KHAO SAT KHA NANG BAO VE CUA MANG BIEN TINH GI CHO THEP CACBON
INVERTIGATION OF PROTECTION CAPACITY OF RUST CONVERTER FOR CARBON STEEL
Lai Thi Hoan'. Nguyen Van Tam', Le Van Cuong", Dinh Thj Mai Thanh' Trudng Dai hpc Giao thdng van tai; "Vien Ky thuat nhiet ddi-Vien KH&CN Viet Nam
Email: l a i t h i h o a n ( a g m a i l . c o m . Tel: 0912067212 Tom tit:
Mdng biin tinh gi dugc hinh thdnh Irin nin thep cacbon dd bi gt iimg vdi cdp dd C) Irong ba logi dung dich bien tinh trin ea sa tcinin cd thdnh phdn khde nhgu BTGl. BTG2 vd BTG3. Cdc phuang phdp phdn lieh be mat SEM vd tdn xg ndng lugng tia X cho thdy mdng biin tinh hinh thdnh cd edu true rd xdp vd tuang ddi ddng diu tren todn bd be mgt. Cdc kit qug dg diin thi mgch ha vd phdn cue diin thi cua 3 logi mdng biin tinh frong dung dieh Aa.-.50./ 0.5M eho thdy mdng biin linh hinh thdnh trong dung dieh BTG3 ed kha ndng bao vi tdt han mdng biin tinh hinh thdnh trong dung dieh BTGl vd BTG2 (vdi cudng do ddng dn mdn khoang 5.267x10 A/cm') ddng thdi ldm tdng ddng ki kha ndng bdm dinh vdi mdng sati hiru ca.
Abstract:
Rust converter is formed on rust carbon steel (corresponding lo level C) in 3 types of denatured solutions basing on tanivn having different components BTGl.
BTG2, BTG3. Suiface analysis methods SEM and energy dispersive X-ray showed that the converter film had porous structure and relatively uniform on the surface.
The results of measuring open circuit potential and potential polarisation of 3 kinds of converter films in .Va.-SOv solution showed that the converter film formed in BTG3 solution had protection belter than the converter film formed in BTGl and BTG2 solutions (with corrosive current density of about 5.26~xl0^ A/enr) and improve significantly the capacity- adherence M-ith the organic coatings.
I. MO DAU
Tinh trang sat thep bi gi gay hu hdng tdn thit Idn \'l kinh tl nga\' cang trim trpng, Wen nay cd nhieu bien phap khic phuc khac nhau nhung phd biln la danh gi bin'g ca hpc gay tdn kem ve siic ngudi \'a ciia cung nhu lam mdi trudng bj d nhiem trim trpng tir chit thai cua qua trinh nay. Viec su dung dung dich biln tinh gi (BTG) da dugc nghien ciki phd biln d thi gidi. d Viet Nam cung dugc de cap tdi do tinh uu viet ciia nd: khdng phai loai bd gi. ma ban than khi bien tinh bang dung dich BTG thi ldp gi chuyin hda thanh ldp mang BTG tren bl mat sat thep tao ldp phu bao \'e rin chic bin khi quyen [1-5].
Trong bai bao nay. chiing tdi khao sat kha nang bao ve ciia mang BTG cho thep cacbon bang mpt sd phuong phap nghien cim hien dai nhu SEM. X-ray... dl Tua chpn ra thanh phin dung dich BTG tdi uu de bao \'e tam thdi cho vat lieu sit thep bi gi trong mdi tmdng khdna khi.
Ngoai ra trong bai bao na\' cdn chi ra \ai trd cua mang BTG khi cd mat fdp son phii.
n. THUC NGHIEM 1. Nguyen lieu va hoa chit:
Mau nghien cuu la thep cacbon kich ihudc 10x5cm cd thanh phin hda hoc (%) nhu sau: Fe (99,406); C (0,150); S (0,037): Mn (0,420); Si a dang v k
Hda chit dugc sir dung (PA): NaCl: tannin; axit glyconic: HF: oxalat amoni...
