Tribomechanical Properties of DLC Coatings Deposited by Magnetron Sputtering on Metallic and Insulating Substrates

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2 Tribomechanical Properties of DLC Coatings Deposited by Magnetron Sputtering on Metallic and Insulating Substrates Dr. Iván Fernández Martínez Indianapolis, May 10th, 2016

3 Diamond Like Carbon (DLC) Diamond-like Carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC coatings are of interest in a wide variety of applications to provide low friction and high hardness and wear resistance. Applications - Glass: anti-scratch. - Molds: prevent plastic transfer - Engine parts: low friction (a-c). - Space parts: low friction (a-c:h). - Cutting tools: lubricated and dry conditions. - Oil & gas: super lubricity in pipes. -.

4 DLC: State of the art Ion assistance required ~ 100eV A. Voevodin, Surf. Coat. Technol. 82 (1996) J. Robertson, Surf. Coat. Technol. 50 (1992)

5 DLC hard coating magnetron deposition Anode to extend the plasma Magnetically linked magnetrons Prof. Wolf-Dieter Munz Industrial scale deposition of well adherent and low friction DLC coatings grown by HIPIMS and anode assisted unbalanced magnetron Private discussion

6 DLC hard coating magnetron deposition 55GPa Microhardess, comparable to filtered arc Bias required Glass? Plastics? Prof. Wolf-Dieter Munz Industrial scale deposition of well adherent and low friction DLC coatings grown by HIPIMS and anode assisted unbalanced magnetron Private discussion

7 Ion assisted deposition on insulators? Magnetron magnetic design (electron filter) + modified asymmetric bipolar pulsed PS 8b 8c ab 1b 9 3 V 2 2b 4 - Positive ion bombardment - No electron bombardent : Reduced thermal load? Proprietary technology: Patent application number GB (March 2016)

8 Ion assisted deposition on insulators? Magnetron size 400x100mm2 (industrial relevant) WC, Graphite targets HIPIMS Ti/Cr + WC improves coating adhesion Optimized magnetic field configuration to enhance ion assisted deposition Proprietary technology: Patent application number GB (March 2016)

9 Ion assisted deposition on insulators? Magnetron size 400x100mm2 (industrial relevant) WC, Graphite targets HIPIMS Ti/Cr + WC improves coating adhesion Optimized magnetic field configuration to enhance ion assisted deposition Sample position Proprietary technology: Patent application number GB (March 2016)

10 Ion assisted deposition on insulators? 3 energy regimes are measured

11 Coating Hardness: above 30GPa on floating substrate Load partial unload curve Hardness = 32 Gpa Young modulus = 220 Gpa 500nm thick DLC Hysitron TI950 Triboindenter Berkovich tip indenter BKL4 Hardness value taken at around 10% total DLC thickness

12 DLC hard coating magnetron deposition 15GPa Microhardess with -75V Bias! Bias required Prof. Wolf-Dieter Munz Industrial scale deposition of well adherent and low friction DLC coatings grown by HIPIMS and anode assisted unbalanced magnetron Private discussion

13 Ion assisted deposition on insulators? Hardness > 30GPa Modified DC- Pulsed PS Hardness < 12GPa Commercial DC- Pulsed PS Proprietary technology: Patent application number GB (March 2016)

14 SEM cross section of WC/DLC coating SEM image : Dense DLC film

15 Adhesion on metals: Standard Rockwell (Daimler or Mercedes) tests DLC on HSS Cr + WC + DLC on HSS HF5 HF1 Indentation HF1 DLC delaminated coating HSS substrate surface DLC coated surface NO DLC coating delamination Rockwell HRC tests - 150kg - Diamond indenter conical tip

16 Adhesion on metals : Rockwell and nano- scratch tests HF1 675mN load 5um tip radius Rockwell HRC tests, 150kg Diamond indenter conical tip

17 Friction and wear ASTMG99 Standard test HF1 DLC coated SS304 SS304 uncoated substrate

18 Friction and wear ASTMG99 Standard test Friction coefficient HF1 Frictioncoeff t (s)

19 Low accumulated high hardness Biased process : high DLC coating stress N4E process : low DLC coating stress Ongoing stress measurements in DLC coatings

20 DLC coating on Glass Delamination problem: Need to reduced thicknesses and ion bombardment DLC Glass Hardness in the range of 20GPa for 40nm thick DLC layer

21 DLC coating on Glass Substrate can be pre-treated with reactive gases such as oxygen +485V Current to floating potential (10mV/A)

22 DLC coating on Glass Untreated glass substrate RMS roughness : 2.6 nm Z[nm] X[nm] Oxygen treated glass substrate RMS roughness : 1.4 nm Z[nm] X[nm]

23 DLC coating on Glass: nano- scratch tests 500mN critical load 5 micron tip radius

24 Nano- impact testing on DLC coatings Characteristics - Acceleration of a test probe (diamond tip) towards sample. - Impact energy can be controlled and quantified. - multiple impacts. - Strain rate: (s -1 ). Loads: 5, 10, 15mN * J.M. Wheeler et al., Surface & Coatings Technology 232 (2013) Analysis of failure modes under nano-impact fatigue of coatings via high-speed sampling

25 Nano- impact testing on DLC coatings Advantages - Produce contact fatigue. - Adhesion failure without substrate deformation - Measure dynamic instead of static hardness Simulate thin film in-situ service for machining operations * J.M. Wheeler et al., Surface & Coatings Technology 232 (2013) Analysis of failure modes under nano-impact fatigue of coatings via high-speed sampling

26 Nano- impact testing a- C:H on Si Test conditions - Conical tip. R= 5(µm) - Impact Height: 10 (µm) - Rest time: 500 (ms) - Specimens: a-c and a-c:h on Si

27 a - C on M2 steel with Cr- HIPIMS implant. Loads: 5 to 30mN Load: 30mN HF1 Rockwell DLC on M2 Steel Multiple Impact with Previous Conditions Multiple impacts: 30 mn during 1200s. No delamination!

28 Submit your abstract in May!!! ecnf conference Main topics: Tribological coatings Energy conversion (solar, batteries) and catalysis Nanostructured coatings From molecules and nanoparticles to thin films Novel 2D materials Guggenheim Museum, Bilbao Characterisation techniques and Properties

29 Thank you for your attention!