Showing papers on "Ceramic matrix composite published in 2005"
05 Dec 2005-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, C/C-SiC composites are considered as the primary materials for hot structures of future launch vehicles and their suitability under extreme thermo-mechanical environments in different structural parts like nose caps, nozzle jet vanes and engine flaps.
Abstract: Ceramic matrix composite materials are being considered the primary materials for hot structures of future launch vehicles. Melt infiltrated composites based on the liquid silicon infiltration process have proven their suitability under extreme thermo-mechanical environments in different structural parts like nose caps, nozzle jet vanes and engine flaps. Considerable progress has been achieved within the last few years to mature the manufacture technology and to tailor the properties of the materials. Among low densities and high damage tolerance behaviour C/C–SiC composites show superior tribological properties predestining these materials for advanced friction systems.
492 citations
TL;DR: In this article, a colloidal processing route was adopted to disperse multi-walled carbon nanotubes (MWNTs) into alumina powders homogenously, and the reinforcement mechanism was discussed based on the microstructure investigation.
149 citations
TL;DR: In this article, a carbon nanotube (CNT)-dispersed Si3N4 ceramics with electrical conductivity were developed based on the lower temperature densification technique, in which the key point is the addition of both TiO2 and AlN as well as Y2O3 and Al 2O3 as sintering aids.
Abstract: Carbon nanotube (CNT)-dispersed Si3N4 ceramics with electrical conductivity were developed based on the lower temperature densification technique, in which the key point is the addition of both TiO2 and AlN as well as Y2O3 and Al2O3 as sintering aids. This new ceramic with a small amount of CNTs exhibits very high electrical conductivity in addition to high strength and toughness. Since Si3N4 ceramics with Y2O3–Al2O3–TiO2–AlN were originally used as a wear material, electrically conductive Si3N4 ceramics are expected to be applied for high-performance static-electricity-free bearings for aerospace and other high-performance components.
140 citations
01 Jan 2005
TL;DR: In this article, the authors present information concerning processes and properties for five silicon carbide (SiC) fiber-reinforced SiC matrix composite systems recently developed by NASA that can operate under mechanical loading and oxidizing conditions for hundreds of hours at 1204, 1315, and 1427°C.
Abstract: The successful replacement of metal alloys by ceramic matrix composites (CMC) in high-temperature engine components will require the development of constituent materials and processes that can provide CMC systems with enhanced thermal capability along with the key thermostructural properties required for long-term component service. This chapter presents information concerning processes and properties for five silicon carbide (SiC) fiber-reinforced SiC matrix composite systems recently developed by NASA that can operate under mechanical loading and oxidizing conditions for hundreds of hours at 1204, 1315, and 1427°C, temperatures well above current metal capability. This advanced capability stems in large part from specific NASA-developed processes that significantly improve the creeprupture and environmental resistance of the SiC fiber as well as the thermal conductivity, creep resistance, and intrinsic thermal stability of the SiC matrices.
131 citations
TL;DR: In this paper, the transformability of the tetragonal zirconia and residual stress in the alumina phase were examined by Raman and fluorescence piezo-spectroscopy, respectively.
Abstract: Samples of zirconia-toughened alumina (ZTA) with small amounts of chromia and magnetoplumbite-type crystalline phase (CeMgAl 11 O 19 ) have been prepared and processed under different conditions. Mechanical properties like hardness and fracture toughness were examined as a function of different parameters. As an example, fracture toughness was increased by the chromia addition, whereas platelets reinforcement addition suppressed the tetragonal zirconia (t-zirconia)–monoclinic zirconia (m-zirconia) transformation. In addition, transformability of the tetragonal zirconia and the residual stress in the alumina phase were examined by Raman and fluorescence piezo-spectroscopy, respectively. In particular, the extent to which t-zirconia transforms to m-zirconia was determined by Raman spectroscopy after Vickers indentation and the transformability was correlated to the fracture toughness. It was demonstrated that the monoclinic content and the toughness were correlated linearly and experimental results were compared with models already available for zirconia-based materials. On the other hand, residual stresses originated by transformation toughening mechanism were correlated to the transformability of the tetragonal phase.
124 citations
Patent•
22 Dec 2005TL;DR: In this paper, the authors proposed a method of making a ceramic nanocomposite comprising a nanostructured carbon component inside a ceramic host, which may further comprise vapor grown carbon fibers.
