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Advisor(s)
Abstract(s)
A utilização de cerâmicas avançadas melhora a resposta dos materiais em condições de
serviço extremas, em particular, aumenta a resistência mecânica ao impacto, flexão,
desgaste e a resistência a temperaturas elevadas. Na indústria automóvel o seu uso
também tem sido crescente, surgindo a sua aplicação em componentes distintos, como
rolamentos, chumaceiras, sistemas de travagem, bocais, difusores, motores térmicos e
principalmente no revestimento de ligas metálicas.
Com o objetivo de melhorar as propriedades mecânicas, neste trabalho, fabricou-se e
caracterizou-se um compósito cerâmico constituído por zirconato de cálcio e óxido de
magnésio (CaZrO3 + MgO), reforçado com a adição de 5 e 10% de duas zirconias, ambas
estabilizadas com ítria (3YSZ e 8YSZ).
Da análise de resultados observa-se a microestrutura dos diferentes materiais é
homogénea, as porosidades são muito reduzidas, correspondendo a uma densidade
relativa superior a 99%. A melhoria da resistência mecânica foi obtida com a adição do
reforço de zirconia estabilizada com ítria, nomeadamente, a resistência à flexão
aumentou em 24% para 336,9 MPa, a dureza de Vickers e a tenacidade à fratura
aumentaram em 12% atingindo-se uma dureza de 9,3 GPa e uma tenacidade à fratura de
2,6 MPa.m1/2
.
Advanced ceramics improves the response of materials in extreme service conditions, in particular, increases the mechanical resistance to impact, compressive, bending, wear and the resistance to high temperatures. In the automotive industry its use has also been growing, appearing its application in different components, such as bearings, journal bearings, braking systems, nozzles, diffusers, thermal engines and mainly in the coating of metallic alloys. In order to improve the mechanical properties, in this work, a ceramic composite consisting of calcium zirconate and magnesium oxide (CaZrO3 + MgO), reinforced with the addition of 5 and 10% of two zirconia, was manufactured and characterized; both zirconia stabilized with yttria (3YSZ and 8YSZ). The analysis of the results shows that the microstructure of the different materials is homogeneous, the porosities are very low, corresponding to a relative density higher than 99%. The improvement in mechanical strength was obtained with the addition of the yttria-stabilized zirconia reinforcement, namely, the flexural strength increased by 24% to 336,9 MPa, the Vickers hardness and the fracture toughness increased approximately 12% reaching a hardness of 9,3 GPa and a fracture toughness of 2,6 MPa.m1/2
Advanced ceramics improves the response of materials in extreme service conditions, in particular, increases the mechanical resistance to impact, compressive, bending, wear and the resistance to high temperatures. In the automotive industry its use has also been growing, appearing its application in different components, such as bearings, journal bearings, braking systems, nozzles, diffusers, thermal engines and mainly in the coating of metallic alloys. In order to improve the mechanical properties, in this work, a ceramic composite consisting of calcium zirconate and magnesium oxide (CaZrO3 + MgO), reinforced with the addition of 5 and 10% of two zirconia, was manufactured and characterized; both zirconia stabilized with yttria (3YSZ and 8YSZ). The analysis of the results shows that the microstructure of the different materials is homogeneous, the porosities are very low, corresponding to a relative density higher than 99%. The improvement in mechanical strength was obtained with the addition of the yttria-stabilized zirconia reinforcement, namely, the flexural strength increased by 24% to 336,9 MPa, the Vickers hardness and the fracture toughness increased approximately 12% reaching a hardness of 9,3 GPa and a fracture toughness of 2,6 MPa.m1/2
Description
Keywords
Caracterização Mecânica Cerâmica Avançada Óxido de Magnésio Zirconato de Cálcio Zirconia Estabilizada Com Ítria