Showing papers on "Ceramic matrix composite published in 2008"
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01 Jan 2008
TL;DR: In this article, the authors present an analysis of the Elastic and Thermal properties of a fiber-reinforced Lamina with respect to the properties of the Fibers and Matrix in a Lamina.
Abstract: Introduction Definition General Characteristics Applications Material Selection Materials Fibers Matrix Thermoset Matrix Thermoplastic Matrix Fiber Surface Treatments Fillers and Other Additives Incorporation of Fibers into Matrix Fiber Content, Density and Void Content Mechanics Fiber-Matrix Interaction in a Unidirectional Lamina Characteristics of a Fiber-Reinforced Lamina Laminated Structure Interlaminar Stresses Performance Static Mechanical Properties Fatigue Properties Impact Properties Other Properties Environmental Effects Long-Term Properties Fracture Behavior and Damage Tolerance Manufacturing Fundamentals Bag Molding Process Compression Molding Pultrusion Filament Winding Resin Transfer Molding Other Manufacturing Processes Manufacturing Processes for Thermoplastic Matrix Composites Quality Inspection Methods Design Failure Predictions Laminate Design Considerations Joint Design Design Examples Applications Examples Metal and Ceramic Matrix Composites Metal Matrix Composites Ceramic Matrix Composites Carbon-Carbon Composites Nanocomposites Nanoclay Carbon Nanofiber Carbon Nanotubes Appendices Woven Fabric Terminology Residual Stresses in Fibers and Matrix in a Lamina Due to Cooling Alternative Equations for the Elastic and Thermal Properties of a Lamina Halpin-Tsai Equations Typical Mechanical Properties of Unidirectional Continuous Fiber Composites Properties of Various SMC Composites Typical Mechanical Properties of Metal Matrix Composites Determination of Design Allowables Useful references Index
1,254 citations
TL;DR: The use of h-BN as a composite material with zirconium oxide for side dams in thin-strip casting is looked at in particular detail in this article, where recent results for corrosion, wear and high-temperature compressive stress of MYCROSINT® SO are presented for the first time.
Abstract: Hexagonal boron nitride (h-BN) is a very versatile material that can be used in a number of applications due to its unique combination of properties. This paper reviews typical h-BN qualities and their applications. The use of h-BN as a composite material with zirconium oxide for side dams in thin-strip casting is looked at in particular detail. Recent results for corrosion, wear and high-temperature compressive stress of MYCROSINT® SO are presented here for the first time.
382 citations
TL;DR: In this article, thermal conductivities for zirconium diboride (ZrB2) and 30 vol% silicon carbide (SiC) ceramics were investigated.
Abstract: Thermophysical properties were investigated for zirconium diboride (ZrB2) and ZrB2–30 vol% silicon carbide (SiC) ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and densities. The thermal conductivity of ZrB2 increased from 56 W (m K)−1 at room temperature to 67 W (m K)−1 at 1675 K, whereas the thermal conductivity of ZrB2–SiC decreased from 62 to 56 W (m K)−1 over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared with previously reported thermal conductivities for ZrB2 and ZrB2–SiC.
266 citations
TL;DR: In this article, the authors investigated using multilayers of high-temperature ceramics such as ZrB 2 and SiC to protect carbon-carbon composites against oxidation.
Abstract: Carbon-carbon (C-C) composites are attractive materials for hypersonic flight vehicles but they oxidize in air at temperatures >500°C and need thermal protection systems to survive aerothermal heating. We investigated using multilayers of high-temperature ceramics such as ZrB 2 and SiC to protect C-C against oxidation. Our approach combines pretreatment and processing steps to create continuous and adherent high-temperature ceramic coatings from infiltrated preceramic polymers. We tested our protective coatings at temperatures above 2600°C at the National Solar Thermal Testing Facility using controlled cold-wall heat flux profiles reaching a maximum of 680 W/cm 2 .
217 citations
TL;DR: In this article, the thermal properties of carbon nanotube-alumina composites have been investigated as a function of CNT content and the sintering temperature, and the notably enhanced thermal properties were achieved including a heat capacity of 6.09 −J/g/k at 400 −°C in the 19.10 −W/mK CNT-Al 2 O 3 nanocomposites sintered at 1450 −C, and a thermal diffusivity of 13.98 −mm 2 /s.
168 citations
26 Mar 2008
151 citations
TL;DR: In this article, carbon nanotubes were employed to reinforce the interfaces between polymer particles, enhancing composite stiffness as well as structural damping, and the results showed that CNT-reinforced samples have advanced impact strength and vibration damping properties over a wide temperature range.
