本文關鍵詞：生物醫(yī)用可降解Zn-Cu合金力學性能和腐蝕性能的研究　出處：《西南交通大學》2017年碩士論文　論文類型：學位論文

  更多相關文章： 可降解金屬 Zn-Cu合金 等通道擠壓 力學性能 腐蝕降解性

【摘要】：生物可降解金屬材料由于其良好的力學性能和可生物降解性能而受到人們廣泛的關注,其中鎂基合金和鐵基合金是研究的熱點,但是由于鎂合金過快的生物降解速率及鐵合金過慢的降解速率難以匹配組織或機體所需,以及鐵基合金腐蝕產物的生物相容性問題,限制了它們在臨床上的使用。而鋅具有介于二者之間的腐蝕電位,并且較均勻的腐蝕類型,使得鋅有望作為新的生物可降解金屬材料。目前關于可降解鋅合金的研究還處于初始階段,只有少量的文獻報道。由于純Zn彈性模量較低,作為生物可吸收材料必須將Zn合金化從而提高純Zn的力學性能。在本文中,我們在鋅中加入不同含量的Cu元素,通過熔煉制備了 Zn-xwt.%Cu(x=0,1,1.5,2,2.5)二元合金,并研究了 Cu含量變化對合金組織和性能的影響,并在此基礎上通過熱處理和等通道擠壓工藝進一步提升材料性能,并研究了加工工藝對合金組織性能的影響。通過電化學平臺及浸泡實驗,本文進一步評價了 Zn-Cu合金的腐蝕行為及降解產物。研究表明,Cu元素的加入能顯著提高合金的強度,隨著元素含量的增加,合金產生固溶強化和第二相強化,使得強度和硬度增加。而合金伸長率隨著Cu含量的增加先升高,后降低,在Cu含量為1wt%時達到最大。對Zn-1Cu和Zn-2.5Cu的等通道研究結果表明,經過等通道擠壓后合金晶粒被擠碎,并且局部出現(xiàn)靜態(tài)再結晶的細晶粒。合金的強度和塑性有很大的提升,其中Zn-2.5Cu在經過2道次的等通道擠壓后抗拉強度和伸長率分別由120MPa、0.5%提高到了 220MPa、35%。經過3道次擠壓后的合金與經過2道次擠壓的結果相比,塑性提高,而強度下降。擠壓后的試樣拉伸斷口形貌具有明顯的韌窩特征。熱處理對合金的顯微組織具有較為明顯的影響。其中經過300℃熱處理1h后的合金晶界清晰明顯,且晶粒組織更細小均勻。將經過熱處理的合金進行3道次的等通道擠壓,結果表明擠壓前熱處理有助于消除內應力,使合金變形更容易。經過300℃熱處理后ECAP 3道次的樣品,晶粒更均勻細小,且強度和塑性均較高,其中強度和伸長率分別為180MPa和45%。采用電化學測試和浸泡實驗對Zn-Cu合金的腐蝕降解性能進行評價,結果表明,Zn及其合金具有較高的自腐蝕電位,腐蝕速率較小。隨著Cu元素的加入及含量的增加,合金的腐蝕速率有所增加,但是變化較小,其中Zn-2.5Cu的腐蝕速率也僅為0.045mm/year,遠低于鎂合金腐蝕速率。經過等通道擠壓后,Zn-Cu合金的腐蝕速率增加,快于鐵基合金的腐蝕速率。浸泡實驗結果表明,在SBF中浸泡一段時間的合金表面腐蝕程度較小,且腐蝕形貌較為均勻,沒有出現(xiàn)嚴重的局部腐蝕。腐蝕產物的EDS結果表明,腐蝕產物主要含有P,Ca,C和O等幾種元素,根據(jù)文獻報道,腐蝕產物可能為磷酸鹽和碳酸鹽。這些結果表明,Zn-Cu合金有可能作為新型的,具有合適的降解速率的可降解金屬材料。
[Abstract]:Biodegradable metallic materials due to its good mechanical properties and biodegradable properties has attracted much attention, including magnesium alloy and Fe based alloy is a hotspot of research, but because of the magnesium alloy rapid biodegradation rate and low degradation rate of iron alloy has been difficult to match the organization or body needed, and corrosion products of iron based alloy the biocompatibility problem, limiting their use in clinical practice. Zinc has a corrosion potential between the two, and a more uniform corrosion type, which makes zinc promising as a new biodegradable metal material. At present, the research on degradable zinc alloys is still in the initial stage, and only a small amount of literature is reported. Because of the low elastic modulus of pure Zn, it is necessary to allot Zn as a bioabsorbable material to improve the mechanical properties of pure Zn. In this paper, we added different content of Cu element in zinc smelting, through the preparation of Zn-xwt.%Cu (x=0,1,1.5,2,2.5) two alloy, and studied the influence of Cu content on Microstructure and mechanical properties, and on the basis of the heat treatment and ECAP process to further improve the properties of materials, and study effect of processing technology on Microstructure and properties of. The corrosion behavior and degradation products of Zn-Cu alloy were further evaluated by electrochemical platform and soaking experiment. The research shows that the addition of Cu can significantly improve the strength of the alloy. With the increase of the element content, the alloy will produce solid solution strengthening and the second phase strengthening, so that the strength and hardness will increase. The elongation of the alloy increases first and then decreases with the increase of Cu content, and reaches the maximum when the content of Cu is 1wt%. The results of the equal channel study of Zn-1Cu and Zn-2.5Cu show that the grain of the alloy is crushed after the equal channel extrusion and the fine grain of static recrystallization occurs locally. The strength and plasticity of the alloy have been greatly improved. The tensile strength and elongation of Zn-2.5Cu increased from 120MPa and 0.5% to 220MPa and 35% after 2 passes. After 3 passes of extrusion, the strength of the alloy is improved and the strength is decreased compared with the result of 2 pass extrusion. The tensile fracture morphology of the specimen after extrusion has obvious dimple characteristics. Heat treatment has an obvious effect on the microstructure of the alloy. The grain boundary of the alloy after 1h heat treatment at 300 C is clear and clear, and the grain structure is even smaller and even. The heat treated alloy is extruded at the 3 pass channel. The results show that the heat treatment before extrusion can help eliminate the internal stress and make the alloy more easily deformed. After heat treatment at 300 C, the samples of ECAP 3 pass are more uniform and finer, and the strength and plasticity are higher, and the strength and elongation are 180MPa and 45%, respectively. The corrosion and degradation properties of Zn-Cu alloy were evaluated by electrochemical test and immersion test. The results showed that Zn and its alloys had higher self corrosion potential and smaller corrosion rate. With the addition of Cu and the increase of content, the corrosion rate of alloy increases, but the change is small. The corrosion rate of Zn-2.5Cu is only 0.045mm/year, which is much lower than that of magnesium alloy. After the equal channel extrusion, the corrosion rate of the Zn-Cu alloy increases, which is faster than the corrosion rate of the iron base alloy. The soaking test results showed that the corrosion degree of the alloy immersed in SBF for a period of time was relatively small, and the corrosion morphology was even. No serious local corrosion occurred. The EDS results of corrosion products show that the corrosion products mainly contain several elements such as P, Ca, C and O. According to the literature, the corrosion products may be phosphate and carbonate. These results show that Zn-Cu alloy may be a new type of degradable metal material with suitable degradation rate.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.13;R318.08

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