Corrosion Resistance Of SS316l In Artificial Urine In Presence Of D-Glucose

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1 E-ISSN: Nagalakshmi et al. In Artificial Urine In Presence Of D-Glucose R. Nagalakshmi [a]*, L. Nagarajan [b], R.Joseph Rathish [c], S. Santhana Prabha [c], N. Vijaya [d], J. Jeyasundari [e] and S. Rajendran [f] The aim of this research is the study of electrochemical corrosion behavior of SS 316L in artificial urine in presence of D- Glucose at 37 C. This temperature is equivalent to human body temperature. The corrosion resistance of SS316 L in artificial urine in the absence and presence of D-glucose has been investigated by polarization study and AC impedance spectra. It is observed that the corrosion resistance of SS316 L in artificial urine decreases in presence of D- glucose. This results indicate that the corrosion film is formed on SS 316L surface than the polished SS 316L surface which is demonstrated by the decrease in polarization resistance and increase in corrosion current density. It is confirmed by Scanning electron microscopy (SEM) and energy dispersive analysis of x-rays (EDAX). It reveals that pits could be observed on the surface of SS 316L in artificial urine in the presence of D-glucose but not on the polished SS 316L surface after electrochemical techniques. However the film seems to be porous and amorphous. The corrosion resistance of SS 316L in artificial urine in the presence of D-glucose was decreased. Keywords: SS 316L, artificial urine, D-glucose. *Corresponding Authors [a] Department of Chemistry, Aarupadai Veedu Institute of Technology,Chennai,India nagalakshmirajan@gmail.com [b] Department of Chemistry, Government Higher Secondary School, Muthunaickanpattti, Tamilnadu, India. [c] PSNA College of Engineering and Technology, Dindigul, India. [d] Department of Chemistry, Vellalar College for women, Thindal, Erode, India. [e] Department of Chemistry, SVN College, Madurai, India [f] Corrosion Research Centre, RVS School of Engineering and Technology, Dindigul-5, India susairajendran@gmail.com 1. INTRODUCTION Metals and alloys have a wide application in dentistry, medicine, orthopaedic, bone fracture and urology as a component of an artificial implant. Nowadays alloys with the ability of passive layer formation on the surface are used for biomaterial applications. Austenitic stainless steel (SS) is the alloy of great interest in technological applications where the materials with high corrosion resistance are required. The stability of passive film formed on SS depends on the alloy composition, temperature, passive time and working environment. Biocompatibility of alloys mainly has a relationship with corrosion. An alloy having high corrosion, releases more metallic elements and corrosion products in the body and increase the unwanted hazardous reactions with tissue. Every metallic element is released in the tissue; it does not cause any problems, but nickel and chromium cause allergy and local problems due to their toxic effects. For this reason, metallic implant corrosion evaluation, particularly SS 316L that is used in body has been admitted over years. Various methods and techniques have been used to evaluate corrosion and effects of different environment on SS 316L implants and corrosion in alive existing body and consequences. Nowadays metallic alloys being used in surgical implants are SS 316L, titanium alloy and chromium- cobalt alloys. The advantages of SS 316L compared with other materials are low cost, mechanical properties related to bone material, acceptable corrosion resistance and ease of fabrication. [1-3] The present work is undertaken to investigate the corrosion resistance body implants made of SS316L immersed in synthetic urine in presence of D-glucose. The results of this study will be useful to diabetic patients implanted with devices made of SS316 L, because their urine will contain glucose. Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 39

