NanoTest scratching module

1
Scratching
NanoTest scratching module

• for
• Scratch testing (critical load determination)
• Nano- and micro- friction (wear regimes)
• Adhesion (delamination at critical load)
• Profilometry (surface roughness)
• Acoustic Emission (scratch-induced cracking)
• Fatigue wear (elastic recovery)

Nanotribometer
2
Ramped load scratch testing (1)

• NanoTest advantages for nanoscratch
• Scratching occurs in high stiffness direction
  for pivot
• Direct calibration of tangential forces possible

Multi-pass scratch test

• 3 scans
• 1) Initial low load
• 2) Ramped scratch
• 3) Final low load
• On-load deformation
• Off-load deformation
• Critical load
• Friction forces
• Acoustic Emission
• Optical Microscopy

3
Ramped load scratch testing (2)
50 microns
100 microns
ta-C films
4
Scratching
Multi-pass sub-critical load scratch testing
2, 4, 6
1, 3, 5, 7
Experimental parameters 25 mm Rockwell
probe scratch load- ramped to 1 mN topography
load 0.1 mN scan speed 0.5 mm/s
Nano-scratching wear of polymer film

• fatigue behaviour
• cohesive failure (fracture)
• adhesive failure (delamination)

Repeat scratches over the same wear track
reveal...
5
Nanotribology
dplast
2 different PET samples - clear differences in
nano-scratching wear with processing history...
dtotal

• extent of ploughing
• differences in
• elastic recovery (dp/dt)

Biaxially drawn PET film - 50 crystalline
dplast
Evaluate sliding wear resistance of different
coating formulations
dtotal
Uniaxially drawn PET film 30 crystalline
BD Beake (MML) and GJ Leggett (UMIST), Polymer
2002, 43, 319-327.
6
Ramped load scratch testing (3)
On-load friction forces are very sensitive to
film failure events Correlate m with
microscopy showing film delamination Micrograph
at x1250 mag. from NanoTest high resolution
microscope with digital camera
Increasing load
Delamination failure