本文選題：EMIC-EG + 電沉積��； 參考：《昆明理工大學(xué)》2015年碩士論文

【摘要】：鑭元素具有獨(dú)特的4f層電子結(jié)構(gòu),使其金屬以及其合金薄膜具有一些獨(dú)特的功能,例如,Ni-La合金具有優(yōu)良的耐腐蝕性能,當(dāng)其成分達(dá)到LaNi5時(shí),是典型的儲(chǔ)氫合金,它具有儲(chǔ)氫量高、吸放氫性能較好、合金循環(huán)次數(shù)高、不會(huì)對(duì)環(huán)境產(chǎn)生污染等特點(diǎn)。本文以EMIC-EG為電解質(zhì),采用循環(huán)伏安曲線法、計(jì)時(shí)電流法等多種電化學(xué)測(cè)試手段,系統(tǒng)地研究了Ni和Ni-La合金在該體系中的電沉積行為,并運(yùn)用XRF、 XRD、 SEM、 XPS等檢測(cè)手段對(duì)鍍層的成分、形貌進(jìn)行分析。對(duì)EMIC-EG-NiCl2電解液進(jìn)行電化學(xué)分析,研究表明,Ni的沉積過(guò)程主要是受擴(kuò)散控制,擴(kuò)散系數(shù)為4.6×10-7cm2／s,擴(kuò)散活化能為21.75 kJ/mol。溫度升高或濃度增大都有利于Ni的還原。在以玻碳電極或鉑電極為工作電極時(shí),Ni的沉積屬于擴(kuò)散控制下的三維瞬時(shí)形核模型。對(duì)EMIC-EG-NiCl2-LaCl3電解液進(jìn)行電化學(xué)分析,研究表明,La在該體系中發(fā)生了氧化還原反應(yīng),并且Ni-La的電沉積遵從誘導(dǎo)共沉積的機(jī)理。溫度升高使Ni-La共沉積的起始還原電位正移,LaCl3摩爾濃度的增加,Ni-La共沉積的起始還原電位負(fù)移。Ni-La在玻碳電極上的電沉積是屬于擴(kuò)散控制下的三維瞬時(shí)形核模型。在含有0.1mol/LNi (II)的EMIC-EG電解液中,在1 mA/cm2恒電流的條件下,以不銹鋼為陰極,沉積得到了光滑有輕微亮度的沉積層,沉積層致密并且粒徑在100 nm以下。在EMIC-EG-NiCl2-LaCl3電解液中,以銅片為陰極,石墨為陽(yáng)極,沉積得到了Ni-La沉積層。沉積層中La的含量隨著溫度和電流密度的增加而增加,隨著La(Ⅲ)濃度的增加呈現(xiàn)先增加后減小的趨勢(shì)。當(dāng)溫度為373 K、Ni(Ⅱ)濃度為0.1 mol/L、 La (III)濃度為0.2 mol、電流密度為5 mA/cm2時(shí),電沉積得到的沉積層中La含量最高,為7.3 at.%。在Ni-La合金中半徑較大的La原子取代了半徑較小的Ni原子,產(chǎn)生同晶取代,形成固溶置換體,晶格常數(shù)比單質(zhì)Ni的大。SEM結(jié)果表明,隨著溫度和電流密度的增加,沉積層顆粒逐漸增大,沉積層表面粗糙,隨著La(Ⅲ)濃度的升高,沉積層表面由圓球形團(tuán)簇形貌變?yōu)橹罱Y(jié)構(gòu)。耐腐蝕性能實(shí)驗(yàn)表明,隨著沉積層中La含量的增加,沉積層的耐腐蝕性能呈現(xiàn)先變好后變差的趨勢(shì),當(dāng)沉積層中La含量在1.00 at.%左右時(shí),沉積層的耐腐蝕性能最好。
[Abstract]:Lanthanum has a unique electronic structure of 4f layer, which makes its metal and its alloy film have some unique functions. For example, Ni-La alloy has excellent corrosion resistance and is a typical hydrogen storage alloy when its composition reaches LaNi5. It has the characteristics of high hydrogen storage, good hydrogen absorption and desorption, high cycle times and no pollution to the environment. In this paper, the electrodeposition behavior of Ni and Ni-La alloys in this system was systematically studied by means of cyclic voltammetry and chronoamperometry with EMIC-EG as electrolyte, and the composition of the coating was measured by XRF, XRD, SEM, XPS and other methods. The morphology was analyzed. The electrochemical analysis of EMIC-EG-NiCl2 electrolyte shows that the deposition process of Ni is mainly controlled by diffusion, the diffusion coefficient is 4.6 脳 10 ~ (-7) cm ~ (2) / s, and the diffusion activation energy is 21.75 kJ 路mol ~ (-1). The increase of temperature or concentration is beneficial to the reduction of Ni. When the glassy carbon electrode or platinum electrode is used as the working electrode, the deposition of Ni belongs to the three-dimensional instantaneous nucleation model under the control of diffusion. The electrochemical analysis of EMIC-EG-NiCl2-LaCl3 electrolyte showed that the redox reaction occurred in the system and the electrodeposition of Ni-La followed the mechanism of induced co-deposition. With the increase of temperature, the initial reduction potential of Ni-La codeposition is positively shifted to LaCl3 molar concentration, and the initial reduction potential of Ni-La codeposition is negatively shifted. The electrodeposition of Ni-La on glassy carbon electrode is a three-dimensional instantaneous nucleation model controlled by diffusion. In the EMIC-EG electrolyte containing 0.1mol/LNi II, under the condition of 1 mA/cm2 constant current and using stainless steel as cathode, a smooth and slight luminance deposit layer was obtained. The deposit layer was compact and its diameter was below 100nm. In the EMIC-EG-NiCl2-LaCl3 electrolyte, the Ni-La layer was deposited with copper as cathode and graphite as anode. The content of La in the deposit increases with the increase of temperature and current density, and then decreases with the increase of La (鈪，

本文編號(hào)：1953125