bionic aircraft · 2018-10-08 · bionic aircraft repair of al components by low temperature high...
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1
Development
Consulting
Education
Research
Bionic AircraftRepair of Al components by low temperature high velocity combustion spraying for aeronautic applications
Dr.-Ing. M. Parco, A. Gómez, I. Fagoaga, G. Barykin, C. Vaquero (Tecnalia)
8th EASN-CEAS International Workshop on
Manufacturing for Growth & Innovation
4-7 September 2018, Glasgow, UK
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Chapters
About Tecnalia..
Background and motivation
Proposed repair technologies
Implemented feedstock materials
Thermal Spray approach: process development
Laser Metal Deposition approach: process development
Conclusions & outlook
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About TECNALIA
TECNALIA is the first applied
research centre in Spain and one
of the most important in Europe
with 1.405 people on staff,
102.1€ millions turnover and
more than 4.000 clients.
A unique commitment, an opportunity, a challenge.
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About TECNALIA
Organized in 7 Business Divisions:
TECHNOLOGICAL
SERVICES
SUSTAINABLE
DEVELOPMENT
SUSTAINABLE
BUILDING
ICT - European
Software Institute
INNOVATION
STRATEGIES
HEALTHINDUSTRY &
TRANSPORT
HEADQUARTERSParque Científico y Tecnológico de Gipuzkoa
Mikeletegi Pasealekua, 2
E-20009 Donostia - San Sebastián (Gipuzkoa)
Tel.: 902.760.000
Aerospace Unit
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Background and motivation
Main goals:
(1) Development of new concepts for high added value repair and recovery of ALM parts based,
including the development of process itself and the investigations of possible post-processing steps
(e.g. laser re-melting, thermal treatment).
(2) Validation of developed repair-concepts on complex ALM.
→ Current repair methods for dimensional restoration of aluminum and magnesium
structures like plasma spray, HVOF, and epoxy bonding, offer no structural benefit
when applied to the affected area.
→ Fusion welding processes while capable of producing structural repairs, often result in
unacceptable dimensional defects due to the thermal residual stress and deformation
resulting from the solidification of the melted material caused by the high thermal
input.
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Proposed repair technologies
High velocity combustion spraying with
controlled temperature (HVOAF process)
• High process flexibility → Thanks to the use of air-
oxygen mixtures and a carefully designed gun, the
system is able to operate with extremely low flame
temperatures (warm spray concept!)
• Suited for the repair of large surfaces, with low thermal
input into the part.
LASER Metal Deposition (LMD process)
• Use of commercial system (TRUMF TruLaser Robot
5020) – Fraunhofer IAPT.
• More suited to local repair and more complex part
shapes.
Two complementary approaches
TECNALIA’s
Technology
High Velocity Oxy/Air-Fuel (HVOAF) spraying
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Proposed repair technologies
Addressing Challenges:
Thermal loading of the part: Limit the heat input
into the repair zone, that would lead to part
deformation and high residual stresses.
Wall thickness: Adapt the technology for minimum
thickness requirements on the part being repaired
– wall thickness down to 5 mm.
Repair of complex surfaces: The repair of parts
with curvatures is clearly much more challenging
than repairing flat surfaces.
Repair of structural parts: Need to match the
mechanical properties of the base material.
Simplified geometries
Not suited for restoring thin sections or highly complex structures!
Focus on surface defects rather than flaws evolving from internal defect!
