Topic
Ceramic matrix composite
About: Ceramic matrix composite is a research topic. Over the lifetime, 7807 publications have been published within this topic receiving 117020 citations.
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TL;DR: In this article, the authors used the heterometallic alkoxide barium bis[tert-butoxistannate(II)], BaSn2(OtBu)6, as molecular precursor in metalorganic chemical vapour deposition (MOCVD) techniques.
Abstract: While exploring new and effective routes to composites of ceramics and metals we have used the heterometallic alkoxide barium bis[tert-butoxistannate(II)], BaSn2(OtBu)6, as molecular precursor in metalorganic chemical vapour deposition (MOCVD) techniques. The solid material obtained is characterized by highly dispersed metal in a ceramic matrix as determined by electron microscopy, electron spectroscopy and X-ray diffraction and therefore has peculiar chemical and physical properties. Furthermore the material is exclusively built of globular particles. In the one-component CVD process at low pressure heating is achieved by a microwave system. To yield the new solid composite we have designed a CVD apparatus as shown in Fig. 1 which is especially useful for alkoxide precursors. The decomposition takes place in the temperature range 300-500 °C. This temperature is sufficient to decompose the precursor completely and is low enough to prevent carbide formation (the highest C-content found is 5% by photoelectron spectroscopy (XPS)). The precursor barium bis[tert-butoxi-stannate (II)], obtained as described [1] and recrystallized from toluene, is incorporated into the system and the substrate is heated by induction to the temperature of decomposition which is 350 °C for Ba Sn2(OtBu)6. The temperature of the outer furnace is successively raised until a continuous flow of precursor gas is reached which can be monitored by the unchanging mass spectrum of the reaction gases. If
40 citations
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TL;DR: In this paper, a mixture of polysiloxane network and rice husk ash (RHA), a reactive filler, was used to construct CMCs with a weight ratio of 4:1.
40 citations
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14 Sep 2007TL;DR: In this paper, a wavy ceramic matrix composite (CMC) wall (214, 532, 603, 609) with a ceramic insulating layer (230, 538, 604, 610) having a distal surface (242) that may define a hot gas passage is described.
Abstract: A ceramic hybrid structure (207, 502, 602, 608) that includes a wavy ceramic matrix composite (CMC) wall (214, 532, 603, 609) bonded with a ceramic insulating layer (230, 538, 604, 610) having a distal surface (242) that may define a hot gas passage (250, 550, 650) or otherwise be in proximity to a source of elevated temperature. In various embodiments, the waves (216, 537, 637) of the CMC wall (214, 532, 603, 609) may conform to the following parameters: a thickness (222) between 1 and 10 millimeters; an amplitude (224) between one and 2.5 times the thickness; and a period (226) between one and 20 times the amplitude. The uninsulated backside surface (218) of the CMC wall (214) provides a desired stiffness and strength and enhanced cooling surface area. In various embodiments the amplitude (224), excluding the thickness (222), may be at least 2 mm.
40 citations
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28 Nov 1997
TL;DR: In this article, a textile reinforcement of fibers made up essentially of silicon carbide, and an interphase layer between the reinforcing fibers and the matrix, is presented, where the reinforcement fibers are long fibers which contain less than 5 % at. of residual oxygen and have a modulus higher than 250 GPa.
Abstract: The material consists of a textile reinforcement of fibers made up essentially of silicon carbide, and an interphase layer between the reinforcing fibers and the matrix. The reinforcing fibers are long fibers which contain less than 5 % at. of residual oxygen and have a modulus higher than 250 GPa, the interphase layer is strongly bound to the fibers and to the matrix such that the shearing strength inside the interphase layer and at the fiber-interphase and interphase-matrix is greater than that inside the matrix.
40 citations
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TL;DR: In this paper, 3Al 2 O 3 ·2SiO 2 ) coatings were found to start out as a nanocrystalline layer, which is an intimate mixture of γ-Al 2O 3 nanocrystites imbedded in a vitreous silica-rich matrix at the substrate/coating interface.
Abstract: Dense, uniform and crack-free mullite (3Al 2 O 3 ·2SiO 2 ) coatings were deposited on SiC by chemical vapor deposition. The coatings were compositionally graded, with the Al/Si ratio increasing towards the outer surface of the coatings for improved corrosion resistance. The coatings were found to start out as a nanocrystalline layer, which is an intimate mixture of γ-Al 2 O 3 nanocrystallites imbedded in a vitreous silica-rich matrix at the substrate/coating interface. Mullite grains nucleated when the surface composition of the growing coating was in a narrow range close to that of stoichiometric mullite. The phase transformations occurring in these coatings during high-temperature anneals in the range 1100–1400 °C were studied. These phase transformations, which include a tetragonal-to-orthorhombic transformation, mullitization and devitrification of silica in the nanocrystalline layer, and α-alumina precipitation and twinning of the alumina-rich mullite, are discussed in light of the adhesion and corrosion resistance of the coatings.
40 citations