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Showing papers on "Ceramic matrix composite published in 2010"


Journal ArticleDOI
TL;DR: In this paper, a well-dispersed multi-walled carbon nanotubes (CNTs) reinforced Al2O3 nanocomposites were successfully fabricated by hot-pressing.

158 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical technique based on the structure tensor is used to determine the local orientation of fibres in fiber-reinforced materials such as ceramic matrix composites, glass fiber reinforced plastics or reinforced concrete.
Abstract: Computed tomography is a non-destructive testing technique based on X-ray absorption that permits the 3D-visualisation of materials at micron-range resolutions. In this article, computed tomography is used to investigate fibre orientation and fibre position in various fibre-reinforced materials such as ceramic matrix composites, glass fibre-reinforced plastics or reinforced concrete. The goal of this article is to determine the quantitative orientation of fibres in fibre-reinforced materials. For this purpose, a mathematical technique based on the structure tensor is used to determine the local orientation of fibres. The structure tensor is easy to implement and results in a fast algorithm relying solely on local properties of the given reconstruction. In addition, the local X-ray transform is used to denoise fibres and to segment them from the matrix.

147 citations


Patent
23 Nov 2010
TL;DR: In this paper, composite materials containing a ceramic matrix and a carbon nanotube-infused fiber material are described in various embodiments, including a passivation layer overcoating at least the carbon-nanotube infused fiber and, optionally, the plurality of carbon Nanotubes, which can be distributed uniformly, non-uniformly or in a gradient manner in the ceramic matrix.
Abstract: In various embodiments, composite materials containing a ceramic matrix and a carbon nanotube-infused fiber material are described herein. Illustrative ceramic matrices include, for example, binary, ternary and quaternary metal or non-metal borides, oxides, nitrides and carbides. The ceramic matrix can also be a cement. The fiber materials can be continuous or chopped fibers and include, for example, glass fibers, carbon fibers, metal fibers, ceramic fibers, organic fibers, silicon carbide fibers, boron carbide fibers, silicon nitride fibers and aluminum oxide fibers. The composite materials can further include a passivation layer overcoating at least the carbon nanotube-infused fiber material and, optionally, the plurality of carbon nanotubes. The fiber material can be distributed uniformly, non-uniformly or in a gradient manner in the ceramic matrix. Non-uniform distributions may be used to form impart different mechanical, electrical or thermal properties to different regions of the ceramic matrix.

140 citations


Journal ArticleDOI
TL;DR: In this article, the sintering and grain growth behavior of alumina + 2, 3.5 and 5 wt.% carbon nanotubes (CNTs) and alumina+ 2,3.5, and 5wt.%.

113 citations


Journal ArticleDOI
TL;DR: Three-phase-percolative composites with ZnO radial nanoclusters (R-ZnO) and BaTiO(3) (BT) nanoparticles embedded into polyvinylidene fluoride (PVDF) were prepared by using a simple blending and hot-molding technique, and the percolation theory was used to explain the experimental results.
Abstract: Three-phase-percolative composites with ZnO radial nanoclusters (R-ZnO) and BaTiO3 (BT) nanoparticles embedded into polyvinylidene fluoride (PVDF) were prepared by using a simple blending and hot-molding technique. The BT + PVDF composite with a volume fraction of 30 vol % BT particles were employed as a thermoplastic-ceramic matrix. Compared with the two-phase-percolative composites of R-ZnO/PVDF, the three-phase-percolative (R-ZnO/(BT + PVDF)) composites showed enhanced dielectric constant and decreased dielectric loss. The percolation theory was used to explain the experimental results. The increased percolation threshold was studied in detail, and the thermal stability was also investigated.

99 citations


Journal ArticleDOI
TL;DR: In this article, a ceramic matrix composites (C/SiC-ZrB 2 ) are prepared by slurry and precursor infiltrations and pyrolysis method.

