Aluminium film has been electrodeposited onto sintered NdFeB magnet at room temperature (25°C) in ionic liquid electrolytes named aluminium chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Electrodeposition mechanism of Al film is analysed using cyclic voltammetry and chronoamperometry measurements. Structure and morphology of specimen are characterised and analysed using X-ray diffraction, energy-dispersive X-ray spectrum and atomic force microscopy. The results indicate that the process of Al electrodeposition follows the three-dimensional instantaneous nucleation mechanism. As the potentials vary from −0.4 to −0.8 V, the diffusion coefficient (D) of
and the calculated number density of Al valid nuclei sites (N0) on the sintered NdFeB magnet both increases. The deposited films consist of pure fcc phase of Al metal, and Al grains with crystal orientation of {111}, {200}, {220} and {311} are dominant components. Al film deposited at −0.6 V has finer and smoother surface, with the roughness value of 135.10 nm.
Sepehri-AminH., OhkuboT., ShimaT. and HonoK.: ‘Grain boundary and interface chemistry of an NdFeB-based sintered magnet’, Acta Mater., 2012, 60, 819–830. doi: 10.1016/j.actamat.2011.10.043
4.
MaJ. Z., LiuX. F., QuW. T. and ZhouC. G.: ‘Corrosion behavior of detonation gun sprayed Al coating on sintered NFeB’, J. Therm. Spray Technol., 2015, 24, 394–400. doi: 10.1007/s11666-014-0188-9
5.
FedelS. M. and DeflorianF.: ‘Electrochemical characterization of atomic layer deposited Al2O3 coatings on AISI 316L stainless steel’, Electrochim. Acta, 2016, 203, 404–415. doi: 10.1016/j.electacta.2016.02.107
6.
MehranQ. M., BushroaA. R., FazalM. A. and AdhesJ.: ‘Evaluation of CrAlN multilayered coatings deposited by PVD magnetron sputtering’, Sci. Technol., 2015, 29, 2076–2089.
7.
ZhangP., LiuJ., XuG., YiX., ChenJ. and WuY.: ‘Anticorrosive property of Al coatings on sintered NdFeB substrates via plasma assisted physical vapor deposition method’, Surf. Coat. Technol., 2015, 282, 86–93. doi: 10.1016/j.surfcoat.2015.10.021
8.
AdabiM. and AmadehA.: ‘Effect of electrodeposition conditions on properties of Ni-Al composite coatings’, Surf. Eng., 2015, 31, 650–658. doi: 10.1179/1743294414Y.0000000449
9.
ArghavanianR., BostaniB. and Parvini-AhmadiN.: ‘Characterisation of coelectrodeposited Ni–Al composite coating’, Surf. Eng., 2015, 31, 189–193. doi: 10.1179/1743294414Y.0000000339
10.
PradhanD. and ReddyR. G.: ‘Mechanistic study of Al electrodeposition from EMIC-AlCl3 and BMIC-AlCl3 electrolytes at low temperature’, Mater. Chem. Phys., 2014, 143, 564–569. doi: 10.1016/j.matchemphys.2013.09.033
11.
ChenJ., XuB. J. and LingG. P.: ‘Amorphous Al–Mn coating on NdFeB magnets: Electrodeposition from AlCl3–EMIC–MnCl2 ionic liquid and its corrosion behavior’, Mater. Chem. Phys., 2012, 134, 1067–1071. doi: 10.1016/j.matchemphys.2012.03.114
12.
GiridharP., El AbedinS. Z. and EndresF.: ‘Electrodeposition of aluminium from 1-butyl-1-methylpyrrolidinium chloride/AlCl3 and mixtures with 1-ethyl-3-methylimidazolium chloride/AlCl3’, Electrochim. Acta, 2012, 70, 210–214. doi: 10.1016/j.electacta.2012.03.056
13.
