TAP CHI HOA HQC
DOl: 10.15625/0866-7144 2014-0007 T. 52(4)435-438 THANG 8 NAM 2014
U'NG DUNG DIATOMIT LAM C H A T PHU GIA CHO Lap PHO BAO VE CHCNG AN MON CHO THEP CACBON
Nguyen Anh Son", Nguyen Thuy Dirong, Pham Gia Vu, Trinh Anh Triic Viin Ky thugt nhiet dai, Viin Hdn Idm Khoa hgc vd Cong nghe Viet Nam
Ddn Tda soan 20-12-2013
Abstract
Diatomite is naturally occurring with over 63 % of silica in the chemical composition. This diatomite was introduced in waterbome epoxy for corrosion protection of carbon steel surface. The morphology of coalings was observed by Field Emission Scanning Electron Microscopy (FESEM). The Electrochemical Impedance Spectroscopy (EIS) method was used for characterized the corrosion protection of epoxy coating and epoxy coating containing diatomite. The results showed that incorporation of 15 % diatomite in waterbome epoxy coatings enhanced anticorrosion protection property of the coating.
Keywords: Diatomite, waterbome epoxy coatings, anticorrosion protection.
1. MO DAU
Ldp phii huu ca dugc sti dung kha phd bien trong linh vyc bao vp chdng an mon. Ca cha bao ve ciia Idp phil dugc chia ra lam 3 nhdm chinh: che chan [ I, 2], bam dinh va bao vp dipn hda [3, 4]. Nhung ldp phil nam trong nhdm bao vp che chan thudng la nhu'ng ldp phii cd kha nang che chan tdt, tra ve mat hda hgc, mdng, khdng bi tham tir mdi trudng ben ngoai. Trong mpt sd trudng hgp, su cd mat ciia chat phy gia tra trong ldp phii cd the gop phan tang kha nang che chan ciia ldp phii dd nhd keo dai dudng dan Clia cac tac nhan an mon tdi ba mat kim logi qua Idp phil. Cac chat phy gia cd dang tam hoac dng dem lai hieu qua tot ban cho tinh chat che chan ciia mang phil chira nd. Mdt sd nghien ciru da chi ra sy cd mat Clia phy gia vd ca nhu oxit silic, oxit kem hay oxit sat cai thipn dang ke kha nang bao ve chdng an mdn ciia Idp phil [5-8].
Diatomit, cdn ggi la kizengua hay dat tao silic, la khoang ty nhien cd thanh phan hda hpc chu yeu la SiOj (> 63 %). c l u true ciia diatomit kha phiic tap hinh dng gdm nhieu Id nhd, khoang (hinh 1), vi tha, vgt lipu nay co dipn tich be mgt kha Idn, kha nang hap thy cao va cd ty trgng thap. Mat khac, diatomit cdn cd tinh din nhipt thlp, nhipt dg ndng chay kha cao, tra hda hgc va co kich thudc hgt nhd. Ben cgnh dd, diatomit cdn cd kha nhilu trong ty nhien va gia dianh thlp. Vi vgy, trong cdng trinh nay, diatomit dugc nghien ciru dua vao trong mang son phii hiru ca epoxy hp nudc va khao sat anh hudng ciia nd ien kha nang bao vp chdng an mdn cung nhu tinh chat
ca ly CLia mang phil.
Hinh } Cau true ciia diatomit [9]
2. THUC NGHIEM 2.1. Nguyen lieu
Diatomit dugc lay tir md quang d Phii Yen da qua xir ly cd thanh phan hda hgc trinh bay trong bang 1.
Mudi nayi clorua (NaCl) tinh khiet ( > 99,5 %) doTrung Quoc san xuat.
Mang son phii dugc tao tir nhua epoxy hp nudc Epikote 828 chira 97 % ham ran va chat ddng rln Epikure 8537 chira 31 % ham rln do hang Momentive (Thai Lan) cung cap.
TCHH, T. 52(4), 2014
Bang 1: Thanh phan hoa hgc cua diatomit Phu Yen [10]
SiO;, % 64,15 CaO, %
1,19
AI2O3, % 12,5 MgO, %
0,62
FeiOj, % 4,75 MKN, %
13,8
TiOi, % 1,04 Khac, %
1,95 (% ve khoi lupng).
Nan kim logi nghien cdu la thep cacbon cd kich thudc 1 5 x 1 0 x 0 , 2 cm.
2.2. Phvong phap nghien ciru
Hinh thai, cau tnic ciia mang epoxy nudc va epoxy nudc chua diatomit dugc quan sat bang kinh hian vi trudng dipn tir quet dp phan giai cao (FESEM). Mau mgt cat ciia mang phu dugc chup tren may do Hitachi S-4800 thudc Vien Khoa hgc Vat lieu, Vien Han lam Khoa hgc va Cdng nghe Viet Nam.
