free electron laser nitriding of metals - aps physics electron laser nitriding of metals: from basic...
TRANSCRIPT
16. Juni 2006
University of Göttingen
University of Göttingen, 2nd Institute of Physics© Peter Schaaf - www.schaaf.physik.uni-goettingen.de 1
Free electron laser Free electron laser nitridingnitriding of metals:of metals:from basic physics to industrial applicationsfrom basic physics to industrial applications
Peter SchaafPeter Schaaf a)a), M. , M. ShinnShinn b)b), E. , E. CarpeneCarpene a)a), J. Kaspar, J. Kaspar c)c)
Zweites Physikalisches InstitutZweites Physikalisches Institut
APS April Meeting 2006, Dallas,TX
Thin Film or FunctionalCoating: made fast
Substrate, work piece
Reactive ornon-reactiveatmosphereN2
Laser Nitriding
a)
b)
c)
University of Göttingen, 2nd Institute of Physics2© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Applications of Thin Films and Coatings
University of Göttingen, 2nd Institute of Physics3© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Preparation/Modification of Thin Films and Coatings
Laser Synthesis of Thin Films and Coatings (Nitriding, Carburizing, Hydriding): experimental principles, interactions, melt, plasma, dynamics, diffusion, solidification, …
Fe-N and Fe-C, Austenitic stainless steelTiN and TiCAlN and AlCSi3N4 and SiC (IBM-Milliped)Laser-Conditioning of MagnesiumLaser-Hydriding Ti-HProduction pc-a:Si(H) (TFT)β-FeSi2 (photovoltaics, optoelectr.)Fe/Ag Multilayers by PLD (GMR, TMR) Polymer-PLD (Applications)Epitaxial recrystallisation (SiC, SiO2)
Excimer LaserExcimer Laser 55 ns55 nsNd:YAG LaserNd:YAG Laser 8 ns8 nsFELFEL 1 1 pspsTi:SapphireTi:Sapphire 150 150 fsfs
University of Göttingen, 2nd Institute of Physics4© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
University of Göttingen, 2nd Institute of Physics5© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Laser Synthesis: temperature, plasma
0 100 200 300 400 500300
1000
2000
3000
4000
5000
6000
7000
Tb
2 J/cm²
2.5 J/cm²
3 J/cm²
6 J/cm²
8 J/cm²
laser pulse
4 J/cm²
Tkrit.
Tm
surfa
ce te
mpe
ratu
re T
s [K
]
time t [ns]
105 10 K/sdTdt
= − ⋅
0 100 200 300 400 5000
200
400
600
800 8 J/cm²6 J/cm²
3 J/cm²
2.5 J/cm²
2 J/cm²
4 J/cm²
mel
ting
dept
h d liq
(t) [n
m]
time t [ns]
liq 5.25m/sd d
dt= −
Fe
plasmaplasma--formationformation
evaporationevaporationablationablation
Excimer Laser: Excimer Laser: λλ=308 nm (4.03 =308 nm (4.03 eVeV))ttpp=55 ns (FWHM), 5x5 mm=55 ns (FWHM), 5x5 mm²²,,H=4 J/cmH=4 J/cm²² (I(I00=70 MW/cm=70 MW/cm²²))
vacuum: vacuum: PLDPLD
but: ambient atmosphere at high pressure prevents ablation, causes high pressures, chemical reactions,take-up into liquid surface, re-solidification, coating forms
FeFe
Laser
Numerical: FDM, incl. evaporation, Knudsen
gas transparent for laser
1-10 bar N2
University of Göttingen, 2nd Institute of Physics6© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Fe, 9 bar9 bar N2, 4 J/cm²
surfacesurface
Process: Principle of Laser Synthesis
Fe, 1 bar1 bar N2, 4 J/cm²
Fe, 9 bar9 bar N2, 4 J/cm²
ImportantImportant: melt pool and plasma dynamics: melt pool and plasma dynamicsPlasma: expansion, but gas pressure, Plasma: expansion, but gas pressure, Laser Laser ⇒⇒ Laser Absorption Waves (LSAW)Laser Absorption Waves (LSAW)LSC LSC –– Laser Supported Combustion WaveLaser Supported Combustion WaveLSD LSD –– Laser Supported Detonation WaveLaser Supported Detonation Wave
Plasma (600 ns) :Laser pulse: 55 ns
surfacesurface
10
20
40
60
150
350
600
10m
m
Hom. Beam0.1 MPa 0.9 MPa
ns600 ( )
3112
0
02⎥⎦
⎤⎢⎣
⎡⋅−=ρ
γ IvLSDw
LSD-modelincreased gas pressureincreased gas pressure ⇒⇒ plasma expansion more slowly –Plasma pressure higher and lasts longer!pp: 1 bar : 500 bar – 9 bar : 1050 bar
surfacesurface1 bar : vLSD = 9.7(16) km/s9 bar : vLSD = 6.6(16) km/s
1 bar : vLSD = 10.4 km/s9 bar : vLSD = 5.0 km/s
Theory Experiment
0 20 40 60 80 1000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
v
9 bar N2
1 bar N2
pulse duration
9 bar N2
1 bar N2
raw beam
hom. beamplas
ma
front
pos
ition
zfro
nt [
mm
]
time t [ns]
University of Göttingen, 2nd Institute of Physics7© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
TiN
•Irradiation of Ti in N2•Free-Electron Laser FEL
University of Göttingen, 2nd Institute of Physics8© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Overview: TiN coatings
FEL2:Ti-37 22 18
Ti:Sapphire+CPA750 nm150 fs
Excimer Laser308 nm55 ns
Nd:YAG1064 nm, 532 nm6 ns
FEL3100 nm, 1050 nm< 1 ps
University of Göttingen, 2nd Institute of Physics9© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Faster and better with FEL ?
