Our present investigation focuses on the thermal stability of already developed electroforms of ZnANi

and ZnANiAAl2O3 thin films induced with triethylamine (TEA) and monoethylamine (MEA) as surfactant

by electrocodeposition on mild steel substrate with the aim to re-examine its micro-hardness and

degradation behaviour in static sodium chloride solution. In the event, the samples were thermally treated

at 200 �C and air cooled. The results obtained showed that the developed composites are thermally

stable with hardness value of the ZnANiAAl2O3 coated; 185 Hv increased to 190.5 Hv indicating a

2.89% improvement. Noticeably, in the ZnANi coatings, a decrease in the hardness with 26.67% was

observed. The oxidation resistance was however favored for both composites

Abdulwahab, M

Dodo, M.R.

Fayomi, O. S. I

Popoola, A. P. I.

Covenant University Repository

Results in Physics 7 (2017) 213–215Contents lists available at ScienceDirectResults in Physicsjournal homepage: www.journals .e lsevier .com/resul ts - in-physicsIn-situ hybrid study of thermal behaviour of ZnANi and ZnANiAAl2O3nanocrystallite thin films induced TEA/MEA by electrocodepositionhttp://dx.doi.org/10.1016/j.rinp.2016.11.0172211-3797/ 2016 Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).⇑ Corresponding authors at: Department of Chemical, Metallurgical and MaterialsEngineering, Tshwane University of Technology, Pretoria, South Africa.E-mail addresses: mabdulwahab@abu.edu.ng (M. Abdulwahab), ojosundayfayo-mi3@gmail.com (O.S.I. Fayomi).M. Abdulwahab a,b,⇑, O.S.I. Fayomi a,c,⇑, A.P.I. Popoola a, M.R. Dodo baDepartment of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South AfricabDepartment of Metallurgical and Materials Engineering, Ahmadu Bello University, Zaria, NigeriacDepartment of Mechanical Engineering, Covenant University, Ota, Ogun State, Nigeriaa r t i c l e i n f o a b s t r a c tArticle history:Received 5 September 2016Received in revised form 14 October 2016Accepted 7 November 2016Available online 11 November 2016Keywords:Thermal stabilityThin filmsOxidationScalingGrain growthOur present investigation focuses on the thermal stability of already developed electroforms of ZnANiand ZnANiAAl2O3 thin films induced with triethylamine (TEA) and monoethylamine (MEA) as surfactantby electrocodeposition on mild steel substrate with the aim to re-examine its micro-hardness anddegradation behaviour in static sodium chloride solution. In the event, the samples were thermally trea-ted at 200 C and air cooled. The results obtained showed that the developed composites are thermallystable with hardness value of the ZnANiAAl2O3 coated; 185 Hv increased to 190.5 Hv indicating a2.89% improvement. Noticeably, in the ZnANi coatings, a decrease in the hardness with 26.67% wasobserved. The oxidation resistance was however favored for both composites. 2016 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).IntroductionSteel and its alloy group have wide range of application due tothe high strength, availability, ease of fabrication, low cost amongothers [1–4]. In most service condition, there exist limitations asper the hardness and corrosion resistant of using this importantalloy. Accordingly, various techniques have been put forward as ameans of enhancing it properties [1,5,6]. In that direction, surfacetreatment has long time gained acceptance as a method of simulta-neously improving the alloy hardness and corrosion/oxidationresistance. Among these surface treatment techniques, the use ofelectrodeposition for surface coating has being promising due toadvantages it has over other; such as wear resistance, self-lubricating, corrosion or oxidation resistance [6,7]. In an event toexamine the thermal stability of our earlier developed ZnANi andZnANiAAl2O3 films onmild steel [8,9], effort wasmade to heat treatthe coated composite and then re-examine its micro-hardness andcorrosion resistance in the thermally treated condition. The presentstudy is aimed at evaluating the micro-hardness and corrosion ofisothermally treated ZnANi and ZnANiAAl2O3 thin films inducedTEA/MEA by electrocodeposition on mild steel substrate.Experimental methodThe dimension of the mild steel (substrate) used was 40 mm 20 mm  1 mm sheet