8217

7615

كارشناسي ارشد

ريخته گري

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1392

دوازده،91ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

بهزاد نيرومند، مرتضي شمعانيان

محمدرضا طرقي نژاد

11/9/92

رحمت اله عمادي، احمد رضاييان

مهندسي مواد

ID7615

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Production of A356 SiO2 cast nanocomposite using ARB produced nanocomposite Mohammadmehdi Hosseininejad m hosseininezhad@ma iut ac ir May14th2013 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors BehzadNiroumand Associate Professor behzn@cc iut ac ir MortezaShamanian Professor shamanian@cc iut ac ir Abstract Research on metal matrix nanocomposites has risen in recent decades due to their unique properties such as high strength hardness and service temperature In the present work cast A356 SiO2nanocomposites were fabricated by vortex and compocasting techniques Nano SiO2 reinforcements were added into the melt in two different forms either as raw SiO 2 particles or as Al1100 SiO2nanocomposite stripes produced by continual annealing and roll bonding process and the effect of SiO2 addition and casting method on microstructural and mechanical properties of the cast nanocomposites were investigated The results showed that in the continual annealing and roll bonding stage number of SiO2 agglomerates decreased and mechanical bonding and wettability between most of SiO2 nanoparticles and the Al1100 matrix were improved by increasing the number of cycles The results of the casting stage for fabrication of the final composites revealed that the average dendrite length was decreased by additions of nano SiO2 particles in the form of Al1100 SiO2nanocomposite stripes but did not change significantly when the reinforcement was added as raw powder For samples cast from fully liquid state the average dendrite length was decreased from 314 m in the monolithic sample to 237 m in the composite sample Furthermore the average secondary dendrite arm spacing in the fully liquid cast samples was increased from 17 m for monolithic sample to 28 m for composite sample This increase is believed to be due to very low thermal conductivity of nano sized SiO2 particles For the semisolid cast samples presence of nano SiO2 particles caused the average equivalent circle diameter of primary Al particles to decrease from 150 to 101 m for samples with 0 1 solid fraction and from 180 to 114 m for samples with 0 2 solid fraction For composite samples the average equivalent circle diameter of the secondary Al particle was also decreased It was 49 and 28 m for monolithic samples cast with 0 1 and 0 2 solid fraction and 37 and 30 m for composite samples cast with 0 1 and 0 2 solid fraction respectively Hardness in all the composite samples was higher than those of the corresponding monolithic samples The highest increase was observed in the semisolid sample fabricated by addition of nanocomposite stripes and cast with 0 2 solid fraction The ultimate shear strength and shear yield strength of the composites produced by addition of nanocomposite stripes were significantly increased compared with those of the matrix alloy In addition the semisolid sample cast with 0 2 solid fraction retained about 45 of its ultimate shear strength and 55 of its shear yield strength at 300 C These values for the monolithic matrix alloy was about 34 and 48 respectively Keywords A356 SiO2nanocomposites vortex method compocasting continual annealing and roll bonding process microstructure shear strength

بهزاد نيرومند، مرتضي شمعانيان

محمدرضا طرقي نژاد

رحمت اله عمادي، احمد رضاييان