Tiiu ban Khoa hoc vdt lieu ISBN: 978-604-913-01
2. Che tao mau:
Mau dugc tao gi bang each nhu:ig :igap theo chu ky trong dung dich NaCl 10 M (tuong img vdi viing khi hau gin biln): Cu 10 phut nhung mpt lin rdi lai dl khd 50 phut d nhiet dp khoang 30°C; lam lien tuc 50 ngay sau dd dem phoi d ngoai khdng khi them khoang 10 ngay. Mang gi tao thanh tuong doi deu va dn dinh. Cae mau gi tao thanh dugc rira sach, chai qua phan gi xdp rdi biln tinh trong dung dich bien tinh gi (BTG) cd thanh phan nhu trong bang 1. Diing ban chai mim, quet 2 lugt deu len be mat mau, moi lugt each nhau 2 gid, sau dd de khd d nhiet dp thudng [5, 7].
Bdng I. Thdnh phdn dung dich biin tinh gi (BTG) linh cho I lit dung dich [5, 7]
Thanh phan dung djch tannin (g)
axit glycolic (g) HF (ml)
oxalat amoni (g) OP 10 (ml)
Dung djch BGTl 30
30 10 16 -
Dung djch BTG2 45
35 15 16 2
Dung djch BTG3 60
45 20 24 2 3. Cac phuong phap nghien ciiu:
Mau gi chua bien tinh va 3 loai mau gi da dupe bien tinh trong 3 dung djcb BTGl, BTG2 va BTG3 dugc tien hanh do phan cue Tafel vdi van tdc quet the 5mV/s tren thiet hi Autolab 30 (Ha Lan) dugc dat tai phdng thi nghiem hda trudng Dai Hpc Giao thdng Van tai.
Binh dien hda dugc thiet lap nhu sau: gan mdt dng nhua cd dudng kinh 3,5cm len be mat mau bang keo epoxy (dien tich lam viec ciia mau dugc gidi ban ben trong dng nhua la 9,62 cm^), de khd sau dd cho 40 ml dung dich Na2S04 0,5M vao thir nghiem. Dien cue lam viec la mau gi, BTGl, BTG2 va BTG3, dien cue so sanh va dien cue ddi la Ag.AgCl /KCl 3M va platin dugc nhiing vao trong dng nhua mdi khi tien hanh do.
Qua trinh phan tich cau triic hinh hpc va thanh phan ciia mau gi va cac mau bien tinhdupc thuc hien tren may SEM Jeol 6490 ket hgp vdi thiet bi phan tich EDX Jeol 2300 ciia Trung tam danh gia hu hdng vat lieu, Vien Khoa bpc Vat lieu.
Mau gi va 3 mau sau khi bien tinh dupe phii mpt ldp son ankyd bang phuang phap phun.
Chieu day mang gi, mang bien tinh va mang bien tinh ket hgp vdi son htai ca dugc do bing thilt bi ERICHSEN- 600 FN2, loai 121-16-00. Dp bam dinh do theo tieu chuin ASTMD 454.
III. KET QUA VA THAO LUAN
1. Phan tich cau triic hinh thai hoc va thanh phan cua mau thep gi trudc va sau khi bien tinh:
Hinh 1 gidi thieu cau triic hinh thai hpc ciia be mat mau gi va 3 mau bien tinh gi trong dung dich BTG. Cd sir khac nhau kha nhau rd ret ciia hinh thai hpc mang gi va cac mang biln tinh gi. Be mat mang gi rat xdp va khdng ddng deu. cd cau true tinh the. Sau khi dugc biln tinh trong dung dich BTGl thi tren be mat thay xuat hien viing nhu mang gi xen ke viing cd
va ddng deu hon. Ket qua na\' cho thay sir anh hudng thanh phan \'a ham lugng cac cau tir trong dung dich BTG din qua trinh hinh thanh \'a tinh chat ciia mang BTG cd ciu true vd dinh hinh dac tnmg ciia mang hiru ca do sir tham gia cua tannin \'a mdt sd chit hiJU ca cd trong dung dich BIG.
