New generation HIPIMS and combined HIPIMS/UBM PVD

[
New Generation Nanoscale Multilayr Coatings to Serve High
Temperature, Corrosion and Tribological Applications Deposited by
HIPIMS
P. Eh. Hovsepian 1 , A. P. Ehiasarian 1 , W. Smarsly 2 , A. Werner 2 , R. Tietema 3 , F. Papa 3 , R.
Jacobs 3 , R. Braun 4
1 Nanotechnology Centre for PVD Research, Sheffield Hallam University, UK
2 MTU Munich, Germany
3 Hauzer Techno Coating, Venlo, The Netherlands
4 DLR, German Aerospace Centre
]

[
Monolithic Columnar
Structure, BF TEM image
TiAlN, University of
Linköping
Nanoscale Multilayer
Structure, BF TEM image
3.2 nm
CrN/NbN, Sheffield Hallam
University
The concept of
"superhardening" introduced
by James Koehler , University ]
of Illinois in 1970.
Q=GA-GB / GA+GB
Q- critical stress to move a
dislocation across the interface
GA, GB, shear modulus of
material A and B

[
Influence of the "superlattice" period on the hardness of
the TiAlN/CrN coating.
I.Wadsworth et al, Surf. and Coat.
Technol. 94-95, (1997).
]

[
Wear mechanism of single and multilayer coatings
]

[
Industrial Scale Hauzer HTC 1000/4 PVD Coater at SHU
a) XSEM of CrN/NbN Coated
knife blade
b) BF XTEM showing the
nanoscale multilayer structure
on the tip of the blade, P.Eh.
Hovsepian et al, Surf. and Coat. Technol. 133,
(2000).
]

[
∆
CrAlYN/CrN
CrAlN
interface
SUBSTRATE
D = 4.0 nm
High temperature
oxidation resistant
Dry machining, automotive
and aero engines.
SHU Nanoscale Multilayer Coating Family
TiAlCN/VCN
TiAlN
interface
SUBSTRATE
D = 3.2 nm
High hardness
low friction
Al and Ti cutting
CrN / NbN
CrN
interface
SUBSTRATE
D = 3.4 nm
Corrosion and
Wear resistant
C / Cr
CrN
interface
SUBSTRATE
D = 2 nm
Low friction -
tribological
]

[
lifetime
mechanical properties
HIPIMS-ABS Days, Sheffield Hallam University, 12-13 July, 2005
A project strongly driven by industrial needs
hot corrosion resistance
titanium aluminides (γ-TiAl)
cost savings
wear resistance
oxidation resistance
]
3

[
Nanoscale Multilayer CrAlYN/CrN Deposited by HIPIMS/UBM, (Pat.
pending, H10245PGB, 13.07.07)
CrAlN
interface
SUBSTRATE
Ti- free formula,
Y- stabilised interface by Y + and Cr +
ion etching using HIPIMS
CrAlYN/CrN nanoscale multilayer,
(∆ = 4.7 nm) deposited by HIPIMS
or UBM or combined HIPIMS/UBM
technique.
]

Target Voltage, V
[ Novel High Power Impulse Magnetron Sputtering (HIPIMS)
Technology
2500
2000
1500
1000
500
0
0 20 40 60 80 100
Time, µ s
]
A powerful source
for highly ionised
metal plasmas
used for surface
pre treatment and
deposition of high
quality coatings.
Patented for surface pre treatment by SHU in USA and Europe: A.P. Ehiasarian, P. Eh. Hovsepian, W.-D. Münz,
US Pat. US 10718435, (2005) , EP 02 011 204.1 (2001).
2.5
2.0
1.5
1.0
0.5
0.0
Target Current Density, A.cm -2

Roadmap to industrialisation
[
100000
10000
Cr (1+) + Cr (0)
Cr (0)
Cr (0)
Cr (1+)
1000
Cr (2+)
100
10
Ar (1+)
1
200 250 300 350 400 450 500
Optical Emission Intensity, a.u.
100
10
}
}
1
200 250 300 350 400 450 500
Wavelength, nm
}
HIPIMS
Continuous
Magnetron
Jan. 2001. First OES
of HIPIMS on lab size
magnetron
Dec. 2003. First
industrially viable
HIPIMS power
supply by AC now
HUETTINGER
Optical emission intensity, a.u.
0.25
0.2
0.15
0.1
0.05
Cr2+
Cr1+ Cr2+
{
Cr2+
{
0
200 210 220 230 240 250
Wavelength, nm
Jan. 2004. First
HIPIMS on industrial
size (500X88 mm)
CemeCon cathode
February 2004.
HIPIMS on large
(600X200 mm)
HAUZER cathode
]
Dec. 2006. First
HIPIMS dedicated
Bias power
supply, SHU,
HAUZER,
HUETTINGER,
pat. pending