LiuQ. X., El AbedinS. Z. and EndresF.: ‘Electroplating of mild steel by aluminium in a first generation ionic liquid: a green alternative to commercial Al-plating in organic solvents’, Surf. Coat. Technol., 2006, 201, 1352–1356. doi: 10.1016/j.surfcoat.2006.01.065
14.
ChangJ.-K., ChenS.-Y., TsaiW.-T., DengM.-J. and SunI.-W.: ‘Electrodeposition of aluminum on magnesium alloy in aluminum chloride (AlCl3)-1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid and its corrosion behavior’, Electrochem. Commun., 2007, 9, 1602–1606. doi: 10.1016/j.elecom.2007.03.009
15.
BardiU., CaporaliS., CraigM., GiorgettiA., PerissiI. and NichollsJ. R.: ‘Electrodeposition of aluminium film on P90 Li-Al alloy as protective coating against corrosion’, Surf. Coat. Technol., 2009, 203, 1373–378. doi: 10.1016/j.surfcoat.2008.11.003
16.
QianH. M.: ‘Mechanism of Magnesium alloy electrodeposited in ionic liquid and its corrosion performance’, PhD thesis, Zhejiang University, Hangzhou, China, 2010, 45–67.
17.
ZhaoH., XuL. B., ChenJ. F. and ZhangP. Y.: ‘Constant current electrodeposition of aluminum from [EMIM] Br-AlCl3 ionic liquid’, Chin. J. Nonferrous Met., 2012, 22, 2683–2692.
18.
TetsuyaT., ToshiyukiN. and YasuhikoI.: ‘Nucleation and surface morphology of aluminum-lanthanum alloy electrodepsited in a LaCl3-saturated AlCl3-EtMeImCl room temperature molten salt’, Electrochim. Acta, 2002, 47, 2817–2822. doi: 10.1016/S0013-4686(02)00168-8
19.
MeiT. Q., YuG. N., HeL. M. and PeiY. R.: ‘Research on Al electrodeposition in ionic liquid A1C13-[bmim]Cl’, J. Chin. Soc. Corros. Protect., 2011, 31, 319–323.
20.
LiY.: ‘Effect of additives on the electrodeposition of Al in ionic liquid AlCl3-BMIC’, PhD thesis, Kuming University of Science and Technology, Kunming, China, 2011, 23–56.
21.
UedaM., HariyamaS. and OhtsukaT.: ‘Al electroplating on the AZ121 Mg alloy in an EMIC-AlCl3 ionic liquid containing ethylene glycol’, J. Solid State Electrochem., 2012, 16, 3423–3427. doi: 10.1007/s10008-012-1801-9
22.
LiB., FanC.-H., ChenY., LouJ.-W. and YanL.-G.: ‘Pulse current electrodeposition of Al from an AlCl3-EMIC ionic liquid’, Electrochim. Acta, 2011, 56, 5478–5482. doi: 10.1016/j.electacta.2011.03.047
23.
ZhangW. and LingG. P.: ‘Effects of Refinement by Al Wires on the Al-deposition from AlCl3-EMIC at Room Temperature’, Surf. Eng., 2013, 42, 66–69.
24.
TangJ. and AzumiK.: ‘Optimization of pulsed electrodeposition of aluminum from AlCl3-1-ethyl-3-methylimidazolium chloride ionic liquid’, Electrochim. Acta, 2011, 56, 1130–1137. doi: 10.1016/j.electacta.2010.10.056
25.
WeiL. Y.: ‘Effect of microstructure on Corrosion Behavior of aluminum and its alloys’, PhD thesis, Harbin Engineering University, Harbin, China, 2009, 122–134.
26.
MaoS., YangH., SongZ., LiJ., YingH., SunK.: ‘Corrosion behaviour of sintered NdFeB deposited with an aluminium coating’, Corros. Sci., 2011, 53, 1887–1894. doi: 10.1016/j.corsci.2011.02.006
27.
