应用拉曼光谱研究了含有防锈颜料涂装特性的钢样 ,在此基础上探讨了三聚磷酸铝防锈颜料对A3钢的保护机理 .三聚磷酸铝溶解后能到达钢样表面 ,其离子可与铁离子化合形成三聚磷酸铁 .三聚磷铁能缓慢地通过化学键牢固地附着在钢样表面 ,最终在钢表面形成一层隔绝腐蚀介质和钢样的紧蜜保护膜阻止了腐蚀的继续发生从而达到保护的目的The painted steel sample whose coating contained anticorrosive pigment has been investigated by Raman spectroscopy.The protective mechanism of aluminum triphosphate pigment for A3 steel is proposed as follows: Aluminum triphosphate can be dissolved and arrive at the surface of the steel.The dissolved triphosphate ions can complex with ferric ions.And the new products,namely ferric triphosphate,can strongly adhere at the surface of the steel by chemical bonds slowly.At last,a compact protective film,which effectively separates the steel substrate from the aggressive media,is formed at the steel surface.作者联系地址：中国科学院福建物质结构研究所,中国科学院福建物质结构研究所,中国科学院福建物质结构研究所,中国科学院福建物质结构研究所,中国科学院福建物质结构研究所 福建厦门361012 ,福建厦门361012 ,福建厦门361012 ,福建厦门361012 ,福建厦门361012Author's Address: Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences,Xiamen 361012,Chin

