Agilent Technologies Nano Indenter G200 User Manual page 439

Agilent Nano Indenter G200 User's Guide
The elastic contact stiffness is related to the contact width by:
This technique is sensitive to a small change in the indenter shape, and
provisions are made for the indenter geometry between scratch
experiments with respect to reproducibly and accuracy. As shown in
Figure E-12, comparison between these curves, obtained with various
indenters, correlate well with critical load values obtained on a paint
sample.
Figure E-12Critical Load data comparing four cube corner indenters
These data illustrate that a slight change in the indenter geometry
actually affects the result of a scratch test, confirming the importance of
a knowledge of the tip geometry. A critical load value is meaningless
unless it is linked to a precise description of the tip used for the
measurement.
Figure E-12 also demonstrates that two indenters of identical geometry
give the same critical load results (CCM5 and CCM1 in this example).
Bars indicate the standard deviation. CCM5 and CCM1 have same
geometry and give identical critical load results. CCM4 and CCM6
show differences due, respectively, to their sharper and blunter
geometry.
Scratch Testing E
S
a = ------ -
2E
(49)
E-15