90 citations


Journal ArticleDOI
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


Journal ArticleDOI
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


Journal ArticleDOI
TL;DR: In this paper, the structural, dielectric and magnetic properties of fifteen BFO samples were discussed in view of possible applications in RF and microwave devices, where polyvinyl alcohol (PVA) and tetraethyl orthosilicate (TEOS) were also added as a binder in fabrication procedure.

64 citations


Journal ArticleDOI
TL;DR: In this article, a pressure infiltration/carbonization combined with liquid silicon infiltration was developed for fabricating carbon fiber reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) for advanced friction materials.

63 citations


Journal ArticleDOI
TL;DR: In this paper, an approach to estimate interface shear stress of ceramic matrix composites during fatigue loading has been developed by adopting a shear-lag model which includes the matrix shear deformation in the bonded region and friction in the debonded region.
Abstract: An approach to estimate interface shear stress of ceramic matrix composites during fatigue loading has been developed in this paper. By adopting a shear-lag model which includes the matrix shear deformation in the bonded region and friction in the debonded region, the matrix crack space and interface debonding length are obtained by matrix statistical cracking model and fracture mechanics interface debonding criterion. Based on the damage mechanisms of fiber sliding relative to matrix in the interface debonded region upon unloading and subsequent reloading, the unloading counter slip length and reloading new slip length are determined by the fracture mechanics method. The hysteresis loops of four different cases have been derived. The hysteresis loss energy for the strain energy lost per volume during corresponding cycle is formulated in terms of interface shear stress. By comparing the experimental hysteresis loss energy with computational values, the interface shear stress corresponding to different cycles can then be derived. The theoretical results have been compared with experimental data of three different ceramic composites.

Journal ArticleDOI
TL;DR: In this article, carbon nanotube (CNT) composites are fabricated by direct in-situ growth of CNTs on the Zirconia particles, followed by densification via the Spark Plasma Sintering (SPS) technique.

Journal ArticleDOI
Hongwei He1, Jianlong Wang1, Kaixi Li1, Jian Wang1, Jianyu Gu1 
TL;DR: In this article, anodic oxidation treatment was used to modify the surface of carbon fibres to improve the interlaminar shear strength of composites by mixing epoxy resins and modifying carbon fibers.

Journal ArticleDOI
TL;DR: In this article, a partially allyl-substituted hydridopoly carbosilane (5 mol% allyl) [AHPCS] has been characterized by spectral techniques and thermal analysis.
Abstract: In present study, partially allyl-substituted hydridopolycarbosilane (5 mol% allyl) [AHPCS] has been characterized by spectral techniques and thermal analysis. The DSC studies show that, the polymer is self-cross-linking at lower temperatures without any incorporation of cross-linking agents. The spectral and thermal characterizations carried out at different processing stages indicate the possibility of extensive structural rearrangement accompanied by the loss of hydrogen and other reactions of C and Si containing species resulting in the conversion of the branched chain segment into a 3D SiC network structure. AHPCS gave ceramic residue of 72% and 70% at 900 and 1500 °C respectively in argon atmosphere. XRD pattern of 1500 °C heat-treated AHPCS, indicates the formation of silicon carbide with the particle size of 3–4 nm. AHPCS was used as matrix resin for the preparation of C/SiC composite without any interfacial coating over the T-300 carbon fabric reinforcement. Flexural strength value of 74–86 MPa for C/SiC specimen with density of 1.7 g/cm 3 was obtained after four infiltration and pyrolysis cycles.

Journal ArticleDOI
TL;DR: In this paper, the tensile creep and rupture behavior of 2D-woven SiC fiber-reinforced SiC matrix composites with potential for advanced high temperature structural applications was determined in air at 1315 °C.
Abstract: The tensile creep and rupture behavior of 2D-woven SiC fiber-reinforced SiC matrix composites with potential for advanced high temperature structural applications was determined in air at 1315 °C. The results are compared to similar SiC/SiC data in the literature in order to understand the underlying creep and rupture mechanisms. Focus was placed on three different near-stoichiometric SiC fiber-types and three SiC-based matrix systems produced by different process routes. In general, the creep and rupture properties of the tested composites were primarily dictated by the creep resistance of the fiber-type, with the Sylramic-iBN fiber typically showing the best behavior. However, the type of matrix did have an effect on the composite creep and rupture lives due to load-sharing differences for the different matrix types and due to stoichiometry in the case of chemical vapor infiltration SiC matrices.

