E n h a n c e d a d h e s i o n o f D L C c o a t i n g s o n m e t a l l i ca n d i n s u l a t i n g s u b s t r a t e s
San Diego, April 27th, 2017
Dr. Iván Fernández Martínez
Jose Antonio SantiagoJon MolinaMiguel Monclus
Iván Fernández MartínezAmbiorn Wennberg
Raquel González-ArrabalAntonio Rivera
Juan C. Sanchez-LopezCristina T. Rojas
Victor Bellido-González
Outline
- DLC on metal substrates.
- Metal ion etching description.- Comparison between Ti and Cr.- Experimental results.
- DLC on insulating.
- Plasma “biasing” for glass pre-treatment.
Adhesion is a critical issue…
High T applicationsHigh loadsT sensitive substrates such as bearings
Metal ion etching : Arc Bond Sputtering (ABS)
Metal ion etching : HIPIMS
Titanium : higher metal to neutral ratio
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)
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 (1A/cm2)
Metal etching with low bias values reduces arcing issues!!
Ti (3A/cm2)
300 400 5000
30
60
90
Inte
nsity (
a.u
.)
Wavelenght (nm)
Ti (1+)Ti (1+)Ti (1+)
Ti (2+)
Ti (1+)/Ar(1+)
Ti
1000A
650V
Titanium : higher metal to neutral ratio
1A/cm2
3A/cm2
Low Bias values : Reduced arcing issues!!!
Net deposition
Etching
Etching conditions to prevent amorphous layer formation
1) Ar glow discharge
2) Ti/Cr metal etching
3) WC/CrC layer
4) DLC layer
Ti/Cr extra bonding layer
WC/CrC layer
DLC layer
DLC coating sequence (1 m thick DLC)
DLC
HSS
WCM2 HSS
WC
Ti
Ti interface
Ti metal etching + Ti extra bonding layer: TEM
Local epitaxy between HSS substrate and Ti bonding layer
No external heating
M2 HSS
Ti layer
Ti metal etching + Ti extra bonding layer: SAED
NO Crystalline alignment between substrate and Cr bonding layer
Cr metal etching + Cr extra bonding layer: SAED
1
2
M2 HSS
1
2
Ti HIPIMS etch Cr HIPIMS etchAr glow discharge
1 m thick WC/DLC onto pre-treated HSS M6
Ar etching Ar etching +Ti bonding layer
Ar etching+Ti HiPIMS
Ar etching +Cr bonding layer
Ar etching + Cr HiPIMS
Critical Load (mN) 80 150 220 240 380
Delamination modes
Conformal cracking
Compressive spallation
Ti
Cr
Nanoscratch tests for 1um thick WC:DLC coating on HSS
Composition along the interface : EELS
Ti-L2,3 Fe-L2,3
C-K
Ti-L2,3
O-K
C-K
Central area Ti extra bonding
Ti, Fe signals : 2-3nm overlap implantation?
nm0
15
Are we doing the HIPIMS metal etching correctly?
50N
60N
55N
0 N 200 N
65N
Cr Bonding layer (15nm)
WC (0.2m)
C-DLC (2m)
2.4 m thick DLC layer stack : Ar glow discharge + Cr bonding
HSS (60HRC)
70N
80N
85N
90N
75N
HiPIMS pret.
C-DLC (2m)
WC (0.2m)
Cr Bonding layer (15nm)
HSS (60HRC)
2.4 m thick DLC layer stack : HIPIMS Cr metal etching + Cr extra b.
What about insulating substrates?
T h i n D L C < 1 0 n m o n d i s p l a y c o v e r p a n e l .
Black : Glass reference = 89.2%Red : 3nm DLC = 88.2%Green : 5nm DLC = 88.0%
Anti scratch glass
D L C c o a t i n g o n G l a s s
Hardness in the range of 20GPa for 400nm thick DLC layer
DLC
Glass
Positive ion assistance by plasma “biasing”
Magnetronpeak current
+150V (Plasma OFF)
-20V at plasma ON
Voltage
Magnetronpeak current
Proprietary technology: Patent application number GB1605162.5 (March 2016)
V/I at magnetron Floating potential at substrate
D L C c o a t i n g o n G l a s s
Substrate can be pre-treated with reactive gases such as oxygen
+485V
Current to floating potential (10mV/A)
Treated
Masked (Treated)
Coated
D L C c o a t i n g o n G l a s s – m o r p h o l o g y c h a n g e
8006004002000
8
7
6
5
4
3
2
1
0
X[nm]
Z[n
m]
8006004002000
12
10
8
6
4
2
0
X[nm]
Z[n
m]
Untreated glass substrate
Oxygen treated glass substrate
RMS roughness : 2.6 nm
RMS roughness : 1.4 nm
S c r a t c h t e s t s : T a b e r a b r a s i o n
DLC Coating description
Total light
transmission (400-
700nm)
Taber test result
15 min O2 plasma cleaning + 6nm DLC 89.2 ≤20 times NG
5 min O2 plasma cleaning + 6nm DLC 91.0 ≤15 times NG
5 min O2 plasma etching + 3nm DLC 91.2 ≤10 times NG
Load 7.5N
15min plasma cleaning with V positive pulses enhances abrasion performance
Conclusions
- Metal etching enhances DLC adhesion on steel.
- Cr shows better performance than Ti
- Plasma “biasing” for glass pre-treatment.