توليد كامپوزيت هاي نانو ساختار آلومينيوم- نانو لوله هاي كربني به روش نورد تجمعي پيوندي ( ARB)

چكيده انگليسي :

Fabrication of Al CNT nano structure composite via accumulative roll bonding ARB process Mahmoud Samadzadeh m samadzadeh@ma iut ac ir January 22 2014 Department Of Materials Engineering Isfahan University Of Technology 84156 83111 Isfahan IranDegree M Sc Language FarsiSupervisor Mohammad Reza Toroghinejad Prof E mail toroghi@cc iut ac irAbstract As a novel experience aluminum matrix composites reinforced with 0 4 wt multi walled carbon nanotubes MWCNTs were successfully fabricated using the accumulativeroll bonding ARB process In order to fabricate Al MWCNT composites by ARBprocesses it was essential to investigate the effect of various parameters on the bondstrength of aluminum strips The effects of MWCNTs dispersion thickness reduction quantity of MWCNTs at the interface and rolling temperature on the bond strength of thecommercial pure aluminum sheets in the peeling test were studied and Optical microscopy OM and scanning electron microscopy SEM were also used to evaluate the surfaceconditions of the peeled surfaces Then Al MWCNT composites in the three quantities ofMWCNTs 0 1 0 4 and 0 7 wt were fabricated In order to achieve optimum MWCNTconcentration mechanical properties and the microstructure of composites in differentMWCNT concentrations were compared with each other For the ARB technique theoptimum CNT content achieved in the composite structure was 0 4 wt Themicrostructure and the fracture surface of the composites were studied during various ARBcycles by scanning electron microscopy SEM and optical microscopy OM Theirmechanical properties were also measured by tensile and Vickers hardness tests Thedislocation density and grain size changes during deformation were calculated using arecently developed JAVA based software Materials Analysis Using Diffraction MAUD which was based on Rietveld s whole X ray pattern tting methodology The resultsindicated that compared to the spread method using the solution dispersion SD methodto disperse MWCNTs reduced aluminum strips bond strength Therefore spreaddispersion method was used for investigating the effects of other parameters on the bondstrength of aluminum strips It was found that after 8 cycles of ARB process Al 0 1 wt MWCNTs composites had non uniform dispersion On the other hand composites with0 4 and 0 7 wt MWCNTs showed a better distribution after 8cycle Also theinvestigation of 8 cycle ARBed composites in three wt of reinforcement indicated thatAl 0 4 wt had higher tensile strength in comparison with other composites So it can bededuced from this study that Al 0 4 wt MWCNTs composites are the optimumcomposites The Al 0 4 wt MWCNT composite microstructures showed excellentMWCNTs distribution in the aluminum matrix on a micrometer scale after 12 ARB cycles It can be concluded that that increasing the number of ARB cycles to 11 improved theelongation and the tensile strength of the composites However these same properties weredeclined at the final 12th cycle due to the development of micro cracks in the compositestrip SEM fractographs of fracture surfaces revealed that the fracture mode of thecomposite was changed to the brittle type in the final cycles while that of monolithicaluminum was ductile The crystallites size as measured by MAUD software for Al MWCNTs composite produced by 12 cycles of ARB process reached to 91 nm Keywords carbon nanotubes aluminum matrix composites accumulative roll bonding microstructure investigation mechanical properties fracture surface

صمدزاده، محمود

توليد كامپوزيت هاي نانو ساختار آلومينيوم- نانو لوله هاي كربني به روش نورد تجمعي پيوندي ( ARB)

كامپوزيت هاي زمينه آلومينيومي , مدول الاستيك , بررسي هاي ريز ساختاري , خواص مكانيكي