Effect of Nb2O5 addition on Al2O3 - Y2O3 sintering

The use of Y3Al5O12 (YAG - Itrium Aluminum Garnet) as reinforcement element in Al2O3 matrix has been studied since the 1990s. The outstanding mechanical properties and creep resistance obtained by the composite Al2O3-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 Al2O3-Y2O3 system, exploring the presence of a liquid phase from using Nb2O5 as a sintering additive for obtaining the Al2O3-YAG biphasic composite. In this study, the following compositions have been produced using high energy milling: Al2O3 with 4wt% Nb2O5 as sintering additive, Al2O3-YAG also with 4 wt% of Nb2O5, and Al2O3-YAG without additive. The green bodies have been pressed at 70 MPa and sintered at 1400 and 1450 degrees C for 2, 3 and 4 h. The materials have been characterized by scanning electron microscopy (SEM) and their porosity was measured. The composite Al2O3-YAG sintered at 1400 and 1450 degrees C has showed a porosity of 40 and 35%, respectively, indicating that there are still needs of adjustments on its processing.