616 M. Schmiicker et al /Composites: Part A 34(2003)613-622 Low magnification was used to cover the entire area of each flaws per x-row is projected onto the z-axis. These projections slice 3-4 micrographs per slice were recorded, put together are then summed up(Fig. 5) and may indicate which plane is d processed by means of a commercial image processing most susceptible to delamination. The fiber density within software( Corel Photopaint) to a black/white image, the lamellae was analyzed by means of fiber cell-size showing all fiber free areas in black. The pictures were analysis. Fiber cells are the areas around individual fiber then analyzed using Scion Image'(Scion Corp. software. centers containing all points closer to the respective fiber centers than to any others [10 The smaller these areas are, 2.5. Image analysis the greater is the fiber density. For the fiber density analys transmission mode pictures with higher magnification Size and position of all fiber free regions larger than 75 (200x) were taken (Fig. 6a) and the fiber cell were tels(5800 um)are recorded. The discriminating size constructed by means of a self-designed program(Fig. 6b) large in comparison to the size of the fibers( 100 um),as too much detail would only distract. From this data the total percentage of flaw area and the 3 Results and discussion distribution of flaw sizes were determined. Fig 4 gives a fow chart showing the individual steps of image processing and 3.1. Distribution of mesostructural flaws analysis In order to estimate the probability of delamination, he faw distribution in the materials was analyzed as to Ideally. WHIPOX all oxide CMCs consist of fibers whether there are planes in which there is a larger than embedded homogeneously in a matrix of high but homo- average area of fiber free material. For this, the amount of geneously distributed microporosity. Starting from this Fig. 5. Analysis of interlaminate matrix agglomerations: The amount of matrix-free areas is projected along x onto the z-axis and summed-up for all slices.Low magnification was used to cover the entire area of each slice. 3–4 micrographs per slice were recorded, put together and processed by means of a commercial image processing software (Corele Photopaint) to a black/white image, showing all fiber free areas in black. The pictures were then analyzed using ‘Scion Image’ (Scion Corp.) software. 2.5. Image analysis Size and position of all fiber free regions larger than 75 pixels (5800 mm2 ) are recorded. The discriminating size is large in comparison to the size of the fibers (<100 mm2 ), as too much detail would only distract. From this data the total percentage of flaw area and the distribution of flaw sizes were determined. Fig. 4 gives a flow chart showing the individual steps of image processing and analysis. In order to estimate the probability of delamination, the flaw distribution in the materials was analyzed as to whether there are planes in which there is a larger than average area of fiber free material. For this, the amount of flaws per x-row is projected onto the z-axis. These projections are then summed up (Fig. 5) and may indicate which plane is most susceptible to delamination. The fiber density within the lamellae was analyzed by means of fiber cell-size analysis. Fiber cells are the areas around individual fiber centers containing all points closer to the respective fiber centers than to any others [10]. The smaller these areas are, the greater is the fiber density. For the fiber density analysis transmission mode pictures with higher magnification (200 £ ) were taken (Fig. 6a) and the fiber cell were constructed by means of a self-designed program (Fig. 6b). 3. Results and discussion 3.1. Distribution of mesostructural flaws Ideally, WHIPOX all oxide CMCs consist of fibers embedded homogeneously in a matrix of high but homo￾geneously distributed microporosity. Starting from this Fig. 5. Analysis of interlaminate matrix agglomerations: The amount of matrix-free areas is projected along x onto the z-axis and summed-up for all slices. 616 M. Schmu¨cker et al. / Composites: Part A 34 (2003) 613–622