High Temperature Ceramic Matrix Composites Research Articles

Radio frequency‐assisted zirconium carbide matrix deposition for continuous fiber‐reinforced ultra high temperature ceramic matrix composites

AbstractZirconium carbide (ZrC) is considered to be a potential candidate for ultra high temperature applications due to its high melting point, good chemical inertness, and ablation resistance, but the monolithic form suffers from low fracture toughness and hence poor thermal shock resistance. Reinforcing it using continuous carbon fibers (Cf) to create an ultra high temperature ceramic matrix composite is an obvious solution, however densifying ZrC requires the use of very high temperatures combined with significant pressure, such as obtained by using hot pressing or spark plasma sintering, which risks damaging fibers. In the present work, radio frequency‐assisted chemical vapor infiltration (RF‐CVI) has been investigated with a view to forming Cf/ZrC composites. These initial experiments revealed the ability to deposit pure, nano‐grained, and near stoichiometric ZrC with deposition occurring preferentially from the center of the sample due to the nature of the inverse temperature profile developed. The deposited ZrC grains were in the range of 4–9 nm in size and had a lattice parameter of 0.4750 nm. The work also showed that the use of RF‐CVI enabled the minimization of early pore sealing, a common problem for conventional CVI.

Predicting density-related mechanical properties of amorphous silicon nitride using molecular dynamics simulations

Silicon nitride fiber is among the most popular candidates for high-temperature wave-transparent ceramic matrix composites (CMC) in aerospace engineering, and the measurement of its mechanical properties has always been the focus of researchers. In this paper, a simple and effective molecular dynamics method is used to generate molecular dynamics models of amorphous silicon nitride (a-Si3N4) materials with different densities, and it is verified that the developed models reflect the microstructure of the fiber. Based on analyzing the effects of size on the results, tensile and shear simulations are carried out to obtain the mechanical properties of the models with different densities. According to the research data obtained, the empirical equation between mechanical properties (Young's modulus, shear modulus, tensile strength, and shear strength) and density of fiber is established, and validated by the published experimental results. The empirical equation can not only predict the mechanical properties of fibers directly from the density but also provide a new way to measure the mechanical properties of fibers nondestructively.

A review on the scope of using calcium fluoride as a multiphase coating and reinforcement material for wear resistant applications

Solid lubricants play a vital role in the smooth and safe operation of many tribological industrial applications like cutting and forming tools, rolling and sliding contact bearings, gears, cams and protective coating in gas turbine engines for aerospace applications. Generally liquid lubricants are widely used for reducing the friction between the contacting parts which reduce the wear rate and increase the life of the parts. However, these liquid lubricants become useless when they are exposed to high temperature, high pressure and vacuum environmental conditions. Solid lubricants are those materials that can suitably reduce the friction and wear between the contacting or sliding surfaces that are in extreme environments like low and high temperature and pressure. Among the different types of solid lubricants, calcium fluoride is widely used owing to its excellent lubricity at elevated temperature. This paper initially describes the criteria for selecting solid lubricant and provides a comprehensive summary on calcium fluoride solid lubricant which can be used as a coating material in various high temperature metal and ceramic matrix composites for wear resistant applications. Further, investigations related to the selection of optimized coating parameters, synerging multiphase solid lubricants and soft metals with optimal percentage, selection of filler materials, mismatch in coefficient of thermal expansion and its impact on coating life are summarised and discussed. Finally, the scope of synthesizing calcium fluoride solid lubricant from discarded eggshell powders is explored.

Experimental characterization of fatigue life of ZrB2-SiC based ultra high-temperature ceramic matrix composites

The development process of new Ultra High-Temperature Ceramic Matrix Composites (UHTCMC) for use in severe environments typical of space applications, such as thermal protection or rocket components, still lacks useful data for what concerns the properties influencing the structural behavior under the different load conditions. In particular, the fatigue life of the material plays a fundamental role in the design of full systems determining their resistance to typical vibrational loads. However, this property has been rarely investigated for UHTCMCs and its experimental characterization presents uncertainties related to the material specific behavior, which does not allow the application of traditional methodology employed for isotropic materials. In the present work, two different methodologies are proposed and applied to new ZrB2-SiC-based UHTCMCs, with either short or long continuous fibers, yielding in combination with numerical analyses to the determination of the σ/N curve for the two classes of materials.

