本文關(guān)鍵詞：微弧氧化對鎂合金絲材性能和微觀組織的影響研究　出處：《東南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鎂合金絲材 微弧氧化 微觀組織 力學(xué)性能 聚乳酸

【摘要】：鎂合金是一種應(yīng)用前景廣闊的可降解生物醫(yī)用材料,通過表面處理可以彌補(bǔ)其在生理環(huán)境中腐蝕過快的缺點(diǎn)。本文采用微弧氧化技術(shù)對AZ31B鎂合金絲材進(jìn)行表面改性處理,研究了氧化時間和電流密度等微弧氧化工藝參數(shù)對鎂合金絲性能和微觀組織的影響,在此基礎(chǔ)上,系統(tǒng)研究了微弧氧化時間、磷酸緩沖液中氯離子濃度以及PLLA封孔處理對鎂絲降解性能的影響規(guī)律,研究表明：鎂合金絲表面微弧氧化膜的組成相以MgO為主,延長氧化時間,陶瓷膜表面裂紋增多,膜層孔隙率先增大后減小,氧化時間為30min (10-30min)時孔隙率最大,而氧化時間對膜層表面孔隙大小沒有明顯影響；增大電流密度,微弧氧化膜生長速率呈線性上升,表面裂紋增多,孔隙率和平均孔徑均先增大再減小,電流密度為8A/dm2(6-108A/dm~2)時兩者達(dá)到最大值,分別為6.4%和2.59μm。延長氧化時間或增大電流密度都會增加膜層厚度,降低抗拉強(qiáng)度。絲材直徑對鎂合金微弧氧化陶瓷膜的微觀組織影響不大,但膜層孔隙率和平均孔徑隨絲徑增大而減小,絲材強(qiáng)度損失率隨之降低。微弧氧化處理會導(dǎo)致小絲徑的鎂合金絲平均晶粒尺寸略有增大。微弧氧化處理能顯著提高鎂絲在含血液濃度氯離子的磷酸緩沖液中的耐腐蝕性。短時間浸泡(低于10天),微弧氧化時間的影響不大；浸泡10天后,10min氧化處理的鎂絲剩余質(zhì)量百分?jǐn)?shù)最大。浸泡10天,光絲表面腐蝕嚴(yán)重,而10min氧化處理鎂絲表面陶瓷層保持完整。浸泡4天后,10min氧化鎂絲的剩余抗拉強(qiáng)度最大,光絲的強(qiáng)度損失率最大。不同濃度氯離子的磷酸緩沖液浸泡實(shí)驗(yàn)發(fā)現(xiàn),浸泡相同時間,磷酸緩沖液中氯離子含量越大,鎂絲裂紋越多,抗拉強(qiáng)度損失率增大。PLLA涂覆處理后,微弧氧化時間對鎂絲浸泡過程中的質(zhì)量和直徑損失率影響小。浸泡33天時,20min和30min氧化并經(jīng)PLLA涂覆處理的兩種鎂合金絲表層均保持完整,后者剩余抗拉強(qiáng)度最大。
[Abstract]:Magnesium alloy is a promising biodegradable biomedical material. Surface treatment can make up for the shortcomings of rapid corrosion in physiological environment. In this paper, the surface modification of AZ31B magnesium alloy wire was carried out by using micro-arc oxidation technology. The effects of oxidation time and current density on the properties and microstructure of magnesium alloy wire were studied. The effect of chloride concentration in phosphate buffer solution and PLLA sealing treatment on the degradation performance of magnesium wire was studied. The results showed that the composition of micro-arc oxide film on magnesium alloy wire surface was mainly composed of MgO and the oxidation time was prolonged. When the surface crack of ceramic membrane increases, the porosity of the film increases first and then decreases, and the porosity is the highest when the oxidation time is 30 min or 10 ~ (-30 min). However, the oxidation time has no obvious effect on the pore size of the film surface. With the increase of current density, the growth rate of micro-arc oxide film increases linearly, the surface cracks increase, and the porosity and average pore size increase first and then decrease. When the current density is 8A / dm ~ (2) 6-108A / d ~ (2), the maximum value is 6.4% 渭 m and 2.59 渭 m, respectively. Increasing the oxidation time or increasing the current density will increase the film thickness. The decrease of tensile strength. The wire diameter has little effect on the microstructure of magnesium alloy micro-arc oxidation ceramic film, but the film porosity and average pore size decrease with the increase of wire diameter. The average grain size of the magnesium alloy wire with small wire diameter increased slightly after microarc oxidation treatment. The microarc oxidation treatment could significantly increase the magnesium wire in the phosphate buffer solution containing chlorine ion in blood concentration, and the average grain size of the magnesium alloy wire with small wire diameter was slightly increased by micro-arc oxidation treatment, which resulted in a slight increase in the average grain size of magnesium alloy wire. Corrosion resistance-soaking for short periods (. Less than 10 days. The effect of the time of micro-arc oxidation is not significant. After soaking for 10 days, the residual mass percentage of magnesium wire treated by oxidation for 10 minutes was the largest, and the surface corrosion was serious after soaking for 10 days. However, the ceramic layer on the surface of the magnesium wire treated by oxidation for 10 minutes remained intact, and the residual tensile strength of the magnesium oxide wire was the highest after immersion for 4 days. The strength loss rate of light filament is the biggest. The experiment of immersion in phosphate buffer with different concentration of chloride ion shows that the more chlorine ion content in phosphate buffer solution, the more cracks in magnesium wire. The effect of microarc oxidation time on the quality and diameter loss rate of magnesium wire during immersion was little after the increase of tensile strength loss rate. After 33 days of immersion, the microarc oxidation time had little effect on the quality and diameter loss rate of magnesium wire. The surface layers of the two magnesium alloy wires, which were oxidized for 20min and 30min and coated with PLLA, remained intact, and the residual tensile strength of the latter was the largest.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG174.4;TG146.22

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