De lam rd anh hudng ciia thanh phan (hda hpc) dung dich BTG din thanh phin. tinh chat mang BTG. chiing tdi tiln banh phan tich EDX mang BTG3. Tir kit qua phan tich phd EDX ham lugng nguyen td mang BTG 3 (hinh 2) chiing ta khang dinh: trong cac phirc tao thanh maiig BTG ludn cd mat cac nguv'en td cd trong dung dich BTG. Cd thi thi\' sir tham gia cua cac cau tir gdc bun co nhu tanin. axit glycolic trong ty le (% khdi lugng) kha cao ciia^C (18.19) va O (33.72), cdn HF trong sir xuit hien ciia F" vdi 9,20% va cudi ciing la Fe vdi 35,87% trong mang BTG3. Ndi each khac. cac dung dich BTG da tao nen mang biln tinh ma nhu trong mpt \'ai nghien ciiu da chi ra la tannat sit va mpt sd phiic chit khac [5^ 7].
Hinh 1: Hinh gnh SEM cua be mgt mdu thep khi dd tgo gi (g), biin tinh trong dung dich:
BTGl (h), BTG2 (c), BTG3 (d)
1800 1600 MOO 1200 1000-
« 0 0 -
600 400 200
Nguyen td C O F S K Fe
% ve khdi lugng
18,2 33,7 9,2 1,2 0,8 35,9
% ve nguyen td
31,2 43,5 9,98 0,74 0,42 13,2 Hinh 2. Phd tdn xg ndng lugng tig X ciig mdng hinh thdnh trong dung dich BTG3
Tiiu ban Khoa hoc vdt liiu ISBN: 978-604-913-011-
2. Ket qua do dien hoa:
Bdn mau: gi. mang gi biln tinh trong BTGl. BTG2 va BTG 3 dugc tiln hanh do dudng cong phan cue trong dung dich NaiSOa 0.5M, tdc dp quet the 5niV/s sau 01 va 21 ngay ngam mau (hinh 3). Cac thdng sd dien hda cd dugc tir ket qua phan tich dudng cong phan cue the hien trong bang 2. Mang bien tinh cd ddng an mdn giam rd ret so vdi mang gi ban dau.
Sau 1 ngay ngam mau ddng an mdn giam theo thir tu nhu sau: mang gi>BTG2>BTG3>BTGl nhung sau 21 ngay ngam mau mang bien tinh gi hinh thanh trong dung dich BTG3 cd mat dp ddng an mdn nhd nhit (2x10'*' A/cm^). Ket qua nay cho phep khang dinh sir hinh thanh mang BTG tir mang gi tren b l mat thep da tang dp ben chdng an mdn cho nen thep cacbon.
a o
- I
o
Ingay
- 2 -
- 4 -
- 6 -
- 8 -
BTGl\V
•: •
i BTG2
'BTGS
21ngay
E(V)
-1 05 -1 00 -0.95 -0.90 -0.85 -0.80 -0,75 -0.70 -0.65 -0,60 E ( V )
t = 1 ngay t = 21 ngay
Hinh 3. Dudng cong phdn cue Tqfel ciig mdng; gi, BTGl, BTG2 vd BTG3 trong dung dieh Na2S04 0,5M
Bdng 2. Cdc thdng sd diin hda cita mdng gi, BTGl. BTG2 vd BTG3 sau 1 ngdy vd 21 ngdy ngdm trong dung dich Na2S04 0,5M
Ten mau Thdi gian do (ngay) iam(A/cm") x 10~'^
Ecb(mV) vani(mm/y) Rp(Ohni)
Gi 1 6,63 -706
1.56 46,72
21
B T G l 1 1,01 -711 0,24 198
21 1,58 -817 0,37
197
B T G 2 1 1.75 -712 0.41 150
21 0.53 -809 0,12 370
BTG3 1 1,24 -677 0,29 182
21 0,2 -766
0.29 301 3. Kit qua do do bam dinh:
De nghien cu'u kha nang bam dinh. \'a tir do cho phep du doan kha nang bao ve chdng an mdn khi qu>'en cua he bao ve: mang BTG/son hiai ca. mau thep vdi cac mang BTG dugc phii son alkyd, sau dd tien hanh do chieu day \'a dp bam dinh. Chieu day can dugc xac dinh dl dam bao cac mang BTG cd dp day tuang duang nhau \'a phii hgp vdi phuang phap do dp bam dinh (ciia he: mang BTG/son huxi co). Ket qua trong bang 3 cho thay: mang gi khi dugc biln tinh cd chieu day nhd ban ban dau. Dieu nay chimg td mang BTG cd cau triic xit chat ban so vdi mang gi ban dau. Mang bao ve: BTG ket hgp vdi son hiin ca cd chieu day tuang ddi ddng diu nen ket qua do dp bam dinh ciia chiing cd the dugc so sanh vdi nhau.