Direct laser powder-bed fusion additive manufacturing of complex-shaped TiB2-B4C composite with ultra-fine eutectic microstructure and outstanding mechanical performances

TiB2-B4C composite has various outstanding properties and great potentials in versatile high-end application fields, and currently the preparation of its monolithic counterpart with arbitrarily-complex shape is eagerly demanded. However, due to the intrinsically strong covalent-bonding and poor laser absorption performances of its constituents, it is still highly-challenging to prepare TiB2-based composite by additive manufacturing method. Herein, by direct laser powder-bed fusion additive manufacturing (selective laser sintering) and the unique strategy of in-situ synthesizing/sintering, dense and complex-shaped TiB2-B4C composites were successfully additively manufactured for the first time. More importantly, benefiting from their ultrafine eutectic microstructures and high relative densities, the resultant TiB2-B4C composites exhibited outstanding Vickers hardness and fracture toughness respectively up to 35.6 GPa and 8.6 MPa·m1/2, which were remarkably higher even than those of the near-fully-dense counterparts prepared by various subtractive methodologies. This work offered a reliable approach to near-net-forming high-temperature ceramic-matrix composites with arbitrarily-complex shapes and superior mechanical performances.

Thermal Qualification of the UHTCMCs Produced Using RF-CVI Technique with VMK Facility at DLR

Ultra high-temperature ceramic matrix composites (UHTCMCs) based on carbon fibre (Cf) have been shown to offer excellent temperature stability exceeding 2000 °C in highly corrosive environments, which are prime requirements for various aerospace applications. In C3Harme, a recent European Union-funded Horizon 2020 project, an experimental campaign has been carried out to assess and screen a range of UHTCMC materials for near-zero ablation rocket nozzle and thermal protection systems. Samples with ZrB2-impregnated pyrolytic carbon matrices and 2.5D woven continuous carbon fibre preforms, produced by slurry impregnation and radio frequency aided chemical vapour infiltration (RF-CVI), were tested using the vertical free jet facility at DLR, Cologne using solid propellants. When compared to standard CVI, RFCVI accelerates pyrolytic carbon densification, resulting in a much shorter manufacturing time. The samples survived the initial thermal shock and subsequent surface temperatures of >2000 °C with a minimal ablation rate. Post-test characterisation revealed a correlation between surface temperature and an accelerated catalytic activity, which lead to an understanding of the crucial role of preserving the bulk of the sample.

Ytterbium Silicate Fibers: Fabrication, Microstructure and Strength

High temperature ceramic and metal matrix composites, which are to be used under complicated loading conditions in a severe atmosphere, have to satisfy a large number of the requirements. Hence, development of such composites calls for a large variety of fibers, matrices and interface materials to make an appropriate choice in designing a particular composite. The fiber is definitely the most important component of a composite. The family of oxide fibers is the most important among possible reinforcements for metal and oxide matrices. In this work, a family of potential oxide reinforcements containing ytterbium monosilicate Yb2SiO5 and disilicate Yb2Si2O7, and ytterbia-ytterbium monosilicate eutectic, was obtained and studied. The interest in those silicates was aroused because (i) they are highly resistant to hot corrosion in the presence of water vapor and (ii) their CTE varies from 8 × 10−6 K−1 for monosilicate to 4 × 10−6 K−1 for disilicate.

Influence of zirconium-based alloys on manufacturing and mechanical properties of ultra high temperature ceramic matrix composites

ABSTRACTFor the continuous development of ultra high temperature ceramic matrix composites manufactured using reactive melt infiltration (RMI), the influence of three different melt alloys and two preform routes on mechanical behaviour and melt infiltration is investigated. Contact angle and viscosity measurement are performed to describe the melt infiltration process. The purpose of these experiments is to further understand the RMI process and increase the mechanical performance of the material. The infiltration height of molten metals within capillary systems depends on the measured contact angles and viscosity as well as the different phases present in the preform, matrix and fibre coating. In order to successfully maintain mechanical performance, minimal reactivity between the melt and coating/fibres is desired. Resulting phase formations, for each manufacturing step, are investigated and analysed using SEM, EDX and XRD. Mechanical performance is determined using flexural strength by three-point-bending, achieving close to 400 MPa with fabrics.

