Temperature Ceramic Composites Research Articles

Exploring processing, reactivity and performance of novel MAX phase/ultra-high temperature ceramic composites: The case study of Ti3SiC2

The reactivity behaviour between a MAX phase and ZrB2 or WC was explored with the aim of developing novel composites by merging the benefits of the individual constituents. Hot pressing of Ti3SiC2 with 30 vol% ZrB2 at 1450 °C led to notable microstructure re-assessment with formation of inter-locked sub-micrometric boride grains. This composite displayed enhanced hardness and showed a strength over 430 MPa up to 1200 °C, which is a great achievement considering the ductile behaviour of typical pure MAX compounds. However, addition of WC led to a highly porous composite with poor performance. These findings set a first basis for the progress of original light ceramics with combined hardness and failure tolerance over a broad temperature range.

Processing of fiber‐reinforced ultra‐high temperature ceramic composites: A review

AbstractUltra‐high temperature ceramics (UHTCs) have emerged as promising materials for high‐temperature aerospace applications due to their high melting temperature and superior ablation performance. Even still, they have yet to reach their full potential due to the catastrophic brittle failure that typically accompanies the intrinsic low fracture toughness of ceramic materials. Therefore, the emerging field of UHTC ceramic matrix composites (UHTCMCs) offers the toughness benefits of a composite with the high temperature stability of UHTCs. Here, we outline work in the last decade on the processing of UHTCs with a reinforcing fiber phase for enhanced fracture toughness. Included are fibers of both carbon and silicon carbide composition in both continuous and chopped fiber lengths. Particular emphasis is given to emerging research from the last few years to highlight novel developments.

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.

Polymer‐Derived Ultra‐High Temperature Ceramics (UHTCs) and Related Materials

Ultra‐high temperature ceramics (UHTCs) represent an emerging class of materials capable of providing mechanical stability and heat dissipation upon operation in extreme environments, e.g., extreme heat fluxes, chemically reactive plasma conditions. In the last few decades, remarkable research efforts and progress were done concerning the physical properties of UHTCs as well as their processing. Moreover, there are vivid research activities related to developing synthetic access pathways to UHTCs and related materials with high purity, tunable composition, nano‐scaled morphology, or improved sinterability. Among them, synthesis methods considering preceramic polymers as suitable precursors to UHTCs have received increased attention in the last few years. As these synthesis techniques allow the processing of UHTCs from the liquid phase, they are highly interesting, e.g., for the fabrication of ultra‐high temperature ceramic composites (UHT CMCs), additive manufacturing of UHTCs, etc. In the present review, UHTCs are in particular discussed within the context of their physical properties as well as energetics. Moreover, various synthesis methods using preceramic polymers to access UHTCs and related materials (i.e., (nano)composites thereof with silica former phases) are summarized and critically evaluated.

Preparation and properties of dense ZrB2 composite reinforced by elongated SiC and Al3BC3 grains

AbstractDense ZrB2‐SiC‐Al3BC3 ultra‐high temperature ceramic composite was fabricated by hot pressing sintering at 1900°C for 1 hour under a pressure of 20 MPa using Zirconium diboride (ZrB2) as the raw material and a powder mixture of SiC, B4C, Al, and carbon as the sintering additive. Al and B4C underwent in situ reaction with carbon powder to produce Al3BC3, which promoted the densification of ZrB2 ceramic. SiC grains were found to be elongated during sintering. The ZrB2‐SiC‐Al3BC3 composite exhibited excellent mechanical properties, such as high flexural strength of 589 ± 147 MPa and fracture toughness of 7.81 ± 1.09 MPa m1/2. Oxidation behavior of the ZrB2‐SiC‐Al3BC3 composite was studied in air at 1500°C for 1 hour. A continuous layer of oxides consisting of a mixture of SiO2, Al2SiO5, and Al2O3 was formed on the surface of the ZrB2‐SiC‐Al3BC3 composite. This layer of oxides efficiently prevented oxygen from diffusing into the specimens during oxidation, which improved the oxidation resistance of the ZrB2 ceramics.

Oxidation Behavior of Aerospace Materials in High Enthalpy Flows Using an Oxyacetylene Torch Facility

The oxyacetylene torch facility is used to measure the ablation rates of graphite and the surface temperatures of different aerospace materials. The free‐stream flame environment is characterized as a function of flame chemistry for heat flux, pO2, and flow velocity. Measured ablation rates for graphite increase as a function of increasing heat flux and pO2, which are validated by applying an oxygen diffusion based model. The model uses experimentally measured values for temperature, pO2, and gas velocity in order to confirm torch testing results are reliable and reproducible. Surface temperatures of ultra‐high temperature ceramic composites are measured as a function of increasing heat flux and show an enthalpic cooling effect on the flame during oxidation testing.

Preparation and Properties of 2D Carbon Cloth Reinforced Ultra-High Temperature Ceramic Matrix Composites

In this paper the preparation of carbon fiber reinforced ultra-high temperature ceramic matrix composites was reported. Polymer infiltration and pyrolysis process was used to prepare 2D C/TaC-SiC, C/NbC-SiC, and C/ZrC-SiC composites. The fracture strengths of all the samples were around 300MPa and toughness around 10MPa-m1/2. Standard oxyacetylene torch tests (>3000°C, 30s) showed that the minimum ablative rate of 2D C/SiC-ZrC was as low as 0.026 mm/s, much smaller than that of 2D C/SiC composites (0.088mm/s).

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.

New Ceramic Composite from a Multioxide Eutectic Melt

ABSTRACTNew high temperature ceramic eutectic composites have been obtained. The composite is self-assembled in one quick step by rapid supercooling of the multioxide alumina-YAG-zirconia eutectic in an arc-image lamp furnace. The new material will find applications as in-situ coating and component for use at ultra-high temperature. Periodic self-assembled layered structures kinetically forced to solidify with interspacing in the submicron range will result in very interesting properties and applications for high temperature multioxide oxide eutectic composites, offering the challenge of design of layered nanostructures tailored to specific applications by kinetic control during solidification.

High Temperature Metal and Ceramic Composites

The Materials Division at NASA Lewis is engaged in research and development efforts on behalf of fiber-reinforced composite materials that are lighter, stiffer, and more structurally reliable than conventional monolithic alloys and ceramics in applications that range from the cryogenic to the refractory. Attention is presently given to metal matrix composites, in which high performance depends on stiff, strong and thermally stable large diameter fibers, with chemically stable interfacial bonding and good coefficient of thermal expansion matching between fibers and matrices, and to ceramic matrix composites, in which intermediate strength interfacial bonds must allow cracks to propagate through the matrix only, while retaining good load transfer characteristics between fiber and matrix.