bionic aircraft · 2018-10-08 · bionic aircraft repair of al components by low temperature high...

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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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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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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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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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+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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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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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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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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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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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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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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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: [email protected]

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

mailto:[email protected]

bionic aircraft · 2018-10-08 · bionic aircraft repair of al components by low temperature high...

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