Manufacturing of Aluminum Composite Sheets Reinforced with Graphene Nanosheets via Accumulative Roll Bonding (ARB) and Characterization of Improved Mechanical Properties
Abstract:
In this research, Accumulative Roll Bonding (ARB) process was used to fabricate metal matrix composites reinforced with graphene oxide. This composite manufacturing method made it possible to take advantage of the fineness obtained of severe plastic deformation (SPD) process to modify the aluminum matrix of the composite. 1020 aluminum sheet was used as the base metal of the composite. The graphene oxide reinforcement was suspended in a stabilized alcoholic solution and sprayed on the surface of the sheets before each process cycle to obtain a homogeneous distribution of particles. To increase the bonding strength of the sheets in the composite manufacturing process, the sheets were preheated in the induction furnace before passing through the rolling rollers. In this research, with the aim of reducing the production cost of aluminum composite reinforced with carbon derivatives, the possibility of replacing graphene oxide with Carbon Black was investigated. Similar to the graphene oxide composite, the production method of this composite was the hot ARB process. In order to evaluate the properties of the resulting composite and separate the effects of fineness of the matrix caused by the severe plastic deformation process, softening caused by preheating and the effects of reinforcing particles, the ARB process was carried out for aluminum sheets in two cold and hot conditions. With the aim of improving the distribution of graphene oxide in the aluminum matrix and taking advantage of the severe plastic deformation process of the sheets, the process of fabricating aluminum-graphene oxide composite and ARB for aluminum sheets was repeated in several passes. The uniaxial tensile test was used to evaluate the strength, ductility and deformation energy per volume of the sheet. For this purpose, samples of the primary sheet, deformed aluminum sheets and the resulting composite were cut according to the ASTM standard. The results showed that cold ARB process increases the strength of aluminum sheet. The use of reinforcing particles in the fabrication of composites also increased the strength of the sheet compared to the sheets obtained from heated ARB. The microhardness test was also performed on the samples using a microvickers device. The cold ARB process increases the hardness of the sample surface; however, the use of preheating during forming process, causes the sheets to recrystallize during the process, and therefore the hardness number is reduced compared to the original aluminum sheet. In order to investigate the structure of the sheet and evaluate the distribution of graphene in the composite, metallographic images were used using an optical microscope and a scanning electron microscope (SEM). Also, the effect of ARB process and composite fabrication on electrical conductivity properties was investigated. The results showed that the use of graphene oxide in the aluminum composite resulted in a lower electrical conductivity loss.