K Nubian et al. Journal of the European Ceramic Society 20(2000)537-544 because the deposition rate on the fibers is not only deter- The scanning electron microscopy observations of the mined by the chemical reaction, but also by the diffusion fibers coated at 310 and 370C demonstrates that the coat- of the reactive gas into the fiber bundle. The deposition ings deposited at 310.C were more uniform and complete conditions are given above. At temperatures T>370 C than those deposited at 370 C. The surface of the Zro the deposition rate of ZrO2 decreases according to Fig. 5 coating, obtained at 310C were smooth and between the because of strong powder formation in the gas phase fibers, no pasting was observed. The 370%C, deposited coat- which was observed on all walls ing surfaces were rough and incomplete. Only a few fibers were coated, while most fibers were free of any coating. In order to determine the distribution of the layer thickness on the single fibers inside the fabric, one fiber engine Slurry Preparation rotating axis Slurry infiltration plates with holes Uniaxial cold-pressing of prepregs(app. 2 MPa) precursor Drying carrier gas ZrO-interface at 1250C under ZrO-interface at 1250C under 20 MPa in flowing argon MPa in to the reactor 250°C,15min 1000°C heated to200°C Fig. 4.(a) Flow chart showing the details in fabrication of composites and(b) schematic presentation of the hot-pressing process during Fig. 2. Evaporation equipment used for CVD-coating experiments. evaporator 2 ubstrate hold th substrates controller 960 V1 Fig 3. Schematic drawing of the CVD-equipmentbecause the deposition rate on the ®bers is not only deter￾mined by the chemical reaction, but also by the di€usion of the reactive gas into the ®ber bundle. The deposition conditions are given above. At temperatures T>370C the deposition rate of ZrO2 decreases according to Fig. 5 because of strong powder formation in the gas phase which was observed on all walls. The scanning electron microscopy observations of the ®bers coated at 310 and 370C demonstrates that the coat￾ings deposited at 310C were more uniform and complete than those deposited at 370C. The surface of the ZrO2- coating, obtained at 310C were smooth and between the ®bers, no pasting was observed. The 370C, deposited coat￾ing surfaces were rough and incomplete. Only a few ®bers were coated, while most ®bers were free of any coating. In order to determine the distribution of the layer thickness on the single ®bers inside the fabric, one ®ber Fig. 2. Evaporation equipment used for CVD-coating experiments. Fig. 3. Schematic drawing of the CVD-equipment. Fig. 4. (a) Flow chart showing the details in fabrication of composites and (b) schematic presentation of the hot-pressing process during fabrication of composites. 540 K. Nubian et al. / Journal of the European Ceramic Society 20 (2000) 537±544