مقايسه خواص مكانيكي و متالورژيكي آندايز معمولي و آندايز رنگي با استفاده از نانو رنگدانه هاي فلزي

چكيده انگليسي :

Comparison of Mechanical and Metallurgical Properties of Conventional Anodized Layers with Colored Anodized Layers by Nano Metallic Pigments Amin hakimi zad a hakimizad@ma iut ac ir Date of Submission 2011 03 13 Department of Materials Engineering Isfahan University of Technology Isfahan 8415683111 Iran Degree M Sc Language Farsi Supervisors Fakhreddin Ashrafizadeh Keyvan Raeissi Abstract Anodizing of aluminum in sulfuric acid produce anodic aluminum oxide AAO with a regular nano porous structure Nano pores are cylindrical and perpendicular to the aluminum substrate Electrocoloring electrolytic coloring precipitate nano metallic particles in the bottom of the regular nano pores leading to induce electrolytic colors on the treated aluminum surface but these colors differ from brown to black modification of nano porous anodic aluminum oxides induces light interference leading to various tones of colors named Interference colors after electrolytic coloring process Interference colors predicted to be as same as the electrolytic colors but with various interesting tones of colors In this research nano morphology of an anodic aluminum oxide was modified via two procedures in sulfuric and phosphoric acid baths The metallurgical changes after the modifications were evaluated and compared with unmodified conventional layer Layer thickness crystalline structure surface topography and morphology mechanical characteristics including elastic modulus and nano hardness corrosion behavior and electronic properties of the oxide layers were evaluated by metallography low angle X Ray diffraction LAXRD atomic force microscopy AFM and field emission scanning electron microscopy FE SEM nano indentation NHT electrochemical Tafel polarization and mott shottky analysis respectively From the overall view the modification had some destructive effects on corrosion performance and mechanical properties of the anodized layers Mott Shottky analysis showed that the aluminum oxide layer was characterized as an n type semiconductor and the modification increased its conductivity The effects of the oxide modification on creating interference colors using the electrolytic coloring method were evaluated The oxide layer modified in the sulfuric acid bath extended conventional electrolytic colors in the same tone Conversely different interference colors were obtained for the oxide layer modified in phosphoric acid bath The electrochemical impedance spectroscopy was employed to examine the differences between the conventional electrolytic and interference colors The results showed that the interference color anodized layer had a thinner barrier layer in comparison with conventional electrolytic anodized layer In addition interference colored layers had some problems with ordinary sealing techniques only steam sealing was found to be effective for these layers The modified layers were colored by electroless precipitation of Fe2O3 nano particles and no interference phenomenon was observed However electrocoloring the layer modified in phosphoric acid by nickel based tin based or copper based electrolyte inhibited the same interference colors It was concluded that the interference colors need electrolytic coloring due to metallic nano pigments precipitation at the bottom of anodized layer nano pores this is dependent on the nature of metallic pigments Electroless inorganic conventional electrolytic and interference colored anodized layers were tested against ultra violet light for 300h exposure to D65 UV lamp Interference colors were more resistant to bending according to ASTM B 571 A standard Steam sealed interference colored anodized layers passed the ASTM B 136 84 and ASTM B 680 80 sealing quality standards ASTM B 137 95 results showed that the interference anodized layers had approximately 30 lower density to conventional electrolytic and electroless colored layers This was in good agreement with estimated porosity by the aid of mechanical properties relationshi

حكيمي زاد، امين

مقايسه خواص مكانيكي و متالورژيكي آندايز معمولي و آندايز رنگي با استفاده از نانو رنگدانه هاي فلزي

آندايزينگ , لايه اكسيدي آلومينيوم , تداخل نور , رنگي سازي الكتروليتي