DingJ., XuB. and LingG.: ‘Al-Mn coating electrodeposited from ionic liquid on NdFeB magnet with high hardness and corrosion resistance’, Appl. Surf. Sci., 2014, 305, 309–313. doi: 10.1016/j.apsusc.2014.03.067
28.
VaughanJ. and DreisingerD.: ‘Electrodeposition of aluminum from aluminum chloride–trihexyl(tetradecyl) phosphonium chloride’, J. Electrochem. Soc., 2008, 155, D68–D72. doi: 10.1149/1.2804422
29.
XueD., ChenY., LingG., LiuK., ChenC. and ZhangG.: ‘Preparation of aluminide coatings on the inner surface of tubes by heat treatment of Al coatings electrodeposited from an ionic liquid’, Fusion Eng. Des., 2015, 101, 128–133. doi: 10.1016/j.fusengdes.2015.10.013
30.
SunadaS., MajimaK., AkasofuY. and KanekoY.: ‘Corrosion assessment of Nd-Fe-B alloy with Co addition through impedance measurements’, J. Alloys Compd., 2006, 408–412, 1373–1376. doi: 10.1016/j.jallcom.2005.04.039
31.
ZhangL. J., FanJ. J., ZhangZ., CaoF. H., ZhangJ. Q. and CaoC. N.: ‘Study on the anodic film formation process of AZ91D magnesium alloy’, Electrochim. Acta, 2007, 52, 5325–5333. doi: 10.1016/j.electacta.2006.12.083
32.
AltimariP. and PagnanelliF.: ‘Electrochemical nucleation and three-dimensional growth of metal nanoparticles under mixed kinetic-diffusion control: model development and validation’, Electrochim. Acta, 2016, 206, 116–126. doi: 10.1016/j.electacta.2016.04.094
33.
MashreghiA. and ZareH.: ‘Investigation of nucleation and growth mechanism during electrochemical deposition of nickel on fluorine doped tin oxide substrate’, Curr. Appl. Phys., 2016, 16, 599–604. doi: 10.1016/j.cap.2016.03.008
34.
LiuF., DengY., HanX., HuW. and ZhongC.: ‘Electrodeposition of metals and alloys from ionic liquids’, J. Alloys Compd., 2016, 654, 163–170. doi: 10.1016/j.jallcom.2015.09.137
35.
ZieglerJ. C., WielgoszR. I. and KolbD. M.: ‘Pb deposition on n-Si(111) electrodes’, Electrochim. Acta, 1999, 45, 827–833. doi: 10.1016/S0013-4686(99)00261-3
36.
NishimuraA., MatsumiyaM., OtaH. and KawakamiS.: ‘Electrochemical analysis of diffusion behavior and nucleation mechanism for neodymium complex in potassium bis(trifluoromethylsulfonyl)amide melts’, Electrochem. Commun., 2016, 65, 23–26. doi: 10.1016/j.elecom.2016.01.005
37.
ZhangJ., AnM., ChenQ., LiuA., JiangX., JiS., LianY. and WenX.: ‘Electrochemical study of the diffusion and nucleation of gallium(III) in [Bmim][TfO] Ionic liquid’, Electrochim. Acta, 2016, 190, 1066–1077. doi: 10.1016/j.electacta.2016.01.027
38.
ShmychkovaO., Luk'yanenkoT., PiletskaA., VelichenkoA., GladyshevskiiR., DemchenkoP. and AmadelliR.: ‘Electrocrystallization of lead dioxide: Influence of early stages of nucleation on phase composition’, J. Electroanal. Chem., 2015, 746, 57–61. doi: 10.1016/j.jelechem.2015.03.031
and the calculated number density of Al valid nuclei sites (N0) on the sintered NdFeB magnet both increases. The deposited films consist of pure fcc phase of Al metal, and Al grains with crystal orientation of {111}, {200}, {220} and {311} are dominant components. Al film deposited at −0.6 V has finer and smoother surface, with the roughness value of 135.10 nm.