Journal of Chemical and Pharmaceutical Research, 2013, 5(12): Research Article

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1 Avilble online Journl of Chemil nd Phrmeutil Reserh, 2013, 5(12): Reserh Artile ISSN : CODEN(USA) : JCPRC5 Study on osion resistne of zin lloy oting of mehnil plting by eletrohemil method Leilei Wng Agriulturl Bio-phrmeutil Lbortory, Institute of Chemistry nd Phrmy, Qingdo Agriulturl University, Qingdo, Chin ABSTRACT Eletrohemil method ws utilized to study the osion resistne of zin lloy otings. These oting, plted by mehnil plting, inlude pure zin oting, Zn-Al oting, Zn-Mn (5:1) oting, Zn-Mn-Al (5:1:1) oting. The prmeters in Stern-Gery formul were obtined by severl tests. Aording to these prmeters, osion eletri urrent ws lulted. The osion resistnes of these zin lloy otings were ompred by osion eletri urrent. Results indite tht the osion resistne of Zn-Al oting ws the best in these zin lloy otings. And the sequene of these otings rnged from high osion resistne to low osion resistne ws s follow, Zn Al> Zn-Mn-Al (5:1:1)>Zn> Zn-Mn (5:1). Keywords: mehnil plting; eletrohemil; osion resistne; zin lloy oting INTRODUCTION Mehnil plting n plte metl to the surfe of workpiee to form oting by mehnil energy produed by medium impt [1]. Mehnil plting proess need not heting nd eletri field don t t diretly in this proess. Therefore, less energy nd metl powders were needed in this proess [2]. It ws reported in litertures [3-6] tht the power onsumption of mehnil plting is only five perent of eletroplting. And zin onsumption in mehnil plting proess is only thirty to fifty perent of hot dip glvnizing. Consequently, the ost of mehnil plting is fr less thn eletroplting nd hot dip plting. Beuse the pure zin oting is omprtively monotonous nd the osion resistne of pure zin oting is inferior to tht of some lloy otings, more nd more lloy oting were studied by reserhers of ll the world [7-9]. In this study, eletrohemil method ws utilized to study the osion resistne of zin lloy otings mde by ourselves. The osion resistnes of different series of zin lloy otings were ompred. The reltionship of osion metl ontent nd osion resistne ws studied. Regents nd Instruments Regents. NCl solution (3%); ethnol; EXPERIMENTAL SECTION Instruments. LZ3-200-type funtion reorder; HDV-7 trnsistor potentiostt; Pltinum eletrode; lomel eletrode; volumetri flsk(00ml, 2000ml); eletrolyzer (self-mde, the eletrolyzer used in this experiment ws shown in Figure 1); 1283

2 Figure 1. The shemti digrm of the eletrolyzer used in this experiment Experimentl priniple There were mny eletrode retions on the metl surfe in osion proess. The whole eletrode system ws oupling system ontining two or mny eletrode retions []. Therefore, eletrohemistry n be used to study the osion resistne of metl [11, 12]. Eletrode potentil nd eletri urrent density were the min prmeters to be mesured by eletrohemil method when studying osion resistne of metl. Eletri urrent density indited the eletrohemil retion speed per unit re on metl surfe. In eletrohemil theory, Stern formul nd Tfel formul were used in this experiment. At 1905, Tefel proposed tht between eletri urrent I losing to single eletrode retion speed on metl surfe nd metl potentil E, their reltionship obeyed empiril formul [13], shown s Formul (1). E=+blogI (1) Corrosion speed formul ws shown s Formul (2). When pplied polriztion ws lrge, it n be dedued by Formul (2) tht the reltionship of impressed eletri urrent nd eletrode polriztion were stright on the E-logi semi-logrithmi oordintes nd meet Tefel reltionship. I 2.303( E E {exp[ b ) 2.303( E E ] exp[ b = I (2) ) ]} At 1957, ording to eletrohemil retion kinetis nd mixed potentil theory, Stern nd Gery dedued liner polriztion formul, lso lled Stern-Gery formul, shown s formul (3). i b 1 b = (3) 2.3(b + b ) Rp where b b were Tfel onstnts of node nd thode polriztion respetively. It n be seen from the formul tht if Rp, b nd b were obtined, i n be lulted by Stern-Gery formul. The vlue of i ws inversely proportionl to metl osion resistne. Therefore, the osion speeds of different metls n be ompred ording to the vlue of i [14]. A three-eletrode system, onsisting of reserh eletrode, referene eletrode nd n uxiliry eletrode, ws used in speifi eletrohemil mesurements [15]. 1284

