本文關(guān)鍵詞： 熔鹽電解 銅鋯母合金 制備 熔鹽電化學(xué)　出處：《江西理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：Cu-Zr系合金在航空航天,核工業(yè),電子芯片,運(yùn)輸?shù)阮I(lǐng)域得到廣泛運(yùn)用。目前制備的銅鋯合金分布不均勻,操作繁瑣,不能連續(xù)化生產(chǎn)。本文以LiF-BaF_2-CaF_2-ZrO_2為熔鹽體系,制備銅鋯合金,研究了不同溫度和陰極電流密度下對(duì)槽電壓和電流效率的影響,制備出Cu-Zr二元母合金。在1233K下以LiF-BaF_2-CaF_2-ZrO_2-MgO為熔鹽體系,純銅棒為自耗陰極,制備出銅鋯鎂三元合金。熔鹽電化學(xué)研究鋯在陰極上沉積機(jī)理:對(duì)電極和參比電極分別為石墨和鉑絲的條件下利用循環(huán)伏安法、計(jì)時(shí)電位法、計(jì)時(shí)電流法研究熔鹽體系中Zr~(4+)在鎢絲工作電極上的電化學(xué)還原機(jī)理,對(duì)電極和參比電極分別為鎢棒和鉑絲的條件下研究Zr~(4+)在鎢絲工作電極上的電化學(xué)還原機(jī)理。將制備的銅鋯合金做XRD和SEM檢測(cè)分析,得到合金的成分及形貌。結(jié)論如下:1.電解質(zhì)體系LiF-BaF_2-CaF_2在溫度1373-1473K下,電解過(guò)程中具有較好的熱穩(wěn)定性和流動(dòng)性,加入二氧化鋯和氧化鎂后保持較好的導(dǎo)電性質(zhì),在高溫下熔鹽密度較合金密度小,制備出的合金沉于石墨坩堝底部被熔鹽覆蓋不易與空氣接觸導(dǎo)致燒損。2.液態(tài)銅為陰極制備銅鋯合金過(guò)程中:1373-1473K溫度下進(jìn)行電解具有可行性。槽電壓隨著電解溫度的升高而下降,槽電壓與陰極電流密度成正比。在溫度為1420K下,電流密度在1.0~1.5A/cm2范圍內(nèi),電流密度小于1.29A/cm2時(shí),電流效率隨著電流密度的增加從62%增加至66.5%,在電流密度大于1.29A/cm2時(shí),電流效率隨著電流密度的增大從66.5%減小至63%,在電流密度為1.29A/cm2時(shí)電流效率有一個(gè)最大值,此時(shí)電流效率最高,為66.5%。3.在溫度為1233K條件下以銅棒為自耗陰極,在電解質(zhì)LiF-BaF_2-CaF_2中加入氧化鎂和二氧化鋯可以制備出銅鋯鎂三元合金。4.三電極體系的熔鹽電化學(xué)研究:石墨作為對(duì)電極,在20%LiF-22%CaF_2-58%BaF_2電解質(zhì)體系中加入質(zhì)量分?jǐn)?shù)為(0.5~0.9%)的ZrO_2,鋯離子在鎢電極上還原為金屬鋯的過(guò)程為兩步還原,即Zr~(4+)+2e→Zr2+,Zr2++2e→Zr,反應(yīng)過(guò)程為準(zhǔn)可逆反應(yīng)。在不同掃描速率下,鋯離子的還原峰電流和掃描速率平方根呈良好的線性關(guān)系,說(shuō)明Zr~(4+)的還原過(guò)程受擴(kuò)散步驟的控制。計(jì)時(shí)電位掃描出兩個(gè)平臺(tái),且析出電位分別為-0.87V和-1.07V,驗(yàn)證了鋯離子在體系中還原為兩步還原。經(jīng)計(jì)算得鋯離子在鎢電極上的還原過(guò)程為兩步,且分別得兩個(gè)電子的反應(yīng)過(guò)程。運(yùn)用計(jì)時(shí)電流法,通過(guò)Cottrell方程計(jì)算出離子擴(kuò)散系數(shù)為6.7×10-6cm2/s。在鎢電極上析出金屬鋯的成核機(jī)理為瞬時(shí)成核。5.三電極體系的對(duì)電極為鎢棒,在20%LiF-22%CaF_2-58%BaF_2-ZrO_2熔鹽體系中,鋯的電化學(xué)還原過(guò)程分為兩步,還原過(guò)程每一步得兩個(gè)電子。
[Abstract]:Cu-Zr alloys are widely used in aerospace, nuclear industry, electronic chip, transportation and so on. In this paper, copper-zirconium alloy was prepared with LiF-BaF_2-CaF_2-ZrO_2 as molten salt system. The effects of different temperature and cathode current density on the cell voltage and current efficiency are studied. Cu-Zr binary master alloy was prepared. LiF-BaF_2-CaF_2-ZrO_2-MgO was used as molten salt system and pure copper rod as self-consuming cathode at 1233K. Copper zirconium magnesium ternary alloy was prepared. Electrochemical study on deposition mechanism of zirconium on cathode: cyclic voltammetry and chronopotentiometry were used under the conditions that the electrode and reference electrode were graphite and platinum wire respectively. The electrochemical reduction mechanism of Zr~(4 on tungsten wire working electrode in molten salt system was studied by chronoamperometric method. The electrochemical reduction mechanism of Zr~(4 on tungsten wire working electrode was studied under the condition that the electrode and reference electrode were tungsten rod and platinum wire respectively. The prepared copper-zirconium alloy was detected by XRD and SEM. The composition and