[
Mass spectroscopy results of the HIPIMS Plasma of Cr used for Pretreatment
During pre-treatment, the peak substrate ion current density
was Js = 155 mAcm-2.
]

[
Mass spectroscopy results of the HIPIMS and DC Plasmas during
deposition of CrAlN
HIPIMS
DC UBM
]

[
Coating-Substrate Interface Microstructure
STEM Bright Field STEM Z-Contrast
CrAlYN/CrN
CrAlN
]
γ-TiAl
High density Y and
Cr implanted zone
5nm

[
Local Epitaxial Growth in HIPIMS – Lattice Imaging
CrAlN
Coating
Interface
γ-TiAl
Substrate
Atomic Resolution TEM
image of the interface
SAD Patterns
]
CrAlN
Coating
γ-TiAl
Substrate

Ultra-high resolution characterisation of the interface between CrAlYN/CrN
coating and the γ-TiAl substrate grown using HIPIMS technology
[
Atomic resolution chemical composition
across the interface
High resolution atomic image showing the
intimate atomic bonding at the interface
]

[
Local epitaxial growth on large areas due to HIPIMS pre treatment of
the substrate
Homogeneous contrast along interface
signifies local epitaxial growth on
substrate (steel) grain
Critical Load L c [N]
80
70
60
50
40
30
20
10
0
56
CrAlYN/CrN
arc etch
65
]
Growth
defects
originating
from
droplets
during arc
etching, ABS
technology
CrAlYN/CrN
HIPIMS etch

[
XTEM images of the structure of CrAlYN/CrN deposited by various
techniques: a) HIPIMS/HIPIMS and b) HIPIMS UBM.
CrAlYN/CrN
nanoscale multilayer
CrAlN base layer
substrate
a) HIPIMS/HIPIMS,
Z-contrast image
b) HIPIMS/HIPIMS,
BF image
c) HIPIMS/UBM,
BF image
]

[
Alternated HIPIMS/DCMS/HIPIMS/DCMS deposition of CrN
]

[
High purity intercolumnar boundaries in TiN films deposited by HIPIMS. a)
cross sectional view, b) plan view, near bulk material density achieved
with PVD coating
]

[ High Temperature Phase and Hardness Stability of CrAlYN/CrN
]

[ High Tempearture Tribological Behaviour of CrAlYN/CrN
]

[
Thermogravimetric data for various CrAlYN/CrN coatings from
quasi-isothermal tests carried out at 850C in air
UBM coated and uncoated γ-TiAl show an increase in mass gain by a factor of 2 and 6
respectively as compared to the HIPIMS-HIPIMS coated γ-TiAl specimens
]

[ Onset of Rapid Oxidation of CrAlYN/CrN deposited by various techniques
]

[
High Temperature Corrosion Resistance of CrAlYN/CrN.
Weight gain after 1000 hours exposure to H 2 /H 2 S/H 2 O at 750C
Weight Gain, mg/cm2
3
2.5
2
1.5
1
0.5
0
CrAlYN/CrN γ-TiAl
uncoated
Al2Au TiAlCr
]

[
Fatigue testing
Experimental conditions of fatigue testing
► after high temperature exposure to air at 850°C for 300 h
the oxides in the thread regions were removed by shot peening
► fatigue tests carried out at room temperature
► R ratio R = -1
► loading frequency was 20 Hz
► maximum testing period was 5 million cycles
]

[
Ultimate tensile strengths of γ-TiAl samples
]

[
Maximum stress vs. number of cycles to failure of γ-TiAl specimens bare and
coated with CrAlYN/CrN using different magnetron sputtering technologies
]

[
Wear and fretting resistance of TiAl turbine blades with best available
coatings in simulated aero engine environment at MTU Munich
New Aero Engine Concept:
Geared Turbo Fan
Up to 30% less CO2
Perceived aircraft noise is halved
Oxidation and
Corrosion Resistant
Coatings
max. 800 °C
35.000 hours
Low Pressure Turbine
Blade required in Gamma
TiAl
CrAlYN/ CrN +
Al2O3
]
Wear Resistant
Coatings
max . 800 °C
25.000 Cycles
50 % weight reduction per blade
compared to current nickel alloy
•Fretting wear tests with contact pressures relevant to blade shroud contact area

2.1 Pulsed DC Al 2 O 3
Technology for you
T-Mode Control System for Al 2 O 3 Coatings
• Special Cathode Design
• Magnetic Field
• Permanent Magnets
• Closed field Unbalanced Magnetron Coils
• Optimised gas introduction system
• Fast reactive gas control system
Plasma
Confinement
• Enables reproducible coatings at adequate deposition speeds.

