توليد و مشخصه يابي كامپوزيت زمينه آلومينيوم تقويت شده توسط نانو لوله هاي كربني به روش ECAP

چكيده انگليسي :

Production and Evaluation of Carbon Nanotube Reinforced Aluminum Matrix Composite via Equal Channel Angular Pressing ECAP Hassan Zare h zare@ma iut ac ir Department of Materials Engineering Isfahan University of Technology 84156 83111 Isfahan Iran Degree M Sc Language Farsi Dr Mohammad Reza Toroghinejad Assoc Prof Supervisor E mail toroghi@cc iut ac ir Dr Mahmoud meratian Assoc Prof Supervisor E mail meratian@ cc iut ac irAbstractEqual channel angular pressing ECAP process is one of the most important methods for powder densificationdue to the presence of shear strain In this research fabrication mechanical and physical properties of Al CNTcomposite produced with the ECAP method was investigated Carbon nanotubes CNTs are expected to beideal reinforcements of composite materials used in aircraft and sports industries due to their high modulus andlow density Carbon nanotubes CNTs have high elastic modulus and high tensile strength typically Young smodulus of 1 TPa and tensile strength of 30 GPa However it is difficult to take advantage of these mechanicalproperties in practice due to their poor formability The best way of application may be to use CNTs as thereinforcement in metallic materials In fact there have been several attempts to produce Al CNTs compositesusing processes such as hot extrusion hot press plasma spray and ball milling However all of these attemptsrequired heating to attain dense packing so that a reaction of CNTs with the Al matrix inevitably occurred andthus aluminum carbides Al4C3 were unintentionally produced Since carbides are brittle cracks are likely tobe initiated when the composite is deformed The non agglomerated CNTs were distributed homogenously with2 consolidation in the Aluminum matrix The ECAP process was performed on the both monolithic andcomposite samples for 8 passes Scanning electron microscopy was utilized to investigate the size of porositiesand the distributed CNTs in the powder Aluminum matrix Transmission electron microscopy was utilized formore detailed investigation of sample microstructure after 8 passes Relative Density differences of sampleswere obtained by the use of Archimedes methods Hardness pressure and shear punch tests were done toevaluate mechanical properties The fracture surfaces of shear punched samples were studied by the scanningelectron microscopy In Aluminum samples both ductile and brittle fracture were observed but the brittlefracture was the only kind in the composite samples MAUD software and Riet Veld were used to analyze theXRD patterns and calculate the minor grains size micro strain and dislocations density of monolithic andcomposite samples In the composite samples the grain size was reduced to 300nm and dislocations density wasincreased due to 8 passes of ECAP process Transmission electron microscopy images showed that increasingthe numbers of passes contributed to decrease of porosities and change of porosities shape from oval elliptic tospherical By 2 consolidation addition of CNTs relative density of composite samples was reduced from 99 to 98 in the eighth pass In addition hardness of composite sample was improved from 68HV to 82HV Pressure strength of nano composite with the 2 consolidation CNTS in the eighth pass was reached to itsmaximum amount of 260MPa which was 20 more than aluminum samples in the same condition Also theamount of reduction for cross sectional area from 23 in the aluminum sample was decreased to 17 in thecomposite sample Furthermore yang module was increased from 74GPa to 94GPa for the monolithic sample Keywords Equal channel angular pressing Nano tubes Ball mill attrition Ultrasonic Strength pressure Dislocation density Reduction of area

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توليد و مشخصه يابي كامپوزيت زمينه آلومينيوم تقويت شده توسط نانو لوله هاي كربني به روش ECAP

پرس كردن در دو كانال هم مقطع زاويه دار , آسيب كاري گلوله اي شافتي , آلتراسونيك , استحكام فشاري , دانسيته نابجايي , مدول يانگ , كاهش در سطح مقطع