and zinc sheets of 30 mm  20 mm  1 mmwere prepared as anodes. The mild steel specimens’ chemical com-position is shown in Table 1. The bath constituent admixture, otherplating parameters and optimum results were adopted from ourprevious study [8].For isothermal treatment of the ZnANi and ZnANiAAl2O3coated composite, the coated composite sample that gave the besthardness in [7,8] were re-examined after thermal treatment. Theelectroform of coated ZnANi–mild steel and ZnANiAAl2O3–mildsteel were heat treated at a temperature of 200 C for 2 h in anelectrical heating furnace under atmospheric conditions and thenquenched in air.Vickers micro-hardness tester under a load of 100 g and a spac-ing of 150 lm with a dwell time of 15 s with an average of fourmeasurements from different locations was used to evaluate thehardness of the as-deposited and thermally treated (heat treated)composite using a hardness tester with model-Dua scaninventor-EMCOTEST. The indentations started at the surface ofthe coated-body through the base of the mild steel substrate. Theelectrochemical studies were done with Autolab PGSTAT 101Metrohm potentiostat using a three-electrode cell assembly in a3.65% NaCl static solution at 40 C. The heat treated compositewas the working electrode, platinum electrode was used as counterTable 1Chemical composition of mild steel used (wt%).Element C Mn Si P S Al Ni FeComposition 0.15 0.45 0.18 0.01 0.031 0.005 0.008 Balance050100150200250Zn-Ni Zn-Ni heat-treatedZn-Ni-Al2O3 Zn-Ni-Al2O3 heattreatedMicro-hardness (Hv) Material deposited/treatedFig. 1. Variation of micro-hardness for the as-deposited and heat-treatedconditions.Table 2Polarization data for the untreated and thermally treated composite sample in a static3.65% NaCl solution.Samples Ecorr,Obs (V)jcorr(A/cm2)icorr (A) CR(mm/yr)Rp(X)ZnANi 1.0665 5.43E05 5.43E05 6.31E01 435.91ZnANi Heattreated1.0622 7.13E08 7.13E08 8.28E04 154ZnANiAAl2O3 1.0103 4.70E05 4.70E05 5.47E01 221.57ZnANiAAl2O3Heat treated0.8460 5.57E12 5.57E12 6.48E08 2224Fig. 2. Linear polarization curve for the as-deposited and heat treated conditions.Fig. 3. Surface optical microstructure of as-coated composite for (a) ZnANi (214 M. Abdulwahab et al. / Results in Physics 7 (2017) 213–215electrode and Ag/AgCl as a reference electrode. The anodic andcathodic polarization curves were recorded by a constant scan rateof 0.012 V/s which was fixed at ±1.5 mV. From the Tafel extrapola-tion plots, the corrosion rate, potential and linear polarization resis-tance was obtained.Results and discussionThe results obtained showed that the developed composites arethermally stable with hardness value of the ZnANiAAl2O3 coated;185 Hv increased to 190.5 Hv indicating a 2.89% improvement (seeFig. 1). The reason for this observation is still unclear, though theceramics phases likely formed might be responsible, such that athigh temperature the oxide layer became hardened and resistanceto any external forces. However, this may scale-off over a prolongperiod of post heat treatment time. Although in the ZnANi coat-ings, a decrease of about 26.67% in the hardness was observed. Thisdemonstrated that the addition of Al2O3 particles in the ZnANimatrix improves its thermal stability by acting as a barrier to dis-location motion and hence reducing the grain growth. Similarclaim was reported [9]. Relatively, an increased micro-hardnessof heat treated ZnANiAAl2O3 coating can be attributed to theceramics particle inoculated. Similar occurrence has been reported[10].The polarization resistance of ZnANi coated decreased fromthat of as-deposited to heat treated sample. While that of heatb) ZnANi heat treated (c) ZnANiAAl2O3 (d) ZnANiAAl2O3 heat treated.M. Abdulwahab et al. / Results in Physics 7 (2017) 213–215 215treated ZnANiAAl2O3 increased with respect to as-depositedZnANiAAl2O3 (Table 2). The oxidation resistance was howeverfavored for both composites (see Fig. 2 and Table 2). Accordingly,the surface morphology of the samples generally indicated anoxidized surface (Fig. 3a–d). This however calls for further investi-gation since it is expected that such surfaces may likely have con-tained un-adhered film coating at that temperature. Considerably,such suggest that the film formed on the mild