Time ( s )
Time ( µs )
Time ( ps )
Micropulse
Macropulse
1 ps
16 ms250 µs
27 ns37.4 MHz
FELNewport News,Virginia, USA
3.1 µm2 kW
flexible in timing
upgrade: 10 kW, UV (300 nm), 2005
F2-Ti-23
10 mm
University of Göttingen, 2nd Institute of Physics10© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEL: TiN Synthesis
b
a
100 µm
bSample
Macrotm (µs)
Macrofm (Hz)
shiftδ (µm)
Fluenceφm (J/cm2)
Ti-a1 250 60 200 123
Ti-a2 250 60 100 123
Ti-a3 250 60 50 123
Ti-b1 500 30 100 246
Ti-c1 750 30 100 369
Ti-d1 1000 10 200 492
Ti-d2 1000 10 100 492
Ti-d3 1000 20 200 492
Ti-d4 1000 30 200 492
Ti-d5 1000 30 100 492
Line scan: velocity u=0.5 mm/s, line width D=0.4 mm, shift δ (50, 100, 200 µm)
formation of TiNconcentration gradientindependent of parametersstructure of surface?D
v
0 100 200 300 4000
10
20
30
40
50
60
Ti-a2: 250 µs/60 Hz Ti-d2: 1000 µs/10 Hz Ti-d3: 1000 µs/20 Hz
FEL - Ti in 1 bar N2
nitro
gen
conc
entra
tion
[at.%
]
depth [nm]
Always TiN
University of Göttingen, 2nd Institute of Physics11© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEL TiN: Surface by SEM
50 µm 50 µma2: 250 µs, 60 Hz, 100µm c1: 750 µs, 30 Hz, 100µm
50 µm 50 µmd5: 1000 µs, 30 Hz, 100 µm d1: 1000 µs, 10 Hz, 200µm
University of Göttingen, 2nd Institute of Physics12© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Ti18: 250µs, 60Hz, 100µm: No Texture
JJöörg Kaspar, IWS Dresdenrg Kaspar, IWS Dresden
EDX
~ 23 at.% N
~ 16 at.% N
~ 8 at.% N
Surface very rough, melting pearls, network of fine cracks, melting depth 30-40 µm, TiN 5-15 µm, primary solidification of TiN at the surface, TiN has a nitrogen rich kerneland less nitrogen cover, α‘-Martensite in between
University of Göttingen, 2nd Institute of Physics13© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Ti23: 1000µs, 10 Hz, 200µm, (100) Texture
JJöörg Kaspar, IWS Dresdenrg Kaspar, IWS Dresden
EDX: ~30 at% N
EDX: ~10 at% N
melting zone 20-30µm, TiN 0-25µm, Very smooth surfaces, very few melt pearls, significant solidificationlines, fine cracks.cracks only within TiN. TiN cover smaller.TiN perpendicular to the surfaces, dendritic solidification
University of Göttingen, 2nd Institute of Physics14© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
GIXRD: Texture, Rocking curves
30 40 50 60 70 80 90 100
100
1000
10000
100000
5 10 15 20 25 30 35 400
10000
20000
30000
40000
50000
α-Ti(N)(102)
TiN(220) TiN(311)
α-Ti(N)(101)
TiN(111)
TiN(400)
TiN(200)
Log(
Inte
nsity
)
2 theta
Ti-a2 Ti-d1 Ti-d5
inte
nsity
theta
1000 µs, 10 Hz, 200 µm
1000 µs, 30 Hz, 100 µm
250 µs, 60 Hz, 100µm
Strong texture for long macropulsesand small overlap
no texture for short macropulses and large overlap
TiN(200)
10 100 6001E-3
0.01
0.1
0.721
0 = perfect (200) texture
perfect polycrystal = no texture
text
ure
para
met
er η
overlap σ0,0 0,5 1,0 1,5 2,0
0
2
4
6
8
10
12
Har
dnes
s [G
Pa]
depth [µm]
Ti-d1 Ti-d2 Ti-d3 Ti-d4 Ti-d5
Rocking curve
hardness
no texture (polycryst.)
