Effect of Nb₂O₅ addition on Al₂O₃ - Y₂O₃sintering

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 1450ºC 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 1450ºC has showed a porosity of 40 and 35%, respectively, indicating that there are still needs of adjustments on its processing.

Composite; sintering; Al₂O₃-YAG; Nb₂O₅