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
c) graphite with low viscosity
ADHESIVE TECHNOLOGIES
Tradename Aremco 670
CeramabondTM
Aremco 569
CeramabondTM
Aremco 835
CeramabondTM
Aremco 685-N
CeramabondTM
Aremco 669
Graphi-BondTM
Co 931
Resbond TM
Major
Constituent Al2O3 Al2O3 ZrO2 - ZrSiO4 ZrO2 - ZrSiO4 Graphite Graphite
Viscosity, cP 2,500 - 5,000 Paste 20,000-40,000 5,000-20,000 20,000 - 40,000 Paste
Temperature
Limit, (°C) 1650 1650 1371 1371 760 2980
CTE,
in/in/oC x 10-6 7.7 7.6 7.2 8.1 7.6 7.38
Performance on
ASTERM© Good Fair Fair Low Good -
Performance on
SICARBON© Good Low Good Low Good -
Pull-off test No material
separation Failed
No material
separation Failed
No material
separation
Partial
failure
Cross section
microstructure Good bonding
Weak bonding
with SICARBON© Good bonding Weak bonding Good bonding
Weak
bonding
Selection Yes No Yes No Yes No
Pre-selection of 3 adhesives:
ADHESIVE TECHNOLOGIES
Low viscosity
High viscosity
High viscosity
Low viscosity High viscosity
Low viscosity
Shear test at NCSRD-Demokritos (Room temperature and LN2)
In the majority of the SICARBON + ASTERM fracture takes place inside ASTERM (similar shear strength of
the ASTERM)
But ultimate shear strain is higher for zirconia and graphite based adhesives.
At LN2 the shear strength, compared to that at RT, increases from 30 % up to 100% because the ablative
material becomes stiffer.
ADHESIVE TECHNOLOGIES
Alumina Zirconia – Zirconia Silicate Graphite
ASTERM
+
SICARBON
Material combination Adhesive
Ult. Shear Strength - USS
(MPa)
Ultimate Shear Strain -
USE (%)
RT LN2 RT LN2
ASTERM© + SICARBON©
Alumina 0.75 ±0.18 - 2.70 ± 0.90 -
Zirconia -
Zirconia Silicate 0.68 ±0.10 0.85 ± 0.08 4.9 ±1.3 5.4 ±3.8
Graphite 0.65 ±0.08 1.30 ± 0.32 3.20 ± 0.60 3.70 ±
0.70
Thermal schock at INCAS
The three adhesives (alumina, zirconia and graphite) characterised under thermal shock
Use of CALCARB (Commercial carbon substrate, similar to ASTERM or PICA preforms), to prevent
damage of the facility.
Samples (30 x 50 x 10 mm3) are heated at a 9.5 ºC/s rate up to 1100 ºC (2 min maintenance).
The temperature is monitored by both a pyrometer and a thermocouple inserted in the joint
Post-test analysis confirms the low performance of the alumina adhesives.
ADHESIVE TECHNOLOGIES
Shear strenght at high temperature (Indutherm)
The material combination is tested at: RT, 150 ºC and 700/900 ºC
ASTERM/SICARBON system fulfil requirements (0.1 MPa) with zirconia at RT, 150 ºC and 700 ºC. With
graphite is very close.