Electromagnetic characteristics and microstructure stability of Nextel 610 fiber after heat treatment

The thermal and microstructure stability of Nextel 610 fibers has great influence on high-temperature application of Nextel 610 fiber-reinforced ceramic matrix composites. In this work, Nextel 610 fibers were heat treated at 500–700°C in vacuum and 800–1100°C in Ar atmosphere, respectively. The sizing agent on Nextel 610 fiber surface could be decomposed into pyrolytic carbon, SiC and gaseous little molecules at lower temperatures, otherwise it was decomposed mainly in the form of gaseous little molecules at higher temperatures, so that the complex permittivity firstly increased and then decreased with the increasing of temperatures. The results showed that the annealed Nextel 610 fiber (T>900°C) could be regarded as electromagnetic wave transparent fibers, while the tensile strength had declined by half when the temperature increased to 1100°C. Therefore, Nextel 610 fibers after being annealed at higher temperatures could be further used as reinforcement to prepare high temperature ceramic matrix composites for electromagnetic wave absorption and transparent applications.

Fabrication of ultra high temperature ceramic matrix composites using a reactive melt infiltration process

Fiber reinforced composites containing a ZrB2 matrix are prepared by reactive melt infiltration, using a Zr based intermetallic compound. The reactive melt infiltration process is further characterized by determining the contact angle of the different melt and preform elements. Two different methods for boron powder impregnation of the preforms, which form ZrB2 during Zr2Cu melt infiltration, are evaluated. Degradation of fibers and different fiber coatings for Zr2Cu melt are evaluated and the microstructure of the infiltrated samples is investigated by means of XRD and SEM.

Preparation, thermal cure and ceramization of liquid precursors of SiC–ZrC

Liquid PEPSI–PZO, as precursor of SiC–ZrC multi-component ceramic, was prepared by facile reactive blending method, using phenylethynylpolysilane (PEPSI) as silicon and carbon source and polyzirconoxanesal (PZO) as zirconium source. The processing capability of PEPSI–PZO met the demands of Precursor-infiltration–pyrolysis technique (PIP) in ceramic composites fabrication. The thermal cure was realized at 130–330°C by ethynyl polymerization and condensations. The thermal cure of PEPSI–PZO precursor was promoted by catalyst Ni(acac)2, and the curing initiation and curing peak temperatures decreased by 25 and 70°C, respectively. Evidenced by ceramic yields and XRD results, the thermal pyrolysis was catalyzed by Ni(acac)2, (ceramic yield was improved by 5–10%). XRD and SEM-EDS results showed that SiC–ZrC by 1600°C pyrolysis was highly crystalline, due to the occurrence of carbothermal reduction reaction. The liquid precursor of SiC–ZrC is an ideal candidate of low cost precursors for high-temperature ceramics and ceramic matrix composites.

Stochastic Virtual Tests for High-Temperature Ceramic Matrix Composites

We review the development of virtual tests for high-temperature ceramic matrix composites with textile reinforcement. Success hinges on understanding the relationship between the microstructure of continuous-fiber composites, including its stochastic variability, and the evolution of damage events leading to failure. The virtual tests combine advanced experiments and theories to address physical, mathematical, and engineering aspects of material definition and failure prediction. Key new experiments include surface image correlation methods and synchrotron-based, micrometer-resolution 3D imaging, both executed at temperatures exceeding 1,500°C. Computational methods include new probabilistic algorithms for generating stochastic virtual specimens, as well as a new augmented finite element method that deals efficiently with arbitrary systems of crack initiation, bifurcation, and coalescence in heterogeneous materials. Conceptual advances include the use of topology to characterize stochastic microstructures. We discuss the challenge of predicting the probability of an extreme failure event in a computationally tractable manner while retaining the necessary physical detail.

Multiscale fatigue life prediction model for heterogeneous materials

SUMMARYA multiscale fatigue life prediction model is developed for heterogeneous materials. The proposed model combines a two‐scale asymptotic homogenization approach in time with a ‘block cycle jump’ technique into a unified temporal multiscale framework that can be effectively utilized for arbitrary material architectures and constitutive equations of microphases. The unified temporal multiscale approach in combination with a spatial multiscale approach based on the reduced order homogenization is characterized for high temperature ceramic matrix composites. Copyright © 2012 John Wiley & Sons, Ltd.

