Volume 17 Preprint 17


Corrosion and hardness characteristics of metalized ABS plastics prepared by FDM rapid prototyping process

K. Raja, C.D. Naiju, S. Narayanan, P.A. Jeeva, S. Karthikeyan

Keywords: Ni-Cr coatings, FDM-RP, corrosion resistance, tensile, SEM

Abstract:
An attempt has been made in this work to develop nickel chromium coatings with enhanced corrosion and hardness properties on ABS plastics prepared by FDM-RP process. The increase of corrosion resistance of Ni-Cr electrodeposited coatings in sea water medium claimed that these coated plastics can find as substitute for metal parts used in automobile components. Hardness values measured by Vickers hardness tested validated the improved mechanical properties. The presence of micro roughness and improved tensile strength values signify that the coatings have firmly absorbed on ABS plastics. The morphology of Ni-Cr coatings was found uniform and analyzed using SEM images.

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` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Corrosion and hardness characteristics of metalized ABS plastics prepared by FDM rapid prototyping process K. Raja1, C.D. Naiju1, S. Narayanan1, P.A. Jeeva1, S. Karthikeyan2* 1School of Mechanical &Building Sciences, VIT University, Vellore-632 014, India. 2*Surface Engineering Research lab, Centre for Nanobiotechnology, VIT University, Vellore-632 014, India. *Corresponding author (skarthikeyanphd@yahoo.co.in) Abstract An attempt has been made in this work to develop nickel chromium coatings with enhanced corrosion and hardness properties on ABS plastics prepared by FDM-RP process. The increase of corrosion resistance of Ni-Cr electrodeposited coatings in sea water medium claimed that these coated plastics can find as substitute for metal parts used in automobile components. Hardness values measured by Vickers hardness tested validated the improved mechanical properties. The presence of micro roughness and improved tensile strength values signify that the coatings have firmly absorbed on ABS plastics. The morphology of Ni-Cr coatings was found uniform and analyzed using SEM images. Keywords Ni-Cr coatings, FDM-RP, corrosion resistance, tensile, SEM © 2014 University of Manchester and the authors. This is a preprint1of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Introduction In the field of surface engineering, Ni-Cr coatings are widely employed for wear and corrosion resistance in piston rings made of mild steel. Nickel and Chromium coatings are the important electrodeposited metals and they are produced by electrodeposition/pulse electrodeposition on metals[1-2]. In recent years. the investigations on the metallization of ABS plastics are gaining much importance owing to their practical application in automobile components[3-6]. This is due to the fact that ABS plastics are having good tensile strength and cushioning effect when it is subject to severe impact loads. Electroless nickel coated ABS injection moldings have been reported for their higher corrosion resistance in aggressive media[7-8]. However, metallization of ABS plastics prepared through RP process is still at entry level. The presence of honey comb structure of ABS obtained by RP method is claiming that metallization on it will improve the mechanical properties considerably better than the injection molded plastics. This gives an idea for identifying a suitable corrosion resistant coating to reduce the damage of automobile vehicles when high impact load is applied. The developed coatings is expected to increase hardness and tensile strength. The performance of coatings is to be screened by mass gain studies, Vickers hardness test, Tensile strength, corrosion resistant measurement by potentiodynamic polarization and AC impedance methods. The uniformity of the surface is a desirable factor for improvement on mechanical properties for metalized ABS which will be determined by micro structural analysis using SEM images. © 2014 University of Manchester and the authors. This is a preprint2of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Experimental Procedure The bath developed in the present study consisted of the following ingredients. I. NiSO4.6H2O = 120 g/l NiCl2 = 25 g/l Boric acid = 60 g/l Cetyl Tri Methyl Ammonium Bromide (CTAB) = 3 g/l Ammonium Sulphate = 5 g/l Sulfamerizine (Brightner) = 0.5 mg/l Bath parameters: pH = 4.3 Current density = 45 mA/cm2 Plating time = 90 min. Anode =Ni plates of size 100 x 300 mm Cathode = ABS plastics coated with electrodeposited copper on EN. II. CrCl3.6H2O = 90 g/l Sodium formate = 50 g/l Gly oxylic acid = 7 g/l Potasium chloride = 72 g/l © 2014 University of Manchester and