基于噴丸強(qiáng)化的生物醫(yī)用鎂合金腐蝕和摩擦學(xué)特性研究
發(fā)布時間：2019-05-24 09:07
【摘要】：為了解決生物醫(yī)用鎂及鎂合金在生物體內(nèi)腐蝕過快的問題,并且保持良好的生物相容性,本文以醫(yī)用WE43鎂合金為研究對象,以高能噴丸表面處理技術(shù)為強(qiáng)化手段,對噴丸強(qiáng)化前后WE43鎂合金試樣的腐蝕和摩擦磨損行為進(jìn)行了深入的研究。(1)對不同噴丸參數(shù)下強(qiáng)化的試樣進(jìn)行殘余應(yīng)力場數(shù)值模擬分析發(fā)現(xiàn),彈丸直徑、入射速度對試樣表面的殘余應(yīng)力場分布及等效應(yīng)變的影響最大,彈丸入射角度的影響次之,直徑為0.8mm和1.0mm、入射速度為90m/s、入射角度為90o的試樣表面噴丸效果最優(yōu)。對試樣分別進(jìn)行了60s、90s和120s的噴丸強(qiáng)化處理,試樣表面的微觀組織分析結(jié)果發(fā)現(xiàn),噴丸強(qiáng)化使WE43鎂合金表面產(chǎn)生了約120~150μm的晶粒細(xì)化層,晶粒細(xì)化機(jī)制為孿晶-位錯堆積-亞晶形成-動態(tài)再結(jié)晶。試樣的硬度從處理表面至心部呈梯度分布,表面硬度達(dá)基體硬度的兩倍。殘余壓應(yīng)力測試結(jié)果與數(shù)值模擬分析結(jié)果一致性良好,噴丸強(qiáng)化120s試樣表面的綜合特征良好。(2)對噴丸強(qiáng)化前后的WE43鎂合金試樣分別進(jìn)行了模擬體液(簡稱SBF)浸泡實(shí)驗(yàn)和鹽霧腐蝕實(shí)驗(yàn),研究了試樣的腐蝕降解行為。腐蝕速率結(jié)果顯示,SBF浸泡中,未噴丸強(qiáng)化試樣的腐蝕速率最大,3組噴丸試樣的腐蝕速率相仿,在腐蝕后期由于強(qiáng)化層逐漸失效導(dǎo)致腐蝕速率上升;鹽霧腐蝕過程中,4組試樣的腐蝕速率相差不大,腐蝕速率逐漸減小直到穩(wěn)定,噴丸強(qiáng)化對試樣耐鹽霧腐蝕性能的提高較小。溶液的PH值變化結(jié)果顯示,噴丸試樣的溶液PH值均小于未噴丸處理試樣的溶液,噴丸強(qiáng)化能夠有效減小試樣在SBF中的腐蝕速率,并且噴丸強(qiáng)化時間越長,強(qiáng)化效果越好。試樣腐蝕后的形貌分析得出,噴丸處理試樣的表面狀態(tài)較未噴丸試樣好,表面均有磷酸鹽的沉積。綜合而言,噴丸強(qiáng)化對WE43鎂合金的SBF浸泡腐蝕性能提高較明顯,耐鹽霧腐蝕性能次之,且噴丸強(qiáng)化120s的試樣耐腐蝕性能最好。(3)分別對噴丸前后的WE43鎂合金試樣進(jìn)行了SBF和質(zhì)量分?jǐn)?shù)為3.5%NaCl溶液中的電化學(xué)測試,結(jié)果顯示,試樣在兩種電解液中的自腐蝕電位均正移,自腐蝕電流密度均減小,試樣的電化學(xué)腐蝕特性增強(qiáng)。未噴丸試樣的開路電位曲線較噴丸試樣的波動更加劇烈,噴丸試樣能夠有效改善試樣表面的缺陷。但試樣在NaCl溶液中的電化學(xué)曲線均比在SBF中的曲線變化小,試樣在SBF中電化學(xué)行為優(yōu)于NaCl溶液中的試樣。(4)開展了生物醫(yī)用鎂合金的摩擦磨損實(shí)驗(yàn)。在定載荷、定轉(zhuǎn)速的條件下,噴丸處理試樣的干摩擦系數(shù)和磨損量較未噴丸試樣的明顯減小,干摩擦下的磨損機(jī)理為磨粒磨損為主;在SBF潤滑條件下,噴丸120s試樣的潤滑摩擦系數(shù)明顯降低,且所有試樣的質(zhì)量損失均大于干摩擦下的試樣,潤滑條件下試樣表面的磨損是磨粒磨損、腐蝕磨損和剝落磨損共存。對于噴丸120s試樣,定轉(zhuǎn)速、動載荷條件下,鎂合金試樣的干摩擦系數(shù)隨載荷的增加而增加,潤滑摩擦系數(shù)先減小后增加,試樣的潤滑摩擦系數(shù)始終小于干摩擦系數(shù);定載荷、動轉(zhuǎn)速的條件下,鎂合金試樣在低速下的摩擦系數(shù)比高速下的大,這是由于低速下試樣表面的微凸體未被完全磨掉的原因;所有試樣的磨損量隨著載荷和速度的增加而增加,且SBF潤滑條件下的磨損量明顯大于干摩擦條件下的磨損量。
[Abstract]:In order to solve the problem of fast corrosion of the biological medical magnesium and the magnesium alloy in the living body, and maintain good biocompatibility, the medical WE43 magnesium alloy is used as the research object, and the high-energy shot blasting surface treatment technology is used as the strengthening means. The corrosion and friction wear behavior of WE43 magnesium alloy samples before and after shot peening is studied. (1) The numerical simulation of the residual stress field of the specimen under different shot-peening parameters shows that the effect of the diameter of the projectile and the incident velocity on the distribution of the residual stress field and the equivalent effect of the surface of the specimen is the most, the effect of the angle of incidence of the projectile is the second, the diameter is 0.8 mm and 1.0 mm, The incident velocity is 90 m/ s, and the surface shot peening effect of the sample with the incident angle of 90 o is the best. The test samples were shot-peened for 60 s,90 s and 120 s, respectively. The results of the microstructure analysis of the surface of the sample show that the surface of the WE43 magnesium alloy has a grain refining layer of about 120-150. m u.m on the surface of the WE43 magnesium alloy, and the grain refining mechanism is the twin-dislocation accumulation-subcrystal formation-dynamic recrystallization. The hardness of the sample is distributed in a gradient from the treatment surface to the core part, and the surface hardness of the sample is twice the hardness of the base body. The results of the residual compressive stress test and the numerical simulation analysis result in good agreement, and the comprehensive characteristics of the surface of the shot-shot reinforced 120s test sample are good. (2) The simulated body fluid (SBF) soaking experiment