J. Phys. IV France 09 (1999) Pr8-1049-Pr8-1056
CVD-produced ZrO2- and C/ZrO2-fiber coatings for mullite/mullite compositesK. Nubian1, B. Saruhan2, H. Schneider2 and G. Wahl1
1 Technische Universität Braunschweig, Institut für Oberflächentechnik, 38108 Braunschweig, Germany
2 German Aerospace Center, Institute of Material Research, 51147 Köln, Germany
The outstanding thermal-mechanical properties make mullite fiber/mullite matrix composites a favorite candidate for high temperature applications, e.g. in turbines. In order to realize crack deflection and fiber pull-out, a coating of the mullite fibers is necessary to obtain a weak bonding between fibers and matrix. ZrO2 coatings were produced by a CVD-process using Zr(acac)4 as precursor. The substrates were Nextel 720 fiber fabrics, which were in some experiments precoated with carbon. The diffusion into the fiber bundle was described. Composites were fabricated by infiltration of coated fibers with a pre-mullite slurry and hot-pressing at < 1300°C. Experiments have shown that C/ZrO2 double layers yield favorable thermo-mechanical properties, while porous ZrO2 single layers did not.
© EDP Sciences 1999