Microstructural and Mechanical Characterization of Graphene Oxide-Reinforced Aluminium-Matrix Nanostructured Composites fabricated by Accumulative Roll Bonding™

• Autor(a) principal: Ferreira, Francisco Branco
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/37538
• topic: Accumulative Roll Bonding (ARB); Metal-Matrix Composite (MMC); Graphene-Oxide (GO); Grain Refinement; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Accumulative Roll Bonding (ARB) was used to fabricate Graphene Oxide-reinforced Al-matrix composites, benefiting from a grain refinement effect of the metal-lic matrix. Graphene Oxide reinforcement was suspended in a stabilized aqueous solution and applied, prior to each ARB cycle, through airgun spraying, in order to obtain a ho-mogeneous distribution. Concentrations of 0.5, 2.5 and 10 mg/ml (graphene ox-ide/millipore water) were used. For each concentration, samples produced have under-gone up to 5 rolling cycles. Optical and electron scanning microscopies were used for microstructural char-acterization of the rolled composites which revealed a non-homogenous deformation of the layers across the composite’s thickness. Although not desired but expected, Alumin-ium oxide formation occurred where the reinforcement was applied. Although the presence of graphene-oxide promoted an increase in the micro-hardness, higher values were obtained with its lowest concentration for the same num-ber of ARB cycles. The number of ARB cycles and the direction of the tested sections also influenced the microhardness results since the 5-cycle samples and the rolling di-rection sections for all the samples achieved higher hardness results. Graphene Oxide revealed to be a major contributor to the increase of stiffness during bending of the test-ed samples. The ARB processed samples revealed a decrease on the electrical conductivity when compared with the annealed Aluminium, since the Graphene Oxide and Alumini-um oxide have insulator properties. The contribution of the reinforcement to this de-crease was only noticeable when using higher concentrations, since the sample with less concentration of the applied Graphene Oxide revealed slightly better results than the sample without any reinforcement.