Abstract: The focus in this paper is directed toward to thermal spraying fabrication and experimental validation of carbon nanotube-reinforced composite structures, providing processing route and design concepts. Sandwiched metal–polymer–ceramics coatings and moulded UHMW-PE polymer composites with carbon nanotubes were investigated at flexural tests and thermal cycling between +200 °C and −80 °C temperature. Carbon nanotubes were employed to reinforce the interfaces between polymer particles, enhancing composite stiffness as well as structural damping. Results on damping behavior and impact toughness of the composite sandwiches showed that CNT-reinforced samples have advanced impact strength and vibration damping properties over a wide temperature range. Experiments conducted using a vibrating clamped beam with the composite layers indicated up to 200% increase in the inherent damping level and 30% increase in the stiffness with some decrease (20–30%) in density of the composite. The cross-links between nanotubes and composite layers also served to improve load transfer within the network resulting in improved stiffness properties. The results are targeted for the application in aerospace and naval engineering.
114 citations
26 Mar 2008
111 citations
26 Mar 2008
TL;DR: In this article, a cost efficient manufacturing route has been developed by DLR based on the infiltration of a reactive fluid phase into porous carbon fiber preforms, where Molten silicon is used as the reactive fluid which replaces the initial pore volume of the preform and reacts subsequently with the carbon matrix to form silicon carbide.
Abstract: High performance ceramics are still largely produced via powder routes. The main disadvantage of these monlithic materials is their brittle failure behaviour and the thus dissatisfactory damage tolerance of ceramic components. The most favourable way to improve the fracture toughness of ceramics is the reinforcement with thermally stable continuous fibres. However, long manufacturing times, multiple reinfiltration steps and expensive raw materials lead to high material costs of these fibre reinforced ceramic matrix composites (CMC) which have prevented their breakthrough to terrestrial applications up until now. To overcome these restrictions and widen the applicability of CMCs - in particular, to enter in fields of mechanical engineering - a novel cost efficient manufacturing route has been developed by DLR. The process is based on the infiltration of a reactive fluid phase into porous carbon fibre preforms. Molten silicon is used as the reactive fluid which replaces the initial pore volume of the preform and reacts subsequently with the carbon matrix to form silicon carbide. A one-shot infiltration is sufficient for the densification of the matrix for this liquid silicon infiltration (LSI) process. Therefore short processing times can be achieved which lead, in addition to the use of commercially available uncoated to carbon fibres and cheap raw materials like phenolics and granules of silicon, to the lowest manufacturing costs of all CMC materials. This paper deals with the fabrication of so-called C/C-SiC composites and with design and cost aspects for the manufacture of C/C-SiC components.
110 citations
TL;DR: In this paper, the effects of such variables as temperature, environment, and stress on carbon fiber-reinforced silicon carbide (C/SiC) composites were investigated.
Abstract: Carbon fiber-reinforced silicon carbide (C/SiC) composites have the potential to be utilized in many high-temperature structural applications, particularly in aerospace. However, the susceptibility of the carbon fibers to oxidation has hindered the composite's use in long-term reusable applications. In order to identify the composites limitations, fundamental oxidation studies were conducted to determine the effects of such variables as temperature, environment, and stress. The systematic studies first looked at the oxidation of the plain, uncoated carbon fiber, then when fiber was utilized within a C/SiC composite, and finally when a stress was applied to the C/SiC composite (stressed oxidation). The first study, oxidation of just the carbon fibers, showed that the fiber oxidation kinetics occurs in two primary regimes: chemical reaction control and diffusion control. The second study, oxidation of the C/SiC composite, showed the self-protecting effects from the SiC matrix at elevated temperatures when the composite was not stressed. The final study, stressed oxidation of the C/SiC composite, more closely simulated application conditions in which the material is expected to encounter thermal and mechanical stresses. The applied load and temperature will affect the openings of the as-fabricated cracks, which are an unavoidable characteristic of C/SiC composites. The main objective of the paper was to determine the oxidation kinetic regimes for the oxidation of carbon fibers in a cracked silicon carbide matrix under stressed and unstressed conditions. The studies help to provide insights in to the protective approaches, that could be used to prevent oxidation of the fibers within the composite.
TL;DR: In this paper, a wide variety of tensile creep, fatigue, and cyclic fatigue experiments were performed in air at 1204°C for the SiC/SiC CMC system consisting of Sylramic-iBN SiC fibers, BN fiber interphase coating, and slurry-cast melt-infiltrated (MI) SiC-based matrix.
TL;DR: In this paper, a 0.5% CNT-reinforced Al 2 O 3 particles were successfully plasma sprayed to obtain a 400μm thick coating on the steel substrate.