Journal ArticleDOI
TL;DR: In this paper, a precursor for zirconium carbide was obtained by just blending Zr(OC4H9)4 and divinylbenzene (DVB), which satisfied the requirements for use in ceramic matrix composites fabrication via precursor infiltration and pyrolysis (PIP).
Abstract: A precursor for zirconium carbide was obtained by just blending zirconium butoxide Zr(OC4H9)4 (ZTB) and divinylbenzene (DVB). This precursor satisfied the requirements for use in ceramic matrix composites fabrication via precursor infiltration and pyrolysis (PIP) process, that is, it was a solution, cross-linked at 150 °C for 2 h, and transformed to ZrC matrix upon heat treatment at 1,600 °C with a ceramic yield around 40%. The cross-linking behavior, pyrolysis process, and optimal molar ratio (ZTB and DVB) of the precursor were investigated by IR, DSC–TGA, and XRD analysis. ZTB and DVB decomposed into ZrO2 and carbon, respectively, at 400–500 °C, and ZrO2 and carbon reacted with each other via carbo-thermal reaction at higher temperature to form ZrC.

Journal ArticleDOI
TL;DR: In this article, boron was introduced into C f /SiC composites as active filler to shorten the processing time of PIP process and improve the oxidation resistance of composites.
Abstract: Boron was introduced into C f /SiC composites as active filler to shorten the processing time of PIP process and improve the oxidation resistance of composites. When heat-treated at 1800 °C in N 2 for 1 h, the density of composites with boron (C f /SiC-BN) increased from 1.71 to 1.78 g/cm 3 , while that of composites without boron (C f /SiC) decreased from 1.92 to 1.77 g/cm 3 . So when boron was used, two cycles of polymer impregnation and pyrolysis (PIP) could be reduced. Meanwhile, the oxidation resistance of composites was greatly improved with the incorporation of boron-bearing species. Most carbon fiber reinforcements in C f /SiC composite were burnt off when they were oxidized at 800 °C for 10 h. By contrast, only a small amount of carbon fibers in C f /SiC-BN composite were burnt off. Weight losses for C f /SiC composite and C f /SiC-BN composite were about 36 and 16 wt%, respectively.

Journal ArticleDOI
TL;DR: In this paper, the ability to correlate the elastic properties of melt infiltrated SiC/SiC composites to properties of constituent phases using a hybrid Finite Element approach is examined and the influence of material internal features, such as the fabric architecture and intra-tow voids, on such correlation is elucidated.

Journal ArticleDOI
TL;DR: In this paper, the activity of Fe-containing ceramic composites for the dehydrogenation of ethylbenzene in the presence of CO 2 was studied, and a low conversion was obtained using CaTiO 3, due to the loss of the Ca species and coke production.
Abstract: The activity of Fe-containing ceramic composites for the dehydrogenation of ethylbenzene in the presence of CO 2 was studied. Ceramic composites containing Fe, Cu, Cr, Pb and/or Ti were obtained by solid-state reaction method. The materials were characterized by XRD, textural properties, chemical analysis, SEM, Mossbauer spectroscopy, TPR, CO 2 -TPD analyses and electrical measurements. A low conversion was obtained using CaTiO 3 , due to the loss of the Ca species and coke production. The improvement of styrene selectivity with iron content, as well as the high stability of Cr 0.75 Fe 1.25 O 3 , resulted in a better activity when using this solid. Fe 2+ is continuously reoxidized to Fe 3+ by CO 2 in the Fe–Ti active phase from the Fe 0.5 Cu 0.75 Ti 0.75 O 3 sample. The latter catalyst exhibited high selectivity but limited stability towards styrene production. The ceramic composites appeared to be quite promising candidates for the dehydrogenation of ethylbenzene under CO 2 , in comparison with the conventional Fe–K doped catalysts, due to the highly stable Fe 3+ in a ceramic matrix.

