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بررسي ريزساختار و خواص مكانيكي نانو كامپوزيت Al356/SiC

كارشناسي ارشد

شناسايي و انتخاب مواد

تير 1396

دكتر حسن ثقفيان

مواد و متالورژي

ﭼﮑﯿﺪه در اﯾﻦ ﺗﺤﻘﯿﻖ، ﻧﺎﻧﻮ ﮐﺎﻣﭙﻮزﯾﺖ آﻟﻮﻣﯿﻨﯿﻮم 356 ﺗﻘﻮﯾﺖ ﺷﺪه ﺗﻮﺳﻂ ذرات ﺳﺮاﻣﯿﮑﯽ ﻧﺎﻧﻮﻣﺘﺮي SiC ﺑﺎ درﺻﺪﻫﺎي وزﻧﯽ 1 ،0/5 و 1/5 ﺑﺎاﺳﺘﻔﺎده از روش رﯾﺨﺘﻪﮔﺮي ﮔﺮداﺑﯽ اﺻﻼح ﺷﺪه ﺗﻮﻟﯿﺪ ﺷﺪ. رﯾﺨﺘﻪﮔﺮي در ﺣﺎﻟﺖ ﻧﯿﻤﻪ ﺟﺎﻣﺪ ﺑﺎ ﺗﺰرﯾﻖ ذرات ﻫﻤﺮاه ﮔﺎز ﺧﻨﺜﯽ ﺑﻪ داﺧﻞ ﻣﺬاب اﻧﺠﺎم ﺷﺪ و ﺗﺎﺛﯿﺮ درﺻﺪ وزﻧﯽ ﻣﻘﺎومﺳﺎز ﺑﺮ رﯾﺰ ﺳﺎﺧﺘﺎر و ﺧﻮاص ﻣﮑﺎﻧﯿﮑﯽ ﻧﺎﻧﻮ ﮐﺎﻣﭙﻮزﯾﺖ ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﺑﺮرﺳﯽﻫﺎي رﯾﺰﺳﺎﺧﺘﺎري ﺗﻮﺳﻂ ﻣﯿﮑﺮوﺳﮑﻮپ ﻧﻮري و اﻟﮑﺘﺮوﻧﯽ روﺑﺸﯽ ﮔﺴﯿﻞ )FESEM( ﻣﺠﻬﺰ ﺑﻪ آﻧﺎﻟﯿﺰ ﻋﻨﺼﺮي )EDS( اﻧﺠﺎم ﮔﺮﻓﺖ درﺻﺪ ﺗﺨﻠﺨﻞ ﻧﻤﻮﻧﻪﻫﺎي رﯾﺨﺘﮕﯽ ﺑﺎ اﺳﺘﻔﺎده از روش ارﺷﻤﯿﺪس و ﻣﺤﺎﺳﺒﻪ اﺧﺘﻼف ﭼﮕﺎﻟﯽ واﻗﻌﯽ و ﻇﺎﻫﺮي اﻧﺪازهﮔﯿﺮي ﺷﺪ. ﻫﻤﭽﻨﯿﻦ ﺳﺨﺘﯽ، اﺳﺘﺤﮑﺎم ﻓﺸﺎري و رﻓﺘﺎر ﺳﺎﯾﺸﯽ ﻧﺎﻧﻮﮐﺎﻣﭙﻮزﯾﺖﻫﺎي رﯾﺨﺘﻪ ﺷﺪه ﺑﺮرﺳﯽ ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻧﺎﻧﻮﮐﺎﻣﭙﻮزﯾﺖﻫﺎ از ﺳﺎﺧﺘﺎر ﻇﺮﯾﻒﺗﺮي ﻧﺴﺒﺖ ﺑﻪ آﻟﯿﺎژ ﺗﻘﻮﯾﺖ ﻧﺸﺪه ﺑﺮﺧﻮردارﻧﺪ و ﺗﻮزﯾﻊ ذرات در زﻣﯿﻨﻪ ﺑﺎ ﮐﺎﻫﺶ درﺻﺪ وزﻧﯽ ﺑﻬﺒﻮد ﻣﯽﯾﺎﺑﺪ. ﺑﺮرﺳﯽ ﺳﺨﺘﯽ و اﺳﺘﺤﮑﺎم ﻧﻤﻮﻧﻪﻫﺎ ﻧﺸﺎن داد ﮐﻪ وﺟﻮد 0/5 درﺻﺪ وزﻧﯽ ذرات ﻣﻘﺎومﺳﺎز ﻣﻮﺟﺐ اﻓﺰاﯾﺶ ﺣﺪوداً 40 درﺻﺪي ﺳﺨﺘﯽ و 80 درﺻﺪي اﺳﺘﺤﮑﺎم ﻓﺸﺎري ﻧﻤﻮﻧﻪﻫﺎي ﮐﺎﻣﭙﻮزﯾﺘﯽ ﺷﺪه اﺳﺖ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺘﺎﯾﺞ ﺑﻪ دﺳﺖ آﻣﺪه از اﯾﻦ آزﻣﺎﯾﺶﻫﺎ، ﻣﺸﺨﺺ ﺷﺪه اﺳﺖ ﮐﻪ ﻧﻤﻮﻧﻪي ﮐﺎﻣﭙﻮزﯾﺘﯽ ﺣﺎوي 0/5 درﺻﺪ وزﻧﯽ ﻣﻘﺎومﺳﺎز ﺑﻬﺘﺮﯾﻦ ﺧﻮاص را دارد و ﻧﻤﻮﻧﻪي ﺑﻬﯿﻨﻪ در اﯾﻦ ﺗﺤﻘﯿﻖ اﺳﺖ از ﻫﻤﯿﻦ رو اﯾﻦ ﻧﻤﻮﻧﻪ ﺑﺮاي آزﻣﻮن ﺳﺎﯾﺶ اﻧﺘﺨﺎب ﺷﺪ. ﻣﻘﺎﯾﺴﻪ ﺧﻮاص ﺳﺎﯾﺸﯽ ﻧﻤﻮﻧﻪي ﺗﻘﻮﯾﺖ ﺷﺪه ﺑﺎ 0/5 درﺻﺪ وزﻧﯽ ﻣﻘﺎومﺳﺎز SiC ﺑﺎ ﻧﻤﻮﻧﻪﻫﺎي ﺗﻘﻮﯾﺖ ﻧﺸﺪه، ﺑﻬﺒﻮد ﻗﺎﺑﻞ ﻣﻼﺣﻈﻪاي را در ﺧﻮاص ﺳﺎﯾﺸﯽ اﯾﻦ ﻧﺎﻧﻮﮐﺎﻣﭙﻮزﯾﺖ ﻧﺸﺎن ﻣﯽدﻫﺪ ﺑﻪ ﺻﻮرﺗﯽ ﮐﻪ ﺣﺪاﻗﻞ 60% از ﻣﯿﺰان ﮐﺎﻫﺶ وزن ﮐﺎﺳﺘﻪ ﺷﺪه اﺳﺖ.

1396/07/01

1/1/1900 12:00:00 AM

Abstract In this research, aluminum alloy (A356) matrix composites reinforced with 0.5, 1 and 1.5 wt. % SiC nano-particles were fabricated via stir casting method. Fabrication was performed at solid–liquid mixed temperatures by the injection of reinforcing particles into molten alloy. The influence of various weight percentages of reinforcing particles on the microstructure and mechanical properties of composites was investigated. The composites were characterized by scanning electron microscopy (SEM) equipped with image analyzer and energy dispersive spectroscopy (EDS) and, Optical microscope (OM). The porosity percentage in the materials was calculated according to the difference between the theoretical and measured density. The density of the samples was measured by the Archimedes’s method, while the theoretical densities calculated by taking the densities of A356 aluminum alloy and SiC particles. Also, the hardness, compression strength and wear behavior of samples were carried out. Microstructure eva​luation revealed a uniform distribution of nano particles with redused in weight precentages. The results indicate about 80 precent improvement in compression strength and 40 precent in hardness due to the effect of nanoparticle addition. Findings showed that 0.5% weight precent nano composite show better wear resistance than unreinforced alloy So that at least 60% of the weight was reduced. Also, result reveals that wear rates of composite is increases with increasing load.