TL;DR: In this article, thermal residual stresses in two SiC-ceramic matrix composites reinforced with carbon fiber (C/SiC) and silicon carbide fiber (SiC and SiC) were completely investigated.
25 Jul 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the authors used Spark Plasminar sintering technique to in situ fabricate high dense Ti3SiC2-TiC composites and calculated the volume content from X-ray diffraction (XRD) is close to the theoretical one.
Abstract: Spark plasma sintering technique was used to in situ fabricate high dense Ti3SiC2–TiC composites. The calculated TiC volume content from X-ray diffraction (XRD) is close to the theoretical one. It is found from fracture surface observation that TiC is about 1 μm, and Ti3SiC2 is about 2–10 μm in grain size. The fracture modes consist of intergranular mainly for Ti3SiC2 and transgranular fracture mainly for TiC. With the increasing of TiC volume content, Vickers hardness increases to the maximum value of 13 GPa for Ti3SiC2-40 vol.%TiC. Fracture toughness and flexural strength of the composites are also improved compared with those of monolithic Ti3SiC2 except for Ti3SiC2-40 vol.%TiC composite. The main reasons for the sudden decrease of fracture toughness and flexural strength of Ti3SiC2-40 vol.%TiC composite can be attributed to the relatively lower density, some clusters of TiC in the composite and the transition of fracture mode from intergranular to transgranular. The thermal conductivities decreased with the addition of TiC. The minimum thermal conductivity is 22 W m °C−1 for Ti3SiC2-40 vol.%TiC composite.
TL;DR: In this paper, a bending strength of 749±15 MPa was achieved when ∼100 nm PyC interphase is deposited in a carbon fiber reinforced ceramic matrix composites.
Abstract: ZrC particles are introduced into carbon fiber reinforced ceramic matrix composites to improve their high-temperature performances. Composites without interphases have higher densities than those with interphases and most ZrC particles remain in the fiber interbundle areas. All composites show typical noncatastrophic fracture behavior regardless of the existence of the interphases. However, the addition of interphases will increase the bending strength and the length of fiber pullouts. A bending strength of 749±15 MPa is achieved when ∼100 nm PyC interphase is deposited. The surfaces of pulled-out fibers without interphases are rough, while those with interphases are smoother. For composites with PyC/SiC interphase, the pulled-out fibers keep their original surface morphology.
20 Dec 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, carbon-carbon, carbon-silicon carbide, and silicon carbide and silicon carbonide -silicon carbonide composites were vacuum brazed to Ti and Hastealloy X using Ni-base metallic glass braze foils (MBF-20 and MBF-30).
Abstract: Carbon–carbon, carbon–silicon carbide, and silicon carbide–silicon carbide composites were vacuum brazed to Ti and Hastealloy X using Ni-base metallic glass braze foils (MBF-20 and MBF-30). Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) of the joints showed that compositional changes due to substrate dissolution led to secondary-phase precipitation which aided interfacial bonding although inter-laminar shear failure occurred within some composites. Residual thermal stresses in the joint led to hardness gradients; however, stress accommodation by the brazes prevented interfacial cracking. The peak Knoop microhardness in the joints was as high as 1165–1294 KHN.
TL;DR: In this paper, the electric resistance of woven SiC fiber-reinforced SiC matrix composites was measured under tensile loading conditions and the results showed that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance.
TL;DR: In this paper, carbon nanotubes were used to increase the hardness, elastic modulus and inter-laminar shear strength of monolithic hydroxyapatite layers.
TL;DR: In this article, two alumina-zirconia laminates with external (ECS-laminates) and internal (ICS-laminate) compressive stresses have been investigated using a fracture mechanics weight function analysis.
Abstract: Layered ceramics have been proposed as an alternative choice for the design of structural ceramics with improved fracture toughness, strength and reliability. The use of residual compressive stresses, either at the surface or in the internal layers, may improve the strength as well as the crack resistance of the material during crack growth. In this work, two alumina–zirconia laminates designed with external (ECS-laminates) and internal (ICS-laminates) compressive stresses have been investigated using a fracture mechanics weight function analysis. An optimal architecture that maximises material toughness and strength has been found for each design as a function of geometry. From a flaw tolerant viewpoint, ECS-laminates are suitable for ceramic components with small cracks or flaws which are embedded in or near the potential tensile surface of the piece. On the other hand, the existence of large cracks or defects suggests the use of ICS-laminates to attain a more reliable response.
28 Mar 2008
TL;DR: The semiamorphous three-dimensional networks of polymeric Na, K, Li, and Mg aluminosilicates of both poly(sialate) and poly(Sialate-siloxo) type, collectively known as geopolymers, harden at 20-120 C and are similar to thermoset resins, but are stable at up to 1200-1400 C without shrinkage as mentioned in this paper.
