5917

5532

كارشناسي ارشد

مهندسي مواد

اصفهان: دانشگاه صنعتي اصفهان،دانشكده مواد

1389

چهارده،101ص.: مصور﴿بخش رنگي﴾، جدول،نمودار

ص.ع.به فارسي و انگليسي

فتح ا.. كريم زاده، محمد حسين عنايتي

25/2/90

مرتضي شمعانيان، احمد كرمانپور

مهندسي مواد

ID5532

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Development of Al356 Al2O3 surface nanocomposite by friction stir processing and evolution of its tribological behavior Yousef Mazaheri Rodbali y mazaheri@ma iut ac ir April 13 2010 Department of Material Science and Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi F Karimzadeh Associate professor Supervisor karimzadeh f@cc iut ac ir M H Enayati Associate professor Supervisor ena78@cc iut ac ir Abstract In this research development of Al356 Al2O3 surface nanocomposite by friction stir processing FSP method was investigated For this purpose first tool shape and geometry and FSP parameters were optimized by examining the samples prepared at a variety of process parameters microstructurally using both optical and scanning electron microscopy The optimum value of tool rotation rate traverse speed and the suitable tilt of the spindle towards trailing direction were found 1600rpm 200mm min and 2 respectively Then Al356 Al2O3 composite powders were prepared by mechanical milling of Al356 chips and 5vol micro and nanoscaled alumina particles The milled powders were used as feedstock to deposit composite coatings on Al356 T6 substrate using high velocity oxy fuel HVOF process Finally the aluminum plates with preplaced composite layers were subjected to FSP With the optimized tool design and processing parameters composite layers of 5mm with well distributed particles and a good bonding with the aluminum substrates was generated X ray diffractometery optical and scanning electron microscopy microhardness nanoindentation and wear tests were used to characterize the composite powders coatings and surface composites Friction stir processing of Al356 resulted in the significant breakup of coarse acicular Si particles and coarse primary aluminum dendrites the closure of casting porosities and the uniform distribution of broken Si particles having an average size of 5 10 m and an average aspect ratio of 2 in the aluminum matrix Results indicated that the presence of Al2O3 in matrix can improve the mechanical properties of specimens The mechanical performances of nanoparticle reinforced composites were far superior to those of microparticle strengthened composites with a similar volume content of particulate It was found that the hardness and elastic modulus of surface nanocomposite were about 110Hv and 86GPa Surface composites revealed low friction coefficients and wear rates which were significantly lower than those obtained for substrate The wear mass loss of the base metal FSP surface micro and nanocomposite specimens after 500m sliding distance were 50 5mg 55 6mg 31mg and 17 2mg respectively Scanning electron microscopy tests revealed different wear mechanisms on the surface of the warn test specimens Key Words Al356 Surface nanocomposite Friction stir processing HVOF Nanoindentation

فتح ا.. كريم زاده، محمد حسين عنايتي

مرتضي شمعانيان، احمد كرمانپور