GU Zhi_jun

GUO Qi_long

LIAO Yong_gui

SU Fang_teng

ZHANG Zhi_gang

廖永贵

张志刚

苏方腾

辜志俊

郭琦龙

Xiamen University Institutional Repository

第 8 卷 　第 1 期2002 年 2 月电化学EL ECTROCHEMISTR YVol. 8 　No. 1Feb. 2002Article ID :1006-3471(2002) 01-0032-08Raman Spectroscopic Study on Mechanism ofAluminum Triphosphate PigmentGU Zhi-jun 3 , L IAO Yong-gui , ZHAN G Zhi-gang , GUO Qi-long , SU Fang- teng( Fujian Instit ute of Research on the S t ruct ure of M atter ,Chinese A cadem y of Sciences , Xiamen 361012 , China)Abstract : The painted steel sample whose coating contained anticorrosive pigment has been in2vestigated by Raman spectroscopy. The protective mechanism of aluminum triphosphate pigmentfor A3 steel is proposed as follows : Aluminum triphosphate can be dissolved and arrive at the sur2face of the steel. The dissolved triphosphate ions can complex with ferric ions. And the new prod2ucts ,namely ferric t riphosphate ,can strongly adhere at the surface of the steel by chemical bondsslowly. At last ,a compact protective film ,which effectively separates the steel substrate f rom theaggressive media ,is formed at the steel surface.Key words : Raman Spectroscopy ,Mechanism ,Pigment ,Sodium chlorideCLC number : O TG 172 ,O 646 　　　　　Document Code : A1 　IntroductionIn 1995 ,the cost on corrosion of metal in the United States has reached Ã300 billion or soper year. In order to reduce the loss of corrosion ,many protection methods have been used. Organ2ic coating is one of the most effective ,economical and popular methods as yet . The various pig2ments in anticorrosive coatings protect the metal substrates by different mechanisms ,either by cre2ation of alkaline environments ,by passivation of the active centers originating from geometrical orst ructural defects ,by decreasing the oxygen permeation from the environment or the metal ion dif2fusion through the coating ,or by buffering the formation of hydrogen ions ,or by sacrificial metalpowders in the coating[1 ] . A small amount of inbhibitors can obviously retard corrosion , so in2hibitors have been considered more and more important . Although some traditional anticorrosivepigments ,such as lead-and chrome- based pigments ,have good inhibitive performances ,but theyReceived date : 11 Oct . 20013 To whom correspondence should be addressed , Tel :86 - 592 - 6013060 , E - mail : zhjgu @ms. fjirsm. ac. cnFoundation item : Project supported by State Key Lab. for Phys. Chem. of Solid Surface(9703)have high toxicity too. They are st rictly limited ,or prohibited to use in many countries and re2gions. Thus the application and research of new anticorrosive pigments are bound to focus on thehighly effective ,multifunctional and environmentally friendly pigments. Aluminum triphosphate isan anticorrosive pigment with good inhibitive performance when it is mixed in the epoxy-polyamide resin on A3 steel coupon[2 ] ,however ,its mechanism is not clear yet .There have been lots of studies that have tried to determine the nature of corrosion species ,especially on copper and iron , in the presence of active inhibitors in solutions by Raman spec2t roscopy[3～11 ] . Raman spectroscopy has been used to investigate corrosion under paint ,but with2out anticorrosive pigment was in the coating[12～14 ] . Therefore ,we report here using Raman spec2t ra for studies of the corrosion species at the artificial defect in the coating ,in the presence of anti2corrosive pigment . It is helpful to better understand the mechanisms of anticorrosive pigments.2 　Experimental2. 1 　Preparation of t wo ferric compoundsTo synthesize ferric phosphate[15 ] ,0. 02 mol ferric chloride ( FeCl3) ,0. 02 mol sodium hydro2gen phosphate (Na2 HPO4) ,and 0. 025 mol sodium acetate (CH3 COONa) were dissolved in 100mL distilled water respectively ,mingled ,filtered ,drie.To synthesize ferric t riphosphate , 0. 05 mol FeCl3 and 0. 03 mol sodium triphosphate(Na5 P3O10) were dissolved in 100 mL distilled water respectively ,mingled ,filtered ,dried.2. 2 　MaterialsTo prepare the coated coupon ,the surface of the A3 steel coupon (200 ×100 mm) was abradedwith 60 # ,80 # sand cloth in succession ,cleaned ,degreased with ethanol ,covered by the epoxy-polyamide resin containing aluminum triphosphate pigment ,air dried in ambient temperature forone week ,placed a plastic tube (inner diameter = 90 mm) on the coated coupon with 704 binder ,air dried. The solution was made of distilled water and sodium chloride(NaCl ,AR) ,and the con2centration was 3. 