二元雙相塊體納米晶Ag-25Ni合金腐蝕性能研究
發(fā)布時間：2018-12-26 17:02
【摘要】：有關(guān)納米材料在各種溶液中穩(wěn)定性的研究,已引起人們的高度關(guān)注。迄今為止,國內(nèi)外在這方面的研究還主要集中在表面納米化、納米薄膜及納米涂層上,而對塊體尤其是塊體納米晶二元雙相合金腐蝕性能的研究還是相對較少。本文采用機械合金化法(MA)和液相還原法(LPR)通過優(yōu)化合成參數(shù)制備納米晶Ag-25Ni合金粉末,利用真空熱壓技術(shù)通過優(yōu)化熱壓參數(shù)制備了塊體納米晶Ag-25Ni合金,并與粉末冶金法(PM)制備的塊體常規(guī)尺寸Ag-25Ni合金對比,利用電化學工作站,通過極化曲線、交流阻抗譜、平均活化能以及Mott-Schottky曲線等測試,研究了它們在中性NaCl、H_2SO_4和酸性NaCl溶液中的腐蝕性能以及顯微組織細化對其腐蝕性能的影響,結(jié)果表明:(1)三種合金的顯微組織如晶粒尺寸、相的結(jié)構(gòu)與分布存在差異。粉末冶金法制備塊體常規(guī)尺寸合金顯微組織極不均勻,組元間固溶度很低;機械合金化法制備塊體納米晶合金顯微組織比較均勻,組元間有一定固溶度,而液相還原法制備塊體納米晶合金顯微組織均勻,組元間固溶度較低;(2)向中性Na_2SO_4溶液中加入NaCl、H_2SO_4和酸性Na Cl溶液后,不同方法制備的三種PM Ag-25Ni、LPR Ag-25Ni和MAAg-25Ni合金的腐蝕電流密度增大,且隨著溶液濃度的增加,三種合金的腐蝕電流密度均增大。晶粒細化后,納米晶MAAg-25Ni合金的腐蝕速度降低,而納米晶LPRAg-25Ni合金腐蝕速度則加快;(3)在中性NaCl溶液中,不同方法制備的三種Ag-25Ni合金的交流阻抗譜均由單容抗弧組成,腐蝕過程受電化學反應控制。在H_2SO_4溶液中,MAAg-25Ni和PMAg-25Ni合金的交流阻抗譜為單容抗弧,而LPRAg-25Ni合金則出現(xiàn)擴散尾,腐蝕過程受擴散控制。在酸性NaCl溶液中,PMAg-25Ni合金的交流阻抗由單容抗弧組成,而LPRAg-25Ni和MA Ag-25Ni合金出現(xiàn)擴散尾。三種合金的電荷傳遞電阻變化趨勢與腐蝕電流密度相反;(4)在中性NaCl、H_2SO_4和酸性NaCl溶液中,不同方法制備的三種Ag-25Ni合金均出現(xiàn)鈍化現(xiàn)象,晶粒細化并沒有改變鈍化膜半導體的類型,均為n型半導體。在中性NaCl和酸性NaCl溶液中,三種合金表面形成的鈍化膜的載流子密度大小按LPRAg-25NiPM Ag-25NiMA Ag-25Ni合金的順序降低。在H_2SO_4溶液中,鈍化膜的載流子密度大小按LPRAg-25NiMAAg-25NiPMAg-25Ni合金的順序降低,與三種合金的維鈍電流大小規(guī)律相符。
[Abstract]:The study on the stability of nanomaterials in various solutions has attracted much attention. Up to now, the researches in this field have mainly focused on the surface nanocrystalline, nanocrystalline films and nanocrystalline coatings at home and abroad, but the corrosion properties of bulk, especially bulk nanocrystalline binary dual phase alloys, have been relatively few. Nanocrystalline Ag-25Ni alloy powder was prepared by mechanical alloying method (MA) and liquid phase reduction method (LPR) by optimizing synthesis parameters. Bulk nanocrystalline Ag-25Ni alloy was prepared by vacuum hot pressing technology by optimizing hot pressing parameters. Compared with the conventional bulk Ag-25Ni alloy prepared by powder metallurgy method (PM), the electrochemical workstation was used to study their effect on neutral NaCl, by means of polarization curve, AC impedance spectrum, average activation energy and Mott-Schottky curve. The corrosion resistance of H_2SO_4 and acid NaCl solution and the effect of microstructure refinement on their corrosion resistance are discussed. The results show that: (1) the microstructure, phase structure and distribution of the three alloys are different, such as grain size. The microstructure of conventional bulk alloy prepared by powder metallurgy method is very uneven, and the solution between components is very low. The microstructure of bulk nanocrystalline alloy prepared by mechanical alloying method is uniform, and there is a certain solution degree among the components, while the microstructure of bulk nanocrystalline alloy prepared by liquid phase reduction method is uniform, and the solution degree between components is low. (2) the corrosion current density of three kinds of PM Ag-25Ni,LPR Ag-25Ni and MAAg-25Ni alloys prepared by different methods increased after adding NaCl,H_2SO_4 and acidic Na Cl solution to neutral Na_2SO_4 solution, and the corrosion current density increased with the increase of solution concentration. The corrosion current density of the three alloys increased. After grain refinement, the corrosion rate of nanocrystalline MAAg-25Ni alloy decreased, while that of nanocrystalline LPRAg-25Ni alloy accelerated. (3) in neutral NaCl solution, the AC impedance spectra of three kinds of Ag-25Ni alloys prepared by different methods are all composed of single capacitive reactance arc, and the corrosion process is controlled by electrochemical reaction. In H_2SO_4 solution, the AC impedance spectrum of MAAg-25Ni and PMAg-25Ni alloys is single capacitive reactance arc, while that of LPRAg-25Ni alloy is diffusion tail, and the corrosion process is controlled by diffusion. In acidic NaCl solution, the AC impedance of PMAg-25Ni alloy is composed of single capacitive reactance arc, while the diffusion tail of LPRAg-25Ni and MA Ag-25Ni alloys appears. The change trend of charge transfer resistance of the three alloys is opposite to the corrosion current density. (4) in neutral NaCl,H_2SO_4 and acid NaCl solution, the three kinds of Ag-25Ni alloys prepared by different methods all appear passivation phenomenon, the grain refinement does not change the type of passivation film semiconductor, all of them are n-type semiconductors. In neutral NaCl and acidic NaCl solutions, the carrier density of passivated films formed on the surface of the three alloys decreased in the order of LPRAg-25NiPM Ag-25NiMA Ag-25Ni alloys. In H_2SO_4 solution, the carrier density of the passivated film decreases in the order of LPRAg-25NiMAAg-25NiPMAg-25Ni alloy, which is consistent with the law of the magnitude of the three alloys.
