Evaluation of the high temperature performance of HfB₂ UHTC particulate filled C_f/C composites

Abstract

Room and high temperature flexural strength and coefficient of thermal expansion (CTE) of HfB2 ultra‐high temperature ceramic (UHTC) particulate filled Cf/C composites are determined along with UHT oxidation behavior. Both room and high temperature strength of the composites were found to be broadly comparable to those of other thermal protection system materials currently being investigated. The CTE of the composites was measured both along and perpendicular to the fiber direction up to 1700°C and the values were found to depend on fiber orientation by approximately a factor of 3. Arc‐jet testing of the UHTC composites highlighted the excellent ultra‐high temperature oxidation performance of these materials.

Development of a slurry injection technique for continuous fibre ultra-high temperature ceramic matrix composites

“…Low solid content, however, translates into low UHTC powder content in the final composites, which can reduce oxidation resistance significantly. Similar results have been obtained by the current research team [28,35,36]. Slurries containing both UHTC powder and a carbon matrix precursor were used for the production of HfB 2 modified C f /C test pieces.…”

“…Details of the measurement procedures may be found elsewhere [37]. Oxyacetylene torch testing proceeded in a purpose built facility at the University of Birmingham, as described in previous publications [28]. Flow rates of 0.8 m 3 hour -1 for acetylene and 1.1 m .…”

“…In particular, there is a lack of data on many of these variables; numerous studies simply opt to describe the composite and omit important fabrication details. Nevertheless, common features across materials that are found to be hard to impregnate are primarily large preform sizes [24,25] and 3D architectures [25,26], whilst the use of large particle sizes in the slurry [25,27] and volatile carrier fluids [27,28] cause similar issues. Penetration mechanics resulting in the clogging effect [29] of larger particles observed at the entrance of micro porosity, as in fibre tows, means that these variables are very relevant.…”

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

“…The contribution of each constituent phase to the final CTE can be estimated provided the mass fraction of each of the constituents is known. For this reason, the values of CTE for Cf‐HfB 2 composite reported preciously, 1.77 × 10 ‐6 °C −1 and 4.70 × 10 ‐6 °C −1 along and across the plies, respectively, were slightly higher than the present work due to the higher quantity of HfB 2 powder in the Cf preform, reflected by the higher final composite densities.…”

Oxidation response of a SiCf/SiC CMC with a HfB2-based coating in an arc jet test

“…To improve ablation resistance of C f /C, coatings or infiltrations of SiC [1][2][3][4][5], MeC (Me: Zr, Hf, Ta, W, etc.) and MeB 2 UHTCs have been utilised and have shown improved oxidation and ablation resistance [1,[6][7][8][9][10]. Formation of SiO 2 , through passive oxidation of the SiC, extends the use range to around 1650°C, where the in situ formed glass layer begins to soften and can flow from the surface under shear.…”