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Implemented feedstock materials
AlSi10Mg (20-63; 45-90; 45-105 m) Spherical powders produced by the induction plasma atomization process at TEKNA
(20-63 m)x200 (45-105 m)(45-90 m)
Feedstock powders from reference material composition (AlSi10Mg)
x200 x200
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Implemented feedstock materials
+20/-63 µm +45/-95 µm -100 µm
d10: 42.49 m; d50: 63.11 m; d90: 93.89 m d10: 15.73 m; d50: 27.58 m; d90: 48.05 m
Final powders: Concept D (AlSi16Sc0.4Zr0.2) / Gas atomised
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TS approach: process development
Main related activities / Main technological challenges
Microstructural, chemical and
mechanical characterization
PropietaryTS technology
(HVOAF) – Gun design
optimization for Al processing
(5 gun design tested)
Feedstock powders:
Spherical particles
between +10/-150 µm
Deposit in thicknesses
of up to 2 mm on cast /
ALM plates in AlSi10Mg
Main development stages & challenges
Start with existing (1st) and
pre-developed design (2nd).
Optimization of critical gun
modules for Al processing:
Powder injector, nozzle.
Process stability, key factor!
Assessment of most suitable
particle distribution in
combination with the gun
design.
Solve problems linked to Al
processing: gun clogging!
Development of suitable
parameter window for Al
alloy deposition on Al base
plates.
Substrate pre-treatment?
(Gri-blasting, pre-heating)
Manufacture of required
samples with the available
feedstock powders.
Optimization of
metallographic preparation
procedures.
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TS approach: process development
Main outcomes during the deposit development process
Small parameter changes
result in either no coating
formation (too cold flame) or
severe sticking of the
powder to the gun barrel
(too hot flame).
Moderate particle sticking to the gun
barrel after few minutes of operation.
Porous deposits, with evidences of
material deposition in solid state.
O content: 0.072% (720 ppm).
Surface roughness: >17 μm in Ra.
AlSi10Mg can be processed within a much
wider parameter window without the
undesirable particle clogging effect.
Dense deposits, with evidences of deposition
in solid / semi-solid state.
Better mechanical anchoring to the substrate
→ better adhesion.
Development of deposits of ASi10Mg
Powder’ PSD in +20 /-60 m initially
used at IAPT – 1st gun config.
Powder’ PSD in +45/-90 µm from
TEKNA – 3rd gun config.Powder’ PSD in , +45/-105µm
from TEKNA – 4th gun config.
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TS approach: process development
Powder PSD: -95+45 µm
Main outcomes:
Same processing conditions as for
AlSi10Mg (particles deposited in solid-
state): Resulting deposit microstructure
evidences the partial melting of the
feedstock material in the flame (in
principle attributed to the presence of
eutectic phase AlSi12).
Relatively porous deposits, with
porosities around 3-5%.
O content (as deposited condition):
0.163% (1,600 ppm).
Surface roughness: 16.5 ± 0.3 μm
in Ra, 83.9 ±14 μm in Rz.
Higher melting limited by particle
clogging in the nozzle.
Development of deposits of AlSi16Sc0.4Zr0.2
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TS approach: process development
Assessment of restored volumes with 12/25 mm in length x 2 mm
Repair material: Concept D (AlSi16Sc0.4Zr0.2) / PSD<100µm
Manufacture of 1st group of tensile/bending test specimens (IAPT)
5 mm
Characterization of mechanical properties
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TS approach: process development
Bending test Tensile test
Sample ref.Repaired
volume (mm3)
Bending strength
(MPa)
Module (MPa)
O-M-T4-01, 02, 03 12 x 25 x 2 181 4 9010 266
O-M-T4-04, 05, 06 25 x 25 x 2 178 5 8369 123
O-M-T4-09, 10, 11 NA 573 10 24647 380
• Thermal sprayed region broke at first and then
delaminated from the base material.
• Finally, the specimen fractured as the base material
broke. Failure of the thermal sprayed region is brittle
(perpendicular to the drawing direction), while failure
of ALM built base material is mixed brittle/ductile
(45° to the drawing direction).
• Weakening and embrittlement of the base material
through the machining step (volume removal).
Corrected values
deducting the
volume restored by
TS AND values for
base material after
machining without
volume restore
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TS approach: process development
Further Development of deposits of AlSi16Sc0.4Zr0.2
5th gun configuration:
• Axial powder feeding and gun nozzle design, but
modifications introduced in the combustion
chamber.