Abstract: The present invention is directed towards a ceramic nanocomposite comprising a nanostructured carbon component inside a ceramic host. The ceramic nanocomposite may further comprise vapor grown carbon fibers. Such nanostructured carbon materials impart both structural and thermal barrier enhancements to the ceramic host. The present invention is also directed towards a method of making these ceramic nanocomposites and for methods of using them in various applications.
119 citations
01 Jan 2005
TL;DR: In this paper, the authors focus on prepreg and slurry cast SiC-based ceramic matrix composites (MI-CMCs) with particular reference to applications in power generation gas turbines.
Abstract: Silicon melt infiltrated, SiC-based ceramic matrix composites (MI-CMCs) have been developed for use in gas turbine engines. These materials are particularly suited to use in gas turbines due to their low porosity, high thermal conductivity, low thermal expansion, high toughness and high matrix cracking stress. Several variations of the overall fabrication process for these materials are possible, but this paper will focus on “prepreg” and “slurry cast” MI-CMCs with particular reference to applications in power generation gas turbines. These composites have recently been commercialized under the name of HiPerComp™.
119 citations
TL;DR: In this paper, an ultra-high-temperature HfB 2 -SiC composite was successfully fabricated by reactive hot-pressing, which consisted of faceted diboride grains (mean size 3μm), with HfC (6vol%) and SiC (22vol%) evenly distributed intergranularly.
112 citations
TL;DR: In this paper, a composite of 3Y-TZP matrix composites containing 0.1-1.5% of MWCNTs and single-wall (SWCNT) carbon nanotubes was fabricated by spark plasma sintering technique.
106 citations
TL;DR: In this paper, a 10-Yttria-stabilized zirconia/alumina composites were fabricated by hot pressing 10-YSZ reinforced with 0-30-mol% alumina particulates or platelets.
101 citations
01 Jan 2005
TL;DR: In this paper, the authors focus on commercially available SiC-based ceramic fiber types of current interest for CMC and on their current state of experimental and mechanistic knowledge concerning their production methods, microstructures, physical properties, and mechanical properties at room and high temperatures.
Abstract: Non-oxide ceramic fibers are being considered for many applications, but are currently being developed and produced primarily as continuous-length structural reinforcement for ceramic matrix composites (CMC). Since only those fiber types with compositions based on silicon carbide (SiC) have demonstrated their general applicability for this application, this chapter focuses on commercially available SiC-based ceramic fiber types of current interest for CMC and on our current state of experimental and mechanistic knowledge concerning their production methods, microstructures, physical properties, and mechanical properties at room and high temperatures. Particular emphasis is placed on those properties required for successful implementation of the SiC fibers in high-temperature CMC components. It is shown that significant advances have been made in recent years concerning SiC fiber production methods, thereby resulting in pure near-stoichiometric small-diameter fibers that provide most of the CMC fiber property requirements, except for low cost.
01 Jan 2005
TL;DR: In the last few years new manufacturing processes and materials have been developed as discussed by the authors, which reduced the costs by almost one order of magnitude in comparison to first generation C/SiC composites which were originally developed for space and military applications.
Abstract: Ceramic matrix composites (CMC), based on reinforcements of carbon fibres and matrices of silicon carbide (called C/SiC or C/C-SiC composites) represent a relatively new class of structural materials. In the last few years new manufacturing processes and materials have been developed. Short fibre reinforcements, cheap polymer precursors and liquid phase processes reduced the costs by almost one order of magnitude in comparison to first generation C/SiC composites which were originally developed for space and military applications. Besides high mass specific properties and high thermal stability, functional properties like low thermal expansion and good tribological behaviour play an increasing importance for new commercial applications like brake disks and pads, clutches, calibration plates or furnace charging devices.
TL;DR: In this paper, a design and processing approach to fabricate ceramic laminates with high mechanical reliability, i.e., high failure resistance, limited strength scatter, and increased damage tolerance is presented.
Abstract: A design and processing approach to fabricate ceramic laminates with high mechanical reliability, i.e., high failure resistance, limited strength scatter, and increased damage tolerance is presented in this paper. Different ceramic layers are stacked together to develop a specific residual stress profile after sintering. By changing the composition of the laminae and the composite architecture it is possible to produce a material with predefined failure stress which can be evaluated from the fracture toughness curve correlated to the residual stresses. In addition, by tailoring the fracture toughness curve, surface defects can be forced to grow in a stable way before reaching the critical condition, thus obtaining a unique-value strength ceramic material. Laminates composed of alumina/mullite composite layers are designed and created in this work by the implementation of the proposed approach. The material obtained shows a “constant” strength of 456 MPa (standard deviation <7%) even when large surface damage is produced by Vickers indentation.
