Adhesion enhancement of DLC hard coatings by HiPIMS metal ion etching pretreatment and its tribological properties José Antonio Santiago Varela Bilbao, October 19 th 2016 E-mail: [email protected]
Adhesion enhancement of DLC hard coatings by HiPIMS metal ion etching pretreatment and its
tribological properties
José Antonio Santiago Varela
Bilbao, October 19th 2016
E-mail: [email protected]
DLCAim of this work
DLCAim of this work
DLCSuperhard DLC
Proprietary technology: Patent application number GB1605162.5 (March 2016)
• Ion assisted pulsed Magnetron Sputtering
• Tailored Magnetic Field Configuration
• No substrate voltage bias required
DLCCoatings architecture
Argon etching Buffer layer DLC coating
Argon etching Bonding layer Buffer layer DLC coating
Bonding layer (Cr/Ti)
Buffer layer (WC)
DLC coating
Buffer layer (WC)
DLC coating
Argon etching HiPIMS pret. Bonding layer Buffer layer DLC coating
DLC coating
Buffer layer (WC)
Bonding layer (Cr/Ti)
HiPIMS pret.
DLCImplantation
Surface preparation
• Contaminant layers
• Gradual interface
• Dangling bonds
DLCHiPIMS
• High peak powers (500-2000 W/cm2)
• Reasonable average power
• Low duty factors (0.5-5%)
DLCHiPIMS
Ar
300 400 500 600 700 800 900 1000 1100
0.0
0.5
1.0
0.0
0.5
1.0
wavelength (nm)
Norm
aliz
ed inte
nsity (
a.u
.)
W (2+)W (1+)
Ar
DC
HIPIMS
Optical emission Spectroscopy
• Highly ionized plasma• Higher density for coating deposition• Enhanced adhesion with pretreatment
DLCHiPIMS pretreatment
E. Broitman et al, Surf. Coat. Technology 204 (2010) 3349 AP. Ehiasarian et al, Journal of appl. Phys. 101(2007)
Implantationzone
as Bias up to 1200V as regular HIPIMS
Cr bias
Ti bias
Cr magnetron
Ti magnetron
Vb= -750 (V)Jb= 30 (mA/cm2)
Vb= -450 (V)Jb= 150(mA/cm2)
VHiP= 1100 (V)JHIP= 1 (A/cm2)
VHiP= 600 (V)JHIP= 5 (A/cm2)
DLCHiPIMS pretreatment
DLC
Metal ion etching
No biasBias
pretreatment
Substrate
Substrate
HiPIMS pretreatment
DLCHiPIMS pretreatment
300 400 500
0
30
60
90
Inte
nsity (
a.u
.)
Wavelength (nm)
Cr (1+)
Cr (2+)
Cr (0)
Cr (1+)
Cr (0)
Cr (0)
Optical emission Spectroscopy
300 400 5000
30
60
90
Inte
nsity (
a.u
.)
Wavelenght (nm)
Ti (1+)
Ti (1+)Ti (1+)
Ti (2+)
Ti (1+)/Ar(1+)
Cr Ti
DLC
120 A (5-6A/cm2)
HIPIMS pretreatment
DLCSurface modifications
0 100 200 300 400
-100
0
100
200
300
400
500
600V
750V
He
igh
t (n
m)
Displacement (m)
0 100 200 300 400 500
-200
-100
0
100
200
300
575V
He
igh
t (n
m)
Displacement (m)
Low Bias voltage achievable!
Net deposition <750V Bias
Etched zone
Height profile after 1hr etch
Masked zone
Electropolished SS304 substrateCr
Ti
DLC
Roughness rms: 1.5nm Roughness rms: 17.4nm
Under the Mask Out of the Mask
Substrate texturing
Surface modifications
No pretreatment Cr HiPIMS pret Ti HiPIMS pret
Roughness (rms) 1.5 6.9 17.4
DLCSurface modifications
DLCTEM
Chromium
• Polycrystalline Cr bonding layer
• Dense amorphous Cr interface by
HiPIMS pretreatement
• No bubbles, voids or droplets
• Gradual interface coating-substrate
Amorphous Cr
Crystalline Cr
M2 HSS Steel
WC
DLCTEM
• Oxygen from the surface is removed
• Argon concentration is kept at low level
• 10-15 nm Fe-Cr interface
• Low thermal diffussion of Cr
Polycrystalline Cr
Amorphous Cr
M2 HSS Steel
DLCTEM
Titanium
DLC
WC
M2 Steel Substrate
Ti
DLCTEM
WC
Ti deposited
+ HSSTi implanted
Titanium
• Gradual interface coating-substrate
• Epitaxial growth
• Alligment from steel substrate to WC
• Ti implanted into the substrate lattice
• No bubbles, voids or droplets
DLCTEM
Ti deposited (5nm)
a-WC
60 80 100
0
30
60
Fe
Ti
W
C
at
[%]
distance (nm)
Titanium 10nm (implanted + deposited)
Ti implanted + M2 HSS
DLCAdhesion
HiPIMS pretreatmentBonding layerNo interlayer
Chromium
Titanium
HF6
HF6
HF2-3
HF4
HF1
HF1
Daimler-Benz test
DLCAdhesion
Lc=500 mN
Nanoscratch
DLCAdhesion
No bonding layer Ti bonding layer Ti HiP pret Cr bonding layer Cr HiP pret
Critical Load (mN) 80 150 220 240 380
• Conical indenter R= 10 µm
• HSS M2 polished substrate
• Loading rate= 2.5 mN/s
• Scratch length 500 µm
Delamination modes
Conformal cracking
Compressive spallationTi
Cr
DLCAdhesion
Nanoscratch
DLCAdhesion
50N
97N
66N
110N 135N
88N
• Extraordinary adhesion in scratch tests• First cracks. Lc1= 100 N• Delamination load. Lc2= 135 N
Macroscratch
DLCAdhesion
Coating Hardness (GPa) μ Wear rate (m3/Nm)
a-C 30 0.2 10-15
a-C:H (Low H) 25 0.17 10-15
a-C:H (High H) 10 0.10 3·10-15
Pin-on-disk
DLCAdhesion
No interlayer Cr bonding layer Cr HiPIMS pret.
Máx. Sliding speed (m/s) 0.31 0.42 0.55
Test conditions ASTM G99P=10 N; ω= 200 rpm; Ball diameter= 6 mm; v= 0.5 m/s
DLCConclusions
1. HiPIMS metal ion etching pretreatment improves adhesion by controlling:
• Surface morphology
• Chemical composition
• Growth modes
2. Degree of ionization is a key factor for the application of HiPIMS pretreatment
3. Cr HiPIMS pretreatment enhances considerably adhesion of DLC coatings
4. Nanoscratch and nanoimpact testing are valuable tools to assess thetribomechanical response of DLC coatings
José Miguel GARCIA MARTINDavid FUSTER
Raquel GONZÁLEZ ARRABALAntonio RIVERA
Miguel CASTILLOJon MOLINA
Miguel MONCLÚS
Víctor BELLIDO-GONZÁLEZFrank PAPA
Iván FERNÁNDEZ MARTÍNEZAmbiorn WENNBERG
DLCThank youEskerrik asko