une 1999 High-Temperature Oxidation of Boron Nitride: Boron Nitride Layers in Composites 1477 (a 10m Si map B map N map O map m园ismp N map o map Si map B map ma O map Fig. 7. SiC/BN/SiC oxidized 140 h at 900oC in dry O2-backscattered electron image and associated elemental maps: (a)4000 um into sample,Fig. 7. SiC/BN/SiC oxidized 140 h at 900°C in dry O2—backscattered electron image and associated elemental maps: (a) 4000 mm into sample, (b) 2000 mm into sample, and (c) ∼10 mm into sample. June 1999 High-Temperature Oxidation of Boron Nitride: Boron Nitride Layers in Composites 1477