morphology of the alloy were obtained. The conclusions are as follows: 1. The electrolyte system LiF-BaF_2-CaF_2 is at 1373-1473K. The electrolysis process has good thermal stability and fluidity, adding zirconia and magnesium oxide to maintain a better conductivity, the density of molten salt at high temperature is lower than the alloy density. The prepared alloy is deposited at the bottom of the graphite crucible and covered with molten salt. 2. During the process of preparing Cu-Zr alloy with liquid copper as cathode, it is difficult to contact with air and cause burning loss. Electrolysis at 1373-1473K is feasible. The cell voltage decreases with the increase of electrolysis temperature. The cell voltage is directly proportional to the cathode current density. At 1420K, the current density is in the range of 1.0 ~ 1.5A / cm ~ 2, and the current density is less than 1.29A / cm ~ 2. The current efficiency increases from 62% to 66.5 with the increase of current density. When the current density is greater than 1.29 A / cm ~ 2, the current efficiency decreases from 66.5% to 63% with the increase of current density. When the current density is 1.29 A / cm ~ 2, the current efficiency is the highest, which is 66.5. 3. The copper rod is used as the self-dissipating cathode at 1233K. Copper zirconium magnesium ternary alloy. 4. electrochemical study of molten salt in the three-electrode system: graphite as opposite electrode is prepared by adding magnesium oxide and zirconia into electrolyte LiF-BaF_2-CaF_2. In the LiF-22F2-58F2 electrolyte system of LiF-22F2, add ZrO_2 with a mass fraction of 0. 5%. The reduction process of zirconium ion to zirconium metal on tungsten electrode is two-step reduction, that is, Zr~(4) 2e. 鈫抁r2 ,Zr2 2e. 鈫扷nder different scanning rates, the reduction peak current of zirconium ion and the square root of scanning rate show a good linear relationship. The results show that the reduction process of Zr~(4 is controlled by diffusion step. Two platforms are scanned by chronopotentiometry, and the precipitation potentials are -0.87V and -1.07V, respectively. It was verified that the reduction of zirconium ion in the system was two steps. The reduction process of zirconium ion on tungsten electrode was two steps and two electrons were obtained respectively. The chronoamperometric method was used. The ion diffusion coefficient calculated by Cottrell equation is 6.7 脳 10 ~ (-6) cm ~ 2 / s. The nucleation mechanism of zirconium precipitates on tungsten electrode is instantaneous nucleation. The opposite electrode of three-electrode system is tungsten. Yes. In the LiF-22F2-58F2-ZrO2 molten salt system, the electrochemical reduction process of zirconium is divided into two steps, and two electrons are obtained in each step of the reduction process.
【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TF811

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本文編號(hào)：1463348