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Abstract
As technology has been developed fast, functional outputs of
machines are forced to be upgraded, which leads to higher
demands on performances of mechanical components. In the past
decade, a number of surface treating processes have been
developed to meet various kinds of functional demands. Of the
various surface treating processes, physical vapor deposition
(PVD) is one of the main research in late years.
In this study the influence of single- and multi-layered PVD
films on mechanical performances has been assessed. The single-
layered coating layers are titanium nitride (TiN), titanium
carbonitride (Ti(C,N)), chromium nitride (CrN) and chromium
carbonitide (Cr(C,N)). Four groups of experiments were
conducted, i.e. characterization of the coatings, wear testing,
milling testing, and tension and fatigue testing. The factor
-film thickness- is considered in each group of the experiments.
When these experiments were completed, a trial on depositions
for multi-layered coatings was made. The same tests (wear,
milling, tension and fatigue testing) were also carried out to
find out the enhanced degrees of the multi-layered coatings
compared with single-layered coatings.
The results showed that the film thickness had an effect on the
mechanical performances to some extent depending on the
experimental conditions. Cr(C,N) itself possessed high brittle
nature and low adhesion to the WC substrate, thus resulting in
limited applications; therefore, the main focus was on CrN. In
the wear testing, CrN showed fantastically excellent wear
performance as compared with the Ti-based coatings. In the
milling testing CrN coated tools was found unsuitable to machine
ferrous materials. Inthe tension and fatigue testing CrN and Ti-
based coated specimens showed nearly equal performances. The
multi-layered Ti-based coatings did not show mechanical
performances obviously exceeding the single-layered coatings.
Although CrN was not suitable for machining of ferrous
materials, it did not show poorer performance than the Ti-base
coatings in the other two groups of the experiments. Thus, CrN
is expected to have wider ranges in engineering applications;
however, deeper knowledge is still emerged.
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