Showing papers on "Ceramic matrix composite published in 1973"
TL;DR: Graphite fibre/lithium aluminosilicate composites of matrix composition Li2O Al2O3·nSiO2 wheren=3, 4, and 8, have been developed with a high volume fraction of undirectionally aligned graphite fibres.
Abstract: Graphite fibre/lithium aluminosilicate composites of matrix composition Li2O Al2O3·nSiO2 wheren=3, 4, and 8, have been developed with a high volume fraction of undirectionally aligned graphite fibres. Graphite fibre/ceramic matrix tapes were produced on a drumwinding apparatus and hot-pressed to final dimensions. This composite system exhibits a combination of useful properties, including high strength, low density, excellent thermal shock resistance and impact strength. Shear strength, cyclic modulus of rupture and modulus of elasticity and optical and electron microscopic evaluation of microstructure are discussed. Modulus of rupture as a function of vol % fibres was studied. The high modulus of rupture and impact strength are discussed in terms of the relative properties of fibre and matrix.
59 citations
Patent•
09 Jul 1973TL;DR: A hot pressed ceramic body is formed of a sandwich comprising an interior layer of a ceramic material having a given coefficient of thermal expansion and two outer surface layers formed by a material with a lower coefficient as mentioned in this paper.
Abstract: A hot pressed ceramic body is formed of a sandwich comprising an interior layer of a ceramic material having a given coefficient of thermal expansion and two outer surface layers formed of a ceramic material having a lower coefficient of thermal expansion When the product is formed as a unitary sandwich by hot pressing at elevated temperature the outer layers are put under compression as the body is cooled to room temperature A preferred form of the invention involves a central layer of a mixture of silicon carbide and silicon nitride and the external layers are pure silicon nitride
30 citations
Patent•
30 Mar 1973
TL;DR: In this article, a hot-pressed ceramic material based on silicon nitride is introduced into a die cavity defined within a graphite die and a barrier layer is provided between the ceramic material and the walls of the die cavity, which forms a substantially nonporous continuous barrier layer at or near the surface of the material.
Abstract: In manufacturing a hot pressed ceramic material based on silicon nitride, the ceramic material is introduced into a die cavity defined within a graphite die. There is provided between the ceramic material and the walls of the die cavity a further material which, at the elevated temperature of the hot pressing process, forms a substantially non-porous continuous barrier layer at or near the surface of the ceramic material so that reaction between the ceramic material and the graphite die is substantially prevented.
10 citations
15 Jan 1973
TL;DR: In this paper, Tungsten reinforced silicon nitride was found to increase the elevated temperature (1300C) Charpy impact strength by a factor of nine over monolithic Si3N4, due to the energy absorbing mechanism of fiber pullout.
Abstract: : Tungsten reinforced silicon nitride was found to increase the elevated temperature (1300C) Charpy impact strength by a factor of nine over monolithic Si3N4, primarily due to the energy absorbing mechanism of fiber pullout. However, the room temperature Charpy impact strength of tungsten reinforced Si3N4 is not increased over that of monolithic Si3N4 due to the brittle nature of the silicide reaction product at the Si3N4-W interface and the notch sensitivity of tungsten. Tantalum wire reinforced Si3N4 was found to increase the room temperature Charpy impact strength of Si3N4 by a factor of 30 (0.5 ft-lbs to 14.8 ft-lbs) and also to affect the mode of failure such that interfacial splitting along with ductile fiber elongation occurs, resulting in very small fragments of matrix breaking off upon impact. This mode of fracture is desirable for use in gas turbine engines. (Author Modified Abstract)
5 citations