Time-Dependent Properties Acting On Scratch Behavior; Relaxation - Agilent Technologies Nano Indenter G200 User Manual

Time-Dependent Properties Acting on Scratch Behavior

Relaxation

Agilent Nano Indenter G200 User's Guide
Time-dependent properties of polymer materials have been studied
extensively, yet only few studies are reported for time dependence in
mechanical characterization of surfaces. During a scratch test, two
time-dependent processes, visco-plastic deformation and visco-elastic
relaxation, occur, as shown in
Figure E-13Visco-elastic recovery of a ductile scratch with time and
temperature
These processes have a strong influence on scratch morphology and can
be characterized quantitatively. Visco-plastic processes are related to a
polymer's sensitivity to deformation rate being applied to the surface.
For a given indenter geometry and penetration depth, this rate is related
to scratch velocity.
Relaxation processes (healing) are important when a scratch is left at
room temperature for some period of time. This phenomenon mostly
affects dimensions normal to the surface, and the scratch width remains
unchanged, as shown in
fracture manifests in front of the indenter tip.
Figure E-13.
Figure E-14 on page E-17. A longitudinal
Scratch Testing E
E-16