δσ
⋅⋅
=v
fD2
fully textured (single cryst.)
University of Göttingen, 2nd Institute of Physics15© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEL TiN: Pole Figures
Symmetric -> columnar growth, fiber texturevery strong texture, well aligned columns
0
100
200
300
400
500
600
0
30
60
90
120
150
180
210
240
270
300
330
0
100
200
300
400
500
60070 72 74 76 78
0
100
200
300
400
500
600
TiN
(311
) pea
k in
tens
ity
Ti-d1 Ti-d5
TiNx(311) Bragg peak (asymmetric scan: γ=25.24°)
Inte
nsity
2 theta
Ti-d3 (Ti-25)
scan: 5° × 5°
ϕ: 0-360°
χ: 0-80°
University of Göttingen, 2nd Institute of Physics16© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Simulation of Melting and Solidification
0
1000
2000
3000
40000 200 400 600 800 1000 1200 1400
0 200 400 600 800 100012001400
50
40
30
20
10
0 0 20 40 600,00,20,40,60,81,0
surfa
ce te
mpe
ratu
re [K
]m
eltin
g de
pth
[µm
]
time [µs]
Ti-N
tmacro=750 µs
N fr
actio
n
depth [µm]
TiNx
Strong dependence of the melting temperature on the nitrogen content
nitrogen concentration gradient:
re-solidification starts at surface
free (200) surface is most favorable
University of Göttingen, 2nd Institute of Physics17© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Comparison: Simulation and cross section
0 250 500 750 1000 1250 150060
50
40
30
20
10
0
mel
ting
dept
h [µ
m]
time [µs]
10 µm
SEM
E. Carpene, PS, MRS Proc. 780 (2003) Y5.8.1E. Carpene, M. Shinn, PS, Appl.Phys. A (2005)
University of Göttingen, 2nd Institute of Physics18© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEM - Simulations
melting depth:TiTiN
diffusion depth (1/e):1 Pulse2 Pulses2 Pulses(corr.)
Phase diagramme:
Tm = f(N%)
23% solubility0,0 0,5 1,0 1,5 2,0 2,5 3,0
100
80
60
40
20
0
dept
h [µ
m]
time [ms]
pulse duration
vS= 2-3 cm/s
0,0 0,5 1,0 1,5 2,0100
80
60
40
20
0vS= 1,5-2,5 cm/s
dept
h [µ
m]
time [ms]
pulse duration
0 100 200 300 400 500100
80
60
40
20
0
dept
h [µ
m]
time [µs]
pulse duration
1,0 1,1 1,2 1,3 1,412
8
4
0
dept
h [µ
m]
time [ms]
University of Göttingen, 2nd Institute of Physics19© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
TiN: hardness – comparison laser
Femtoseconds – verysoft (nanocluster)
FEL highest hardnessand thickest coating
Ti
Excimer = „smooth“ (Ra < 0.5 µm)Nd:YAG: Ra ~ 1-2 µmFEL: smooth (cracks)
0.01 0.1 1 100
2
4
6
8
10
Nd:YAG
Excimer Laser
FEL
Untreated Titanium Femtosecond Pulses
Har
dnes
s HU
1 [G
Pa]
Depth [µm]
University of Göttingen, 2nd Institute of Physics20© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEL TiN: Surface by SEM
50 µm 50 µm
veryvery promisingpromising forfor
implantimplant surfacesurface structuringstructuringa2: 250 µs, 60 Hz, 100µm c1: 750 µs, 30 Hz, 100µm
Kieswetter K, Schwartz Z, Hummert TW, Cochran DL, Simpson J, Dean DD, Boyan BD.
Surface roughness modulates the local production of growth factors and cytokines by osteoblast-like MG-63 cells. Journal of Biomedical Material Research 1996; 32 (1): 55-63.