【學位授予單位】：沈陽師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1;TG178
本文編號：2392420
[Abstract]:The study on the stability of nanomaterials in various solutions has attracted much attention. Up to now, the researches in this field have mainly focused on the surface nanocrystalline, nanocrystalline films and nanocrystalline coatings at home and abroad, but the corrosion properties of bulk, especially bulk nanocrystalline binary dual phase alloys, have been relatively few. Nanocrystalline Ag-25Ni alloy powder was prepared by mechanical alloying method (MA) and liquid phase reduction method (LPR) by optimizing synthesis parameters. Bulk nanocrystalline Ag-25Ni alloy was prepared by vacuum hot pressing technology by optimizing hot pressing parameters. Compared with the conventional bulk Ag-25Ni alloy prepared by powder metallurgy method (PM), the electrochemical workstation was used to study their effect on neutral NaCl, by means of polarization curve, AC impedance spectrum, average activation energy and Mott-Schottky curve. The corrosion resistance of H_2SO_4 and acid NaCl solution and the effect of microstructure refinement on their corrosion resistance are discussed. The results show that: (1) the microstructure, phase structure and distribution of the three alloys are different, such as grain size. The microstructure of conventional bulk alloy prepared by powder metallurgy method is very uneven, and the solution between components is very low. The microstructure of bulk nanocrystalline alloy prepared by mechanical alloying method is uniform, and there is a certain solution degree among the components, while the microstructure of bulk nanocrystalline alloy prepared by liquid phase reduction method is uniform, and the solution degree between components is low. (2) the corrosion current density of three kinds of PM Ag-25Ni,LPR Ag-25Ni and MAAg-25Ni alloys prepared by different methods increased after adding NaCl,H_2SO_4 and acidic Na Cl solution to neutral Na_2SO_4 solution, and the corrosion current density increased with the increase of solution concentration. The corrosion current density of the three alloys increased. After grain refinement, the corrosion rate of nanocrystalline MAAg-25Ni alloy decreased, while that of nanocrystalline LPRAg-25Ni alloy accelerated. (3) in neutral NaCl solution, the AC impedance spectra of three kinds of Ag-25Ni alloys prepared by different methods are all composed of single capacitive reactance arc, and the corrosion process is controlled by electrochemical reaction. In H_2SO_4 solution, the AC impedance spectrum of MAAg-25Ni and PMAg-25Ni alloys is single capacitive reactance arc, while that of LPRAg-25Ni alloy is diffusion tail, and the corrosion process is controlled by diffusion. In acidic NaCl solution, the AC impedance of PMAg-25Ni alloy is composed of single capacitive reactance arc, while the diffusion tail of LPRAg-25Ni and MA Ag-25Ni alloys appears. The change trend of charge transfer resistance of the three alloys is opposite to the corrosion current density. (4) in neutral NaCl,H_2SO_4 and acid NaCl solution, the three kinds of Ag-25Ni alloys prepared by different methods all appear passivation phenomenon, the grain refinement does not change the type of passivation film semiconductor, all of them are n-type semiconductors. In neutral NaCl and acidic NaCl solutions, the carrier density of passivated films formed on the surface of the three alloys decreased in the order of LPRAg-25NiPM Ag-25NiMA Ag-25Ni alloys. In H_2SO_4 solution, the carrier density of the passivated film decreases in the order of LPRAg-25NiMAAg-25NiPMAg-25Ni alloy, which is consistent with the law of the magnitude of the three alloys.
【學位授予單位】：沈陽師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1;TG178
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