Bdng 3. Chiiu ddy mdng gt mdng biin tinh gi vd mdng bien tinh kit hgp vdi mdng san
Mang Gi
Mang BTG BTG + San alkyd
Chieu day mang (pm) Xu Iy trong BTGl
25 23 35
Xu ly trong BTG2 24
22 37
Xu ly trong BTG3 27
24 38
Hinh 4 va bang 4 gidi thieu be mat mau sau khi thir dp bam dinh va cac thdng sd lien quan den dp bam dinh chi ra vdi he bao ve: mang BTG3/san alkyd cao hon ban so \'di mang gi xir ly co hpc (1,25 N/mm" va 0,75 N/mm'*, cao hon mpt chut (1,25 N/mm" so vdi 10,90 va 1,20 N/mm") so vdi he mang BTGl/son alkyd va mang BTG2/san alkyd). Ty le % bong trdc be mat ciia 4 loai mau thir nghiem ciing phii hgp vdi cac ket qua neu tren.
b)BTGl
c) BTG2 d) BTG3
Hinh 4; Hinh dnh bi mdt cua mdng gt, BTG kit hgp vdi san Idt sau khi do do bdm dinh Bang 4. Kit qua do dd bdm dinh mdng san
Mau Gi BTGl BTG2 BTG3
Do bam dinh (N/mm^) 0.75
0,90 1,20 1.25
% bong trdc 100%
90%
80%
50%
Tieu ban Khoa hoc vdt lieu ISBN: 978-604-913-0!! -3
IV. KET LUAN
Da che tao thanh cdng mang bien tinh gi trong ba loai dung dich cd thanh phan khac nhau la: BTGl, BTG2 va BTG3. Cau triic hinh hpc va thanh phin cua cac mang da dugc phan tich bang SEM va tan xa nang lupng tia X.
Cac ket qua do dien hda va do dp bam dinh mang son cho thay, trong cac mang bien tinh nghien cuu thi mang bien tinh trong dung dich BTG3 cd kha nang bao ve chdng an mdn tdt hon ca cho thep cacbon trong dung dich Na2S04 0,5M. Cac ket qua nay da khang dinh kha nang bam dinh tdt cua mang BTG vdi mang son trong viec tai bao ve cho vat lieu lam bang sat thep da bi gi va he bao ve mang BTG/mang son cd kha nang bao ve tdt trong mdi trudng khdng khi.
TAI LIEU THAM KHAO
1. C A . Barrero, L.M.Ocampo, C.E.Aroyave., Possible improvement in the action of some mst converters. Corrosion Science 43 (2001) 1003-1018.
2. Francisco Bolivia, Julio Molitas, Cesar Barrero and others. Optimization of a rust converter fomulation. Proceedings of the 15' Intemational Corrosion Congress, Spain, Oct. 2002.
3. L.M.Ocampo, I.C.P.Magarit and others, Perfomance of rust converter base in Phosphoric and Tarmic acids. Proceedings of the 15' Intemational Corrosion Congress, Spain, Oct. 2002.
4. A. A. FepacHMeHKO, T. E. .HivinojibCKaa, PaccjiaHsaiomaa Kopposna anioMU-HHeBbix cnjiaBOB, III. HpeodpaaoBaxejiH npoaycxoB Koppo3HH, 3auynia MexajiJioB, 2001, TOM 3 7 , N o l , c c . 88-98.
5. Tran Thi Lan Anh, Nghien ciru sit dung biin tinh gi bdo ve vd tdi bdo vi thep CT3, Khoa Hda Tmdng Dai hpc Su pham Ha ndi, 2003.
6. EIS study of the rust converter effectiveness under different conditions. Electrochimica Acta, In Press, Corrected Proof, Available online 8 December 2007.
7. Role of tannic acid based rust converter on formation of passive film on zinc rich coating exposed in simulated concrete pore solution. Surface and Coatings Technology, Volume 202, Issue 8, 15 January 2008, pages 1526-1542.