3 Experimentl methods Mesurement of Rp. Aording to Stern-Gery formul, glvnostti by-point method ws utilized to determined polriztion potentil. A series of eletri urrents, I 1 I 2 I 3 I n, I n =ni 1, were pplied on the smples in step pproh. After eh djustment of pplied eletri urrent, the of polriztion potentil were reorded every two minutes. From this, line n be drwn nd its slope ws the vlue of Rp, R p = E/ I, (E<mV). Mesurement of b nd b. It n be known by Tefel empiril formul nd osion speed formul tht b =( b =( de d logi de d logi ) E>>E ) E<<E Glvnostti by-point method ws lso used to determined node polriztion potentil nd thode polriztion potentil. Applying methods of eletri urrent ws similr to tht used in determining Rp. Eletri urrents, I 1 I 2 I 3 I n, I n =ni 1, were pplied on the smples in step pproh. Every step ws 0.5mA. After eh djustment of pplied eletri urrent, the of polriztion potentil were reorded when the eletri urrent ws stble. The intervls of reording were different. At norml ondition, the intervls of the first four points, bout -15 minutes, were longer thn followed points, bout five minutes. Then, esponding E-logi digrm ws drwn on Crtesin oordinte pper nd its slope ws obtined by lulting. The verge vlue of three groups of dt ws the vlue of b. The method of mesuring b ws similr to tht of mesuring b. The different point ws tht polriztion urrent ws set to be negtive nd glvnized sheet beme eletrode to be studied. RESULTS AND DISCUSSION Aording to the test priniple, the of polriztion potentil were reorded t sme intervls. Polriztion urves of different series of oting were drwn nd the of Rp were obtined from polriztion urves. The vlue of b nd b were obtined from E-logi urves. Then, the of Rp, b nd b were put into Stern-Gery formul nd then the vlue of i ws obtined by lulting. Polriztion urves of Zn-Mn (5:1) were shown in Figure 2. E-logi urves of Zn-Mn (5:1) were shown in Figure 3. Due to limited spe, polriztion urves nd E-logi urves of other zin lloy won t be shown in this pper. The eletrohemil test results of zin lloy oting were listed in Tble Rp=1714 mv ma/m

4 14 12 Rp=2361 mv ma/m Rp=2254 mv ma/m 2 Figure 2. Polriztion urves of three Zn-Al prllel smples b = V lg(a/m 2 ) 1286

5 b = V lg(a/m 2 ) b = V Smples lg(a/m 2 ) Figure 3. E-logi urves of three Zn-Al prllel smples Tble 1. Eletrohemil test results of zin lloy oting Rp(Ω) Mngnese Test ontent(%) Rp Averge b (V) Test b Averge -b (V) Test -b Averge i (ma) Pure Zn Zn-Al Zn-Mn (5:1) Zn-Mn-Al(5:1:1) It n be indited tht the osion urrent density of Zn Al lloy oting ws the smllest mong ll these zin lloy otings. Therefore, the osion resistne of Zn Al oting ws the best. When Zn-Mn series of otings were ompred with eh other, it n be found tht if little luminum ws dded into Zn-Mn lloy oting, the osion urrent density of the oting would derese. This n led to inresing of osion resistne. CONCLUSION In this study, eletrohemil method ws utilized to study the osion resistne of zin lloy otings. The prmeters in Stern-Gery formul were obtined by severl tests. Aording to these prmeters nd their polriztion urves, osion eletri urrent ws lulted. The osion resistnes of these zin lloy otings were ompred with eh other by osion eletri urrent. Results indite tht the osion resistne of Zn-Al 1287

6 oting ws the best in these zin lloy otings. And the sequene of these otings rnged from high osion resistne to low osion resistne ws s follow, Zn Al> Zn-Mn-Al (5:1:1)>Zn> Zn-Mn (5:1). These series of tests verified tht luminum n improve the osion resistne of zin lloy. These experiments hve guiding signifine for mehnil plting pplitions in industry. REFERENCES [1] CW Zou; HJ Wng; L Feng, et l., Appl Surf Si, 2013, 286, [2] D Jin Cheng; Z Zeng Din; L Jie, et l., Key Eng Mter, 2008, , [3] G Ngrj; S Agrwl; D Shenoy, et l., J Chem Phrm Res, 2013, 5(6), [4] DK Khtri; H Jie; RL Prsons, et l., J Mter Civil Engi, 2013, 25(12), [5] SV Komrov; SE Romnkov; N Hyshi, et l., Surf Cot Tehnol, 20, 204(14), [6] S Wng; M He; X Zho, et l., Chin J Meh Engi, 2009, 22(4), [7] A Shrifnbi; MH Fthi; BE Yekt, et l., Appl Surf Si, 2013, 288, [8] M Jvidi; H Fdee, Appl Surf Si, 2013, 286, [9] M Chndrn, J Chem Phrm Res, 2013, 5(3), [] E Dur; ON Cor; M Ko, J Power Soures, 2013, 246, [11] MK Punith Kumr; TV Venktesh, J Chem Phrm Res, 2013, 5(5), [12] BN Nlluri; B Srvni; KM Mheswri, et l., J Chem Phrm Res, 2013, 5(3), [13] SF Rudy, Plt Surf Finishing, 2007, 94(7), [14] HB Murlidhr; J Blsubrmnym; YA Nik, et l., J Chem Phrm Res, 2011, 3(6), [15] SV Komrov; SH Son; N Hyshi, et l., Surf Cot Tehnol, 2007, 201(16-17),