Dual Magnetron
Modified
T-mode
Midfrequency
supply
Al
AlTi
(Arc)
Technology for you
AlTi
(Arc)
Al
Modified
T-mode
Separate T-mode control for
selection of working point on
each cathode (patent pending)
Reactive oxide process
stable behind shutters
Possibility to co-sputter
different materials at
the same time – each at a
different working point

2.2 Dual Magnetron
Deposition rates up to 1µm per hour
Stable process over long run times
Improved ionization
Nanocrystalline γ-Al2O3 Thick oxides within a reasonable timeframe
Low maintenance
Technology for you

[
Production and tests of prototype γ-TiAl components for
aeronautic/aerospace application at MTU Munich
Coating of TiAl LPT blades:
CrAlYN/CrN /SHU + Al 2 O 3 /
Hauzer
z - notch hard
phase
AlCrYN/CrN +
Al2O3(Oxidation) + Zr2O3
TiAl LPT blade Coatings Test rig /850C Air 100 h
Test results
- Thermal barrier coating by DLR
- Fretting wear coating by SHU and Hauzer
Test of thermal barrier coating by thermal ageing in air
Test of fretting wear resistant coatings by wear resistnce tests at elevated temperatures
tests
running
]

[
Fretting wear test results at Room temperature and 700C
Test Parameters
R.T. and 700 °C in air,
55 h, 20.000 cycles, frequency 0,1 Hz,
contact pressure 25 MPa
]
RT,
CrAlYN/CrN
RT,
CrAlYN/CrN
+ Al2O3
700C,
CrAlYN/CrN
700C,
CrAlYN/CrN
+ Al2O3

[ Final Conclusions from turbine blade tests
MTU supported by DLR, Hauzer, SHU and BTUC :
Evaluation of specimen and component tests results:
Wear resistance coatings show potential for TiAl turbine blade root applications
Thermal barrier coatings show potential for TiAl cooled turbine blades
Oxidation and corrosion resistant coatings show potential for TiAl turbine airfoil
applications
Need for industrialization of coatings technology, e.g. cost reduction measures in
order to meet cost targets
]

[ NP gas turbine buckets and OSVAT engine valves coated with CrAlYN/CrN
nanoscale multilayer coating at SHU
]

[
Rolling dies and pushing rods for diesel engines coated with CrAlYN/CrN
nanoscale multilayer coating.
]

[
CONCLUSIONS
A new generation nanoscale CrAlYN/CrN multilayer PVD coatings to operate in
harsh environment have been successfully deposited in an industrial sized
Hauzer HTC-4 1000 PVD coater enabled with the HIPIMS technology.
The novel HIPIMS technology offers better plasma conditions with higher
percentage of Me + to Ar + ratio:
For pre-treatment conditions: ratio of 3:1 (ionisation state for Cr +3)
For deposition conditions: ratio of 1:3 (factor of 6 higher than DC)
HIPIMS deposited coatings have clean and sharp interfaces, flat multilayers and
very dense structures with evidence of epitaxial growth promoting high
adhesion.
The new coatings have shown excellent mechanical, tribological, and high
temperature oxidation resistance. The technology and the coatings are close to
industrialisation
]

[
Acknowledgements
• The hard work and dedication of all the researchers at the
Nanotechnology Centre for PVD Research at Sheffield Hallam
University in UK is highly acknowledged.
• The authors acknowledge the use of the Centre for Microanalysis of
Materials, University of Illinois, which is partially sponsored by the U.S.
Department of Energy under grant DEFG02-91-ER45439.
• The research on CrAlYN/CrN nanoscale multilayer coatings utilising
HIPIMS pre treatment have been carried out within FP6 Integrated
Project INNOVATIAL, n° NMP3 - CT- 2005 – 515844. The financial
support of the EC and the intellectual support of all partners are deeply
acknowledged.
]