Investigation on microstructure an‎d mechanical properties of aluminium nanocomposites reinforced with hybrid alumina-graphene synthesized in situ

11/20/2024 12:00:00 AM

Due to its low density an‎d high specific strength, aluminum-based composites have been widely used in various industries such as automobiles, aerospace, an‎d sports equipment. In this thesis, using the molecular level mixing method, in order to prevent the weak wetting of the hybrid of reinforcing nanoparticles with the matrix, first the surface of copper oxide is functionalized with graphene oxide, an‎d then the obtained nanocomposite is milled with aluminum powder through the high energy ball milling method an‎d Aluminum matrix reinforced with alumina nanoparticles an‎d graphene oxide was obtained in situ. According to X-ray diffraction analysis, simultaneous thermal analysis an‎d field emission scanning electron microscope analysis along with X-ray energy dispersive spectroscopy on the synthesized powders, it was observed that alumina nanoparticles were formed in situ during 40 hours of grinding an‎d the alloying process took place. Therefore, the optimum conditions for mechanical millimg were 40 hours, the weight ratio of balls to powder was 20 to 1, 2wt.% of stearic acid as the controlling agent of the process an‎d the rotation speed was considered to be 320 rpm. In the following, taking into account the optimal conditions of sintering plasma spark such as temperature 500 ℃, pressure 50 MPa an‎d time 10 minutes, this operation was carried out in the mold of graphite an‎d a bulk sample was obtained. In order to identify the type of particles, distribution an‎d morphology of the obtained sample, FESEM analysis along with its EDS-map was used. Further, according to the results obtained from FESEM analysis, from the fracture surface of all samples an‎d the cross section of the sample containing 0.75wt.% of graphene oxide, in situ synthesis of alumina nanoparticles, homogeneous distribution of graphene oxide layers an‎d aluminum-copper alloy were observed in the matrix. Also, in order to investigate the effect of different concentrations of graphene oxide on mechanical properties, microhardness an‎d tensile tests were conducted. According to the results obtained from the mechanical properties tests, it was observed that increasing the concentration of graphene oxide leads to the improvement of mechanical properties such as microhardness, yield strength, tensile strength, modulus of elasticity an‎d elongation percentage. It was observed that microhardness, yield strength an‎d tensile strength were improved by adding 0.75wt.% of graphene oxide to the nanocomposite compared to the nanocomposite without graphene oxide by 45.52%, 69.73% an‎d 124.47%, respectively.

نانوكامپوزيت زمينه آلومينيومي، آلومينا، اكسيد گرافن، آسياكاري پرانرژي، روش درجا، خواص مكانيكي

aluminum matrix nanocomposite, alumina, graphene oxide, high energy ball milling, in situ method, mechanical properties

Fateme Salimian

DR. Roohollah Rahmanifard