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.

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Optimization of a Pyrolysis Procedure for Obtaining SiC-SiCf CMC by PIP for Thermostructural Applications

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.77.153 ◽

2012 ◽

Vol 77 ◽

pp. 153-158 ◽

Cited By ~ 1

Author(s):

Claudio Mingazzini ◽

Alida Brentari ◽

Federica Burgio ◽

Emiliano Burresi ◽

Matteo Scafè ◽

...

Keyword(s):

Chemical Vapour ◽

Ceramic Matrix Composites ◽

Cost Effective ◽

Ceramic Matrix ◽

Pyrolytic Carbon ◽

Matrix Composites ◽

Mechanical Characterisation ◽

Steel Furnace ◽

Cost Effective Technique ◽

Polymer Impregnation

Polymer Impregnation Pyrolysis (PIP) is a cost effective technique for obtaining Ceramic Matrix Composites (CMC) modified with nanoparticles. Commercial UBE polymeric precursor (Tyranno polymer VL-100, diluted in xylene) of a SiC ceramic matrix (with 11 wt% O and 2 wt% Ti) was used to infiltrate 100x85x3 mmSuperscript text3 SiC felts (Tyranno ZM fibers, diameter 14 microns, 800 filament/yarn, 270 g/mSuperscript text2, with 9 wt% O and 1 wt% Zr), applying different pyrolysis procedures. In particular, pyrolysis was performed in two conditions: 1) at 1000 °C for 60 min; 2) at 900 °C for 120 min. A pyrolysis at 900 °C could be more convenient since it can be easily performed in a steel furnace, without a refractory lining. The SiC felts were pretreated by CVD (Chemical Vapour Deposition) in order to deposit a pyrolytic carbon interphase (about 0.1 microns). Impregnation was performed under vacuum, and drying was carried out in an explosion-proof heating oven. Pyrolysis at 900°C was performed in a AISI 310S austenitic steel furnace, under nitrogen flow. Geometric density was monitored during densification. Mechanical characterisation (bending tests at room temperature, following UNI EN 658-3:2002) was performed after 11 PIP cycles. The results were used to compare the influence of pyrolysis temperature on densification.

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