Materials characterisation and mechanical properties of Cf-UHTC powder composites

Abstract

Ultra-high temperature ceramic composites based on carbon fibre, Cf, preforms impregnated with hafnium diboride, HfB 2 , powder and then densified with carbon by chemical vapour infiltration, CVI, have been mechanically tested to measure the room temperature flexural, interlaminar shear, compressive and tensile strengths.

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

“…The structure of the Cf preforms consisted of layers of fabric stacked in an arrangement of random/0°/random/90°/random orientation fibers, where 0° and 90° are unidirectional layers and the random layers were formed as a result of Surface Transform's needling process. The Cf preforms were impregnated using a new injection vacuum impregnation (IVI) process, details of which can be found elsewhere . In brief, however, it should be noted that one of the main advantages of the new process is that it has been shown that the resulting powder distribution within the preform is very homogeneous .…”

“…17 In brief, however, it should be noted that one of the main advantages of the new process is that it has been shown that the resulting powder distribution within the preform is very homogeneous. 17 The Cf preforms were injected manually with the slurry. The injection procedure was to insert the needle from the top to the bottom of the preform and then to inject the slurry as the needle was withdrawn at a constant velocity and with a constant pressure on the syringe to achieve a homogeneous distribution of the slurry across the full thickness of the samples.…”

“…This paper focused purely on composites that are based on carbon fibers and a carbon matrix deposited using CVI, ie conventional C/C composites, but into which slurries of HfB 2 powders have been injected prior to the CVI stage with the specific goal of enhancing the oxidation and ablation resistance. The processing of these UHTCMCs have been extensively investigated and their mechanical performance has been reported …”

“…The processing of these UHTCMCs have been extensively investigated 16 and their mechanical performance has been reported. 17 The thermophysical and thermomechanical characteristics of these composites are of critical importance, however, and both the type and amount of UHTC powder involved has a significant effect on the resulting performance. 18 In terms of the thermophysical performance of the composites, the thermal diffusivity, conductivity, coefficient of thermal expansion (CTE), and specific heat capacity all affect the behavior of the composite as a function of temperature as well as its ability to avoid failure due to thermal shock.…”

Effect of Acetone Content on the Preparation Period and Curing/Pyrolysis Behavior of Liquid Polycarbosilane

“…It is necessary to introduce ceramic phase into carbon fiber braid in practical production; therefore, the quality of CMCs will largely depend on the properties of the ceramic matrix and the mobility of ceramic precursors. Among CMCs, C/SiC composites or ultra-high-temperature ceramic (UHTC)-modified C/SiC composites are the most important materials in the engineering application [10][11][12][13], and the composites are usually fabricated by the precursor infiltration and pyrolysis (PIP) process using polycarbosilane precursors as raw materials [14][15][16].…”