TL;DR: In this paper, a series of multi-walled carbon nanotube-reinforced ceramic matrix composites (NT-CMCs) were fabricated and the structure and properties were characterized.
Abstract: Carbon nanotubes have generated considerable excitement in the scientific and engineering communities because of their exceptional mechanical and physical properties observed at the nanoscale. Carbon nanotubes possess exceptionally high stiffness and strength combined with high electrical and thermal conductivities. These novel material properties have stimulated considerable research in the development of nanotube-reinforced composites (Thostenson et al 2001 Compos. Sci. Technol. 61 1899, Thostenson et al 2005 Compos. Sci. Technol. 65 491). In this research, novel reaction bonded silicon carbide nanocomposites were fabricated using melt infiltration of silicon. A series of multi-walled carbon nanotube-reinforced ceramic matrix composites (NT-CMCs) were fabricated and the structure and properties were characterized. Here we show that carbon nanotubes are present in the as-fabricated NT-CMCs after reaction bonding at temperatures above 1400 °C. Characterization results reveal that a very small volume content of carbon nanotubes, as low as 0.3 volume %, results in a 75% reduction in electrical resistivity of the ceramic composites. A 96% decrease in electrical resistivity was observed for the ceramics with the highest nanotube volume fraction of 2.1%.
TL;DR: In this paper, the fracture behavior and damage development in mullite fiber reinforced-mullite matrix composites have been investigated using chevron notch technique and ballistic impact tests, and the composites retained some of their load bearing capacity even after penetration of the projectile, since structural damage caused by projectiles remained localised, preventing catastrophic failure.
TL;DR: In this article, a self-lubricating ZrO2(Y2O3)-50BaCrO4 composite has been fabricated by spark plasma sintering by tailoring the composition.
TL;DR: In this article, the preparation and characterization of yttria-stabilized zirconia/nickel oxide composites (YSZ/NiO) is reported.
Abstract: We report the preparation and characterization of yttria-stabilized zirconia/nickel oxide composites (YSZ/NiO) This composite is the precursor material of the cermet YSZ/Ni, which is used as solid oxide fuel cell anode material The performance of the anode is strongly dependent on the microstructural properties of the cermet Therefore, the control of the microstructure of the YSZ/NiO composite is a key step for the fabrication of high-performance anodes In this study, the composites were prepared by a modified liquid mixture technique Scanning electron microscopy analysis evidenced the good dispersion of the phases and that NiO nanoparticles are spread over the YSZ surface Sintered pellets were studied by X-ray diffraction and impedance spectroscopy The main results show that the composite is comprised of a well-dispersed mixture of the two phases The electrical conductivity data show that there is a strong dependence of the transport mechanism on the relative composition of phases
TL;DR: In this paper, the authors investigated the fatigue behavior of two Nicalon-fabric-reinforced SiCON matrix composites at room temperature and found that the composites exhibited fatigue runout at 10 7 cycles at ~80% of the monotonic strength.
Abstract: The monotonic and high-frequency (100 Hz) fatigue behavior of two Nicalon-fabric-reinforced SiCON matrix composites was investigated at room temperature. The matrix composition was varied by the addition of BN and SiC particulate fillers, to contain shrinkage from processing by polymer infiltration and pyrolysis (PIP). The composites had strong fiber/matrix bonding, which resulted in substantially less frictional heating than observed with weakly bonded composites. Both composites exhibited fatigue runout at 10 7 cycles at ~80% of the monotonic strength. Comparison with existing fatigue data in the literature (for the same composites) at 1 Hz shows no change in fatigue life; i.e., no frequency effect was observed. Most of the stiffness reduction in the composites occurred in the first fatigue cycle, whereas subsequent decreases in moduli were attributed to limited fiber cracking. The major driving force for failure was the localized debonding of transverse and longitudinal plies at the crossover points in the fabric, which, when linked, resulted in interlaminar damage and failure in the composite.
TL;DR: In this article, a porous mullite matrix was designed to obtain damage-tolerant behavior as well as high-temperature long-term stability for all-oxide continuous fiber-reinforced ceramic matrix composites.