Journal ArticleDOI
Hebao Du1, Ya-Li Li1, Fu-Qiang Zhou1, Dong Su1, Feng Hou1 
TL;DR: In this article, the in situ growth of CNTs is realized by premixing a metal catalyst in the precursor and adding a hydrocarbon (ethanol) at a certain pyrolysis temperature.
Abstract: A ceramic (SiOC) and carbon nanotube (CNT) composite (SiOC/CNT) is fabricated by a one-step process via the in situ growth of CNTs in a ceramic body during its formation from a polymer precursor (polysiloxane) by pyrolysis. The in situ growth of CNTs is realized by premixing a metal catalyst in the precursor and adding a hydrocarbon (ethanol) at a certain pyrolysis temperature. The CNTs grow inside the pores that are developed in the ceramics at the intermediate stage of pyrolysis through catalytic cracking of the hydrocarbon by the metal catalyst particles nestling in the pores during ceramic formation. The subsequent pyrolysis at a higher temperature leads to densification of the ceramic dispersed with the in situ-grown CNTs. Microstructural observation reveals a homogeneous growth of crystallized multiple-walled CNTs in nanosize pores formed in the ceramic. The in situ-grown CNTs combine well with the ceramic matrix that forms a strong interface bonding. The in situgrown CNTs increase the electrical conductivity of the ceramics by eight orders of magnitude compared with a CNT-free SiOC ceramic. This in situ growth strategy can be generalized as the fabrication of ceramic–CNT composites with promising mechanical and electrical properties.

Journal ArticleDOI
TL;DR: In this paper, the performance of reinforced carbon and SiC dual matrices composites (C/C-SiC) for brake and clutch systems was investigated and the results indicated that the composites were composed of 50{60 wt pct carbon, 2{10 wt Pct residual silicon and 30{40 wtPct silicon carbide.

Journal ArticleDOI
TL;DR: In this paper, a melt-infiltrated (MI) woven ceramic matrix composite consisting of a silicon carbide matrix reinforced by boron nitride coated Hi-Nicalon type STM SiC fiber, Hi-Nic-S/BN/SiC, was tested under tension-tension fatigue loading in combination with combustion conditions representative of those experienced by turbine blades and vanes in modern gas turbine engines.
Abstract: A melt-infiltrated (MI) woven ceramic matrix composite consisting of a silicon carbide matrix reinforced by boron nitride coated Hi-Nicalon type STM SiC fiber, Hi-Nic-S/BN/SiC, was tested under tension-tension fatigue loading in combination with combustion conditions representative of those experienced by hot-section components such as turbine blades and vanes in modern gas turbine engines. The burner rig fatigue data and fracture surfaces were analyzed for the effects of oxidation on life, failure, and damage mechanisms. These test results were then compared with those obtained from similar fatigue tests performed in a standard furnace under laboratory air environment. Fatigue life in the combustion condition was lower by an order of magnitude in comparison to the isothermal furnace results across the range of applied stress, and so demonstrates the importance of representative combined environment testing in conjunction with fundamental load testing. The observed difference in fatigue performance is att...

