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

Abstract

Abstract In an earlier work, we identified barium zirconate, BaZrO3, as a candidate material for interfacial coating for alumina fiber/alumina matrix composites. That work involved making laminates of barium zirconate and alumina. During processing at 1475°C, the alumina and barium zirconate reacted to 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™ and Nextel™ 610). The coated fibers were embedded in alumina powder and hot pressed at 1400°C at 24 MPa for 30 min to produce alumina fiber/alumina matrix composites. Indentation cracks were produced on polished cross sections to investigate the potential for crack blunting and/or deflection. Scanning electron microscopy with energy dispersive X-ray analysis and optical microscopy were used to characterize the coatings.