ADHESIVE TECHNOLOGIES
-50
-30
-10
10
30
50
70
90
110
130
150
0,0
100,0
200,0
300,0
400,0
500,0
600,0
700,0
800,0
900,0
1000,0
0 1000 2000 3000 4000 5000 6000
Forc
e [N
]
Tem
pe
ratu
r [°
C]
Timesteps
Sample Interface
Sample Holder
Load cell
Test results at 900 ºC ASTERM/SICARBON sample before and after test at 700 ºC
K. Triantou, K. Mergia, S. Florez, B. Perez, J. Barcena, W. Rotärmel, G. Pinaud, W.P.P. Fischer, Thermo-mechanical performance of an
ablative/ceramic composite hybrid thermal protection structure for re-entry applications, Composites Part B Engineering 12/2015; 82:159-
165. DOI:10.1016/j.compositesb.2015.07.020
PRECERAMIC POLYMERS
AND REACTION BONDED
PRECURSORS
PRECERAMIC POYMERS & REACTION BONDING
When the temperature requirement is quite high (over 1000 ºC) there are two interesting
approaches for the bonding of ceramic substrates, by means of:
Application of preceramic-polymers
Reaction bonded joining
Both methods are derived from techniques from the manufacture of monolithic ceramics and
ceramic matric composites (mainly SiC based)
The use of pre-ceramic polymers involves the application of a polymer which is a precursor of
a ceramic (polysilane, polysiloxane), Further steps are curing and ceramization step (mostly
up to 1600 ºC). Ceramic fillers are added to increase the yield and reduce the shrinkage
Reaction bonded means to “in-situ” obtain the filler from the element precursor. In the case of
SiC from Si and C sources and produce a chemical reaction. Also typically ceramic fillers are
added to increase the yield and reduce the shrinkage.
Both methods have been explored to the joining of CMCs to ceramic lattices (more details are
available at www-thor-project.com)
PRECERAMIC POYMERS & REACTION BONDING
The study has consisted in the trade-off of the different joining routes for the integration of the
SiC/SiC material to the SiC lattice structure:
Ceramic adhesives
Polysilazane modified by different fillers (preceramic polymers)
Phenolic resin modified by fillers (reaction bonding)
After different optimization loops a selected design of the composition was defined.
Different samples trials were performed to evaluate the mechanical behaviour at high
temperature. Shear strength was selected as the best test for the selection route (at AAC)
PRECERAMIC POYMERS & REACTION BONDING
Ceramic adhesives showed reduced adhesion with the base materials at RT. Resbond fails
already at 830 ºC
Preceramic polymers based on phenolic and polysilxane modified with filler showed promising
results
Polysiloxane shows 425 +/-72 N at 1,220 °C
Phenolic Resin shows 633 +/-153 N at 1,220 °C
Both polysiloxane and phenolic Resin have residual strength up to 1,520 °C =>
substantial thermal safety margin
From testing, both bonding systems are suitable for application
Testing of Joints at 1,220 °C
EXAMPLES FOR TPS
CONCEPTS
TPS VALIDATION EXAMPLES
Validation of the joining technologies on different TPS concepts and applications through
three FP7 European projects:
PROJECT APPLICATION JONING TECHNOLOGY VALIDATION
SMARTEES REUSABLE FOR EARTH
ATMOSFERIC RE-ENTRY
• BRAZING • PRECERAMICS
TEST RIG
HYDRA SEMI-REUSABLE FOR EARTH ATMOSFERIC
RE-ENTRY
• BRAZING • ADHESIVES
THERMAL SCHOCK VIBRATION RIG PLASMA WIND
TUNNEL
THOR HYPERSONIC
VEHICLES • REACTION
BONDING ARC JET
HYDRA SMARTEES THOR
TPS VALIDATION EXAMPLES
PROJECT SMARTEES
Definition, selection and implementation of the bonding processes.
External hot-structure to CMC assembly1 -> Temperatures > 1500 ºC
Assembly of stand-offs to the structure2 -> Temperatures < 900 ºC
Multilayer/CMC Joining, Credit:NCRSD/TECNALIA
CMC/Stand-off Joining, Credit:NCRSD/TECNALIA
1. C. Jimenez, M. Lagos, I. Agote, K. Mergia, C. Badini, E. Padovano, C. Wilhelmi and J. Barcena. ““High Temperature Joining Solution For Thermal
Protection Systems Based On Intermetallic Alloys” 37th International Conference and Exposition on Advanced Ceramics and Composites. Daytona
Beach, USA, 27 January – 1 February 2013.
2. X. Hernandez, C. Jiménez, K. Mergia, P. Yialouris, S. Messoloras, V. Liedtke, C. Wilhelmi, J. Barcena, “An Innovative Joint Structure for Brazing
Cf/SiC Composite to Titanium Alloy”. Journal of Materials Engineering and Performance , vol. 23, pp. 3069.3073. ISSN 1059-9495.
