Growth of Al2O3/ZrO2(Y2O3) eutectic rods by the laser floating zone technique : effect of the rotation

• Published in: Journal of the European Ceramic Society Vol. 25; no. 8; pp. 1341 - 1350
• Main Authors: DE FRANCISCO, I, MERINO, R. I, ORERA, V. M, LARREA, A, PENA, J. I
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Oxford Elsevier 2005
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Cermets, ceramic and refractory composites; Chemical industry and chemicals; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Other materials; Physics; Specific materials; Structural ceramics; Technical ceramics; Scanning electron microscopy; Forced convection; Composites; Laser heating; Directional solidification; Stabilized zirconia; Al2O3-ZrO2; Floating zone; Experimental study; Oxide ceramics; Composite material; Structural ceramic; Bar; Zirconium oxide; Eutectic; Fabrication structure relation; Yttrium oxide; Manufacturing; Microstructure; Alumina; Directionally solidified eutectics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2005.01.017

The laser floating zone technique has been applied to the growth of Al2O3/ZrO2(Y2O3) rods in the eutectic composition to reveal the effect of forced convection induced by rotation on the rod microstructure. A systematic experimental study of this effect has been carried out combining different source rod and/or eutectic rod rotation (0--200rpm) and travelling speeds (10--1500mm/h) in an axial thermal gradient close to 6x10(5)C/m. The results indicate that the rotation is useful to achieve a more homogeneous temperature distribution, especially in thick rods but it has a limited effect in the change of the solidification front shape. The forced convection in the floating zone caused by rotation slightly flattens the solidification interface enhancing the homogeneity of the phase distribution across the sample. However, it introduces several new microstructural features like banding and phase coarsening that can deteriorate the mechanical behaviour of the rods. On the other hand, rods above 1*6mm in diameter cannot be grown without cracks, even with fast eutectic rod rotation. Rotation does not change the pulling rate threshold (50mm/h) at which the transition from coupled to dendritic and cellular growth morphology takes place.