• Wider parameter window, processing of fine
fractions possible and shit to higher spray
distances.
• Very dense deposits with fine fraction (+20/-63
µm). Medium size fraction results in moderate
porosity (<2%).
• Deposition efficiencies (DE) of 35% for powders
with PSD between 45-95 µm). Increase of DE
up 80% when using fine fractions (20-63µm).
Powder PSD: -20+63 µm
Deposit, DE:80%
x40Substrate
x200
x40
Powder PSD: -45+95 µm Deposit, DE:35%
Substrate
x200
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LMD approach: process development
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LMD approach: process development
Width of the bead is almost constant (around
5,5mm) and seems to be independent from the
process parameters.
The maximum of deposition rate is obtained with
the soft condition (ref.2: Low P, low V, High F).
The depth of penetration is of 2.8mm (on a 10mm
support thick) with the hardest condition for the
support (ref.6: High P, low V).
The densest beads are achieved for low feeding
rate F, low velocity V and low power P.
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LMD approach: process development
Ref.10
No cracks were detected between
the beads.
Porosity of ~1.2% but difference
can be seen between the first bead
and the last one. It seems that the
annealing former beads due to the
second LMD path enhanced the
degasification.
Overlapping tests Influence of support thickness
10 mm 5 mm 2 mm
“Soft condition” P=3500W, V=0.17mm/min, F=11.6g/min.
10 mm 5 mm 5 mm with a
groove of 1 mm
“hard condition”: P=5200W, V=0.01mm/min, F=11.6g/min.
When reducing the thickness with a
groove, the bead always cross through
the support.
Influence of ALM support
Cast support
ALM support
Deposits with higher porosity on
ALM supports, probably due to
degasification of hydrogen from the
SLM support during the laser path.
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Conclusions & outlook
Factor of comparison Thermal Spraying Laser Metal Deposition
Density of the deposit and
suitability to restore
volumes on ALM parts-
Almost fully dense deposits out of AlSi10Mg and
AlSiSc in as-sprayed condition (<1%).
No differences observed on cast or ALM supports.
lSi10Mg bBeads with a porosity as low as 0.5%
have been achieved on cast supports, but porosity
dramatically increases up to 8.8% when depositing
on ALM supports.
Wall thickness of the
repaired component
Thick deposits of up to 2 mm in thickness achieved
on flat plates with thickness down to 2 mm.
Trials performed on flat plates with thickness down
to 5 mm with intensive melting/deformation of the
base material. Possible adjustment through the
decrease of the power density must be still proved.
Building rate Even in high deposition efficiencies can be reached
when using the right feedstock powder sizes (80%),
several spray passes are needed to deposit 2 mm
(around 40 spray passes).
Few milometers (2-4 mm) could be restored in two
passes (beads).
Safety issues The large amount of over spray material imposes the
need of special means/procedures to dispose the
scrap powder and mitigate explosion risks.
High reflection of Al base materials imposes the
need of special means/safety conditions to protect
the hardware and operators during deposition.
Mechanical properties of
the repaired part
Based on preliminary results, further improvements
needed to increase the deposit cohesion/ductility.
Assessment of higher melting degree/deposit density
in progress.
Not tested yet, but presumably good, since the
deposited material is fully melted and adhesion to
the base material is guaranteed by the formation of
a thick diffusion zone.
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Dr.- Ing. María ParcoLeader of theThermal Spray Group
Industry and Transport Division
TECNALIA
Parque Tecnológico de San Sebastián
Mikeletegi Pasealekua, 2
E-20009 Donostia-San Sebastián -
Gipuzkoa (Spain)
M +34 667119601
e-mail: maria.parco@tecnalia.com
Thank you for your attention!
This project has received funding under the European Union's Horizon 2020 research and innovation programme under grant agreement No 690689
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