ADVANCED JOINING TECHNOLOGIES FOR THERMAL PROTECTION SYSTEMS ADMACOM workshop 14 - 15 September 2016 Regione Piemonte - Bruxelles Dr.-Ing. Jorge Barcena Industry and Transport Division TECNALIA Research & Innovation C. Jimenez, S. Florez, B. Perez, X. Hernandez, K. Mergia, K. Triantou, V. Liedtke, C. Wilhelmi, W. P.P. Fischer, J.-M. Bouilly, A. Ortona and B.Esser
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ADVANCED JOINING TECHNOLOGIES
FOR THERMAL PROTECTION
SYSTEMS
ADMACOM workshop
14 - 15 September 2016
Regione Piemonte - Bruxelles
Dr.-Ing. Jorge Barcena
Industry and Transport Division
TECNALIA Research & Innovation
C. Jimenez, S. Florez, B. Perez, X. Hernandez, K. Mergia,
K. Triantou, V. Liedtke, C. Wilhelmi, W. P.P. Fischer,
J.-M. Bouilly, A. Ortona and B.Esser
MOTIVATION OF THE WORK
APROACHES USING BRAZING TECHNOLOGIES
USE OF ADHESIVE BASED TECHNOLOGIES
USE OF PRECERAMIC POLYMERS AND REACTION BONDED PRECURSORS
EXAMPLES FOR TPS CONCEPTS
CONCLUSIONS AND FURTHER WORK
ACKNOWLEGMENTS
MOTIVATION OF
THE WORK
MOTIVATION OF THE WORK
There is a strong interest in the development of new system concepts (lighter, cost efficient,
more robust) to accessing and return from Space. I.e. new reusable systems, novel ablator
materials, hybrid material concepts, etc…
Those new solutions demands a huge effort, not only in the development of new materials but
also in the integration of them into the subsystems.
Current state-of-the-art protection materials is mainly based on bolted solutions. The
approach is now to keep the bolted solution at the cold structure. The foreseen advantages
are:
Increased reliability of the system against failures, vibrations, etc…
Decrease the complexity of the system: simpler S/O and fixation (bolts not exposed to
plasma)
Cost efficient structures: easy reparability and tile replacement.
Therefore we propose the use of advanced joining technologies as method for integration of
multimaterials on complex thermo-structural shield.
Integration with substrate and subsystems is a big challenge!
MOTIVATION OF THE WORK
The envisaged solutions are based on “in-situ” joining technologies able to create sound
bonding on the different TPS subsystems:
Integration of ceramic matrix composites
Assembly of S/O
High temperature gluing of ablator systems
These technologies are classified according to the different joining processes and the thermal
levels of new system concepts:
Brazing technologies, for the assembly of stand-off and able to withstand temperature
levels up to 1000 ºC
Use of adhesive based technologies (up to 1200 ºC), for the assembly of ablators or
reusable systems.
Use of preceramic polymers and reaction bonded precursors for high and ultrahigh
temperature (above 1500 ºC).
The development and verification approach according to the different envisaged missions is
showed, including physical, mechanical and thermal characterisation addressed to the
envisaged applications, such as capsules for earth re-entry, leading edges for hypersonic
vehicles and so on.
APROACHES USING
BRAZING TECHNOLOGIES
BRAZING TECHNOLOGIES
The brazing technology involves the joining of two dissimilar materials substrates by means of
the incorporation of a third material in-between, commonly a metal filler (foil, paste or
powder) which is heat-up above its melting temperature (liquidus)
Special attention must be paid to the CTE mismatch of the whole system. Typically the filler
metal must have an intermediate value between the base materials to be joined.
Also important parameter are wetting and the diffusion of the filler metal to the surface and
the reaction of the filler metal with the substrates.
The temperature limit of this technology is around 900 -1000 ºC, depending on the nature of
the filler metal and substrates.
The envisaged approach is specific for the joining of Ceramic matrix composites with Titanium
parts, particularly in term of the joining of S/Os:
Substrates: CfSiC (SICARBONTM from AIRBUS Group) and Ti6Al4V – Grade 5 (Ti shop)
Metal filler: TICUSILTM (Ag-26.7Cu-4.5Ti, wt.%), paste form from WESGO.
The selected system for the study was:The brazing was carried out in an IPSENVFCK-124
(HV) vacuum furnace. The brazing temperature was 930C and the holding time 10 min.
BRAZING TECHNOLOGIES
The joining or flat surfaces showed poor mechanical properties. In order to address the
problem an innovative approach was implemented, which consists in manufacturing a
perforation on the CMC, with two patterns and different parameters;
BRAZING TECHNOLOGIES
Joints specially fabricated for the mechanical tests are tested in INSTRON universal testing
machine in which the force was applied at a speed of 1 mm/s to determine the shear strength.
The joint area was 20 x10 mm2.
The determined average shear strength of the CMC was 6.2 MPa (ILSS).
This procedure results in six-fold increase of the shear strength of the joint compared to the
unprocessed CMC
BRAZING TECHNOLOGIES
The mechanical shear tests show that failure occurs always within the ceramic material and
not at the joint level.
A fracture mechanism is proposed. More than one CMC interlayers are involved. This is
further confirmed by the fact that the low depth perforations (B1_S, B2_S) do not have an effect
on the shear strength.
Fracture surfaces of perforated CMC/Ti alloy brazed joints
Schematic drawing of the CMC/Ti alloy joint with non-perforated (left) and
perforated CMC (right).
C. Jiménez, K. Mergia, M. Lagos, P. Yialouris, I. Agote, V. Liedtke, at al. Joining of ceramic matrix composites to high temperature ceramics
for thermal protection systems., Journal of the European Ceramic Society 10/2015; 36(3). DOI:10.1016/j.jeurceramsoc.2015.09.038
BRAZING TECHNOLOGIES
At the CMC/filler, Ti from the filler metal interacts with the SiC matrix to form carbides and
silicides.
BRAZING TECHNOLOGIES
Additional shear test at high temperature have been performed (up to 600 ºC), at AAC at their
tets rig chamber.
The strength is still around six times higher as compared with the baseline solution: 6.97 ±
0.32 MPa vs. 1.00 ± 0.24 MPa
Test Rig Chamber & Set-up
Shear load results: No perforations ( left) and with perforations (right)
BRAZING TECHNOLOGIES
Another important issue is the fact that the perforation could guarantee a non catastrophic
failure
Comparation of the results obtained at RT
USE OF ADHESIVE BASED
TECHNOLOGIES
ADHESIVE TECHNOLOGIES
The high temperature adhesive technology involves the application of an inorganic glue
(ceramic particles + silicate binder) between to substrates and its further curing step. The
adhesive withstand the mechanical loads at high temperature due to the pyrolisis of the
binder and the performance of the ceramic fillers.
Usually these technologies are coming from US, while the development in Europe and its
commercially availability is quite limited.
Product Portfolio from AREMCO (US)
The adhesive technology has been employed to glue a low density ablator (ASTERM) onto a ceramic
matrix composites (SICARBON).
6 different adhesives has been envisaged for both hybrid family systems
Pull-off test and wetting tests and microstructural investigation has led to the pre-selection of 3 adhesives:
a) alumina with low viscosity
b) zirconia and zirconia silicate with high viscosity and