4608

4336

كارشناسي ارشد

خوردگي و حفاظت از مواد

اصفهان : دانشگاه صنعتي اصفهان ، دانشكده مواد

1387

ده ، 85 ، [II] ص: نمودار ، مصور ، جدول

ص. ع. به: فارسي وانگليسي

كيوان رئيسي ، احمد ساعتچي

88/5/21

محمد علي گلعذار ، محمد ‍‍ژياني

1396/09/13

كتابنامه

مهندسي مواد

ID4336

به فارسي وانگليسي : قابل رويت در نسخه ديجيتال

Electrodeposition of Ni W amorphous and nanocrystalline alloys and their corrosion behaviour sara kabi sara kabi@ma iut ac ir Department of materials engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors K Raeissi k raeissi@cc ac ir A Saatchi asaatchi@cc iut ac ir Abstract Nickel tungsten nanocrystalline coatings were electrodeposited from a watts type bath onto a copper substrate at different current densities selected from activation mixed and diffusion controlled regions from cathodic scan plots at 25 and 50 C The coatings obtained were single phase solid solutions and their grain sizes were increased by current density and temperature Tungsten content was increased by current density and temperature At 25 C the Tungsten content was in the range of 4 15 at and at 50 C Tungsten content increased to the range of 15 24 at The surface morphology was changed according to the polarization region A cauliflowers surface morphology was obtained when the current density was in the activation controlled region The surface morphology obtained in the mixed controlled region was somewhat distorted and then converted to a pyramidal morphology at the diffusion controlled region This behaviour was seen in all electrodeposition conditions The corrosion resistance was depended to W content and morphology of coating At the mixed controlled region the coatings with the highest corrosion resistance were obtained The Coatings with 7 at tungsten had the best corrosion resistance At 25 C the corrosion resistance was between 0 6 7 3 A cm2 and at 50 C it was at the range of 1 3 3 7 A cm2 decrasing amoniom chloride concentration in bath resulted on amorphous coationg was obtained due to the increase in Tungsten content off alloys By using pulse current grain size was decrease and Tungsten content and corrosion resistance was increased The hardness of coatings was strongly depended on Tungsten content and the highest hardness obtained was about 514 Hv The EIS results confirmed that the mechanism of W co deposition is changed with current density in both temperatures The results confirm that the tungsten codeposition proceeds via the reduction of tungsten oxide and or adsorption and consequent reduction of complexes formed in the bulk of solution At current densities belong to the activation polarization region the reduction of tungsten oxide by adsorbed hydrogen was dominated By increasing the current density to the region of mixed polarization the adsorption and reduction of W containing ion complexes overcome At current densities belong to the diffusion polarization region the diffusion of ion complexes were reached to the limitations Key words Ni W Coating Electrodeposit ion EIS Nanocrystalline Corrosion pdfMachine A pdf writer that produces quality PDF files with ease Produce quality PDF files in seconds and preserve the integrity of your original documents Compatible across nearly all Windows platforms simply open the document you want to convert click print select the Broadgun pdfMachine printer and that s it Get yours now

كيوان رئيسي ، احمد ساعتچي

محمد علي گلعذار ، محمد ‍‍ژياني