2 2. EXPERIMENTAL 2.1. Preparation of the Specimen SS316L was used in the present study. Its composition is as follows: The composition of SS316L was (wt%) 18Cr, 12 Ni, 2.5 Mo, <0.03 C and the balance iron. The metal specimens were encapsulated in Teflon. The surface area of the exposed metal surface was 1 cm 2.The metal specimens were polished to mirror finish and degreased with trichloroethylene. The metal specimens were immersed in artificial urine (AU) [4] whose composition was: Solution A: CaCl 2.H 2 O-1.765g/l, Na 2 SO g/l, MgSO 4.7H 2 O g/l, NH 4 Cl g/l, KCl g/l. Solution B :NaH 2 PO 4.2H 2 O g/l, Na 2 HPO g/l, C 6 H 5 Na 3 O 7.2H 2 O g/l, NaCl g/l. The ph of the solution was 6.5[5]. Just before the experiment, equal volumes of A and B were mixed and used as artificial urine. In electrochemical studies the metal specimen was used as working electrodes. Artificial urine (AU) was used as the electrolyte (10 ml). The temperature was maintained at 37±0.1 0 C. Commercially available D- Glucose was used in this study. 50 ppm and 100 ppm of D-Glucose was dissolved in artificial urine Potentiodynamic Polarization Polarization studies were carried out in a CHI- Electrochemical workstation with impedance, Model 660A. A three electrode cell assembly was used. The working electrode was SS 316L. A saturated calomel electrode (SCE) was the reference electrode and platinum was the counter electrode. From the polarization study, corrosion parameter such as corrosion potential (E corr ), Corrosion current (I corr ) and Tafel slopes (anodic = b a and cathodic = b c ) were calculated AC Impedance Spectra The instruments used for polarization study was used to record AC impedance spectra also. The cell set up was the same. The real part (Z ) and imaginary part (Z ) of the cell impedance were measured in ohms at various frequencies. Values of the charge transfer resistance (R t ) and the double layer capacitance (C dl ) were calculated from Nyquist plots. Impedance log (Z/ohms) value was calculated from Bode plots. 2.4 SEM and EDAX SS316L specimens were immersed in the blank solutions and in presence of the D-Glucose for period of one day. They were removed, rinsed with distilled water and dried. Te surface morphology of the film formed on the surface was analyzed with SEM by using JEOLMODEL6390 computer controlled scanning electron microscope. The same instrument was used for EDAX also. 3. RESULTS AND DISCUSSION 3.1. Analysis of Potentiodynamic polarization curves Polarization study has been used to confirm the formation of protective film formed on the metal surface during corrosion inhibition process. If a protective film is formed on the metal surface, the linear polarization resistance value (LPR) increases and the corrosion current value (I corr) decreases. [6] The polarization curves of SS 316 L immersed in artificial urine (AU) in the absence and presence of glucose is shown in Figure 1. The corrosion parameters namely LPR, I corr, E corr, Tafel slopes (b c = cathodic, b a = anodic) are given in Table 1. It is observed from Table 1 that when 50 ppm of glucose is added to AU, the LPR value decreases from 1.68 x 10 6 to 1.37 x 10 6 ohmcm 2 and the corrosion current (I corr ) increases from 2.40 x 10-8 to 2.77 x 10-8 A/cm 2. When 100 ppm of glucose is added to AU, the LPR value further decreases from 1.37 x 10 6 to 9.74 x 10 5 ohmcm 2 and the corrosion current (I corr ) increases to 3.86 x 10-8 A/cm 2. In general it is observed that the corrosion resistance of SS 316 L in AU decreases in the presence of glucose [7-12]. Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 40

3 It is observed from the table that the corrosion potential slightly shifts to cathodic side in the presence of glucose. Hence it is concluded that in presence of glucose, the cathodic reaction is not completely controlled. The thin film is formed on the metal surface and it was broken easily and induces the further corrosion Analysis of AC impedance spectra AC impedance spectra (electrochemical impedance spectra) have been used to confirm the formation of protective film on the metal surface [12-13]. If a protective film is formed on the metal surface, charge transfer resistance (R t ) increases, double layer capacitance value (C dl ) decreases, and the impedance log (z/ohm) value increases. Table: 1: Corrosion parameters of SS 316 L immersed in AU in absence and presence of Glucose obtained by polarization study. System E corr mv vs SCE b c mv/decade b a mv/decade LPR ohmcm 2 I corr A/cm 2 AU x x 10-8 AU + 50 ppm glucose x x 10-8 AU ppm glucose x x 10-8 Table: 2: Corrosion parameters of SS 316 L immersed in AU in absence and presence of Glucose obtained from AC impedance spectra. System Nyquist plot R t ohmcm 2 C dl F cm -2 Bode plot Log Z/ohm AU 2.42 x x AU + 50 ppm glucose 4.20 x x AU ppm glucose 2.39 x x AC impedance parameters such as charge transfer resistance (R t ), double layer capacitance (C dl ) (derived from Nyquist plots) and impedance value log Z/ohm (derived from Bode plots) of SS 316 L immersed in AU and AU containing D- Glucose are given in Table 2. The AC impedance spectra are shown in Figures 2 to 7 (Nyquist plots), and Figures 8 to 10. (Bode plots). It is observed from the Table 2 that when glucose is added to AU the R t value decreases, the C dl value increases (Nyquist plot). This indicates that in presence of glucose, the corrosion resistance of SS 316 L decreases. This is in agreement with the results of polarization studies. This is further supported that in presence of glucose the impedance value (Log Z/ohm) decreases. Further the phase angle value decreases (Bode plots). The polarization study and AC impedance spectra lead to the conclusion that in the presence of glucose the corrosion resistance of SS 316 L in AU decreases. The enlarged graph in the high frequency region of Figure.2, 3 and 4 are shown in Figures.5, 6 and 7 respectively. It is observed from these graphs that the reactions are diffusion controlled processes; that is Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 41

