Joining of Al2O3 by epitaxial growth of aluminum borate whiskers for high-temperature applications

Alumina ceramics were directly bonded for high-temperature applications by epitaxial growth of aluminum borate whiskers in air. The Al2O3/whisker/Al2O3 joints were characterized via scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The microstructural observations showed that the Al18B4O33 whiskers along the [001] crystallographic direction grew across the seam and thereby achieving the joining of alumina substrates. Both of whiskers diameter and density of joints increased with the increase of bonding temperatures. Three-point bending results showed that the maximum strength of the joints tested at 800 degrees C was 27 MPa. The possible mechanism of the bonding process was discussed as well. (C) 2015 Elsevier B.V. All rights reserved.