3471

3277

كارشناسي ارشد

شناسايي و روش انتخاب مواد فلزي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1385

ده، 102، [II] ص.: مصور، جدول، نمودار

ص. ع. به فارسي و انگليسي

بهزاد نيرومند

15/2/86

احمد كرمانپور، ايوب حلوائي

مهندسي مواد

ID3277

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

AbstractHigher viscosities of semisolid metallic slurries have practically made their gravity castingimpossible and resulted in a need for some sort of mechanical force to push such viscousslurries into die cavities High pressure die casting has been conveniently used for thispurpose However due to high manufacturing cost of dies only mass production of semisolidcomponents has been economically justified and practiced so far The main objective of thiswork was to study the ways by which the fluidity of semisolid slurries cast in expendablemolds could be improved and to explore the possibility of production of semisolid castcomponents in limited numbers In this study Al 7 1wt Si alloy semisolid slurry wasprepared in a mechanical stirrer type rheocaster It was then continuously cooled and stirreduntil reaching the desired fraction liquids after which the resultant slurries were poured into asand mold placed on a vertical axis centrifuging casting system Molds were made of sodiumsilicate bonded silica sand and had four straight channels with different square cross sectionsto provide different cooling rates This dissertation reports the effects of solid fraction stirring speed mold rotation speed andsection thickness on the fluidity and microstructure of Al 7 1wt Si semisolid slurry cast in asand mold It was found that fluidity of Al 7 1wt Si semisolid slurry was improved by use ofcentrifuging force Fluidity showed linear and exponential relationships with section thicknessand square of the initial fraction liquid respectively Roundness of primary solid particlesincreased with increasing the stirring speed and decreasing the solid fraction Averageequivalent diameter of particles increased with an increase in solid fraction and a decrease instirring speed Moreover solid fraction changed along the length of the channels and washighest close to the sprue Porosity of samples was reduced with increasing the solid fractionand the stirring speed and optimizing the mold rotation speed

بهزاد نيرومند

احمد كرمانپور، ايوب حلوائي