4 diffusion of ions from the bulk of the solution towards the metal surface. The equivalent circuit diagram for such system is shown in Scheme.1. It is observed that the graphs seen in Figures. 5, 6 and 7 are very close to that of very corrosive protective system (insulator). That is electron transfer from metal to system is very difficult. Since the protective film formed on the metal surface is unstable and easily broken and starts the further corrosion on the metal surface. It is observed from the impedance Bode plots (Figures. 8, 9 and 10) that the value of impedance decreases sharply as the log Z value increases. The slope of the line in the middle frequency region is 0.5. This is characteristic of very protective film [14]. But the film formed on the metal surface is not stable. Figure.1 Polarization curves of SS 316 L in various test solutions. a) AU b) AU+ 50ppm of glucose c) AU+ 100ppm of glucose Figure.2 AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU Figure.3 AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU+50 ppm glucose Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 42

5 Figure.4 AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU+100 ppm glucose Figure.5. AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU(zoomed) Figure.6 AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU + 50 ppm glucose (zoomed) Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 43

6 Figure.7. AC impedance spectra (Nyquist plots) of SS 316 L immersed in AU ppm glucose (zoomed) Figure.8 AC impedance spectra (Bode plots) of SS 316 L immersed in AU Figure.9 AC impedance spectra (Bode plots) of SS 316 L immersed in AU + 50 ppm glucose Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 44

7 Figure.10 AC impedance spectra (Bode plots) of SS 316 L immersed in AU ppm glucose The equivalent circuit diagram for such system is shown in scheme.1 R s R ct W C dl = Solution resistance = Charge transfer resistance = Warburg diffusion resistance = Double layer capacitance Scheme SEM Analysis of Metal Surface SEM provides a pictorial representation of the surface. To understand the nature of the surface film in the absence and the presence of D-Glucose are examined [15-17]. The SEM images of different magnifications (500X, 1000X, 5000X, 10000X, 50000X) of SS 316 L specimen immersed in AU for one day in the absence and presence of D-Glucose are shown in Figure.11. The SEM micrographs of polished SS 316 L (control) in Figure.11 (a, b, c, d, e) images illustrate the smooth surface of the metal. These show the absence of any corrosion products formed on the metal surface. The SEM micrographs of SS 316 L immersed in AU are shown in Figure.11 (a.1, b.1, c.1, d.1, e.1). It shows the roughness of the metal surface which indicates the corrosion of SS 316 L in AU. Figure.11 (a.2, b.2, c.2, d.2, e.2) indicates that in the presence of 100 ppm of glucose in AU, pits are formed on the metal surface. This indicates that in presence of glucose the corrosion resistance of SS316 L in AU decreases. Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 45

8 3.4. Analysis of Energy Dispersive Analysis of X-rays (EDAX) EDAX spectra were used to determine the elements present on the SS 316 L surface before and after exposure to the D-Glucose solution [18-21]. The objective of this section is to confirm, whether a protective film is formed on the metal surface or not. To achieve this goal, EDAX examinations of the metal surface were performed in the absence and presence of an D-Glucose system. The energy dispersive analysis of X-rays (EDAX) of SS 316 L specimen polished is shown in Figure.12 a. This indicates the presence of iron (Fe), Manganese (Mn), Nickel (Ni), Chromium (Cr), Silicon (Si), and Carbon (C) on the metal surface. Figure.12 b shows the EDAX analysis of SS 316 L surface immersed in AU. The analysis shows the presence of characteristic peaks of corrosion product elements (Fe, Ni, Cr, Si, O, and C). Figure.12 c represents the EDAX analysis of SS 316 L immersed in AU containing 100 ppm of glucose. The appearance of these peaks of C and O, the notable decrease in iron peak in the presence of D-Glucose indicated that the film formed is slightly adhered to the surface. However the film is not compact and stable. It is broken by the aggressive ions presents in the artificial urine. Hence corrosion resistance decreases. (a) (b) (c) (d) (e) Figure.11 SEM Micrographs of (a, b, c, d, e) Polished SS 316 L; Magnification (500X, 1000X, 5000X, 10000X, 50000X) (control) (a.1) (b.1) (c.1) Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 46