Tinh chat ca ly: cac mau thep sau khi dugc phii mang epoxy cd hogc khdng cd diatomit dugc khao sat cac tinh chat ca ly nhu: kha nang bam dinh khd, udt va dp ben va dap. Do ben va dap ciia cac mau dugc xac djnh theo tieu chuan ISO 6272 tren thidt bj Erischen model 304. Dg bam dinh khd va udt dugc xac djnh theo phuang phap keo gigt theo tiau chuin ASTM D-4541 tren thiet bi Positest AT-A tgi Vipn Ky thugt nhipt ddi, Vipn Han lam Khoa hgc va Cdng nghp Vipt Nam.
Phuang phap tdng trd dipn hda sir dung he 3 dipn cyc: dipn cue lam viec la tam thep phii mau mang son, dipn cyc so sanh la dipn cyc calomel bao hda va dipn cyc ddi la ludi platin. Cac phep do dugc thyc hien tren may Autolab PG30 (Ha Lan) tgi Vien Ky thuat nhipt ddi, Vien Han lam Khoa hgc va Cdng nghp Vipt Nam. Mdi trudng xam thyc la dung dich dien ly NaCl 3 %, dipn tich bl mat son tidp xuc vdi moi trudng xam thyc la 7 cm^. Mdi phep do dugc tian hanh tran 3 mau de khing djnh kha nang lap lai.
2.3. Che tao mau
Mau thep dugc iam sach dau ma blng xa phdng rdj rira bang nudc cat, etanol va sly khd. Sau do, cac mau thep dugc mai bd mgt blng gily nham SIC den dp mjn 400. Diatomit dugc nghien min blng c6l nghian trudc khi nghien trgn vdi nhua epoxy. Hdn hgp mang epoxy chira diatomit dugc phii tren mat tam thep bang phuang phap ly tam tren may Filmfuge 11 ION (Sheen) tgi Vipn Ky thuat nhiet ddi, Vipn Han lam Khoa hgc va Cdng nghe Vipt Nam.
Nguyen Anh Scm vd cgng su Diatomit dugc dua vao mang epoxy vdi ham lugng 15 % ve khdi lugng. ChiSu day mang sau khi kho la 30±2 pm.
3. KET QUA VA THAO LUAN
3.1. Hinh thai hoc cua diatomit trong nen polyme Hinh thai hgc cua cac mau mang son dugc quan sat qua anh chup FESEM mat cat (hinh 2). Hinh dgng mat cat ciia mang epoxy tuang ddi tran nhin, cho thay vet niit Ian truyen mgt each bang phang dudi tac dgng ciia lyc xe. Mang epoxy chua diatomit cd cau true mat cat gd gha ban, do sy cd mat ciia cac phan tir diatomit lam dudng xe bi bi6n dang, sy niit gay trd nen khd lan truyen ban. Tren binh 2b quan sat thay xuat hien diatomit dgng tam va dang dng.
Day cd tha la do trong qua trinh nghian min, nhimg dng diatomit cd kich thudc Idn bi vd ra thanh cac manh nhd dang tim. Mat khac, giira diatomit va nen polyme van thay xuat hien vet nurt nhd. Hipn tugng nay do sy sy tuang hgp yeu giira diatomit va nSn epoxy. Dieu nay cd thd anh hudng den ti'nh chit ciia mang san.
Hinh 2: Anh chup FESEM mat clt mang son epoxy trang (A) va mang scm epoxy chua diatomit (B) 3.2. Tinh chat cff ly
Do bam dinh cua mang son khi dS ngoai khdng khi hay sau khi ngam 1 khoang thdi gian trong nudc cung nhu kha nang chju va dap la nhirng tinh chat co ly kha quan trgng da danh gia mang son phii. Ket qua do cac tinh chit ca ly cua cac mau mang son dugc trinh bay trong bang 2.
Bdng 2: Tinh chat co Iy ciia mang son epoxy Eo va mang son epoxy chira phu gia diatomit EDA
STT 1 2
Mau scm Eo
E D A
Do ben va dgp, kg.cm
100 100
Dg bam dinh khd,
N/mm^
3,5 3,3
Dp bam dinh udl, N/mm^
3,2 3
TCHH, T. 52(4), 2014
Theo ket qua do dg ben ca Iy trong bang 2, vdi ty Ip pha trgn 15 % ve khoi lugng, dg bdn va dap cua mang scm chua diatomit khong thay ddi so vdi mang son epoxy trlng (100 kg.cm). Tuy nhien, kha nang bam dinh khd va bam dinh sau khi ngam trong mdi tnidng an mdn (NaCI 3 %) cd giam nhp (tuang limg, 3,3 N/mm^ so vdi 3,5 N/mm^ va 3 N/mm^ so vdi 3,2 N/mm^), Cac ket qua khao sat tinh chat ca ly cua mang son cho thay sy cd mat ciia diatomit trong mang khdng lam anh hudng den cac tinh chat co ly ciia mang son epoxy.
