TAP CHI HOA HOC
DOL 10.15625/0866-7144.2015-0092
T. 53(1)79-83 T H A N G 2 N A M 2 0 1 5
T 6 N G Hap VA NGHIEN CUU HJNH THAI CAU TRUC, T I N H CHAT CUA MANG Fe304 TAO THANH TREN N^N THEP B A N G PHU'aNG PHAP
OXI HOA HOA HOC
Ngo Thi Lan'•^ Doan Anh Tu^ Dinh Thi Mai Thanh^' 'Bg mdn Hda, Hgc Viin Ky thuat Qudn su, Bg Qudc phdng
^Trung ldm Nhiet ddi Viet- Nga, Bd Qudc phdng
^ Viin Ky thugt Nhiit ddi, Viin Hdn ldm Khoa hgc vd Cdng nghe Vi?t Nam Din Tda soan 9-9-2014; Chip nh^n dang 13-2-2014
Abstract
Iron oxide layers fonned on mild steel substrates in alkaline media by chemical method were studied. The effects of some factors such as: NaOH, NaNOs, NaN02 solution concentration, temperature on synthesized magnetite films on mild steel were investigated. Morphology and structure of the oxide film on mild steel, were formed in solution of (500 g/L NaOH, 100 g/L NaNOj, 200 g/LNaN02), at temperamre 120 "C, in 40 minutes were studied. The results showed that synthesized magnetite films have thickness 1.29±0.20 |J.m, crystal uniform globes, average diameter 20 nm.
Keywords. FejO^ film, chemical method, mild steel.
l.MCJDAU
Mang magnetite (FesOj) dugc tdng hgp tren nhieu vat li^u nen khac nhau nhu Cu [I], MgO [2], Si [3], Si02 [4], thuy tinh [5], sit [6, 7].... Tren nin sit, mang oxit Fe304 cd thi dugc tdng hgp bang phuong phap kit tiia dien hda d nhiet do cao [8], phuang phap bay hoi hda hgc [3], phuong phap oxi hda hda hgc [4, 9] va phuang phap oxi hda dien hda [6, 7, 10, II]. Phuang phap oxi hda dien hda true tilp nin th^p trong dung dich kilm cho phep tdng hgp mang oxit sit d dang tinh the hmh lap phuang [13], bam dinh tdt, chilu day vai micromet [6, 11], dang xdp, hinh ciu kich thude tiir 10^30 nm [14] vdi mau sic phong phii [6, 7]. Phuang phap hoa hpc cd thi tao mang oxit Fe304 tren nin thep bing each phan hiiy nhi^t mudi sit II [3], oxi hda tryc tiep thep trong khdng khi [13], trong mdi trudng axit hay mdi trudng kilm [9]. Cac kit qua nghien ciiu cho thiy mang oxit Fe304 cd kha nang chdng an mdn [6, 7, 14], vi vay chiing dugc dung dl bSo ve thep trong mdi trudng khf quyln va trong be tdng [9,15], Sit cd phu mang oxit Fe304 cdn dugc su dung lam dien eye dk tdng hgp dien hda, xu Iy nude thai, khur muoi trong nude va phan hiiy xianua, khii trimg [16, 17]
va de chi tao dien eye cho nguon di$n [11,12, 18].
Bai bao nay trinh bay ket qua khao sat cac ylu to CO ban anh hudng den hinh thai ciia mang oxit tdng
hgp bang phuang phap oxi hda hda hpc tryc tilp nin thep trong mdi trudng kilm. Mang oxit tdng hgp dugc tren nen thep dinh hudng su dyng lam v§t lifu nen de che tao di^n eye Pb02.
2. THl/C NGHIEM
Qua trinh tong hgp mang oxit dugc thuc hien trong binh bang sii chiia 200 mL dung dich NaOH 300H-600 g/L,NaN03 5(^300 g/L, NaN02 50^300 g/L, dupe gia nhi?t d khoang nhiet dp tir 80 den 120
°C va khuiy trgn bing may khuiy tir IKA (Diic).
Nhiet do dugc theo doi bang nhiet ke va duy tri vdi dg chinh xac ±0,5 °C. La thep mem cd thanh phan 0,056 % C, 0,02 % Si, 0,48 % Mn, 0,06 % Ni, day 0,05 mm, kich thuoc 2 cm x 2 cm, sau khi tiy sach dau md, dugc riia bang nude cat, siy khd. Hinh thai va ciu true ciia mang oxit dugc nghien cuu bang phd EDX tren thiit bi OXFORD ISIS (Anh). Pho XRD dugc ghi tren may SIMENS D5005 BRUKER (Diic). Hinh anh SEM bl mat mang oxit dugc chup tren may S4800-NIHE Hitachi (Nhat Ban). Dp day mang dugc do tren may KHV Axiovert 40 MAT.