9 (d.1) (e.1) Figure.11 SEM Micrographs of (a.1, b.1, c.1, d.1, e.1) SS 316 L immersed in AU Magnification (500X, 1000X, 5000X, 10000X, 50000X) (a.2) (b.2) (c.2) (d.2) (e.2) Figure.11 SEM Micrographs of (a.2, b.2, c.2, d.2, e.2) SS 316 L immersed in AU containing 100 ppm of glucose Magnification (500X, 1000X, 5000X, 10000X, 50000X) (a) (b) (c) Figure.12. EDAX spectra of SS 316 L a) Polished SS 316 L b) SS 316 L immersed in AU c) SS 316 L immersed in AU containing 100 ppm of glucose Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 47

10 4. CONCLUSION The corrosion resistance of SS316 L in artificial urine in the absence and presence of D-glucose has been investigated by polarization study and AC impedance spectra. It is observed that the corrosion resistance of SS316 L in artificial urine decreases in presence of D- glucose. Polarization study reveals that, in presence of D-glucose Linear polarization resistance (LPR) value decreases and Corrosion current value increases AC impedance spectra reveal that, in presence of D-glucose Charge transfer resistance value (R t ) decreases Double layer capacitance value (C dl ) increases and Impedance value increases. Scanning electron microscopy (SEM) study reveals that, in presence of D-glucose pits are formed on SS 316 L surface. Analysis of energy dispersive analysis of x-rays (EDAX) reveals that a film is formed on the metal surface. There is decrease in intensity of iron peaks. There is decrease in intensity of C and O peaks due to the presence of glucose. However the film seems to be porous and amorphous. The film is broken by the aggressive ions such as chloride, sulphate etc, present in artificial urine. The present study leads to the following conclusion. i. The corrosion resistance of SS316 L in artificial urine decreases in presence of D-glucose. ii. The implant devices made of SS 316 L must be avoided for diabetic patients, where SS316Lcomes in contact with urine containing D-glucose. ACKNOWLEDGEMENTS The authors are thankful to their respective managements for their help and encouragement. REFERNCES [1] M. H. Fathi, M. Salehi, A. Saatchi, V. Mortazavi, S. B. Moosavi, Dental Mater. 19 (2003), 188. [2] D. Sharan, Orthopaedic Update (India), 9 (1999), 1. [3] C.C. Shih, C. M. Shih, Y. Y. Su, L. H. J. Su, M. S. Chang, S. J. Lin, Corros. Sci. 46 (2004), 427 [4] J. Przondziono, W. Walke, J. Achiev. Mater. Manuf.Engg, 35(1) (2009), 21 [5] W. Kajzer, A. Krauze, W. Walke, J. Marciniak, J. Achiev. Mater. Manuf.Engg, 18 (2006), 115. [6] R.Epshiba, A.Peter Pascal Regis, S.Rajendran, Int. J. Nano. Corr. Sci.and Engg. 1(1) (2014) [7] K.Kavipriya, J.Sathiyabama, S.Rajendran and A.Krishnaveni, Int. J. Advancess. Engg. Sci and Tech, 2(2) (2012). [8] N.Manimaran and S. Rajendran, M.Manivannan and R.Saranya, J. Chem Bio and Phys Sci 2(2), [9] Anthony Samy Sahaya Raj and Susai Rajendran, J.Electrochem.Sci.Eng, 2 (2012) [10] R. Nagalakshmi, S. Rajendran, J. Sathiyabama, M. Pandiarajan and J. Lydia Christy, Eur. Chem. Bull. 2(4) (2013), 150. [11] R.Nagalakshmi, S.Rajendran and J.Sathiyabama, Int. J. Inno. Research in Sci, Engg and Tech, 2(2) (2013), [12] N. Kavitha, P. Manjula, Int. J. Nano. Corr. Sci. and Engg. 1(1) (2014) [13] A. Leemarose, Peter pasgal Regis, Susai Rajendran, A. Krishnaveni,Felicia Rajammal selvarani,arabian J for sci and Engg, 37(2012), [14] V. Sribharathi and Susai Rajendran, Int. J. Advances in Engg, sci and Tech, 1(1) (2011). [15] H. Yang, L. Qian, Z. Zhou,X. Ju, H. Dong, Tribology Letters, 25(2007), 215. [16] Gowri S., Sathiyabama J., Prabhakar P and Rajendran S., Int. J. Research. Chem and Environ, 3(1)( 2013), [17] Brightson Arul Jacob Y., Sayee Kannan R. and Jeyasundari J., Research J. Chem Sci, 3(4) (2013), 54-58, [18] R.Nagalakshmi, S.Rajendran, J.Sathiyabama, Int. J. Advan. Engg & Technol, 6(4)(2013), Int. J. Nano. Corr. Sci. Engg. 1(1) (2014) 48

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