Journal ArticleDOI
TL;DR: This work compares the colloidal behavior of the as-received multi wall carbon nanotubes (ar-MWCNT) and the partially coated MWCNT (pc-MWcNT) when immersed in a nanozirconia matrix and an improvement in the dispersion is proved.
Abstract: Zirconia ceramics are widely used as femoral heads, but case studies show that delayed failure can occur in vivo due to crack propagation. The addition of carbon nanotubes (CNT) is aimed to avoid the slow crack propagation and to enhance the toughness of the ceramic material used for prostheses. However, to really enhance the mechanical properties of the material it is necessary to achieve a uniform distribution of the CNT in the zirconia matrix. Colloidal processing has demonstrated to be suitable for obtaining ceramic-based composites with homogeneous distribution of the phases and high green density. This work compares the colloidal behavior of the as-received multi wall carbon nanotubes (ar-MWCNT) and the partially coated MWCNT (pc-MWCNT) when immersed in a nanozirconia matrix. With pc-MWCNT an improvement in the dispersion is proved. Moreover, the sintered samples that contain pc-MWCNT show higher density, lower grain size, improved toughness and enhanced hardness under the same sintering cycle when compared to the samples with ar-MWCNT.

Journal ArticleDOI
Zhao-Hui Zhang1, Fuchi Wang1, Jie Luo1, Shu-Kui Lee1, Lu Wang1 
TL;DR: In this paper, a high volume fraction of SiC was synthesized by spark plasma sintering (SPS) technique with sinting temperatures ranging from 1500°C to 1800°C, a pressure of 50 MPa, and a heating rate of 150 MPa using Al and SiC powders.
Abstract: Al–SiC ceramic–matrix composites containing high volume fraction of SiC were synthesized by spark plasma sintering (SPS) technique with sintering temperatures ranging from 1500 °C to 1800 °C, a pressure of 50 MPa, and a heating rate of 150 °C/min, using Al and SiC powders. Microstructures and mechanical properties of the composites sintered at different temperatures were investigated. Results reveal that the Al–SiC composites synthesized by SPS process consist of Al, SiC, Si, and Al4C3 phases. The volume fraction of Al4C3 and Si phases in the composites were reduced remarkably with increasing the sintering temperature up to 1700 °C. As a result, the composite sintered at 1800 °C provides the optimal combination of dense microstructures and excellent properties, including the relative density of 99.6%, micro-hardness of 25.5 GPa, bending strength of 451 MPa, and fracture toughness of 6.05 MPa m1/2. Compared with the monolithic SiC ceramics, both the bending strength and the fracture toughness of the composites are improved due to the dense microstructures, fine SiC grains, and infiltration of the molten Al into the interfaces of the SiC grains.

Journal ArticleDOI
TL;DR: In this article, the long-term tensile creep behavior of all-oxide ceramic matrix composites (CMCs) was investigated and the accompanying fiber bundle tests revealed a strong influence of processing conditions on the creep resistance.
Abstract: The long-term tensile creep behavior of all-oxide ceramic matrix composites (CMCs) was investigated. The accompanying fiber bundle tests revealed a strong influence of processing conditions on the creep resistance. CMCs with perpendicular fiber orientations were tested under two different load directions, moreover CMCs with nearly unidirectional fiber texture were investigated. Depending on the conditions, the absence of a steady-state creep stage was observed in most cases and due to an early onset of damage. As the majority of the samples was tested up to high strains and rupture, different failure mechanisms could be evaluated. An attempt was made to estimate fiber controlled creep rates via bundle data, but this approach also revealed problems when elastic data from unidirectional composites are transferred to CMCs with more complex fiber architecture.

Journal ArticleDOI
TL;DR: In this paper, small amounts of silica were added to a CMC starting material with a porous alumina matrix via the sol-gel technique, which effectively suppresses grain growth in fibers and matrix.
Abstract: Nextel™ 610 alumina fibers embedded in ceramic matrix composites (CMCs) with a pure alumina matrix show pronounced grain coarsening above 1350°C, which is not observed for stand-alone fibers under identical conditions. Moreover, a size gradient with small grains in the fiber center and large grains at the fiber periphery occurs. This can be explained in terms of the outward diffusion of silica traces, which normally reduces the fiber grain-boundary mobility. Silica outdiffusion and the related excessive grain growth can be suppressed if small amounts of silica are added to the alumina matrix in the green state. Aluminosilicate green compositions, on the other hand, result in a lower matrix sinterability, thus leading to inferior mechanical properties of the CMC. In this communication, we present a novel method to design a CMC that combines the key benefits of an alumina matrix (superior strength) with that of an aluminosilicate matrix (superior thermal stability). Small amounts of silica were added to a CMC starting material with a porous alumina matrix via the sol–gel technique. The silica post treatment effectively suppresses grain growth in fibers and matrix. Mechanical testing revealed significant strength retention in case of the silica-infiltrated CMC.

