Efeito da adição de Nb2O5 na sinterização de Al2O3-Y2O3

Abstract

A utilização de Y 3 Al 5 O 12 (YAG -"Ittrium Aluminum Garnet" -Garnet de Alumínio e Ítrio), como reforço em matriz de Al 2 O 3 tem sido estudada desde a década de 1990. As propriedades mecânicas e de resistência à fluência obtidas pelo compóstito Al 2 O 3 -YAG têm revelado um grande potencial para seu emprego a temperaturas elevadas por períodos longos de tempo, permitindo a sua utilização na indústria aeroespacial e energética. O objetivo desta pesquisa foi investigar a sinterização do ABSTRACTThe use of Y 3 Al 5 O 12 (YAG -Itrium Aluminum Garnet) as reinforcement element in Al 2 O 3 matrix has been studied since the 1990s. The outstanding mechanical properties and creep resistance obtained by the composite Al 2 O 3 -YAG have revealed a great potential for its use at high temperatures for long periods, allowing its use in aerospace and energy. The objective of this research has been to investigate the sintering of Al 2 O 3 -Y 2 O 3 system, exploring the presence of a liquid phase from using Nb 2 O 5 as a sintering additive for obtaining the Al 2 O 3 -YAG biphasic composite. In this study, the following compositions have been produced using high energy milling: Al 2 O 3 with 4wt% Nb 2 O 5 as sintering additive, Al 2 O 3 -YAG also with 4 wt% of Nb 2 O 5 , and Al 2 O 3 -YAG without additive. The green bodies have been pressed at 70 MPa and sintered at 1400 and 1450°C for 2, 3 and 4 h. The materials have been characterized by scanning electron microscopy (SEM) and their porosity was measured. The composite Al 2 O 3 -YAG sintered at 1400 and 1450°C has showed a porosity of 40 and 35%, respectively, indicating that there are still needs of adjustments on its processing.