10402

9597

كارشناسي ارشد

خوردگي و حفاظت از مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1394

سيزده، 76ص.: مصور، جدول، نمودار

كيوان رئيسي، فخرالدين اشرفي زاده

1394/06/08

علي اشرفي، اكبر اسحاقي

1396/10/04

كتابنامه

مواد

مهندسي مواد

ID9597

به فارسي و انگليسي

67 Effect of modifier on wettability characteristic of nickel electrodeposited coatings with micro nano hierarchical structures Mehri Hashemzadeh m hashemzadeh@ma iut ac ir Date of submission 10 June 2015 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors k raeissi@cc iut ac irashrafif@cc iut ac irAbstractNickel coatings were prepared in the presence of different concentrations of ammoniumchloride by two step electrodeposition method Surface morphology topography andpreferred orientation of the coatings were characterized by scanning electron microscopy SEM confocal profilometer and X ray diffractometer XRD respectively The SEMresults showed that the coating prepared in the absence of ammonium chloride has a micro cones structure By adding ammonium chloride more regular sharp and symmetric micro cones were formed The formation mechanism of this structure can be explained by screwdislocation driven growth theory XRD results showed that ammonium chloride haschanged the preferred grain orientation of nickel coatings from 220 to 111 The role ofammonium chloride was studied by cyclic voltammetry and electrochemical impedancespectroscopy EIS techniques The results showed that ammonium chloride increased thecharge transfer resistance in electrodeposition by forming nickel ammonia complexes Therefore it inhibits nucleation of nickel deposits The wettability of prepared coatingswas investigated by measuring the water contact angle on the coatings surface It wasobserved that the freshly prepared nickel coatings were super hydrophilic and by storingthem in air for two weeks they became super hydrophobic Corrosion resistance of thecoatings was evaluated through long term immersion in 3 5 wt NaCl solution using EIStests The results showed that the superhydrophobicity has increased polarization resistancealmost twelvefold The polarization resistance gradually decreased due to lowering ofhydrophobicity After hydrophobicity loss the polarization resistance of all coatingsconsiderably increased This behavior was due to the passive film formation on thecoatings surface in corrosive solution Nickel coatings also prepared in presence of otheradditive called ethylenediammonium dichloride by the two step electrodeposition Theprepared nickel coatings were lack of appropriate micro nano cone structures Theroughness of these coatings was lower than the roughness of coatings prepared in presenceof ammonium chloride Therefore by storing in air they could be only hydrophobic Theincrease of polarization resistance of these coatings versus time was due to theaccumulation of corrosion products and its surface plugging effect Keywords Super hydrophobicity Nickel Electrodeposition Ammonium chloride ethylenediammonium dichloride

كيوان رئيسي، فخرالدين اشرفي زاده

علي اشرفي، اكبر اسحاقي