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N P Bansal, J.A. Setlock/Composites: Part A 32(2001)1021-1029 vW014 10Nn WD19 Fig 5 SEM micrographs showing surface and cross-section of BNSiC coated Hi-Nicalon fibers. the set-up reported earlier by Prewo [16]. BSAS powder that slurry was squeezed out of the fiber tow before winding at had been calcined at 900-920C for 20-24 h was made into 0.977 mm tow spacing (26 fiber tows/inch) on a rotatin a slurry by dispersing it in methyl ethyl ketone along with drum. After drying, the prepreg tape was cut to size. Uni- organic additives as binder, surfactant, deflocculant and directional fiber-reinforced composites were prepared by plasticizer followed by ball milling. Tows of BN/SiC-coated tape lay up (12 plies) followed by warm pressing at Hi-Nicalon fibers were spread using rollers and coated with 150.C to form a green'composite. The fugitive organics the matrix precursor by passing through the slurry. Excess were slowly burned out of the sample in air at -500"C, N Fig. 6. SEM micrographs showing polished cross-sections of Hi-Nicalon fibers with a duplex CVD BN/SiC coating Table 1 Hi-Nicalon fiber-reinforced Bao.75 Si2Os celsian composites(Unidirectional; 12 Plies) Sample #f Fiber coating Fiber content, Ve Density, p(g/cm) Phase from XRD HI-NIC-BSAS-I- 0.42 HI-NIC-BSAS-1-3 BN/SiC Monoclinic celsian # ! B57C ! 6))-6.)' .)-.1 ! # # & # # & ! & L 0 ! # & (! % ' $ ! & ! # & & # ; # ! K 0 ! ! & )6** ! & >.7 !% ? & # & & ! 0 M ! # # >5. ? ! # ! & 5+)' N& 9 ( & & ! !# +))' 5).1 / 0 1 2 . / 3 43** 5 *3 6 *3! & + ;4 & ! & % ' $ & 7 ;4 & ! & $ ! '3D % ' & ( 5 $ )*+ ).+. .,A >M @ 5. ? O & 7 D # >&%/ ? GJD $" "'- 5 .6 67 % ' )1. /)+ 4 $" "'- 5 /5 67 % ' )1. /)6 4