3. KET QUA VA T H A O LUAN
3.1. Khao sat mot so yen to anh huomg den binh thai hoc cua mang oxit
TCHH, T.53(I), 2015
3.1.L Anh hirdng nong do cua NaOH
Trong dung dich kiem d?c d nhiet do cao va cd mat oxi, sit se bj hda tan tao thanh NajFeOi va Na2Fe204. Hai mudi nay tac dung vdi nhau tao thanh FeaOi [9,20]:
4Fe + O2 + 4NaOH -^ 2Na2Fe204 + 2H2O (1) Fe + O2 + 2NaOH -^ Na2Fe02 + H2O (2) Na2Fe204+Na2Fe02+ 2H2O -^Fe304 +NaOH (3)
Hinh 1 gidi thieu hinh thai be mat eiia cac mang oxit tdng hgp trong dung dich NaOH vdi ndng dp thay doi: 300; 400; 500; 600 g/L. 0 dung dich cd nong dO NaOH thip 300 g/L, qua trinh hinh thanh mang oxit cham, be m&t thep gdm tap hgp cac hat vdi bien gidi khdng ro rang va cdn nhung viing thep chua hi oxi hda (hinh la). Khi tang nong do NaOH trong dung dich, cac hat oxit hinh thanh ddng deu han, viing chua bi oxi hda tren be mat giam (hinh lb,lc- mau Mj, Id). Tuy nhien, vdi ndng do NaOH trong dung dich Idn (600 g/L), d nhiet dp tdng hgp 100 °C, xay ra hien tugng bay hoi nude nhanh lam tang ndng dp NaOH. Do vay, dung dich oxi hda chiia 500 g/L NaOH dugc lya chgn cho nhirng nghien cihi tiep theo.
TD ::. ...
Binh Thi Mai Thanh vd cdng sif SEM cua mang oxit tdng hgp trong cac dieu kien tren dugc gidi thieu d hinh 2.
Sy cd m§t ciia NaN03 cd anh hudng ro r?t din hinh thai be mat ciia mang oxit. O ndng dp NaNOj thip (50 g/L) cac h^t oxit xuit hi?n vdi bien gioi khdng ro rang, kich thude kha Idn, tir 26 nm din 41nm (hinh 2a).
-• 1 . ^
Hinh 2: Anh SEM be mat mang oxit tao thanh trong dung dieb NaOH 500 g/L, thdi gian 20 phiit, ^
nhiet dd 100 °C, ndng dp NaNOj (g/L):
a. 50;b. 100; c 200; d. 300 Khi ndng dp NaNOj tang len 100 g/L, cac h^t oxit cd kich thude dong deu hon bien ddi trong khoang tir 30 den 35nm, cd bien gidi ro rang (hinh 2b). Tilp tuc tang ndng dp NaNOs den 200 g/L, cac hat oxit cd dang hinh cau vdi dudng kinh biin do!
trong khoang 15 nm din 25 nm (hinh 2c). Tuy nhien, khi tang ndng do NaNOs din 300 g/L, hinh dang ciia cac hat oxit tuang ty nhu tdng hgp trong dung djch cd NaNOs ndng do 200 g/L. Kit qua xac dinh chieu day bing phuong phap chup anh mat cat ngang tren kinh hiin vi phdng dai 1000 lin cho thiy d nong do NaNOs 100 g/L do day trung binh cua mang oxit xac dinh tai 5 vj tri la 0,81±0,20 |im (hinh 3a-miu M2) va d ndng dg NaNOa 200 g/L la 0,88±0,20 |im (hinh 3b).
Hinh 1: Anh SEM bl mat mang oxit tao thanh trong thdi gian 20 phiit, nhiet dd 100 °C, ndng dp NaOH
(g/L): a. 300; b. 400; c. 500; d. 600 3.1.2. Anh hudng nong do NaNOj
Trong dung djch kiem dung dl oxi hda thep, NaN03 thudng dugc them vac dl tang nhiet dp soi eiia dung dich [9].
