IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
adjustable compressive stress.
In the present work, we
demonstrate the synthesis of
Ni/CrN coatings prepared by
magnetron sputtering as they
impart properties such as
improved wear resistance,
good corrosion resistance, low
friction coefficients, and
attractive appearance.
Intensity(a.u)
2000
0 sccm
1600 2 sccm
3sccm
1200 5 sccm
10 sccm
800
15 sccm
(111)CrN
(200)CrN/ (111)Ni
(200)Ni
DC magnetron sputtering
from 50Wt% Ni- 50wt%Cr
target of 32.5mm diameter and
3 mm thickness was used to
deposit the Ni/CrN coatings in
the present study. The
microstructural properties as a
function of nitrogen flow rate
and substrate temperatures
were investigated using the
(220)CrN
(311)CrN / (220)Ni
20 sccm
400
25 sccm
0
20 30 40 50 60 70 80 90
Two Theta(degrees)
(311)Ni
Fig.2 XRD traces of the nanocomposite films as a
function of nitrogen flow rates
Fig.3 TEM microstructure of nanocrystalline composite film of Ni/CrN.
The inset shows the diffraction pattern containing reflections of Ni and CrN.
techniques of x-ray diffraction,
scanning electron microscopy
and
microhardness
measurements. SEM/EDX
analysis indicated a fine
distribution of particles (Fig.1a)
and the composition of the
films is close that of the target
stoichiometry (Fig 1b). XRD
analysis indicted that the films
contained Ni, Cr 2 N and CrN
for flow rates less than 2
standard cubic centimeter per
minute (sccm) and Ni and CrN
for flow rates >2sccm ( Fig.2).
The particle size of the CrN and
Ni were found to be 5 nm and
9.5-13 nm, respectively. The
films deposited at 773 K
showed that the particle size of
the Ni was found to remain at 5
nm, while the partcle size
decreased from 13 nm to 9.5
nm with increasing flow rate of
nitrogen. A typical TEM bright
field image of Ni/CrN film
deposited on NaCl and the
corresponding diffraction
pattern (inset of Fig.3) confirms
the XRD results.
Nanoindentation
measurements of the films
showed hardness values of
about 12 GPa which is
significantly lower than the
hardness of pure CrN (~ 20
GPa) indicating that the
composite coatings might have
more ductility than that of pure
intermetallic nitride phase.
148 BASIC RESEARCH