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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 paper, the porosities of the C/C-SiC composites were about 0.89-2.8 vol%, which is denser than traditional C/Cs composites, and three annular regions were present on the ablation surface.
Abstract: C/C-SiC composites were prepared by molten infiltration of silicon powders, using porous C/C composites as frameworks. The porosities of the C/C-SiC composites were about 0.89-2.8 vol%, which is denser than traditional C/C composites. The ablation properties were tested using an oxyacetylene torch. Three annular regions were present on the ablation surface. With increasing pyrocarbon fraction, a white ceramic oxide layer formed from the boundary to the center of the surface. The ablation experimental results also showed that the linear and mass ablation rates of the composites decreased with increasing carbon fraction. Linear SiO2 whiskers of diameter 800 am and length approximately 3 mu m were formed near the boundaries of the ablation surfaces of the C/C-SiC composites produced with low-porosity C/C frameworks. The ablation mechanism of the C/C-SiC composites is discussed, based on a heterogeneous ablation reaction model and a supersaturation assumption. (C) 2013 Elsevier Ltd. All rights reserved.
68 citations
TL;DR: The structural and chemical stability of multiwall carbon nanotubes (MWNTs) in ceramic nanocomposites prepared by spark plasma sintering was studied in this article, where high resolution electron microscopy, X-ray diffraction and Raman spectroscopy were used to evaluate any degradation of the MWNTs.
Abstract: The structural and chemical stability of multiwall carbon nanotubes (MWNTs) in ceramic nanocomposites prepared by spark plasma sintering was studied. High resolution electron microscopy, X-ray diffraction and Raman spectroscopy were used to evaluate any degradation of the MWNTs. They were found to be well preserved in alumina after sintering up to 1900°C/100 MPa/3 min. In boron carbide, structural degradation of MWNTs started from 1600°C when sintered for 20 min. Multiwall carbon nanotubes maintained their high aspect ratio and fibrous nature even after being sintered in boron carbide at 2000°C for 20 min. However, no Raman vibrations of MWNTs were observed for nanocomposites processed at temperatures 2000°C, which indicates that they were severely degraded. Structural preservation of MWNTs in ceramic nanocomposites depends on the ceramic matrix, sintering temperature and dwell time. Multiwall carbon nanotubes were not preserved for matrices that require high sintering temperatures (>1600°C) and longer processing times (>13 min).
68 citations
TL;DR: In this article, reaction-bonded silicon carbide was used to fabricate the 250mm diameter circular mirror with 30mm thickness and 1.72-kg weight and the 120mm hexagonal mirror with 15mm thickness, and 0.23kg weight.
68 citations
TL;DR: In this paper, a novel toughening method for tungsten is proposed based on reinforcement by Tungsten wires, which is analogous to that of fiber-reinforced ceramic matrix composites.
67 citations
Patent•
13 Oct 1987
TL;DR: In this article, the main ingredients of a geopolymeric compound expressed in terms of molar ratios of oxides being equal to or comprised between the following values: M2O/SiO2: 0.10 to 0.95; SiO2/Al2O3: 2.50 to 6.00; M2 O/Al 2O3 : 0.25 to 5.70, M 2O representing either Na2O and/or K2O, or the mixture of at least one alkaline oxide with CaO.
Abstract: Ceramic-ceramic composite material based on a ceramic fiber reinforcement and of which the ceramic matrix is comprised of a geopolymeric compound containing, a) a geopolymer poly(sialate) Mn(-Si-O-Al-O-)n, and/or poly(sialate-siloxo) Mn(-Si-O-Al-O-Si-O-)n, M representing at least one alkaline cation and n the polymerization degree; b) ultrafine siliceous and/or aluminous and/or silico-aluminous elements, of a size smaller than five microns, preferably smaller than two microns, said geopolymeric compound being obtained by polycondensation at a temperature comprised between 20°C and 120°C of an alkaline alumino-silicate reaction mixture, the composition of the main ingredients of said geopolymeric compound expressed in terms of molar ratios of oxides being equal to or comprised between the following values: M2O/SiO2: 0.10 to 0.95; SiO2/Al2O3: 2.50 to 6.00; M2O/Al2O3: 0.25 to 5.70, M2O representing either Na2O and/or K2O, or the mixture of at least one alkaline oxide with CaO. The fiber reinforcement consists of ceramic fiber such as SiC, Al2O3, SiO2, glass, carbon. The addition of alkaline sulphides and alkaline sulphites enables the method to protect the glass fibers against chemical attack due to alkalinity of the matrix.
67 citations