steel substrate arethermally stable and hence indicates good bath admixture duringthe electrocodeposition of the coatings.ConclusionsThe thermal stability of already developed ZnANi andZnANiAAl2O3 thin films induced TEA/MEA by electrocodepositionwas evaluated with the aim to re-examine its micro-hardnessand degradation behaviour in static sodium chloride solution. Inthe event, the samples were thermally treated at 200 C and aircooled. The results obtained showed that the developed compos-ites are thermally stable with hardness value of the Zn-ANiAAl2O3coated; 185 Hv increased to 190.5 Hv indicating a 2.89% improve-ment. Although in the Zn-Ni coatings, a decreased hardness wasobserved, while the oxidation resistance was rather favored forboth composites.AcknowledgementsThe authors appreciate with thanks the financial andequipment support of National Research Foundation and SurfaceEngineering Research Center, Tshwane University of Technology,Pretoria, South Africa.References[1] Popoola API, Fayomi OSI, Popoola OM. Comparative studies of microstructural,tribological and corrosion properties of plated Zn and Zn-alloy coatings. Int JElectrochem Sci 2012;7:4860.[2] Fayomi OSI, Popoola API. An investigation of corrosion and mechanicalbehaviour of Zn coated mild steel in 3.65% NaCl. Int J Electrochem Sci2012;7:6555.[3] Rahman MJ, Sen SR, Moniruzzaman M, Shorowordi KM. Morphology andproperties of electrodeposited Zn–Ni alloy coatings on mild steel. J Mech Eng,Trans of the Mechanical Eng Division, The Institution of Engineers, Bangladesh2009;40(9).[4] Fei JY, Liang GZ, Xin WL, Wang WK. Surface modification with zinc and Zn–Nialloy compositionally modulated multilayered coatings. J Iron Steel Res Int2006;13(4):61.[5] Ochonogor OF, Meacock C, Abdulwahab M, Pityana S, Popoola API. Effect of Tiand TiC ceramic powder on laser-cladded Ti-6Al-4V in-situ intermetalliccomposite. Appl Surf Sci 2012;263:591–6.[6] Loto CA, Olefjord I. Influence of organic additives on the surface characteristicsof zinc electrodeposition on mild steel in acid chloride solutions: pH, bathcomposition and time variation effects. Corr Prev Control J 1992;39:142.[7] Chitharanjan HA, Venkatakrishna K, Eliaz N. Electrodeposition of Zn–Ni, Zn–Feand Zn–Ni–Fe alloys. Surf Coat Technol 2010;205:2031.[8] Fayomi OSI, Abdulwahab M, Popoola API. Properties evaluation of ternarysurfactant-induced Zn-Ni-Al2O3 films on mild steel by electrolytic chemicaldeposition. J Ovonic Res 2013;9(5):123–32.[9] Fayomi OSI, Tau V, Popoola API, Abdulwahab M, Madhilabar R. Interfacialinvestigation and strengthening behaviour of Zn-Ni multifacial TEA/MEA thinfilms induced by electrodeposition. Appl Phys A, Mater Sci Process2013;121:749–55.[10] Srivastava M, Balaraju JN, Ravishankar B, Rajam KS. Improvement in theproperties of nickel by nano-Cr2O3 incorporation. Surf Coat Technol2010;205:66–75.Further reading[11] Kumar K, Chandramohan R, Kalyanaraman D. Appl Surf Sci 2004;227:383.

In-situ hybrid study of thermal behaviour of ZnANi and ZnANiAAl2O3

nanocrystallite thin films induced TEA/MEA by electrocodeposition

Our present investigation focuses on the thermal stability of already developed electroforms of ZnANi and ZnANiAAl2O3 thin films induced with triethylamine (TEA) and monoethylamine (MEA) as surfactant by electrocodeposition on mild steel substrate with the aim to re-examine its micro-hardness and degradation behaviour in static sodium chloride solution. In the event, the samples were thermally treated

at 200 �C and air cooled. The results obtained showed that the developed composites are thermally stable with hardness value of the ZnANiAAl2O3 coated; 185 Hv increased to 190.5 Hv indicating a 2.89% improvement. Noticeably, in the ZnANi coatings, a decrease in the hardness with 26.67% was

observed. The oxidation resistance was however favored for both composites

In-situ hybrid study of thermal behaviour of ZnANi and ZnANiAAl2O3 nanocrystallite thin films induced TEA/MEA by electrocodeposition

http://eprints.covenantuniversity.edu.ng/9401/1/Fayomi%205.pdf

In-situ hybrid study of thermal behaviour of ZnANi and ZnANiAAl2O3 nanocrystallite thin films induced TEA/MEA by electrocodeposition

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