5). In contrast to metallic multilayers, SEM examination
(Fig. 4) reveals that these instances of film damage
were mainly due to scrape. Unfortunately, since the
delamination is only partial, it is rather difficult to
establish whether, and in particular to what extent,delamination has occurred. Furthermore, in contrast to
the point at which total delamination occurs, it is very
difficult to relate the generation of these possible partial
delamination to the friction data.
An element analysis of metallic multilayers at different
scratch area was practiced by EDAX is displayed in
Table 1. For example AuyNiCryTa films in Table 1, the
content of Au, Ni, Cr, Ta decrease and O and Al increase
with scratch process, it indicate indenter continuous
downwards to substrate. When indenter contacts the
substrate, there are full of O and Al element. So at
different scratch area, there are different elements content,
and it is good agreed with scratch stage. From
different elements content, we can conclude if the
indenter has got to the substrate.
The critical characteristic load of AuyNiCryTa films
at different deposition temperatures is displayed in Fig.
6. There are almost no changes at different deposition
temperatures, so it can be concluded that the critical
characteristic load of muti-layered metallic films by
scratch method was not sensitive to deposition
temperature.
The post-annealing was carried out for the AuyNiCry
Ta films at 400 8C in Ar gas for 60 min. The critical
characteristic load of AuyNiCryTa films after annealing
is displayed in Fig. 7. There are no obvious changes
between Figs. 7 and 6. So it indicates that the critical
load of metallic films by scratch method was not
sensitive to post-heating process.
The critical load can be affected by the film thickness.
The Au film was fixed to different thickness by plating.
Fig. 8 shows the critical load as a function of the film
thickness of AuyNiCryTa and AuyNiCr films deposited
on Al O substrate. The results show that the critical 2 3
load increases approximately linear with film thickness.
In general, if we assume that the adhesion is the same
and the critical load is determined by the extent of the
deformation, an increased film thickness requires an
increased indenting load to obtain the same deformation,
so that the critical load increases with the film thickness.
It can relevant the resistance scratch of films. But,
considering the residual stress effect in the film, the
variation of critical load with film thickness may be
complication. In our experiments, the mean residual
stress state of AuyNiCryTa films can be changed by
plating w9x, so that the effect of residual stress on critical
load is not dominating, the film thickness becomes the
mainly factor which affect the critical load.