Abstract: The semiamorphous three-dimensional networks of polymeric Na, K, Li, and Mg aluminosilicates of both poly(sialate) and poly(sialate-siloxo) type, collectively known as geopolymers, harden at 20-120 C and are similar to thermoset resins, but are stable at up to 1200-1400 C without shrinkage A wide variety of alkaline-resistant inorganic reinforcements, notably SiC fibers, have been combined with geopolymer matrices to yield nonburning, nonsmoking high-temperature composites An SiC fiber-reinforced K-poly(sialate-siloxo) matrix, shaped and hardened at 70 C for 15 hr, develops flexural mean strengths of the order of 380 MPa that are retained after firing at up to 900 C 16 references
TL;DR: In this article, a ZrB2-20-vol.% SiC-based ceramic matrix composite containing 20 vol.% short carbon fibers was top pressed at 2000°C and 30MPa for 1 1/2 hours.
TL;DR: In this paper, the structural characteristics of carbon/silicon carbide (C/SiC) aircraft brake materials were studied by means of optical microscopy, SEM, XRD and TEM, and their frictional properties were investigated using a full-size aircraft wheel and brake assembly on a fullscale dynamometer.
TL;DR: In this article, the fabrication of C/Si-B-C-N fiber reinforced ceramic matrix composites (FRCs) is reported, which consists of three individual steps: (i) vacuum-assisted infiltration of a liquid two-component Si−B−C−N precursor into stacked woven carbon fiber fabrics, (ii) stepwise thermal cross-linking and (iii) thermal transformation of the polymer matrix composite into a ceramic matrix composite.
26 Mar 2008
TL;DR: In this paper, the microstructural and mechanical properties of the HA/titania composites are studied by X-ray diffractometry analysis, Raman spectrometry, and scanning electron microscopy.
Abstract: Hydroxyapatite-reinforced nanocomposites with titania nanocrystals addition are prepared by a homogeneous mixing of hydroxyapatite nanoparticles and titania nanocrystals based on high-energy ball milling and spark plasma sintering processes. The microstructural and mechanical properties of the HA/titania composites are studied by X-ray diffractometry analysis, Raman spectrometry, and scanning electron microscopy. The hardness and Young's modulus of the composites are characterized by a nanoindenter and they show that the incorporation of the titania nanocrystals improves the mechanical properties of the composites obviously and the improvement should be ascribed to the main solitary effect of the ceramic as additives as well as a denser composites due to combining high-energy ball milling with spark plasma sintering techniques. The bioactivity of the HA/titania composites is evaluated by immersing the spark plasma sintering (SPS) compact disk in the simulated body fluid (SBF) and the results indicate that the bioactivity of the composites is related to the addition of titania by inducing apatite nucleation on the sample's surface after being immersed in SBF.
TL;DR: In this paper, a new class of alumina composites based on a novel hybrid microstructure design, in which multiwalled carbon nanotubes (MWNTs) and SiC nanoparticles are combined to give a new type system of ceramic nanocomposites.
TL;DR: In this article, the effects of pyrolytic carbon (PyC) interface thickness between fibers and matrix on density, microstructural evolution and mechanical properties were characterized. And they showed that induced PyC interface conditions strongly affect the density and therefore dominate mechanical properties and fracture behaviors.
TL;DR: In this article, a modified Lees' disk setup was used in order to determine the thermal conductivity of a series of experimental ceramic disks, and the most important parameters emerged as the degree of vitrification and porosity of the ceramic matrix.
TL;DR: In this article, the microstructure and behavior of the interface region are the key factors in obtaining an effective control of damage in composites and enhancement of toughness, and the feasibility of producing fully dense, tough oxide/oxide composites by interface engineering.
Abstract: Mullite fiber/mullite matrix composites are attractive because of their inherent oxidation resistance at high temperatures. Mullite has better creep resistance than alumina. However, chemical interactions between oxides are often very severe; with the result no gain is made over monolithic mullite in terms of toughness. Even in the absence of chemical bonding, a strong mechanical bond component may be present. This originates from radial compressive stress due to thermal expansion mismatch and/or the surface roughness of interface. Thus, the microstructure and behavior of the interface region are the key factors in obtaining an effective control of damage in composites and enhancement of toughness. This body of work on mullite/mullite composites shows the feasibility of producing fully dense, tough oxide/oxide composites by interface engineering. Coatings such as BN alone or SiC/BN double coating function effectively for mullite fiber/mullite matrix composites in that they provide a nonbrittle fracture and increased work of fracture at room temperature. It would appear that for use at high temperatures in air, one needs to identify structural analogs of BN among oxides.