microhardness and tensile test at room temperature, and the mechanical properties of the alloy were measured by electrochemical experiment and weightlessness analysis. The corrosion resistance was tested by hydrogen evolution analysis. Finally, the antibacterial properties of the as-cast Mg-Zn-Y-Nd-xCu alloy were analyzed by in vitro antibacterial experiments. The as-cast Mg-Zn-Y-Nd-xCu alloy had coarse grains, uneven microstructure and a certain degree of dendritic segregation. The number of the second phase in the alloy gradually increased, and gradually connected to each other into a network structure. After extrusion, the grain size of the alloy was obviously refined, the structure was changed into equiaxed crystal, and most of the second phase particles were dissolved into the matrix. With the increase of Cu content, the grain size of extruded Mg-Zn-Y-Nd-xCu alloy becomes smaller, and the grain size decreases from 18 渭 m at 0.1wt.Cu to 3 渭 m.Cu at 0.5wt.Cu to form CuMg2 phase. The microstructure of the as-cast Mg-Zn-Y-Nd-xCu alloy is composed of magnesium matrix and the second phase MgZnZn-CuMg2OMg-12YZnOMg-41Nd5. After extrusion processing, the existence of binary phase of CuMg2 is detected only in the extruded Mg-Zn-Y-Nd-0.5Cu alloy. It is mainly because the alloy containing 0.1wt.Cu and 0.3wt.Cu is completely or mostly dissolved into the matrix during hot extrusion, resulting in the decrease of the volume fraction of the second phase containing Cu. No CuMg2 phase was detected. The presence of CuMg2 phase in as-cast Mg-Zn-Y-Nd-xCu alloy reduced the mechanical properties of magnesium alloy. After extrusion, the tensile strength and elongation of the alloy were obviously improved. The tensile strength of the extruded Mg-Zn-Y-Nd-0.1Cu alloy can reach 325 MPA. With the increase of Cu content, the mechanical properties of the extruded Mg-Zn-Y-Nd-0.1Cu alloy decrease gradually. Due to the addition of Cu, the CuMg2 phase is formed in the alloy. The galvanic corrosion of magnesium alloy matrix is increased, and the corrosion resistance of magnesium alloy is reduced. After extrusion, the grain size of the alloy is refined and the microstructure is uniform, and most of the second phase particles are dissolved into the matrix. The corrosion resistance of the extruded alloy is better than that of the as-cast alloy. With the increase of Cu content, the corrosion resistance of the extruded alloy decreases gradually. The antibacterial rates of extruded Mg-Zn-Y-Nd-xCu alloy against Escherichia coli and Staphylococcus aureus were above 99%, which met the requirements of class I antibacterial materials and had strong antibacterial effect. The antibacterial properties of the extruded alloy gradually increased. By extruding the Mg-Zn-Y-Nd-xCu alloy, the stability of the mechanical properties of the alloy was obtained during the limited service period. At the same time, the release of Cu ions in the degradation process has a good antibacterial effect, which provides a theoretical basis for the clinical application of magnesium alloys as medical materials.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG146.22;R318.08

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