Processing and characterization of barium zirconate coated alumina fibers/alumina matrix composites

In an earlier work, we identified barium zirconate, BaZrO3, as a candidate material for interfacial coating for alumina fiber/alumina matrix composite s. That work involved making laminates of barium zirconate and alumina. Dur ing processing at 1475 degreesC, the alumina and barium zirconate reacted t o form a series of thermally stable layers, which led to crack deflection, mainly at the BaZrO3/ZrO2 interface. In the present work, a sol-gel method was used to apply a barium zirconate coating to alumina fibers (Saphikon (T M) and Nextel (TM) 610). The coated fibers were embedded in alumina powder and hot pressed at 1400 degreesC at 24 MPa for 30 min to produce alumina fi ber/alumina matrix composites. Indentation cracks were produced on polished cross sections to investigate the potential for crack blunting and/or defl ection. Scanning electron microscopy with energy dispersive X-ray analysis and optical microscopy were used to characterize the coatings. (C) 2001 Els evier Science Ltd. All rights reserved.