3.3. Kha nang bao vp chong an mon
Cac mau mang son dugc danh gia va so sanh kha nang bao vp chdng an mdn bang phuang phap tdng trd dipn hda theo thdi gian ngam trong mdi trudng an mon la dung dich NaCl 3 % ve khdi lugmg. Nham quan sat ro ban kha nang irc cha qua trinh an mdn cua chit phy gia dem vao mang phii, cac mau dugc rach hinb chu' thap tren bd mat vdi kich thudc 1 cm.
Kat qua tong trd cua cac mau do dugc theo thdi gian dugc trinh bay tren hinh 3.
(A),
S.0110
"24.0110'
fjl 1.0x10*
0.0
I ISmHz I • MTI
0.0 2.O1IO' 4.Oxl0' 6.O1IO' 8.0xlo' I.O1I0'
Z' / Q,cm^
3.0I10
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Hmh 3: Phd tdng trd ciia cac mau mang scm epoxy cd (DA) ho§c khdng chiia diatomit (MT) ngam trong dung djch NaCl 3 % trong 5 gid (A),
4 8 g i d ( B ) v a 7 2 g i d ( C )
ifng dung diatomit ldm chat phu gia...
Pho tdng trd tren hinh 3 deu cd I cung chua hoan chinh vdi gia tri tdng trd khac nhau. Sau 5 gid va 48 gid thu nghiem, gia tri tdng trd ciia mimg son epoxy chira diatomit cao hon mang epoxy, cho thay sy cd mat ciia diatomit lam qua trinh an mdn phat trien cham ban so vdi mang phii epoxy trang trong 48 gid ngam trong dung dich NaCl 3 %. Tuy nhien, tir 72 gid ngam trong dung dich NaCl 3 %, phd tdng trd ciia ciia cac mau la gan nhu nhau.
24giar
Hinh 4: Anh cliup mang san epoxy (A, C) va mang son epoxy chira diatomit (B, D) sau 24 gid va
72 gid thd nghipm trong dung djch NaCl 3 % Hinh 4 trinh bay anh chyp cac mau cd vet rgch sau 24 gid va sau 72 gid thu nghipm trong dung dich NaCl 3 %. Quan sat anh chyp sau 24 gid thly ro hien tugng ngam nudc xung quanh vet rgch d tat ca cae mau vdi mirc dg khac nhau. Phii hgp vdi cac ket qua do tdng trd, mau epoxy chua diatomit cd mirc dp ngam nudc it ban va cd miic dg gi tai vet rgch it ban so vdi mau trang.
Hmh 5: Bien thian modul tdng trd tgi tan so 15 mHz ciia Idp phil epoxy (MT) va epoxy chira diatomit
(DA)
TCHH, T. 52(4), 2014
Hinh 5 bilu diln su bi^n thien cua modul tdng trd tai tan s6 15 mHz theo thdi gian thir nghiem trong mdi trudng NaCl 3 % cua mang epoxy va epoxy chua 15 % diatomit ve khdi lugng. Quan sat hinh 5 thly rd modul tdng trd ciia mang epoxy chiia diatomit cao ban ciia mang epoxy va deu suy giam theo thdi gian thir nghipm.
Ket hgp cac kdt qua do dipn hda vdi cac quan sat clu tnic tren hinh 2, cd the giai thich sy cd mat ciia diatomit trong ldp phii lam keo dai dudng dan ciia cac tac nhan xam thyc den ba mat kim loai, lam cham qua trinh an mdn kim logi.
4. KET LUAN
Cac ket qua nghien ciru budc dau cho thay sir dung diatomit trong mang son epoxy he nudc khdng Iam suy giam nhieu cac tinh chat ca ly ciia mang son, tuy nhien tinh chat bao vp chdng an mdn ciia mang son da dugc cai thien. Sy cai thien nay do su gia tang kha nang che chan ciia mang epoxy khi sir dung chat phu gia diatomit. Dieu nay cd the md ra irng dyng ciia diatomit trong he son bao ve chdng an mdn.
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Lien he: Nguyen Anh Son Vien Ky thuat Nhipt ddi
Vipn Han lam Khoa hgc va Cdng nghp Vipt Nam 18 Hoang Qudc Viet, Cau Gily, Ha Npi.
Email: [email protected].