the authors. This is a preprint3of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 CTAB = 1 g/l Sulfamerizine (Brightner) = 1 mg/l Bath parameters: pH = 3 Current density = 100 mA/cm2 Plating time = 5 min. Anode =Lead plates of size 100 x 300 mm Cathode = Nickel plated ABS plastics coated with electrodeposited copper on EN. The autocatalytic deposition of nickel with 10 microns thickness has been carried out on ABS plastics as described earlier[9]. The electrodeposition of copper was performed on EN coated ABS as reported elsewhere[10]. Evaluation of high strength coatings through different techniques Mass-gain method ABS plastics prepared by RP process with size 20 x 50 x 2 mm3 were used in the plating bath. They were mechanically polished with fine grit paper, washed with distill water and then degreasing was carried out by tri choloro ethylene to remove finger prints and oily substances. It is again washed and etched in 2% HCl and 1% H2O2 solution. Then the plastics were sensitized and activated by adopting the © 2014 University of Manchester and the authors. This is a preprint4of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 procedure as reported earlier[11]. The initial mass of ABS plastic was weighed using electronic weighing machine. Then the plastics were subjected to EN plating(10 µm) and electrodeposition of copper(2 µm), nickel and chromium(38 µm). The rate of deposition was calculated using the following formula: Where, W – Weight of the deposit (g) D – density of the deposit (g/cm3) T – plating duration (h) A – Surface area of the specimen (cm2) Micro hardness measurements Micro hardness measurements for all the as metalized ABS (20 x 50 x 2 mm3) were measured using Vicker’s harness tester as per ASTM E-384 with a load of 100 g. A diamond shaped indentation was created on each coated plastics at eight different locations and the mean of hardness was calculated from the diagonal of indendation on Vicker’s scale using the formula. V.H.N = (1854 x load) / d2 where d = diagonal of the indentor © 2014 University of Manchester and the authors. This is a preprint5of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Corrosion resistance measurements The potentiodynamic polarization and impedance studies were performed on metalized ABS plastics with the Ni-Cr coated area of 10 mm2 exposed surface (test electrode) in 3.5% NaCl, 40 mm2 of platinum electrode (counter electrode) and saturated calomel as reference electrode in three electrode cell assembly. Potentiodynamic polarization method A constant quantity of 250 ml of 3.5% NaCl (sea water) solution was taken in a 250 ml beaker. The test electrode, reference electrode and the counter electrode were positioned in the electro chemical workstation (Sinsil Model 604E, USA) and the readings were recorded by shifting the potential ± 300 mV from OCP at a scan rate 10 mV.second-1 for the metalized ABS. The corrosion rate factors like Ecorr and Icorr, were recorded. The reduction in Ecorr and Icorr values indicated that the coatings are having good corrosion resistance than those reported earlier[12-13]. Impedance measurement AC impedance was carried out in the frequency range of 100 kHz to 0.01 Hz under potentiostatic conditions using 3.5% NaCl as corrosive environment for Ni-Cr. The impedance measurements were performed on metalized plastics at room temperature. The electrical equivalent circuit[14] used which is equivalent to Randell’s investigations for the corroding system is appended below: © 2014 University of Manchester and the authors. This is a preprint6of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 RS - Solution resistance Rt - Charge transfer resistance W - Warburg impedance Cdl - Double layer capacitance submitted 6 March 2014 The cell impedance consisted of real part (Z’) Vs imaginary part (Z’’). A plot of real part (Z’) Vs imaginary part (Z’’) gave a distorted semicircle which indicated the presence of highly resistive surface. The experimental plots maping was carried out for calculating charge transfer resistance(Rt) by considering the components of circuits[15] as reported in Warburg impedance analysis. The double layer capacitance can be determined from the frequency at which Z’’ is maximum from the relation ‫ܥ‬ௗ௟ ൌ ଵ ଶπ୞′′ౣ౗౮ ୖ౪ Tensile strength measurements This measurement was carried out using Instron 8801 as per ASTM D638 at a strain rate of 2 mm/min. © 2014 University of Manchester and the authors. This is a preprint7of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Scanning electron microscopic studies (SEM) The micro structural images of Ni-Cr coated ABS plastics were studied using SEM analyzer. The coated test electrodes were