5 %(wt %) .2. 3 　Micro- Raman spectroscopy—Raman spectra were obtained by LabRam I confocal microscopic Raman spectrometer(Dilor) with a He-Ne laser (632. 8mm) in the pore covered with 1 mm solution at ambient tem2perature and air-open system. ( The Raman spectra of ferric phosphate and ferric thiphosphatewere obtained from their powder samples directly. )3 　Results and Discussion3. 1 　Two ferric compoundsFig. 1 and Fig. 2 show micro- Raman spectra of synthetic ferric phosphate and ferric t riphos2phate ,respectively. In figure 1 , the characteristic peak is at 1 010 cm - 1 . Additional features areobserved at 270 ,541 ,1 444 cm - 1 ,and a shoulder peak of 439 and 478 cm - 1 . In figure 2 ,the char2·33·第 1 期 　　　　　　　　　辜志俊等 :防锈颜料三聚磷酸铝的拉曼光谱研究acteristic peak is 1 107 cm - 1 . Additional features are observed at 412 ,704 ,928 and 994 cm - 1 .Fig. 1 　Micro- Raman spectrum of ferric phosphate( FePO4)Fig. 2 　Micro- Raman spectrum of ferric triphosphate( FeTP)3. 2 　Characterization of painted blank A3 steel couponTable 1 summarizes the Raman shifts and corrosion species for painted blank A3 steel couponTab. 1 　Nominal Raman frequencies (cm - 1 ) of corrosion species observed with exposure time (day) for paintedblank painted steel coupon immersed in 3. 5 % NaCl solution. The underlinedpeaks exhibit strong intensities1 day 2 days 6 daysinner outerInner ofyellowOuter ofyellowblack yellow blackAssignment220 α- Fe203257 252 256 256 251 γ- FeOOH295 Fe3O4282 296 α- Fe2O3314 314 311 311 FeCl3 (s) 3351 345 347 γ- Fe2O3377 377 377 γ- Fe2O3382 α- FeOOH +γ- Fe2O3527 529 γ- FeOOH528 538 534 Fe3O4652 655 γ- FeOOH658 668 668 664 670 Fe3O41304br 1293br 1302br γ- FeOOHγ- FeOOH + Fe3O4 Fe3O4 Fe3O4 γ- FeOOH + Fe3O4 Fe3O4 γ- FeOOH Fe3O4 Corrosion+γ- Fe2O3 +γ- FOOH +α- Fe2O3 +γ- Fe2O3 +γ- Fe2O3 species+α- FeOOH +γ- Fe2O3 +γ- Fe2O3 + FeCl3 (s) +γ- FeOOH+ FeCl3 (s) + FeCl3 (s) +αFe2O3 + FeCl3 (s)　　3 brrepresents broad wave. 3 Without illustrated particularly ,the location measured was the inner point .·43· 电 　化 　学 2002 年that was exposed in 3. 5 % NaCl solution with immersion time. At different points ,the corrosionspecies are different . Namely , the special dist ribution of corrosion species is inhomogeneous. Thecorrosion species for painted blank A3 steel coupon are iron oxides and iron oxyhydroxides.Immersion 1 day ,the corrosion species at inner point are mainlyγ- FeOOH ,Fe3O4 ,γ- Fe2O3 ,α-FeOOH ,and scare FeCl3 in solution. Althoughα- Fe2O3 exhibites mode in the 1 300 to 1 310cm - 1 range ,no peak is observed at the frequency that its most intense mode(290 cm - 1) is expect2ed. It indicates that this species is not present in detectable concentration. The corrosion species atouter point is mainly Fe3O4 . Figure 3 shows their Raman spectra. Immersion 2 days ,yellow andblack spots can be observed by naked eyes. Only Fe3O4 can be detected at the black. However ,γ- FeOOH ,Fe3O4 andγ- Fe2O3 at the inner of the yellow ,γ- FeOOH , Fe3O4 ,α- Fe2O3 and scareγ- Fe2O3 and FeCl3 in solution at the outer of the yellow , can be detected. Immersion 6 days ,γ- FeOOH ,α- Fe2O3 ,γ- Fe2O3 and scare FeCl3 in solution at the inner of the yellow ,Fe3O4 ,γ- Fe2O3and scareγ- FeOOH ,α- Fe2O3 ,FeCl3 in solution at the inner of the black ,can be detected. Figure 4shows the micro- Raman spectra of corrosion species for painted blank A3 steel coupon immersed in3. 5 % NaCl solution for 6 days at inner of yellow point (a) ,and at inner of black point (b) .Fig. 3 　Micro- Raman spectra of corrosion species forpainted blank A3 steel coupon immersed in3. 5 % NaCl solution for 1 day at inner point(a) ,and at outer point (b)Fig. 4 Micro- Raman spectra of corrosion species forpainted blank A3 steel coupon immersed in3. 5 % NaCl solution for 6 days at inner in yel2low point (a) and at inner in black point (b)Because of the artificial defect ,”large cathode ,little anode”is formed ,the defective area be2comes the anode relative to the other. When the blank painted A3 steel coupon is immersed in3. 