Temperature Ceramic Matrix Composites Research Articles

From properties of zirconium carbide to the reverse design of ultra‐high temperature CMCs

AbstractThe development and commercialization of aerospace vehicles have posed significant challenges to the performance requirements for the corresponding materials. To meet these challenges, ceramic matrix composites (CMCs) have been developed and are widely used in the aerospace industry. However, their stability under extreme environmental conditions still needs to be improved. In this review, some properties of zirconium carbide (ZrC), which are related to extreme environmental applications of CMC are discussed first. Then, the effect of ZrC on the properties of CMC is comprehensively reviewed. ZrC can be introduced into the matrix and coated on the surface to increase the ablation resistance. The protection mechanisms of ZrC addition to CMCs, and the improvement in ZrC ablation resistance are explained. In addition, some perspectives on future developments are given.

Characterization of temperature dependence of fracture behavior of monolithic and laminated ultra‐high temperature ceramic matrix composites

AbstractThe fracture behavior of ultra‐high temperature ceramic matrix composites at high temperature has received increasing attention. However, few studies consider the effect of particle/crack interaction on the high temperature fracture strength of materials. In this work, the effect of particle/crack interaction is introduced into temperature‐dependent fracture strength model of monolithic ultra‐high temperature ceramic matrix composites, which also considers effects of flaw size, grain size, and residual thermal stress. Furthermore, by considering the influence of laminated structure, a theoretical model of the temperature‐dependent fracture strength of laminated ceramic matrix composites is developed. The effect of particle/crack interaction is also included in this model. It should be noted that the predictions of models agree well with the experimental data of both monolithic and laminated materials without using any fitting parameters. The effect of particle/crack interaction is found to have a significant weakening effect on the strength of materials at different temperatures.

Thermal properties and performance of carbon fiber‐based ultra‐high temperature ceramic matrix composites (Cf‐UHTCMCs)

AbstractThe thermophysical properties of carbon fiber‐based ultra‐high temperature ceramic matrix composites have been determined to aid designers who need these properties when considering using the composites in ultra‐high temperature aerospace applications. The coefficient of thermal expansion (CTE) and thermal diffusivity of the composites were measured parallel and perpendicular to the ply direction; the thermal conductivity was measured using the laser‐flash method and the heat capacity calculated from the relationship between the thermal diffusivity, density, and thermal conductivity. Both the CTE and thermal conductivity showed higher values across the ply and increased with increasing temperature as expected, whilst the thermal diffusivity showed higher values parallel to the ply and increased smoothly with temperature. In addition, two different but related oxyfuel torch tests, based on oxyacetylene and oxypropane, were used to evaluate the thermo‐ablation behavior of the composites. The tests showed how good the composites were at withstanding the ultra‐high temperatures, high heat fluxes, and gas velocities involved.

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.