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Florian Wirth (IWF, ETH Zürich)

22.10.2018 1

Additive Manufacturing of Metal Matrix Composites

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Introduction: The LMD process Powder nozzle simulation Melt pool simulation

22.10.2018 2

Contents

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Introduction: The LMD process

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Laser beam maintains a melt pool Powder supply into the melt pool Feed motion of laser beam and powder jet Multiple overlapping weld beads form a layer/coating Multiple layers form a 3D part

22.10.2018 4

The Laser Metal Deposition (LMD) process

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Coating against corrosion/wear Repair Additive manufacturing of 3D parts

22.10.2018 5

Application

50 mm

mining power generationmaterial processing

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Powder nozzle simulation

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One sixth of the three-jet powder nozzle and the space below is modeled

Used modules Turbulent flow k-ɛ Transport of

concentrated species 3 gases: He, Ar, Air

Particle tracing

22.10.2018 7

Powder nozzle model

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Results: Oxygen concentration, powder jet

carrier gas 5 l/min He 5 l/min Ar 5 l/min Ar

shield gas 15 l/min Ar 15 l/min Ar 5 l/min Ar

O2

vol.

%

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Oxidation can be reduced by He instead of Ar as carrier gas Reduced carrier gas flow rate (often not possible) Powder nozzle design: Larger powder channel Ø

22.10.2018 9

Absorptivity measurement

0.40.45

0.50.55

0.60.65

0.7

5 10 15

abso

rptiv

ity

shield gas flow rate Ar [l/min]

0.40.45

0.50.55

0.60.65

0.7

5 l/min Ar 3.5 l/min Ar 5 l/min He

abso

rptiv

ity

carrier gas

ba

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Melt pool simulation

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Used modules (in the 1st step) Heat transfer Laminar flow

→ Surface tension, Marangoni effect Deformed geometry Boundary PDE

→ Tracing of freely deforming surface

2nd step Particle tracing Behavior of carbide

particles inside themelt pool

22.10.2018 11

Model overview

deformed geometry

pow

der /

lase

r be

am a

xis

xy

z

outlet

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Absorptivity Melt pool Solid material Powder

(Attenuation → from powder jetsimulation)

Powder particle densitydistribution (→ powder jet Ø)

22.10.2018 12

Crucial input data

10 mm

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Good agreement between experiment and simulation in the case of sufficient bonding and low dilution

22.10.2018 13

Validation

2 mm

9

11

13

15

10

12

14

16

1

5

3

7

2

8

6

4

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Metal powder is mixed with carbide particle powder

The melt pool flow has only a minor effect on the carbide particle distribution The homogeneity of the carbide particle distribution can be improved by a

shorter melt pool lifespan and a proper choice of the particle size22.10.2018 14

Additive Manufacturing of MMCs

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Aknowledgement