prepared for size 10 x 10 mm2 and placed firmly on crusible to be examined for SEM images. The SEM images were portrayed by using VEGA3 TESCAN model with an acceleration voltage range of 3,000 V and with the magnification range of 1kx. Results and Discussions Mass gain studies The results of Ni-Cr coatings on ABS plastics obtained by mass gain method and eddy current tests are given in Table 1. It has been noticed that the incorporation Cr improves brightness besides micro hardness values. The addition chromium into nickel matrix significantly improved the tensile strength because of its higher ductility. The rate of deposition for Ni-Cr was calculated as 50µm at the plating duration of 90 minutes. Micro hardness measurements The hardness of the electrodeposited Ni-Cr coatings determined by Vicker’s hardness tester is presented in Table 2. The increased hardness of Ni alloy coatings could be due to the combined effect of hard coatings with soft copper layers formed on EN coatings. © 2014 University of Manchester and the authors. This is a preprint8of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Corrosion resistance studies Potentiodynamic polarization studies The corrosion resistance experiments were performed for hard coatings on ABS plastics has been done by employing current-voltage measurements using polarization studies. The coated surface was exposed to sea water medium for 5 hours and OCP was noted. This study was carried out by changing potentials ± 300 mV from OCP vs Hg/Hg2Cl2/KCl(Satd.). The corresponding corrosion potential and corrosion current were measured for the polarized coatings. Ecorr values for Ni-Cr alloy coatings were noted as -362 mV. Also, Icorr values have been shifted to 501x10-8 A which is the lowest Icorr values for Ni-Cr coatings. The results are given in table 3. Electrochemical Impedance Spectroscopy (EIS) studies The calculated impedance values of Ni-Cr coated ABS in 3.5% sea water medium are given in the table 4. It is evident from table 4 that the Rt values are enhanced where as Cdl values decreased. It has been noticed that Nyquist plot has not shown perfect semi-circle and best fitted curve was drawn by changing the equivalent circuits as indicated by Randell’s. This could be the reason for a highly resistive surface. The decreased Cdl values have been claimed for Warburg’s impedance. It is evident that Ni-Cr hard coatings on ABS plastics prepared by FDM RP method can be used for automobile machine parts as an alternate to metal frames/fittings. Tensile strength measurements The tensile strength of hard surfaces coated on ABS plastics which was electrodeposited by copper on EN. It has been observed that the tensile fracture on © 2014 University of Manchester and the authors. This is a preprint9of a paper that has been submitted for publication in the Journal of Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 the coated ABS plastics was 0.8 mm at 790 N loads. It is validated that Ni-Cr coatings offer high mechanical properties. Scanning Electron Microscopic studies Figure 3 indicates the micro structural images of Ni-Cr coatings prepared from nickel electroplating bath. It is visualized that globular structures along with spherical particles aggregation confirm the existence of nickel and chromium on ABS matrix. The appearance of black patches might be due to the formation of oxide layers i.e. Cr2O3. The formation of pin holes in micro structure indicating the hydrogen evaluation which has to avoided to nullify hydrogen embrittlement. In comparison with Ni-Cr coated micro structural images, the presence of layered polystyrene group (Figure 4) of rapid prototyped plastics. The appearance of black patches could be due to the removal of polymeric film from ABS matrix by etching process and the later has played a dominant role for making effective adherence of coatings on ABS plastics. Conclusion An attempt has been made successfully to develop hard coatings based on Ni-Cr on FDM rapid prototyped ABS plastics coated with copper on EN. The hard coatings exhibited excellent hardness, corrosion resistance and tensile strength. SEM images confirmed the existence of Ni-Cr in ABS polymer matrix. This investigation was found useful to develop an alternate coating materials for automobile parts replacing metals. 