TPS VALIDATION EXAMPLES
PROJECT SMARTEES - CMC SANDWICHES
Preparation of upper skin (high temperature joint)
LC1 50 x 50 mm2 sub-scale
samples
LC2 50 x 50 mm2 sub-scale
samples
TPS VALIDATION EXAMPLES
PROJECT SMARTEES - STAND-OFF BRAZING
LC1 50 x 50 mm2 sub-scale samples
TPS VALIDATION EXAMPLES
PROJECT SMARTEES - STAND-OFF BRAZING
LC1 50 x 50 mm2 sub-scale samples
BEFORE BRAZING AFTER BRAZING
The joining process does not produce any
cracks in the foam material!!
TPS VALIDATION EXAMPLES
PROJECT SMARTEES - STAND-OFF BRAZING
LC2 150 x 150 mm2 samples
TPS VALIDATION EXAMPLES
PROJECT SMARTEES –THERMAL TEST
Initial tests
performed in LC1 (target temperature at metallic interface ~600 °C)
and in LC2 (target temperature at metallic interface ~840 °C)
Tests performed under vacuum
30 cycles each
Results:
Neither a mass change nor any visible degradation – apart from the apparent removal of an
oxide layer from manufacturing
LC1 as received LC1 after50 cycles LC2 as received LC2 after 50 cycles
Figure 1: CMC/Ti joints after testing
TPS VALIDATION EXAMPLES
PROJECT SMARTEES –THERMAL TEST
TPS VALIDATION EXAMPLES
PROJECT HYDRA
Validation of brazed and glued structures
CMC/Ti BRAZING ABLATOR/CMC ADHESION
TPS VALIDATION EXAMPLES
PROJECT HYDRA - Infra-red test (Airbus DS SAS)
Use of IR lamps to achieve 0.6 MW/m2
Test duration 60s for graphite and 100s for zirconia adhesive
Temperatures at the Ablator/CMC interface are at the service range of the adhesive: 800 ºC
for graphite and 1300 º C for zirconia.
No apparent and visible damage was observed (debonding or failure)
TCs recording for IR test: Graphite and Zirconia Predicted temperatures
TPS VALIDATION EXAMPLES
PROJECT HYDRA - Vibration test (HALT Facilities at CTA)
5 200010 100 10006 7 8 9 20 30 40 50 60 70 80 90 200 300 400 500 600 700 800
Decade
Unknown (HERTZ)
1e-3
200
10e-3
100e-3
1.0
10
100
2.0e-3
3.0e-3
5.0e-3
7.0e-3
20e-3
30e-3
50e-3
200e-3
300e-3
500e-3
700e-3
2.0
3.0
5.0
20
30
50
Log
Unknow
n (
(G))
S15001_Z_SL.002 AUX Channel 8 000:04:18 0.000 ACL029 (3)x 29-Jan-2015 13:22:40 Bx
S15001_Z_SL.003 AUX Channel 8 000:04:19 0.000 ACL029 (3)x 29-Jan-2015 13:52:05 Bx
5 200010 100 10006 7 8 9 20 30 40 50 60 70 80 90 200 300 400 500 600 700 800
Decade
Unknown (HERTZ)
1e-3
200
10e-3
100e-3
1.0
10
100
2.0e-3
3.0e-3
5.0e-3
7.0e-3
20e-3
30e-3
50e-3
200e-3
300e-3
500e-3
700e-3
2.0
3.0
5.0
20
30
50
Log
Unknow
n (
(G))
S15001_Y_SL.003 AUX Channel 8 000:04:18 0.000 ACL029 (3)x 29-Jan-2015 16:04:52 Bx
S15001_Y_SL.002 AUX Channel 8 000:04:19 0.000 ACL029 (3)x 29-Jan-2015 15:45:32 Bx
5 200010 100 10006 7 8 9 20 30 40 50 60 70 80 90 200 300 400 500 600 700 800
Decade
Unknown (HERTZ)
1e-3
200
10e-3
100e-3
1.0
10
100
2.0e-3
3.0e-3
5.0e-3
7.0e-3
20e-3
30e-3
50e-3
200e-3
300e-3
500e-3
700e-3
2.0
3.0
5.0
20
30
50
Log
Unknow
n (
(G))
S15001_X_SL.002 AUX Channel 7 000:04:18 0.000 ACL029 (2)z 29-Jan-2015 16:59:00 Bz
S15001_X_SL.003 AUX Channel 7 000:04:19 0.000 ACL029 (2)z 29-Jan-2015 17:15:51 Bz
Launcher specifications
Low sine sweep before and after test
Test configuration Z, Y and X axis
TPS VALIDATION EXAMPLES
PROJECT HYDRA - Plasma Wind Tunnel Verification (MAIN CAMPAIGN)
The thickness of the ablator is fixed to 10 and 12 mm
Heat flux of 5MW/m2, stagnation pressure of 3710 Pa, time extended to 85 seconds.