5 % sodium chloride solution ,the corrosion occurs at the surface of the defect . Furthermore ,atthe surface of the defect ,geometrical and physical st ructures are different . Different points havedifferent activities. Their corrosion rates are different too. The points whose corrosion rates arequicker grow quicker because the volume of iron corrosion species is larger than that of the metal.The corrosion species immersed can be oxidized with time ,and the stable species can be formed. So·53·第 1 期 　　　　　　　　　辜志俊等 :防锈颜料三聚磷酸铝的拉曼光谱研究the special dist ribution of corrosion species is inhomogeneous , and the corrosion species for thepainted blank A3 steel coupon are iron oxides and iron oxyhydroxides.3. 3 　Characterization of the painted A3 steel coupon whose coating contained alu2minum triphosphate pigmentTable 2 shows the Raman shifts and corrosion species for the painted A3 steel coupon ,ex2posed in 3. 5 % NaCl solution ,whose coating contained aluminum triphosphate pigment ,with im2mersion time. Figure 5 shows the micro- Raman spectra of corrosion species for the sample im2mersed in 3. 5 % NaCl solution for one day (a) ,and for two days(b) at inner points.Tab. 2 　Nominal Raman frequencies (cm - 1) of corrosion species observed with exposure time (day) for the paintedsteel coupon whose coating contained aluminum triphosphat pigment immersed in 3. 5 % NaCl solutions.The underlined peaks exhibit strong intensities1 day 2 days 19 days 21 days assignment225 α- Fe2O3251 245 247 γ- FeOOH272 FePO4288 α- Fe2O3 +γ- Fe2O3376 377 γ- Fe2O3376 γ- Fe2O3 +γ- FeOOH408 α- Fe2O3499 α- Fe2O3 + FeCl2534 γ- FeOOH611 α- Fe2O3642 γ- Fe2O3658 γ- Fe2O3 + Fe3O4710 715br FeTP 3840 PO43 -990-1100 1090br 1077br FeTP 31309 γ- FeOOH1314br α- Fe2O31342br Fe (OH) 3γ- Fe2O3 +γ- FeOOH γ- FeOOH γ- Fe2O3 +α- Fe2O3 + γ- FeOOH + γ- Fe2O3 Corrosion species+ FePO4 +γ- Fe2O3 + Fe TP Fe3O4 + FeCl2 + Fe TP + Fe TP　3 br represents broad wave. 3 FeTP represents ferric triphosphate.　3 Without illustrated particularly ,the location measured was the darker point .Immersion 1 day ,the mode at 272 cm - 1 is exhibited ;although the mode at 1 010 cm - 1 can2not be distinguished obviously ,it can be regarded to be covered by the very broad wave in the 900·63· 电 　化 　学 2002 年to 2 700 cm - 1 range. Moreover ,the oxides and hydroxides of iron have not characteristic peaks at270 cm - 1 or so. So the mode at 272 cm - 1 can be regarded as the mode of ferric phosphate. Immer2sion 2 days ,an intense peak at 710 cm - 1 ,a broad wave in the 990 to 1 100cm - 1 range ,and nopeak at 270 cm - 1 are exhibited. So they can be regarded as the modes of ferric t riphosphate. Im2mersion 19 days ,the centric wave number that the ferric t riphosphat is at 1 107 cm - 1 moves tothe lower frequency ,1 090 cm - 1 . Immersion 21 days ,it moves to 1 077cm - 1continuously. ( Seefigure 6)Fig. 5 　Micro- Raman spectra of corrosion species forthe painted A3 steel coupon whose coatingcontained aluminum triphosphate pigment im2mersed in 3. 5 % NaCl solution for one day(a) ,and for two days(b) at inner pointsFig. 6 　Micro- Raman spectra of corrosion species forthe painted A3 steel coupon whose coatingcontained aluminum triphosphate pigment im2mersed in 3. 5 % NaCl solution for 19 days(b)and 21 days (c) , contrary to ferric triphos2phate powder (a)The corrosion species for the painted A3 steel coupon whose coating contained aluminumtriphosphate pigment are iron oxides and oxyhydroxides ,besides ferric phosphate at first and ferrict riphosphate which strongly adheres at the surface of the iron by chemical bonds.Aluminum triphosphate can dissolve and reach the surface of the steel. The triphosphate ionscan be hydrolyzed ,so the phosphate ions are formed. The latter can react with iron corrosion prod2ucts ,e. g. ,Fe2 + and Fe3 + ,so the ferric phosphate can be detected by Raman spectroscopy initial2ly. With the increase of t riphosphate ions and iron corrosion products at the surface ,the triphos2phate ions cannot be hydrolyzed in time ,and they can complex with the latter. Furthermore ,theprodut ,ferric t riphosphate can strongly adhere at the surface of the iron by chemical bonds slowly.So the centric wave number of ferric t riphosphate moves to the lower frequenies. At last ,a com2pact protective film ,which effectively separates the steel substrate f rom the aggressive media ,isformed at the steel surface.4 　Conclusions(a) The corrosion species for the painted metal ,such as A3 steel ,whose coating contained an2·73·第 1 期 　　　　　　　　　辜志俊等 :防锈颜料三聚磷酸铝的拉曼光谱研究ticorrosive pigment ,can be obtained ,and much information for mechanism of anticorrosive pig2ment can be provided by Raman spectroscopy study.