Fabricação e caracterização mecânica da alumina reforçada com grafeno
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Data
2019-12-13
Autores
Pereira, Cristian Guilherme Barbosa
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os avanços na área da tecnologia e ciência dos materiais têm possibilitado grande evolução e contribuição para o desenvolvimento de materiais cerâmicos. Pesquisas associadas a esse tipo de material estão cada vez mais difundidas por apresentar características como: alta dureza, biocompatibilidade, estabilidade térmica, inércia química e resistência à corrosão. Entretanto, seu uso acaba sendo limitado por sua fragilidade. A utilização dos alótropos de carbono (grafeno, nanotubos e fulerenos) como material de reforço nas cerâmicas, têm sido muito estudados, no entanto, o desempenho desses alótropos está restrito a condições específicas de mistura e sinterização. Esta pesquisa trata da fabricação e caracterização mecânica do compósito Al2O3-MLG. Partindo de um pó cerâmico de Al2O3 e adicionando diferentes concentrações, 0,5%; 0,75%; 1,0% e 1,25%, em peso de MLG em sua matriz, corpos de prova foram fabricados através da mistura em meio úmido dos pós, secagem da mistura, compactação dos pós secos e posterior sinterização com atmosfera redutora. As amostras obtidas pelo método proposto foram submetidas a caracterização física, microestrutural e mecânica, sendo comparadas diretamente a amostra contendo apenas Al2O3. Foi verificado que a sinterização com atmosfera redutora, preservou a estrutura do MLG em matriz de Al2O3. A análise dos resultados indicou que a utilização de concentrações menores que 1,0% em peso de MLG, proporcionou a fabricação de compósitos com maior dispersão e menor formação de aglomerados. Os valores para limite de resistência à flexão do compósito Al2O3-MLG, apresentam similaridade quando comparados a Al2O3 nas concentrações de até 0,75%. Já, os valores de microdureza e tenacidade à fratura apresentam aumento de 75% e 45% para concentrações de 0,75% em peso de MLG. A utilização do MLG como material de reforço e os meios de mistura e sinterização, possibilitaram a fabricação de compósitos Al2O3-MLG com boas propriedades mecânicas.
Advances in the area of technology and materials science have enabled major evolution and contribution to the development of ceramic materials. Research associated with this type of material is becoming more widespread due to characteristics such as: high hardness, biocompatibility, thermal stability, chemical inertia and corrosion resistance. However, its use ends up being limited by its fragility. The use of carbon allotropes (graphene, nanotubes and fullerenes) as reinforcement material in ceramics has been widely studied, however, the performance of these allotropes is restricted to specific mixing and sintering conditions. This research is about the fabrication and mechanical characterization of the Al2O3-MLG composite. Starting from an Al2O3 ceramic powder and adding different concentrations, 0,50%; 0,75%; 1,0% and 1,25% by weight of MLG in their matrix, samples were fabricated by wet powder mixing, drying of the mixture, dry powder compaction and subsequent sintering with reducing atmosphere. The samples obtained by the proposed method were subjected to physical, microstructural and mechanical characterization, being directly compared to the sample containing only Al2O3. It was verified that the sintering with reducing atmosphere preserved the structure of the MLG in Al2O3 matrix. The analysis of the results indicated that the use of concentrations lower than 1.0% by weight of MLG, allowed the fabrication of composites with greater dispersion and less formation of agglomerates. The flexure strength limit values of the Al2O3-MLG composite are similar when compared to Al2O3 at concentrations up to 0.75%. Microhardness and fracture toughness values increased by 75% and 45% for concentrations of 0.75% by weight of MLG. The use of MLG as reinforcement material, mixing and sintering media made it possible to manufacture Al2O3-MLG composites with good mechanical properties.
Advances in the area of technology and materials science have enabled major evolution and contribution to the development of ceramic materials. Research associated with this type of material is becoming more widespread due to characteristics such as: high hardness, biocompatibility, thermal stability, chemical inertia and corrosion resistance. However, its use ends up being limited by its fragility. The use of carbon allotropes (graphene, nanotubes and fullerenes) as reinforcement material in ceramics has been widely studied, however, the performance of these allotropes is restricted to specific mixing and sintering conditions. This research is about the fabrication and mechanical characterization of the Al2O3-MLG composite. Starting from an Al2O3 ceramic powder and adding different concentrations, 0,50%; 0,75%; 1,0% and 1,25% by weight of MLG in their matrix, samples were fabricated by wet powder mixing, drying of the mixture, dry powder compaction and subsequent sintering with reducing atmosphere. The samples obtained by the proposed method were subjected to physical, microstructural and mechanical characterization, being directly compared to the sample containing only Al2O3. It was verified that the sintering with reducing atmosphere preserved the structure of the MLG in Al2O3 matrix. The analysis of the results indicated that the use of concentrations lower than 1.0% by weight of MLG, allowed the fabrication of composites with greater dispersion and less formation of agglomerates. The flexure strength limit values of the Al2O3-MLG composite are similar when compared to Al2O3 at concentrations up to 0.75%. Microhardness and fracture toughness values increased by 75% and 45% for concentrations of 0.75% by weight of MLG. The use of MLG as reinforcement material, mixing and sintering media made it possible to manufacture Al2O3-MLG composites with good mechanical properties.
Descrição
Palavras-chave
Alumina pura, Grafeno multicamadas, Propriedades mecânicas, Pure alumina, Multilayer graphene, Mechanical properties