Abstract: All-oxide continuous fiber-reinforced ceramic matrix composites are enabling materials for high-temperature structural applications in oxidizing environments. However, their industrial use requires further improvements in material performance as well as a significant reduction of the processing costs. This article gives some insight into a novel colloidal processing route. A porous mullite matrix was designed to obtain damage-tolerant behavior as well as high-temperature long-term stability. Laminated composites were formed with conventional techniques similar to the manufacture of polymer matrix composites. This simple and low-cost process leads to homogeneous microstructures with improved material properties compared with the state of the art in continuous fiber-reinforced oxide/oxide composites. The developed composites in the present study exhibit favorable mechanical properties both at room temperature and after thermal aging for 1000 h at temperatures up to 1300°C.
TL;DR: In this paper, the porosity dependence of Young's modulus (E), modulus of rupture (σR), toughness (K1C), and fracture energy (G1C) was found to be well described on the entire range of porosity by relations of the form X0(1−P)mX.
Abstract: Porous laminar materials and alternate laminates of silicon carbide dense and porous layers have been elaborated by tape casting and liquid phase sintering processing. Porosity was introduced by incorporation of pore forming agents (corn starch or graphite platelets) in the slurry. Homogeneous distributions of porosity have been obtained for both monolithic and composite laminates. The microstructure of the SiC matrix was equiaxed and was not affected by the porosity. The porosity (P) dependence of Young’s modulus (E), modulus of rupture (σR), toughness (K1C) and fracture energy (G1C) was found to be well described on the entire range of porosity by relations of the form X0(1−P)mX proposed by Wagh et al. from a model that takes into account the tortuosity of the porosity. In the case of our materials, mE=2.7, m σ R =m K 1 C =m E +0.5 and m G 1 C =m E +1 . All the ex-corn starch composites behaved in a brittle manner, even those having weak interlayers with a porosity content higher than the critical value of about 0.4 predicted by the model developed by Blanks et al. A non-purely brittle behaviour started to be obtained with ex-graphite laminar composites in which the pores are elongated and oriented parallel to the interfaces.
TL;DR: In this article, polymeric and oligomeric carbosilanes having Si atoms linked by methylene (CH2 ) groups were used to prepare nano-sized tubules and bamboo-like SiC structures by both CVD and liquid precursor infiltration and pyrolysis inside of nanoporous alumina filter disks, followed by dissolution of the alumina template in HF(aq).
Abstract: Polymeric and oligomeric carbosilanes having Si atoms linked by methylene ( CH2 ) groups were used to prepare nano-sized tubules and bamboo-like SiC structures by both CVD and liquid precursor infiltration and pyrolysis inside of nanoporous alumina filter disks, followed by dissolution of the alumina template in HF(aq). These initially amorphous SiC structures were characterized by SEM, EMPA, TEM, and XRD. Typical outer diameters of the SiC nanotubes (NTs) were 200–300 nm with 20–40 nm wall thicknesses and lengths up to the thickness of the original alumina templates, ca. 60 μm. In the case of the CVD-derived SiC NTs, annealing these structures up to 1600 °C in an Ar atmosphere yielded a nanocrystalline β-SiC or β-SiC/C composite in the shape of the original NTs, while in the case of the liquid precursor-derived nanostructures, conversion to a collection of single crystal SiC nanofibers and other small particles was observed.
TL;DR: In this article, a crack growth mechanism map for SiC/SiC composites has been developed for chemical and nuclear environments as a function of temperature and time, which is an effective tool for identifying operating regimes and predicting behavior.
Abstract: Ceramic matrix composites have the potential to operate at high temperatures and are, therefore being considered for a variety of advanced energy technologies such as combustor liners in land-based gas turbo/generators, heat exchangers and advanced fission and fusion reactors. Ceramic matrix composites exhibit a range of crack growth mechanisms driven by a range of environmental and nuclear conditions. The crack growth mechanisms include: (1) fiber relaxation by thermal (FR) and irradiation (FIR) processes, (2) fiber stress-rupture (SR), (3) interface removal (IR) by oxidation, and (4) oxidation embrittlement (OE) resulting from glass formation including effects of glass viscosity. Analysis of these crack growth processes has been accomplished with a combination experimental/modeling effort. Dynamic, high-temperature, in situ crack growth measurements have been made in variable Ar + O 2 environments while a Pacific Northwest National Laboratory (PNNL) developed model has been used to extrapolate this data and to add radiation effects. In addition to the modeling effort, a map showing these mechanisms as a function of environmental parameters was developed. This mechanism map is an effective tool for identifying operating regimes and predicting behavior. The process used to develop the crack growth mechanism map was to: (1) hypothesize and experimentally verify the operative mechanisms, (2) develop an analytical model for each mechanism, and (3) define the operating regime and boundary conditions for each mechanism. A map for SiC/SiC composites has been developed for chemical and nuclear environments as a function of temperature and time.