(b) The special dist ribution of corrosion species is inhomogeneous.(c) The corrosion species for painted blank A3 steel coupon are iron oxides and iron oxyhy2droxides. The corrosion species for painted A3 steel coupon whose coating contained aluminumtriphosphate pigment are iron oxides and oxyhydroxides ,besides ferric phosphate at first and ferrict riphosphate.(d) The protective mechanisms of aluminum triphosphate pigment for A3 steel are as fol2lows . aluminum triphosphate can dissolve and arrive at the surface of the steel. The dissolvedtriphosphate ions can complex with ferric ions. And the new products ,namely ferric t riphosphate ,can strongly adhere at the surface of the iron by chemical bonds slowly. At last ,a compact protec2tive film ,which effectively separates the steel substrate f rom the aggressive media ,is formed at thesteel surface.Reference s :[ 1 ] 　Th Shoulividis ,et al. Correlation between protection of steel from corrosion and the conductivity of n- semicon2ductor pigments[J ] . Corrosion ,1998 ,54(5) :386.[2 ] 　Yong- gui Liao ,et al. Electrochemical impedance spectroscopy studies on inhibitve performance of aluminumtriphophate pigment [J ] . Electrochemistry ,2001 ,7 (1) :126.[3 ] 　Bunding K A ,et al. Surface-enhanced raman scattering by pyridine on a copper electrode[J ] . J . Elextroanal.Chem. ,1985. 184 :405.[ 4 ] 　Thierry D ,et al. Simultaneous raman spectroscopy and electrochemical studies of corrosion inhibiting moleculeson copper[J ] . J . Electrochem. Soc. ,1985 ,132(5) :1 009.[5 ] 　Da Costa S L F A ,et al. Inhibiting action of benzotriazole on copper corrosion in deaerated sulfuric acid con2taining ferric ions by the rotating disc electrode ,fluorescence ,and raman spectroscopies[J ] . Corrosion ,1987 ,43(3) :149.[ 6 ] 　Youda R ,et al. A SERS study on inhibition mechanisms of benzotriazole and its derivatives for copper corrosionin sulphate solutions[J ] . Corrosion Science ,1988 ,28(1) :87.[7 ] 　Aramaki K ,et al. A SERS study on adsorption of some organic compounds on iron[J ] . J . Electrochem. Soc. ,1989 ,136 (5) :1 299.[8 ] 　Youda R ,et al. SERS and impedance study of the equilibrium between complex formation and adsorption ofbenzotriazole and 4- hydroxybenzotriazole on a copper electrode in sulphate solutions [J ] . Electrochim. Acta ,1990 ,35 (6) :1 011.[ 9 ] 　Aramaki K ,et al. In situ raman spectra of pyridinium chloride adsorbed on iron in K2 SO4 and H2 SO4 solutions[J ] . J . Electrochem. Soc. ,1992 ,139(6) :1 525.[ 10 ] 　Oblonsky L J , et al. Adsorption of octadecyldimethylbenzylammonium chlorede to two carbon steel mi2crostructures as observed with surface-enhanced raman spectroscopy[J ] . Corrosion ,1995 ,51(12) :891.[11 ] 　Aramaki K ,et al. Surface-enhanced raman scattering spectroscopy studies on the inhibition mechanisms of·83· 电 　化 　学 2002 年propargy1 alcohol for iron corrosion in hydrochloric acid[J ] . Corrosion ,1996 ,52(2) :83.[12 ] 　Thierry D ,et al. In situ determination of corrosion species formed on painted galvanized steel by raman spec2troscopy[J ] . J . Electrochem. Soc. ,1991 ,138(3) :879.[13 ] 　Bernard M C ,et al. Underpaint corrosion of zinc-coated steel sheet studied by in situ raman spectroscopy[J ] .Corrosion Science ,1993 ,35(5～8) :1 339.[14 ] 　Bernard M C ,et al. In situ Raman study of the corrosion of zinc-coated steel in the presence of chloride[J ] . J .Electrochem. Soc. ,1995 ,142(7) :2 167.[15 ] 　Shou-chun Chen. Some Important Inorganic Reactions[ M ]. Shanghai :Shanghai press of science and technol2ogy. 1963 :380.防锈颜料三聚磷酸铝的拉曼光谱研究辜志俊 3 ,廖永贵 ,张志刚 ,郭琦龙 ,苏方腾(中国科学院福建物质结构研究所 ,福建 厦门 361012)摘要 : 　应用拉曼光谱研究了含有防锈颜料涂装特性的钢样 ,在此基础上探讨了三聚磷酸铝防锈颜料对 A3 钢的保护机理. 三聚磷酸铝溶解后能到达钢样表面 ,其离子可与铁离子化合形成三聚磷酸铁. 三聚磷铁能缓慢地通过化学键牢固地附着在钢样表面 ,最终在钢表面形成一层隔绝腐蚀介质和钢样的紧蜜保护膜阻止了腐蚀的继续发生从而达到保护的目的.关键词 : 　拉曼光谱 ;机理 ;颜料 ;氯化钠·93·第 1 期 　　　　　　　　　辜志俊等 :防锈颜料三聚磷酸铝的拉曼光谱研究

Raman Spectroscopic Study on Mechanism of Aluminum Triphosphate Pigment

http://dspace.xmu.edu.cn/bitstream/handle/2288/57705/%e9%98%b2%e9%94%88%e9%a2%9c%e6%96%99%e4%b8%89%e8%81%9a%e7%a3%b7%e9%85%b8%e9%93%9d%e7%9a%84%e6%8b%89%e6%9b%bc%e5%85%89%e8%b0%b1%e7%a0%94%e7%a9%b6%28%e8%8b%b1%e6%96%87%29.pdf?sequence=1&isAllowed=y

Raman Spectroscopic Study on Mechanism of Aluminum Triphosphate Pigment

Abstract

Similar works

Full text

Available Versions

Xiamen University Institutional Repository