50 µm50 µm
d5: 1000 µs, 30 Hz, 100 µm d1: 1000 µs, 10 Hz, 200µm
University of Göttingen, 2nd Institute of Physics21© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Real Human Implant (hip joint)3D image of a laserstrcutured hio joint (drillingholes of D=200 µm)
Aim: durable osseo-integration and implant stability
Way: Surface must be a good stimulus for boneingrowth (good microcontacts=osseo-integration) very stable bone-implant-connection
chemical modification for chemical resistivity
Laser-Structuringof an hip-joint
University of Göttingen, 2nd Institute of Physics22© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Femtosecond pulses (Ti:sapphire laser)
nitrogengas (N2)
150 150 fsfslaserlaserpulsepulse
plasmatp=1.5·10-13 s (pulse duration):⇒ non-thermal treatment
(Coulomb explosion)
• affected depth ~ 10 nm• plasma only after laser pulse• highly ionized vapor
TiTi--sapphire, 780sapphire, 780--850 nm850 nm150 150 fsfs, 1.5 bar N, 1.5 bar N22
tp<< te ⇒ Telec >> Tlatt
Ti:Saphir mit CPA, tTi:Saphir mit CPA, tpp=150 =150 fsfs, , λλ=800 nm=800 nm
University of Göttingen, 2nd Institute of Physics23© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
University of Göttingen, 2nd Institute of Physics24© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Applications: Cylinder Liners
J. Lindner, AUDI AG
University of Göttingen, 2nd Institute of Physics25© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
In series production: V6 engine
Treatment: mirror inside cylinder; rotating engine block, in series production, 5 Excimer simultaneous, 2 min/engine
J. Lindner, AUDI AG
University of Göttingen, 2nd Institute of Physics26© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Application: Cylinder liners (grey cast iron)
After honing
After laser treatmentReduction of oil consumption (30x)increase in efficiency and power
University of Göttingen, 2nd Institute of Physics27© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Application: Cam Shafts
University of Göttingen, 2nd Institute of Physics28© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
FEL: from basic to applied physics
University of Göttingen, 2nd Institute of Physics29© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Summary
Reactive Laser treatments enable flexible, clean and fast ways for the production of new materials, thin films and coatingsEasy and fast modification and functionalizing of thin films andcoatings by laser beams.But: sensitive adaptation of material, laser, and laser treatment for the specific application.Combination of several methods for resolving complicated processes and optimization of processing necessary.FEL is very attractive for fast (competitive) surface treatmentsNanostructuring, Pulse tailoringMany Perspectives for thin films
University of Göttingen, 2nd Institute of Physics30© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
CooperationsFEL, Jefferson Lab, Newport News, Virginia, USAAUDI AG, Daimler Benz, INA Wälzlager, IBM, StihlProf. H.-W. Bergmann (†), Uni Bayreuth, Metall. WerkstoffeProf. A. Emmel, FH Amberg-Weiden, FB MaschinenbauProf. M. Bamberger, Dr. W.D. Kaplan, Technion Haifa, IsraelProf. J. Wilden, TU Illmenau, FertigungstechnikBIAS Bremen, LZH HannoverFraunhofer ILT, IPT, RWTH AachenIWT, IWS Dresden, MPI HalleLURE Paris, ESRF, Grenoble, BESSY, ANKAProf. H.-J. Spies, TU Freiberg, WerkstoffkundeProf. M. Somers, TU Kopenhagen, Materials ScienceProf. E. Mittemeijer, Dr. G. Dehm, MPI StuttgartUni München, Nancy, Leuven, Krakow, Padova, Trento, Jena, Durban, Dortmund, Bratislava, Brno, Budapest, Helsinki, Erlangen, Belgrad, …
University of Göttingen, 2nd Institute of Physics31© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
Thanks to ….Funding:
DFGUni GöttingenDAAD, EC
Co-workersand Group:
E. Carpene, M. Kahle, A. Müller, F. Landry, M. Han, S. Wagner, C. Illgner, S. Dhar, S. Cusenza, IWT Dresden: J. KasparFH Amberg: A. Emmel, R. Queitsch
FEL@Jefferson Lab: Fred Dylla, Gwyn Williams, Jo Gubeli, Kevin Jordan
•• Your interest and patienceYour interest and patience
University of Göttingen, 2nd Institute of Physics32© Peter Schaaf - www.schaaf.physik.uni-goettingen.de16. Juni 2006
You are welcome to visit Göttingen
New Physicsbuilding