Chung tdi da khao sat su hinh thanh mang oxit trong dung djch kilm vdi sir c6 mat NaNOj d cac ndng dp khac nhau 50; 100; 200 va 300 g/L. Anh
Hinh 3: Anh mat cat ngang mang oxit tdng hgp trong trong dung dich NaOH 500 g/L, thdi gian 20 phut,
nhiet dd dung dich 100 "C, n6ng do NaNOj:
a. l60g/L;b.200g/L
TCHH, T. 53(1), 2015
Su cd m|t cua NaNOs trong dung dich vdi ndng do idn (200g/L, 300g/L) lam cho Idp oxit hinh thanh min va kin kbit tren nin thep, can trd qua trinh oxi hda s§u vao phia trong. Vi vay, khi ndng dp NaNOs trong dung dich tang tir 100 g/L din 200g/L chilu day trung binh ciia mang oxit gan nhu khdng thay ddi. Do dd ndng do NaN03 trong dung dich lalOO g/L dugc lya chgn cho cac khao sat tiep theo.
3.1.3. Anh hudng cua ndng do NaN02
NaN02 dugc dua thfim vao dung djch kiem de tang kha nSng oxi hda thep [9, 19]. NaN02 tham gia phan limg tao thanh mang oxit nhu sau [20]:
2NaN02+ Fe + HjO ^ FeO + 2NaOH + 2N0 (5) 2NaN02+ 3FeO + HjO -^ Fe304 + NaOH + 2N0 (6)
Chung toi da khao sat sy hinh thanh ciia mang oxit trong dung dich dugc b6 sung NaN02 vdi ndng do 50; 100; 200; 300 g/L. Hinh thai bl mat cua mang oxit dugc gidi thi?u tren hinh 4.
Tdng hgp vd nghien ciru cdu true...
3.1.4. Anh hudng cua nhiet do
Hinh thai bl mat cua mang oxit tdng hgp d nhiet do thay ddi tir 80 "C din 120 °C dugc gidi thieu tren hinh 5. 6 nhiet dp 80 °C tdc dp cac phan iing tao thanh mang oxit cham, mang oxit chua ddng deu va khdng mjn (hinh 5a). Chilu day mang oxit la 0,60 Jim (hinh 6a). Khi nhiet do tang den 120 °C, be mat mang oxit nhan mjn, cac hat oxit hinh cau khdng cdn bien gidi ro rang (hinh 4d - mau M4), chieu day trung binh ciia mang oxit la 1,21 )J.m (hinh 6b). Dl phii hgp vdi dieu kien thi nghiem va mang oxit t^o thanh cd chieu day Idn nhat chiing tdi chgn nhiet dp 120 °C cho cac khao sat tiep theo
Hinh 4: Anh SEM be mat mang oxit tdng hpp trong dung dich NaOH 500 g/L, NaNO, 100 g/L, thdi gian 20 phut, nhiet dp 100 °C, nong dp NaN02 (g/L):
a. 50;b. 100; c. 200; d. 300 Trong vung ndng do khao sat kich thude cac hat oxit tuong ddi ddng deu, dao ddng tir 15nm den 20 nm. Ci nong do NaN02 50 va 100 g/L, cac hat oxit cd bien gidi rd rang va xip xep khdng kbit nhau (hinh 4a, 4b). Khi ndng dp NaN02 trong dung dich tang din 200 va 300 g/L, bl mat mang oxit gdm cac hat hinh ciu xip sit nhau va phat trien ddng deu tren nen thep (hinh 4c - mau M3 va 4d). Tuy nhien, su khac biet hinh dang va kich thuoc ciia cac hat oxit tao thanh d ndng dp 200 g/L va 300 g/L khong ldn.
Vi v3y, chung tdi lua chgn ndng do NaN02 200 g/L dl tilp tuc khao sat.