and salt spray corrosion test were carried out on the WE43 magnesium alloy samples before and after shot peening, and the corrosion and degradation behavior of the sample was studied. The corrosion rate results show that, in the SBF immersion, the corrosion rate of the non-shot-shot reinforced sample is the highest, the corrosion rate of the three-group shot-shot test sample is similar, and the corrosion rate is increased due to the gradual failure of the reinforcing layer in the later stage of corrosion. In the process of salt spray corrosion, the corrosion rate of the four samples is not much different. And the corrosion rate is gradually reduced until the corrosion rate of the salt fog resistance of the sample is small. The change of the PH value of the solution shows that the PH value of the solution of the shot-shot test sample is less than that of the non-shot-shot test sample, and the shot-peening strengthening can effectively reduce the corrosion rate of the sample in the SBF, and the longer the shot-shot strengthening time, the better the strengthening effect. The morphology of the sample after the corrosion of the sample shows that the surface state of the shot-shot test specimen is better than that of the non-shot-shot sample, and the surface has the deposit of phosphate. In general, the corrosion resistance of the SBF of the WE43 magnesium alloy can be improved obviously, and the corrosion resistance of the salt-resistant fog can be the second, and the corrosion resistance of the test piece of the shot-shot strengthening 120s is the best. (3) The electrochemical measurements of the SBF and the mass fraction of 3.5% NaCl solution were carried out on the WE43 magnesium alloy samples before and after the shot peening. The results show that the self-corrosion potential of the sample in the two electrolytes is positive, the self-corrosion current density is reduced, and the electrochemical corrosion characteristic of the sample is enhanced. The open-circuit potential curve of the un-peened sample is more severe than that of the shot-peened sample, and the shot-peened sample can effectively improve the defect of the sample surface. However, the electrochemical behavior of the sample in the NaCl solution is smaller than that in the SBF, and the electrochemical behavior of the sample in the SBF is better than that in the NaCl solution. (4) The friction and wear experiment of biomedical magnesium alloy was carried out. Under the condition of constant load and fixed speed, the dry friction coefficient and the wear amount of the shot-peened specimen are less than that of the un-peened sample, and the wear mechanism under dry friction is the abrasive wear. Under the condition of SBF lubrication, the lubrication friction coefficient of the shot-peened 120s sample is obviously reduced. And the wear of the surface of the sample under the condition of lubrication is the coexistence of abrasive wear, corrosion wear and peeling and abrasion. the dry friction coefficient of the magnesium alloy sample is increased with the increase of the load, the lubricating coefficient of friction is increased firstly, the lubricating coefficient of friction of the sample is always less than the dry friction coefficient, the friction coefficient of the magnesium alloy sample at low speed is higher than that at high speed due to the fact that the micro-convex body on the surface of the sample at low speed is not completely worn off; the wear amount of all the samples is increased with the increase of the load and the speed, And the wear amount under the condition of the SBF lubrication is obviously higher than that of the dry friction condition.