TL;DR: In this article, a micromechanics based model of the thermomechanical behavior of minicomposites is proposed, based on the model of mechanical behavior proposed by Lissart et al.
TL;DR: In this paper, the authors developed boron carbide-silicon carbide layered ceramics with controlled compressive and tensile stresses in separate layers, which can provide high apparent fracture toughness and damage tolerance.
Abstract: Boron carbide-silicon carbide ceramic composites are very promising armor materials because they are intrinsically very hard. However, their fracture toughness is not very high. Their ballistic performance could be significantly increased if the brittleness of these materials could be decreased. Here we report development of boron carbide-silicon carbide layered ceramics with controlled compressive and tensile stresses in separate layers. Such B4C-SiC laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with high protection capabilities. The theory of heterogeneous layered systems was used to develop optimal design parameters allowing the evaluation and maximization of apparent fracture toughness. The layered composites were designed in a way to achieve high compressive residual stresses in thin B4C-SiC based layers and low tensile residuals stresses in thick B4C layers. The residual stresses were controlled by the phase composition of layers and the layers thickness. The estimated apparent fracture toughness was calculated for both three layered and nine layered composites. B4C-30 wt%SiC/B4C laminates were made based on the optimized design for high apparent fracture toughness. Processing of laminates involved preprocessing of powders, forming green tapes and hot pressing. Work is in progress to measure fracture toughness of laminates, as well as their strength, hardness and the ballistic performance.
TL;DR: In this paper, the effects of phase evolution caused by the addition of a new sintering agent, lithium borosilicate, Li2O·B2O3·SiO2 (LBS) glass to 0.9MgTiO3-0.1CaTiO 3 ceramic and resultant dielectric properties were investigated.
Abstract: Effects on phase evolution caused by the addition of a new sintering agent, lithium borosilicate, Li2O·B2O3·SiO2 (LBS) glass to 0.9MgTiO3–0.1CaTiO3 ceramic and resultant dielectric properties were investigated. The added LBS glass, a liquid phase sintering agent, significantly lowered the densification temperature from 1300° to about 950°C, while yielding decomposition of MgTiO3 into MgTi2O5 and Mg2TiO4. At the same time, the by-products of the decomposition reaction, MgO and TiO2, were dissolved into the glass network. Such phase evolution partly compensated the influence of deleterious glass addition so that the specimen demonstrated fairly good apparent dielectric properties.
TL;DR: In this article, the surface oxygen content of the whiskers was shown to strongly affect the composite thermomechanical properties, thus decreasing the amount of crack deflection, whisker pullout and bridging which are required to reach high fracture toughness values.
Abstract: Thermomechanical properties of a 35 vol.% SiC whiskers/Al2O3 matrix composite were investigated as a function of whisker surface quality. Two batches of SiC whiskers (Tateho-SCW-1-S) were studied. Whisker surface chemistry, as determined by X-ray photoelectron spectroscopy and whisker morphology, as determined by SEM or TEM, was correlated to the thermomechanical properties of the composites. The surface oxygen content of the whiskers was shown to strongly affect the composite thermomechanical properties. High oxygen surface content appears to affect the whisker/matrix interfacial bonding thus decreasing the amount of crack deflection, whisker pullout and whisker bridging which are required to reach high fracture toughness values.
TL;DR: In this article, a strategy is described to develop high toughness yttria-stabilised tetragonal zirconia polycrystalline (Y-TZP) composites reinforced with hard TiB 2 particles.
Abstract: In this paper, a strategy is described to develop high toughness yttria-stabilised tetragonal zirconia polycrystalline (Y-TZP) composites reinforced with hard TiB 2 particles. The experimental results revealed that fully dense Y-TZP composites with 30 vol.% TiB 2 can be obtained with a moderate hardness of 13 GPa, a high strength up to 1280 MPa and an excellent indentation toughness up to 10 MPa m 1/2 by hot pressing in vacuum at 1450 °C. The toughness of the composites can be tailored between 4 and 10 MPa m 1/2 by varying the yttria stabiliser content of the ZrO 2 matrix between 3 and 2 mol%. An optimum composite toughness was achieved for a ZrO 2 matrix with an overall yttria content of 2.5 mol%, obtained by mixing pure monoclinic and 3 mol% Y 2 O 3 co-precipitated ZrO 2 starting powders. An important observation is that the thermal residual tensile stress in the ZrO 2 matrix due to the TiB 2 addition, needs to be taken into account when optimising the transformability of the ZrO 2 matrix in order to develop high toughness Y-TZP composites.