Journal ArticleDOI
TL;DR: In this paper, a ZrC-20 vol% SiC based ceramic matrix composite containing 10 vol% graphite flake was fabricated by hot press sintering and the thermal shock resistance of the materials was investigated through the water-quench method and subsequent three-point bend testing of flexural strength diminution.
Abstract: A ZrC-20 vol% SiC based ceramic matrix composite containing 10 vol% graphite flake was fabricated by hot press sintering. The thermal shock resistance of the materials was investigated through the water-quench method and subsequent three-point bend testing of flexural strength diminution. The ZrC-20 vol% SiC composite containing 10 vol% graphite flake exhibited higher critical temperature difference and higher residual ratio of strength compared with that of ZrC-20 vol% SiC composite. It is the main reason that addition of the graphite flake provides a weak interface into the material which acts to deflect propagating cracks, and the bridging of the cracks occurred. Meanwhile, a laminar structure of the graphite flake would relax the interface stress by sliding of interlayers and provide favorable sites for the dissipation of energy associated with crack growth during fracture.

Journal ArticleDOI
TL;DR: In this article, the influence of fabrication process on the crystalline phases, microstructures and microwave dielectric properties of TiO2-Bi2O3-CuO ceramics were investigated.
Abstract: Temperature stable high-K LTCC material was prepared. The influence of fabrication process on the crystalline phases, microstructures and microwave dielectric properties of TiO2-Bi2O3-CuO ceramics were investigated. The crystalline phases and microstructures of TiO2-Bi2O3-CuO ceramics were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. It was found that rutile TiO2 phase and Bi2Ti4O11 phase co-existed in the TiO2-Bi2O3-CuO ceramics. Separate TiO2 grains and Bi2Ti4O11 grains distributed uniformly in the ceramic matrix. The composition 0.92TiO2-0.08Bi2Ti4O11 with 2 wt% CuO addition that was sintered at 900 °C for 2 h showed high dielectric constant (er ~ 81), high quality factor (Q × f ~ 3,500 GHz) and near zero temperature coefficient of resonant frequency (τf ~ −5.1 ppm/°C), meanwhile the compatibility test showed that it could co-fire with silver electrode. The processing-microstructure-property interrelationship was also studied.

Patent
22 Apr 2010
TL;DR: In this article, a process for producing a silicon-containing CMC article that exhibits improved physical, mechanical, and microstructural properties at elevated temperatures exceeding the melting point of silicon is described.
Abstract: A process for producing a silicon-containing CMC article (10) that exhibits improved physical, mechanical, and microstructural properties at elevated temperatures exceeding the melting point of silicon. The process entails producing a body containing a ceramic reinforcement material (14,16) in a solid matrix that comprises solid elemental silicon and/or silicon alloy and a ceramic matrix material (18). The ceramic matrix composite article (10) is produced by at least partially removing the solid elemental silicon and/or silicon alloy from the solid matrix and optionally reacting at least part of the solid elemental silicon and/or silicon alloy in the solid matrix to form one or more refractory materials. The solid elemental silicon and/or silicon alloy is sufficiently removed from the body to enable the ceramic matrix composite article (10) to structurally and chemically withstand temperatures above 1405°C.

Journal ArticleDOI
TL;DR: In this paper, a finite element analysis based multi-linear elastic orthotropic materials approach has been developed to predict the stress-strain and fracture behavior of ceramic matrix composites with strain-induced damage.