| 摘要 |
A preferred composite which is useful at temperatures in excess of about 1000 DEG C. comprising a ceramic matrix and 40-60% on volume basis of coated and uncoated fibers embedded in the matrix generally parallel to each other and in a controlled arrangement; the matrix is selected from the group consisting essentially of silicon nitride, silicon carbide and zirconium titanate; the fibers are silicon carbides fibers 5-20 microns thick; the coating on the coated fibers is boron nitride 0.1-0.3 microns thick; cross-section of the composite contains about one half, on volume basis, of uncoated fibers in one band extending from one side edge of the cross-section to the opposite side edge; the composite having unexpectedly improved strength and/or toughness compared to a composite composed of only coated or only uncoated fibers.
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