【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG668;TG146.22
[Abstract]:In order to solve the problem of fast corrosion of the biological medical magnesium and the magnesium alloy in the living body, and maintain good biocompatibility, the medical WE43 magnesium alloy is used as the research object, and the high-energy shot blasting surface treatment technology is used as the strengthening means. The corrosion and friction wear behavior of WE43 magnesium alloy samples before and after shot peening is studied. (1) The numerical simulation of the residual stress field of the specimen under different shot-peening parameters shows that the effect of the diameter of the projectile and the incident velocity on the distribution of the residual stress field and the equivalent effect of the surface of the specimen is the most, the effect of the angle of incidence of the projectile is the second, the diameter is 0.8 mm and 1.0 mm, The incident velocity is 90 m/ s, and the surface shot peening effect of the sample with the incident angle of 90 o is the best. The test samples were shot-peened for 60 s,90 s and 120 s, respectively. The results of the microstructure analysis of the surface of the sample show that the surface of the WE43 magnesium alloy has a grain refining layer of about 120-150. m u.m on the surface of the WE43 magnesium alloy, and the grain refining mechanism is the twin-dislocation accumulation-subcrystal formation-dynamic recrystallization. The hardness of the sample is distributed in a gradient from the treatment surface to the core part, and the surface hardness of the sample is twice the hardness of the base body. The results of the residual compressive stress test and the numerical simulation analysis result in good agreement, and the comprehensive characteristics of the surface of the shot-shot reinforced 120s test sample are good. (2) The simulated body fluid (SBF) soaking experiment and salt spray corrosion test were carried out on the WE43 magnesium alloy samples before and after shot peening, and the corrosion and degradation behavior of the sample was studied. The corrosion rate results show that, in the SBF immersion, the corrosion rate of the non-shot-shot reinforced sample is the highest, the corrosion rate of the three-group shot-shot test sample is similar, and the corrosion rate is increased due to the gradual failure of the reinforcing layer in the later stage of corrosion. In the process of salt spray corrosion, the corrosion rate of the four samples is not much different. And the corrosion rate is gradually reduced until the corrosion rate of the salt fog resistance of the sample is small. The change of the PH value of the solution shows that the PH value of the solution of the shot-shot test sample is less than that of the non-shot-shot test sample, and the shot-peening strengthening can effectively reduce the corrosion rate of the sample in the SBF, and the longer the shot-shot strengthening time, the better the strengthening effect. The morphology of the sample after the corrosion of the sample shows that the surface state of the shot-shot test specimen is better than that of the non-shot-shot sample, and the surface has the deposit of phosphate. In general, the corrosion resistance of the SBF of the WE43 magnesium alloy can be improved obviously, and the corrosion resistance of the salt-resistant fog can be the second, and the corrosion resistance of the test piece of the shot-shot strengthening 120s is the best. (3) The electrochemical measurements of the SBF and the mass fraction of 3.5% NaCl solution were carried out on the WE43 magnesium alloy samples before and after the shot peening. The results show that the self-corrosion potential of the sample in the two electrolytes is positive, the self-corrosion current density is reduced, and the electrochemical corrosion characteristic of the sample is enhanced. The open-circuit potential curve of the un-peened sample is more severe than that of the shot-peened sample, and the shot-peened sample can effectively improve the defect of the sample surface. However, the electrochemical behavior of the sample in the NaCl solution is smaller than that in the SBF, and the electrochemical behavior of the sample in the SBF is better than that in the NaCl solution. (4) The friction and wear experiment of biomedical magnesium alloy was carried out. Under the condition of constant load and fixed speed, the dry friction coefficient and the wear amount of the shot-peened specimen are less than that of the un-peened sample, and the wear mechanism under dry friction is the abrasive wear. Under the condition of SBF lubrication, the lubrication friction coefficient of the shot-peened 120s sample is obviously reduced. And the wear of the surface of the sample under the condition of lubrication is the coexistence of abrasive wear, corrosion wear and peeling and abrasion. the dry friction coefficient of the magnesium alloy sample is increased with the increase of the load, the lubricating coefficient of friction is increased firstly, the lubricating coefficient of friction of the sample is always less than the dry friction coefficient, the friction coefficient of the magnesium alloy sample at low speed is higher than that at high speed due to the fact that the micro-convex body on the surface of the sample at low speed is not completely worn off; the wear amount of all the samples is increased with the increase of the load and the speed, And the wear amount under the condition of the SBF lubrication is obviously higher than that of the dry friction condition.
【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG668;TG146.22
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