10of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 References [1]. ‘Nickel and Chromium plating’, J.K. Dennis, T.E. Such.. Butterworth & Co, Londres 1972. [2]. ‘Effects of electroplating on the mechanical properties of stereolithography and laser sintered parts’, N.Saleh, N.Hopkinson, R.F.M. Hague, S.Wise, Rapid Prototyping Journal, 10, 5, pp305-315, 2004. [3]. ‘Intergrated used of rapid prototyping and metal plating technique for development of micro air vehicles’, U.Chandrasekhar, K. Venkatesh, K. Elangovan, T.Rangaswamy, Int. J. of Engg. Sci. and Tech., 3, 1, pp188-193, 2011. [4]. ‘Study of electroless nickel plating on PerFactory rapid prototype model’, J.C. Rajaguru, C.Au, M. Duke, J. of Achiv. In Mater. and Manuf. Engg., 55, 2, pp782-789, 2012. [5]. ‘Description and modeling of the additive manufacturing technology for aerodynamic coefficients measurement’, S. Daneshmand, C. Aghanajafi, J. of Mech. Engg., 58, 2, pp125-133, 2012. [6]. ‘Electroless copper deposition on aluminium-seeded ABS plastics’, D.Li, K.Goodwin, C. Lu Yang, J Mater Sci., DOI 10.1007/s10853-008-3031-1. [7]. ‘Surface modification with copper by electroless deposition technique: an overview’, K.G. Mishra, R.K. Paramguru, African J of Pure and Appl. Chem., 4, 6, pp87-99, 2010. [8]. ‘Corrosion inhibition of mild steel in 1M H2SO4 by Ampicillin as an inhibitor’, S. Hari Kumar, S. Karthikeyan, P.A. Jeeva, Journal of Corrosion Science and Engineering, Vol.16, 2013. [9]. ‘Quantum mechanical approach for electroless plating process’, S. Karthikeyan, P. A. Jeeva, S. Narayanan, K. N. Srinivasan, X. Hu, Surface Engineering, 28, 10, pp 743-746, 2012. [10]. ‘Electrodeposition of copper’, Hans-Gerhard Creutz, Roy W. Herr, US4110176 A, US 05/793,701, 1978. [11]. ‘Impedance measurements for electroless nickel plating process’, S. Karthikeyan, K.N. Srinivasan, T. Vasudevan, S. John, Port. Electrochim. Acta, 24, 4, pp405-413, 2006. [12]. ‘Ethane-2- thioamido-4-amino-N-(5-methylisoxazol-3-yl)-benzene sulfonamide: A novel inhibitor for the corrosion of mild steel in 1N HCl’ , S. 11of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Karthikeyan, Volume 17, Preprint 17 N. Arivazhagan, S. Narayanan, submitted 6 March 2014 Journal of Corrosion Science &Engineering, Vol.16, 2013. [13] ‘Performance characteristics of 1, 3-diorthotolyl thiourea on the corrosion of mild steel in 5% NaCl’, S. Karthikeyan, N. Arivazhagan, D. Ramkumar, S. Narayanan, Journal of Corrosion Science &Engineering, Vol.16, 2013. [14]. ‘4-Chloro-2-((furan-2-ylmethyl) amino)-5-sulfamoylbenzoic Acid (FSM) and N-(Isopropylcarbamoyl)-4-(m-tolylamino) Pyridine-3-sulfonamide (TSM) as Potential Inhibitors for Mild Steel Corrosion in 1 N H2SO4 Medium. Part I’, S. Harikumar, S. Karthikeyan, Ind. Eng. Chem. Res., 53, 9, pp 3415–3425, 2014. [15]. ‘Torsemide and Furosemide as Green Inhibitors for the Corrosion of Mild Steel in Hydrochloric Acid Medium’, S. Harikumar, S. Karthikeyan, Ind. Eng. Chem. Res., 52, 22, pp 7547–7469, 2013. 12of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Table 1 The results of mass gain studies and eddy current test obtained for Ni-Cr coatings on Cu electroplated ABS plastics coated with EN Thickness (µm) S.No. Deposition Weight Eddy timings (sec.) gain current method test 50 51 1 180 Inference Bright with uniformity Table 2 Micro hardness values for Ni-Cr coatings on Cu electroplated ABS plastics coated with EN Hardness (V.H.N) S.No Load:100g Coatings 1. Ni-Cr coatings on ABS 2. ABS coated 995 with 550 electrodeposited Cu on EN 3. ABS plastic 70 13of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Table 3 Potentiodynamic polarization studies of Ni-Cr coatings on Cu electroplated ABS plastics coated with EN Nature of deposit Ecorr Icorr (mV vs SCE) (x 10-8 A. cm-2) -362 501 Ni-Cr coatings on ABS Table 4 Impedance values of Ni-Cr coatings on Cu electroplated ABS plastics coated with EN Nature of deposit Ni-Cr coatings on ABS Rt Cdl (Ohm.cm2) (µF. cm-2) 990 0.357 Legends for figure 1. Potential current curves for Ni-Cr coatings on ABS plastics in sea water medium 2. Nyquist plots for Ni-Cr coatings on ABS plastics in sea water medium 3. Load-Extension curve for Ni-Cr coatings on ABS plastic surfaces. 4. SEM image of Ni-Cr coated ABS plastics 5. SEM image of uncoated ABS plastics 6. EDAX for Ni-Cr coated ABS plastics 14of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Figure 1 Figure 2 15of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Figure 3 Fig gure 4 16of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work. ` ISSN 1466-8858 Volume 17, Preprint 17 submitted 6 March 2014 Fig gure 5 cp ps/eV 12 10 8 6 C O Cr C Ni Cr Ni 4 2 0 2 4 6 eV ke 8 10 12 14 Fig gure 6 17of a paper that has been submitted for publication in the Journal of © 2014 University of Manchester and the authors. This is a preprint Corrosion Science and Engineering. It will be reviewed and, subject to the reviewers’ comments, be published online at http://www.jcse.org in due course. Until such time as it has been fully published it should not normally be referenced in published work.