| 摘要 |
Multiphase ceramic composites containing single phase silicon aluminum oxynitride and boron nitride wherein the boron nitride is one phase in the composite and the single phase silicon aluminum oxynitride is the matrix phase in the composite. The boron nitride phase is uniformly distributed in the form of discrete particles throughout the single phase silicon aluminum oxynitride matrix. A window transparent to electromagnetic radiation in a predetermined frequency spectrum is made by forming a homogeneous, finely-divided mixture of boron nitride and single phase silicon aluminum oxynitride matrix-forming compound and compacting the homogeneous, finely-divided mixture at an elevated temperature and pressure for a sufficient time to form the composite. In a preferred embodiment, about 75% by weight homogeneous, finely-divided mixture of single phase silicon aluminum oxynitride matrix-forming compound and the balance boron nitride is densified at a temperature of 1,760 DEG C. and at a pressure of about 3,775 p.s.i. for about 1 hour. The single phase silicon aluminum oxynitride corresponds to the formula: Si6-x Alx Ox N8-x, where x is at least 0.1 and less than or equal to 4.2, and preferably 3 or 4. The single phase silicon aluminum oxynitride matrix is derived from any effective combination of aluminum nitride, silicon nitride, silica and alumina.
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