TL;DR: In this paper, a modern ceramic-matrix composite (CMC) has been extensively characterized for a high-temperature aerospace turbine-engine application, and the CMC system has a silicon-nitrogen-carbon (Si-N-C) matrix reinforced with Nicalon fibers woven in a balanced eight-harness satin weave fabric.
Abstract: A modern ceramic-matrix composite (CMC) has been extensively characterized for a high-temperature aerospace turbine-engine application. The CMC system has a silicon-nitrogen-carbon (Si-N-C) matrix reinforced with Nicalon fibers woven in a balanced eight-harness satin weave fabric. Tensile tests have demonstrated that this CMC exhibits excellent strength retention up to 1100°C. The room-temperature fatigue limit was 160 MPa, ∼80% of the room-temperature tensile strength. The composite reached run-out conditions under cyclic (105 cycles at 1 Hz) and sustained tension (100 h) conditions at a stress of 110 MPa, which was ∼35 MPa above the proportional limits at temperatures up to 1100°C in air. At stress levels >110 MPa, cyclic loading at 1000°C caused a more severe reduction in life, based on time, compared with sustained tension. Further life degradation was observed in the 1000°C fatigue specimens that were exposed to a salt-fog environment. This degradation decreased the fatigue life ∼85% at the stress levels that were tested.
TL;DR: In this article, the authors developed composite coatings (fluoropolymer/ceramic) by plasma spaying, which are characterized by a well-melted ceramic matrix in which rounded polymer particles are randomly distributed.
Abstract: Even if polymer coatings are widely used for industrial applications, their performances are often limited by a poor scratch resistance or a high water and gas permeability. To overcome such limitations, the composite coating of ceramics with polymer can be a solution to be adopted. Thermal spraying may help to achieve this objective, thanks to its ability permitting to deposit many kinds of materials with an important range of coating thicknesses. The aim of this paper is to develop composite coatings (fluoropolymer/ceramic) by plasma spaying. Due to different thermal characteristics of the initial materials (PTFE or PFA polymers and Al 2 O 3 –TiO 2 ceramic), three types of powders injections are elaborated. To compare these three conditions, microstructure, surface wettability and wear resistance deposits behaviour were characterized. Al 2 O 3 –TiO 2 /fluoropolymer (PTFE or PFA) composite coatings are characterized by a well-melted ceramic matrix in which rounded polymer particles are randomly distributed. The as-sprayed polymer particles kept at the coatings surface can however be spread thanks to a thermal treatment at 350 °C during 15 min. Unlike the PFA, a large PTFE loss was noticed during the spraying process. Thus, the highest polymer/ceramic ratio is observed in the coatings made with the separated injection of the Al 2 O 3 –TiO 2 and PFA powders. The lowest friction coefficient is also measured for this coating.
TL;DR: In this article, high-strength mullite/SiC/Y 2 O 3 composite ceramics with a great crack-healing ability were developed and subjected to three-point bending.
Abstract: High-strength mullite/SiC/Y 2 O 3 composite ceramics with a great crack-healing ability were developed and subjected to three-point bending. A semicircular surface crack 100 μm in diameter was made in each specimen. Crack-healing behaviour was systematically studied as a function of crack-healing temperature and healing time, and the bending strength of the specimens crack-healed up to 1573 K was investigated. The effects of the crack-healing treatment on the structural integrity and reliability of machined components were studied systematically. Four main conclusions were drawn from the present study: (1) mullite/SiC/Y 2 O 3 composite ceramics have the ability to heal after cracking from 1423 K to 1673 K in air, (2) the heat-resistance limit temperature for strength of the crack-healed specimen is ≅1473 K, while at 68% of the specimens fractured from outside the crack-healed zone in the tested-temperature range of 300–1573 K, (3) due to the crack-healing treatment, the strength of the machined specimen increased by 40–200%. Local fracture strength was assumed to recover completely, and the cracks formed by machining were healed completely, and (4) a large self-crack-healing ability is desirable for obtaining a higher structural integrity in ceramic components.