7215

6721

كارشناسي ارشد

خوردگي و حفاظت از مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1391

91ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

محمدعلي گلعذار

كيوان رئيسي

14/8/91

احمد ساعتچي، مهدي صالحي

1396/09/20

كتابنامه

مواد

مهندسي مواد

ID6721

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

95 Characterization and Evaluation of Corrosion and Tribocorrosion and Passivation of Anodized Ti 6Al 4V Alloy Mohammad reza Garsivaz Jazi m garsivaz@ce iut ac ir 23 04 2012 Department of Materials Engineerig Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiMohammad Ali Golozar supervisor m golozar@cc iut zc irAbstractIn this study the surface characteristic of oxide films on Ti 6Al 4V alloy formed by an anodic oxidationtreatment in H2SO4 H3PO4 electrolyte was evaluated The oxide film was formed under potentiostaticcondition at potentials higher than the breakdown voltages The effect of anodizing voltage on the corrosionand tribocorrosion behavior of material was also investigated The corrosion of oxide layers was studiedusing electrochemical potentiodynamic polarization and electrochemical impedance spectroscopy EIS techniques in 0 9wt NaCl solution Polarization curves showed a significant rise in the corrosion resistanceafter spark oxidation Moreover the results exhibited more positive corrosion potential and higher corrosioncurrent density at higher anodizing voltage The obtained EIS spectra and their interpretation in terms of anequivalent circuit with the circuit elements representing the electrochemical properties of two oxide layers composed of porous outer layer and dense inner layer space charge region and diffusion were in a goodagreement Evaluation of tribocorrosion of oxide layers produced at various anodizing voltages was studiedin 0 9wt NaCl measuring the free corrosion potential with respect to Ag AgCl2 reference electrode It wasobserved that for samples anodized at lower voltages the open circuit potential drops sharply down tonegative values due to the removal of oxide films But for samples anodized at higher voltages the resultsindicated lower potential drop having a slower slop After being tested the surface of samples wereinvestigated by SEM and EDS Results obtained indicated that the oxide layer on samples anodized at lowervoltages is totally removed but for samples anodized at higher voltages the oxide layer is only locallyremoved within the wear track Moreover measurement of wear volume loss exhibited lower wear volume insamples anodized at higher voltages These results indicated a better tribocorrosion behavior due toincreasing the anodizing voltage Morphology of the surface layers was studied by scanning electronmicroscope SEM The results indicated that the diameter of pores and porosity of oxide layer increase withanodizing voltage The thickness of the layer was measured on the cross sections of samples by SEM Theresults showed a linear increase of thickness with increasing the anodizing voltage The EDS analysis ofoxide films formed in H2SO4 H3PO4 at potentials higher than breakdown voltage demonstrated theprecipitation of sulfur and phosphor elements from electrolyte into the oxide layer The roughnessmeasurement of oxide layer showed that in spark anodizing the Ra and Rz parameters would increase withincreasing anodizing voltage Key Words anodizing breakdown voltage tribocorrosion EIS

محمدعلي گلعذار

كيوان رئيسي

احمد ساعتچي، مهدي صالحي