Finely dispersed refractory compounds for high-temperature ceramic matrix composite applications

Application of finely dispersed refractory compounds in the creation of high-temperature ceramic matrix composites (HTCMC) is briefly reviewed. Examples of successful combination of nanomaterials and HTCMC technologies are given.

Monitoring damage accumulation in ceramic matrix composites using electrical resistivity

The electric resistance of woven SiC fiber-reinforced SiC matrix composites were measured under tensile loading conditions. The results show 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. Such self-sensing capability provides the possibility of on-board/in situ damage detection and accurate life prediction for high-temperature ceramic matrix composites.

Preparation and Properties of 2D C/SiC-TaC Composites

Ultra high temperature ceramic matrix composites (UHTCC) are being considered as the most promising materials for leading edge and nose cap of hypersonic spacecrafts, reusable space vehicles and so on. In the paper, 2D carbon fiber cloth reinforced silicon carbide-tantalum carbide (2D SiC-TaC) UHTCC was fabricated by slurry-pasting and precursor infiltration pyrolysis process (PIP). Influences of the volume ratio (10, 20, 30, 60, 80 and 100%) of TaC powder on mechanical properties and ablative resistance of 2D C/SiC-TaC composites were studied. The results showed that the relative density of composites with 60vol% TaC powder was the highest, the flexural strength of the composites reached 356MPa and the mass loss rate and recession rate were 0.0116g/s and 0.026mm/s respectively, while those of C/SiC composites were 0.0166g/s and 0.062mm/s respectively. Moreover, the higher TaC powder content, the smaller the fracture toughness of the composites was. The fracture toughness of the 2D C/SiC-TaC composites with 100vol% TaC powder was only 8.69 MPa-m1/2, while that of C/SiC composites was over 15.0 MPa-m1/2.

Interfacial Coatings on Inorganic Fibers for High Temperature Ceramic Matrix Composites

Ceramic matrix composites reinforced by carbon or SiC-based fibers achieve high toughness and damage tolerance through the disposal of weak fiber coating which can deflect cracks and promote debonding at the fiber/matrix region. The methods for fabrication, as well as different techniques including SEM/EDS, XPS, XRD, AFM, micro Raman for evaluation of properties of the interphase zone are considered. The morphology, composition, topography, roughness, tensile properties of coated carbon and SiC fibers are discussed in details. The behavior of coated fibers is governed by the chemistry, procedure for coating fabrication, nanostructural factors.

High Temperature Ceramic Matrix Composites

High temperature ceramic matrix composites , High temperature ceramic matrix composites , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Book Review: High Temperature Ceramic Matrix Composites. By Walter Krenkel, Roger Naslain, and Hartmut Schneider (Eds.).

Advanced MaterialsVolume 14, Issue 23 p. 1785-1785 Book Review Book Review: High Temperature Ceramic Matrix Composites. By Walter Krenkel, Roger Naslain, and Hartmut Schneider (Eds.). S.-H. Lee, S.-H. LeeSearch for more papers by this author S.-H. Lee, S.-H. LeeSearch for more papers by this author First published: 25 November 2002 https://doi.org/10.1002/1521-4095(20021203)14:23<1785::AID-ADMA1785>3.0.CO;2-ECitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume14, Issue23December, 2002Pages 1785-1785 RelatedInformation

Fabrication of high-temperature resistant oxide ceramic matrix composites

Abstract The main objectives of this work are to develop and apply new ceramic matrix materials by which a relatively high level of densification of the final composite may be achieved by pressureless-sintering at temperatures close to 1200°C. A cost-effective processing method for the production of oxide/oxide CMCs materials and components has been achieved. A range of interphase materials is applied to Nextel™ 720 fibres. These include zirconia, neodymium and lanthanum phosphate. A combination of ZrO 2 and the AKP50 alumina powder have been selected as the successful candidates for the interphase and the matrix material, respectively. Work has been conducted on the preparation of slurry systems consisting of these two materials. The prime target was to establish the possibility of achieving good coating around the bulk of the fibres together with a high level of impregnation with the matrix material. Furthermore, the pressure infiltration technique has been applied and as a result composite samples with fibre volume content of 40%, and remaining porosity of around 20 vol% have been routinely produced. Composite room and high-temperature tensile strengths of around 200 MPa have been accomplished.