Hinh 5: Anh SEM be mat mang oxit t6ng hgp trong dung dich NaOH 500 g/L NaNOj 100 g/L, thdi gian 20 phiit, ning dg NaNOi 200(g/L), nhiet dp dung
dich thay ddi la ("C): a. 80; b. 120
Hinh 6: Anh mat cat ngang mang oxit tong hgp trong dung djch NaOH 500 g/L, NaN03 100 gfL, NaN02 200 (g/L), thdi gian 20 phiit. Nhiet do dung
dich CC): a. 80 b. 120 3.1.5. Anh hudng cua thdi gian
Thdi gian oxi hda thep cd the anh hudng den hinh dang hat oxit cung nhu chieu day ciia mang oxit [8, 9]. Chiing toi da khao sat su hinh thanh mang oxit vdi thdi gian oxi hda khac nhau 10; 20; 30 va 40 phiit. Hinh anh SEM be mat ciia mang oxit tdng hop dugc the hien tren hinh 7. Trong thdi gian 10 phiit, mang oxit hinh thanh vdi kich thuoc hat ldn (hinh 7a). Khi thdi gian tdng hgp tang len, be mat mang oxit gdm cac hat sap xep kin khit tren be mat (hinh
TCHH, T. 53(1), 2015
7d). Tuy nhien, chilu day cua mang oxit thay ddi khdng dang kl tir 1,09 jim (hinh 8a), 1,21 ^m (hinh 6b) va 1,29 ^m (hinh 8b - miu M5), tuang irng vdi thdi gian tong hgp 10, 20 va 40 phut
Hinh 7- Anh SEM be mat mang oxit tdng hgp trong dung dich NaOH 500 g/L NaNOa 100 g/L, ndng do NaNOj 200 (g/L), nhiet do dung dich 120 °C. Thdi
gian (phut): a. 10; b. 20; c. 30; d. 40
Dinh Thi Mai Thanh vd cgngs^
M2 (0,81 nm), M3 mang oxit mdng nen chi xuat hien vach nhilu xa tiii 35,50" (d = 2,527) dac Uung cho Fe304 [21], cac vach nhilu xa cd cudng dg ldn tJii 44,71° (d - 2,025) va 65,11° (d = 1,430) cd cudng dp nhd dac trung cho sat, do anh hudng cua v§t liSu nin (hinh 9 M|, M2, M3). Tuy nhien, khi dg day cua mang oxit tang 1,21 |J.m (M4) va 1,29 |im (M5) tren aian dd nhilu xa tia X xuat hien them cac vach nhilu xa tai 29,95° (d - 2,981), 53,34° (d = 1,716) va 56,83° (d = 1,619) dac trung dac trung cho Fe304 (hinh 9 M^, M5). Vi vay, cdng thirc ciia mang oxit tren nin sit tao trong cac dieu kien tdng hgp dugc xac dinh la Fe304 [21].
Bdng 1: Kit qua phan tich phd tan xa tia X theo nang lugng ciia cac mau mang oxlt/thep
Hinh 8: Anh mat cat ngang mang oxit tdng hop trong dung dich NaOH 500 g/L, NaNOj 100 g/L, NaNOs 200 g/L, nhiet do dung dich 120 °C.
Thdi gian (phiit) a. 10; b. 40 3.2. Phan tich thanh phan, hinh thaipha cua mang oxit
Ket qua phan tich phd tan xa tia X theo nang lugng cua mang oxit mau Mi, M2, M3, M4 va Mjdugc lya chpn tii cac khao sat d phin tren dugc gidi thieu d bang I.
Kit qua cho thay, phin tram khli lugng ciia hai nguyen to chinh O va Fe trong cac miu khac nhau khdng nhieu. Ty le ve sd lugng nguyen tu gitTa O va Fe xap xi 1:1.
Mang sat oxit dugc xac dinh hinh thai pha bing phan tich nhilu xa tia X trong khoang 26 tii 10°- 70°. Gian dd nhieu xa tia X cho thiy cac mlu M,,
Mau
M, M2 M J M, M,
Nguyen 16 Fe 0 Fe 0 Fe 0 Fe 0 Fe 0
%
khoi lircmg 77,78 22,22 77,82 22,18 77,73 22,27 76,96 23,04 77,01 22,99
%
nguyen tli 50,00 50,00 50,06 49,94 49,93 50,07 48,89 51,11 48,97 51,03
Tile nguyen tu
(Fe:0) 1:1,00 1:1,00 1:1,00 1:1,05 1:1,04
\ "*'Xj\ji,098,
1,716 1,43
'-A'. U.-.,>-Av,^v—M,
~ MJ
-^ -, M,
~^---,,
-M, 1,43
JD ED D
26 M61 Hinh 9: Ket qua phan tich nhieu xa tia X
T C H H , T. 53(1), 2 0 1 5
Clia n e n t h e p Mo v a m a n g oxit M i , M2, M3, M4, M5 T A I L I E U T H A M K H A O
1. Richard L. Kurtz, J. Kanmamuni, and R. L.
Stockbauer. Synthesis of epitaxial Fe304 films on Cu.001. The American Physical Society, 60(24), R16342-R16345(1999).
2. N. TH. Kim Ngan, A.G. Balogh, J.D. Meyer. Brtz, S.
Hummelt, M. Zaja, T. Sleza, J. K.orsck\.Structure, composition and crystallinity of epitaxial magnetite thm films. Surface Science, 602, 2358-2362 (2008).