Surface temperature is around 3300 K
Temperature at the ablator/CMC interface
up to 1400 ºC were achieve with 10 mm ablator samples
800 ºC in the 12 mm ablator samples
no visible damage at this interface.
Laser Recession Measurements -> up to 8 mm
More details given by G. Herdrich
TPS VALIDATION EXAMPLES
PROJECT THOR – ASSEMBLY OF SHARP LEADING EDGES
Leading edge thermal management concept based on convective cooling
After curing After pyrolisis
TPS VALIDATION EXAMPLES
PROJECT THOR – ASSEMBLY OF SHARP LEADING EDGES
Ceramization step & assembly
General comments
Visual inspection shows no cracks
appeared after the cycle.
The lattice structure is well joined
to the CMC material
Arc Jet test details at THOR website (www.thor-project.com)
CONCLUSIONS AND
FURTHER WORK
MOTIVATION OF THE WORK
Different joining methods for thermal protection system have been traded-off
Different solutions are envisaged depending on the specific mission and application and the
corresponding temperature levels:
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).
A basic manufacturing study of these three systems have been carried out to determine the
process feasibility basic mechanical properties, heatflux and temperature limits.
A second step have been carried out to verify and qualify the solutions in representative
system re-entry conditions.
Further studies and developments are required to increase the TRL and implement the
solutions in real flight conditions
ACKNOWLEDMENTS
European Space Agency (M. Bottacini and B. Jeusset )
European Commission
Research Executive Agency (C. Ampatzis, T. Branza, P. Mota-Alves)
Airbus Safran Launchers GmbH (W. Fischer)
Airbus Safran Launchers SAS (J.M. Bouilly, G. Pinaud)
EADS-Innovation Works (C. Wilhelmi, F. Meistring).
NCSRD (S. Messoloras, K. Mergia , P. Yialouris, K. Triantou).
ERBICOL SA (D. Gaia and S. Gianela)
Aerospace and Advanced Composites GmbH (V. Liedtke)
SUPSI (M. Barbato, C. D’Angelo and A. Ortona)
Politecnico di Torino (E. Padovano and C. Badini)
Tecnalia (C. Guraya, X. Hernandez, C. Jimenez, M. Lagos, I. Agote, B. Perez, S. Florez, I. Iparraguirre)
HPK Liéges (A. de Montbrun, M. Descomps)
DLR (B. Esser, A. Gülhan, H. Hald, C. Zuber, W. Rotaermel)
HPS (P. Portela)
INCAS (G. Ionscu, C. Band and A. Stefan)
ICMCB (D. Bernard and V. Leroy)
IRS (G. Herdrich, B. Massuti, R. Wernitz)
Tübitak (A. Okan)
JAXA (H. Tanno)
FGE (J. Merrifield and L. Haynes)
Thales Alenia Space (D. Francesconi, M. Portaluppi)
The research leading to these results has received funding from the European Union Seventh
Framework Programme (FP7/2007-2013) under grant agreement n° 262749, 283797, 312807
ACKNOWLEDMENTS
MANY THANKS FOR YOUR
ATTENTION!
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