Claims
- 1. A ceramic matrix composite article comprising:
- a crystalline glass-ceramic matrix wherein alkaline earth aluminosilicate crystals constitute the principal crystal phase;
- a fiber reinforcing phase composed of a multiplicity of inorganic fibers disposed within the glass-ceramic matrix; and
- a borosilicate glass phase disposed as an intergranular glass within the glass-ceramic matrix; the borosilicate glass phase being present in a proportion constituting from 1-12% by weight of the total weight of the matrix.
- 2. A ceramic matrix composite in accordance with claim 1 wherein the concentration of B.sub.2 O.sub.3 in the composite does not exceed about 2.5% by weight of the total weight of the glass-ceramic matrix.
- 3. A ceramic matrix composite in accordance with claim 2 which further comprises, in addition to the fiber reinforcing phase, a whisker reinforcing phase consisting of a multiplicity of inorganic whiskers disposed in the glass-ceramic matrix.
- 4. A ceramic matrix composite in accordance with claim 3 wherein the inorganic whiskers are silicon carbide whiskers, and wherein the whiskers are present in a proportion constituting 1-15% by weight of the total weight of the matrix.
- 5. A ceramic matrix composite in accordance with claim 4 wherein the inorganic fibers comprise silicon oxycarbide fibers and wherein the silicon oxycarbide fibers constitute 30-50% by volume of the composite.
- 6. A ceramic matrix composite in accordance with claim 5 wherein the glass-ceramic matrix comprises a predominant crystal phase selected from the group of anorthite (CaO.Al.sub.2 O.sub.3.2SiO.sub.2) and its pseudo-binaries with mullite (3Al.sub.2 O.sub.3.SiO.sub.2), cordierite (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2), barium osumilite (BaO.2MgO.3Al.sub.2 O.sub.3.9SiO.sub.2), albite solid solution (Na.sub.2 O.Al.sub.2 O.sub.3.6SiO.sub.2), Al.sub.2 O.sub.3, SiO.sub.2, CaO.SiO.sub.2, and gehlenite (2CaO.Al.sub.2 O.sub.3.SiO.sub.2), and wherein the matrix has a composition consisting essentially, in weight percent, of about 0-25% CaO, 0-30% SrO, 10-30% CaO+SrO, 0-15% MgO, 0-25% BaO, 0-4% Na.sub.2 O, 0-6% K.sub.2 O, 25-38% Al.sub.2 O.sub.3, 35-60% SiO.sub.2, 0-15% ZrO.sub.2, 0-3% As.sub.2 O.sub.3, 0-30% total of BaO+MgO+ Na.sub.2 O+K.sub.2 O+TiO.sub.2 +ZrO.sub.2 +As.sub.2 O.sub.3, and 0-10% total of nucleating agents selected in the indicated proportion from the group consisting of 0.1-3% Cr.sub.2 O.sub.3, 0.25-3 % HfO.sub.2, 2-5% MoO.sub.3, 0.25-3% Nb.sub.2 O.sub.5, 0.25-3% Ta.sub.2 O.sub.5, and 0.25-3% WO.sub.3.
- 7. A ceramic matrix composite in accordance with claim 5 wherein the glass-ceramic matrix comprises a predominant crystal phase of triclinic anorthite in solid solution with at least one of mullite and alpha alumina, and wherein the matrix has a composition consisting essentially, in weight percent, of about 16-20% CaO, 38.5-46% Al.sub.2 O.sub.3, 35-42% SiO.sub.2, 0.25-1.5% As.sub.2 O.sub.3, and up to 10% total nucleating agent selected in the indicated proportion from the group consisting of 0.1-3% Cr.sub.2 O.sub.3, 0.25-3% HfO.sub.2, 2-5% MoO.sub.3, 0.25-3% Nb.sub.2 O.sub.5, 0.25-3% Ta.sub.2 O.sub.5, 0.25-3% WO.sub.3, and 1-10% ZrO.sub.2, the composition being substantially free of TiO.sub.2 and containing Al.sub.2 O.sub.3 in an amount which is at least 10 mole percent and up to 50 mole percent in excess of that present in stoichiometric triclinic anorthite.
- 8. A ceramic matrix composite in accordance with claim 5 wherein the glass-ceramic matrix comprises a predominant crystal phase selected from the group consisting of barium osumilite, cordierite, and stuffed cordierite, and wherein the matrix has a composition consisting essentially, in weight percent, of about 35-60% SiO.sub.2, 17-40% Al.sub.2 O.sub.3, 5-15% MgO, 1-18% total of one or more oxides of stuffing species selected from the group consisting of BaO, CaO, SrO and Cs.sub.2 O, 0-5% Nb.sub.2 O.sub.5, 0-10% Ta.sub.2 O.sub.5, 0-6% ZrO.sub.2, 0-1% Si, 0-3% As.sub.2 O.sub.3 and 0-10% ZnO.
- 9. A ceramic matrix composite in accordance with claim 5 wherein the glass-ceramic matrix comprises 0.1-5% by weight of Nb.sub.2 O.sub.5.
- 10. A method for increasing the use temperature of a ceramic matrix composite comprising an alkaline earth aluminosilicate glass-ceramic matrix and a silicon carbide fiber reinforcing phase which comprises the step of introducing a borosilicate glass into the composite matrix composition in a proportion sufficient to provide an intergranular glass phase in the glass-ceramic matrix of the composite.
- 11. A method in accordance with claim 10 wherein the borosilicate glass contains 1-30% B.sub.2 O.sub.3 by weight, and wherein the intergranular glass phase constitutes 1-12% by weight of the total weight of the glass-ceramic matrix.
- 12. A method in accordance with claim 11 wherein the concentration of B.sub.2 O.sub.3 in the composite does not exceed about 2.5% by weight of the glass-ceramic matrix.
- 13. A method in accordance with claim 12 wherein the borosilicate glass is introduced into the composite by the step of mixing the borosilicate glass with a powdered glass precursor for the glass-ceramic matrix.
- 14. A method in accordance with claim 12 wherein the borosilicate glass is introduced into the composite by a process comprising the steps of:
- melting the components for the borosilicate glass together with the components for the glass-ceramic matrix of the composite as a single glass; and
- concurrently developing aluminosilicate crystals in the glass-ceramic matrix and an intergranular glass phase disposed within the matrix by a thermal nucleation and crystallization heat treatment of the single glass.
- 15. A method in accordance with claim 14 which comprises the further step of introducing silicon carbide whiskers into the glass-ceramic matrix in a proportion of about 1-15% by weight of the matrix.
Parent Case Info
This application is a continuation of application Ser. No. 07/289,834, filed Dec. 27, 1988, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2211837 |
Dec 1989 |
GBX |
Non-Patent Literature Citations (1)
Entry |
Brennan, "Interfacial Studies of SiC Fiber Reinforced Glass-Ceramic Matrix Composites", Final Report Contract N00014-82-C-0096, Oct. 1987. |
Continuations (1)
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Number |
Date |
Country |
Parent |
289834 |
Dec 1988 |
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