3. J. -Y. Lee, B. -C. Kang, D. -Y. Jung, and J.-H. Booa.
Selective growth of iron oxide thin films using the combined method of metal-organic chemical vapor deposition and microcontact printing, Journal Vacuum Society, B 25,4, 1516-1519 ( 2007).
4. Alona Gabrene, Janina Setina, Inna Juhnevica and Gundars Mezinskis. Stabilization of Magnetite anoparticles byEncapsulation into the Silica Matrix, J. Chem. Chem. Eng.,8, 42-46 (2014).
5. Jianrong Sun, Zhiguang Wang, Yuyu Wang, Yabin Zhu, Kongfang Wei, Tielong Shen, Fashen Li.
Synthesis, characterization and magnetoresistance properties study of magnetite thin films by electroless plating in aqueous solution. Vacuum, 86, 461-465
(2011).
6. T. D. Burleigh, P. Schmuki, and S. Virtanen.
Properties of the Nanoporous Anodic Oxide Electrochemically Grown on Steel in Hot 50%
NaOH, Journal of The Electrochemical Society, 156(1), C45-C53 (2009).
7. T. D. Burleigh, T. C. Dotson, K. T. Dotson, S. J.
Gabay, T. B. Sloan, and S. G. Ferrell. Anodizing steel in KOH and NaOH solutions, Joumal of The ElecUochemical Society, 154(10), C579-C586 (2007).
8. Huanan Duan, Xiangping Chen, Boquan Li, Jianyu Liang. Growth morphology study of cathodically electrodeposited Fe^O^ thin films at elevated temperatures. Materials Research Bulletin, 45, 1696- 1702 (2010).
9. Tran Minh Hoang. Cong nghe mg dien, 217, Nxb.
Khoa hoc va ky thuSt, Hk Noi (1998).
Tdng hgp vd nghien ciru cdu true...
10. L. Freire, X. R. Novoa, M. F. Montemor, M. J.
Carmezim. Study of passive film formed on mild steel in alkaline media by the application of anodic potentials. Materials Chemistry and Physics, 114, 962-972 (2009).
l l . N g 6 Thi Lan, DoSn Anh Tii, Dinh Thi Mai Thanh.
Tong hap vd nghien ciru hinh thdi, tinh chdt cua mdng Fe^O^ tren nen thep bdng phirang phdp ddng dp dat. Tap chi Hoa hoc, 15(6ABC), 701-705 (2013).
i2.Ng6 Thi Lan, Pham Manh Thao, Doan Anh Tii. Khdo sdt bo nguon 8M-EA ciia ten tieaX29T. Tap chi Khoa hoc va ky thuat, 148, 183-189(2012).
13. H. Xiang, F. -Y. Shi, C. Zhang, M. S. Rzchowski, P. M.
Voylesa and Y. A. Chang. Synthesis ofFciO^ thm films by selective oxidation with controlled oxygen chemical potential, ScriptaMaterialia, 65, 739-742 (2011).
14. Jie Chen, Kelong Huang, Suqin Liu. Hydrothermal preparation of a protective FcjO^ film on Fe foil.
Corrosion Science, 50, 1982-1986 (2008).
15. Fauziatul Fajaroh, Hem Setyawan, W. Widiyastuti, Sugeng Winardi Synthesis of magnetite nanoparticles by surfactant-free electrochemical method in an aqueous system. Advanced Powder Technology, 23, 328-333 (2012)
16. A. T. Kuhn and P. M. Wright. Industrial electrochemical, Processes Elsevier Press., p i 5 3 (1971).
17 M. Hayes, A. T. Kuhn. The preparation and behaviour of magnetite anodes, Joumal of applied electrochemistry, 8, 327-332 (1978)
18. S. Ito, K. Nakaoka, M. Kawamura, K. Ui, K.
Fujimoto, N. Koura. Lithium battery having a large capacity using Fe^O., as a cathode materiaUoumal ofPowerSources, 146, 319-322(2005).
19. Maan Hayyanl, Shatha A. Sameh, Adeeb Hayyan, Inas M AlNashef. Sodium nitrite as inhibitor for protection of carbon steel in salt solution, J, Elecuochem Sci., 7, 6941-6950 (2012)
20. N Arab, M. Rahimi Nezhad Soltani. A Study of coating process of cast iron blackening, Joumal of Applied Chemical Research, 9, 13-23 (2009).
21. International Center for Diffraction Data. Powder diffraction file, alphabetical index, inorganic phases, (1984).
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