ICMCTF 2012! - CD-Lab Application Oriented Coating Development

damage modes of TiN and TiAlN coated cutting tools and their mechanisms
aiming to improve machinability of high-hardness die and mold steels. For
this purpose, the wear surface and closs-section after cutting was
investigated using FE-EPMA, TEM, and STEM. Particularly, the adhesive
materials formed on the cutting edges were analyzed and tools damage was
studies.
EPMA analysis of tool-work interface showed that the belag was formed on
the coating surface during cutting, which was Mn-Si-O or Al-O. Formation
of the Mn-Si-O based belag could help increasing the cutting speed
compared to formation of an Al-O based belag, while Al-O based belage
was performed as protective layer against wear resistance. The belag
formation was related to the chemical composition of work materials,
chemical composition of the coatings and cutting temperature.
BP-9 Annealing effects on nanostructure and mechanical properties of
laminated Ta–Zr coatings, Y.I. Chen (yichen@mail.ntou.edu.tw), S.M.
Chen, National Taiwan Ocean University, Taiwan
The as-deposited laminated Ta–Zr coatings exhibited nanocrystalline or
amorphous states, depending on the chemical compositions. As annealed in
oxygen containing atmospheres, Zr oxidized preferentially. The hardness
increased as the oxygen content in the coating increased, due to the
formation of ZrO2. To behave as a protective coating applied in high
temperature with an appropriate hardness, such as coatings on glass
molding dies, the coating need to endure annealing treatment in an oxygen
containing atmosphere at 600 o C. In this study, the periods of laminated
coatings were controlled by rotating speeds of the substrate holder. T he
annealing treatments were conducted at 600 o C under atmospheres of 20 and
50 ppm O2-N2, respectively. The variations in crystalline structure,
hardness, surface roughness and chemical composition profiles in depth
after various annealing times were investigated. The lifetime of a protective
Ta–Zr coating was justified by exposed the coating in a 50 ppm O2-N2
environment to achieved a high hardness of 10 GPa and then annealed in a
20 ppm O2-N2 atmosphere for long times.
BP-10 Influence of thickness on mechanical and corrosion properties
of Ti-Si-N coatings on D2 steel by unbalanced magnetron sputtering.,
Y.K. Cheng, G.P. Yu, J.H. Huang (jhhuang@mx.nthu.edu.tw), National
Tsing Hua University, Taiwan
In order to fulfill the requirements in industrial applications, hard coatings
possessing both high hardness and good corrosion resistance are demanded.
Ti-Si-N is one of the coatings that have been extensively studied in recent
years. Most studies on Ti-Si-N coatings were focused on the hardening
mechanisms due to structure evolution, composition variation, or impurity
effect; however, few studies have been performed on the relation between
residual stress and thickness variation. In this study, a series of Ti-Si-N
coatings were deposited on AISI D2 tool steel without interlayer using
unbalanced magnetron sputtering at different deposition durations. The
coating thickness of all specimens was larger than 1μm. The purpose of this
study was to investigate the mechanical properties and corrosion resistance
of the Ti-Si-N coatings. X-ray diffraction results showed that the thick Ti-
Si-N coatings were composed of nanocrystalline TiN and amorphous Si3N4.
Coating thickness was obtained from focused ion beam (FIB) measurement.
X-ray photoelectron spectroscopy (XPS) was used to characterize the
bonding state and compositions of the coatings. The hardness of the
coatings was measured by nanoindentation. The residual stress was
determined by modified sin 2 ψ x-ray diffraction and laser curvature methods
to explore the residual stress state and stress distribution in the coatings.
The adhesion of Ti-Si-N coatings was evaluated by scratch test. The
influence of the coating thickness on corrosion resistance was evaluated by
potentiodynamic scan and salt spray test. From the corrosion results, the
thick Ti-Si-N coatings could effectively prevent the D2 steel from
corrosion. The hardness of the coatings was related to the compositions and
texture. The coating thickness was correlated to the residual stress, where a
critical stress was found for the spallation of the coatings.
BP-11 Effect of Nitrogen Flow Rate on The Structure And Mechanical
Properties of TiZrN Thin Films by Unbalanced Magnetron Sputtering,
C.W. Lu, J.H. Huang, G.P. Yu (gpyu@ess.nthu.edu.tw), National Tsing Hua
University, Taiwan
Nanocrystalline TiZrN films were produced using unbalanced magnetron
sputtering. The aim of this study was to investigate the effect of nitrogen
flow rate on the microstructure and properties of the TiZrN films with
nitrogen flow controlled form 1.3 to 2.5 sccm. Thin films of TiZrN were
deposited by magnetron unbalanced sputtering on our previous optimum
coating conditions for TiZrN. The results of the variation of nitrogen flow
rate did not significantly affect the film thickness. The major effects of the
nitrogen flow rate were on the texture coefficient, N/(Ti, Zr) ratio, hardness,
and resistivity of the TiZrN films. The texture coefficients could be
calculated from the integrated intensity of the corresponding XRD peaks.
Thursday Afternoon Poster Sessions 98
The results indicated that (111) plane was the dominant preferred
orientation for all TiZrN specimens. Two other peaks (200) and (220) of
TiZrN films could be observed for the specimen at higher nitrogen flow
rate. The N/(Ti, Zr) ratio of the TiZrN films increased with respect to the
nitrogen flow rate, but increased slowly as nitrogen flow rate further
increased. Hardness of TiZrN films first increased to its maximum of
33.1GPa and then decreased as nitrogen flow rate further increased. The
result showed that film hardness was not directly dependent on the (111)
preferred orientation. The hardness of TiZrN thin films was due to solid
solution strengthening and nanograin boundary sliding mechanism. The
electrical resistivity and packing density of thin film related to the lattice
defects. Similar to hardness, packing density also increased to a maximum
at a critical nitrogen flow rate and the lowest resistivity corresponded to the
highest packing density.
BP-12 Ternary d-TixTa1-xN: An addition to superhard materials?, L.
Koutsokeras, University of Ioannina, Greece, A. Skarmoutsou, National
Technical University of Athens, Greece, G. Abadias, University of Poitiers,
France, P. Psyllaki, Technological Education Institute of Piraeus, Greece,
C. Charitidis, National Technical University of Athens, Greece, C. Lekka,
P. Patsalas (ppats@cc.uoi.gr), University of Ioannina, Greece
The quest of ultraperformant, hard protective coatings [1] is of major
technological importance due to their applications in cutting tools,
automotive and space industry, among others. Within this framework
materials that exhibit hardness above 40 GPa are considered as superhard.
Supehard materials are usually nanostructured, like the well known nc-
TiN/a-Si3N4 [1]. Recently it was possible to grow the ternary compound d-
TixTa1-xN [2] and its hardness has been measured to be as high as 42 GPa
[3]; the later makes it a strong candidate for being a member of the group of
superhard materials.
In this work, we investigate the effects of composition and microstructure
of d-TixTa1-xN coatings on their mechanical performance. The d-TixTa1-xN
coatings have been grown by dual-cathode magnetron sputtering (DCMS)
and dual ion beam sputtering (DIBS). The DIBS-grown samples exhibit
globular grain morphology and similar grain sizes for all values of x. On the
contrary, the DCMS-grown samples exhibit strong variations of their
microstructure, from globular to strongly columnar, with varying x, as
identified by X-ray Diffraction and Electron Microscopy analyses.
Therefore, by comparing their mechanical performance we can discriminate
the effects of composition and microstructure. The mechanical testing has
been performed in terms of hardness measurements by nanoindentation,
tribological testing by lateral force measurements and wear testing by ball
on disk measurements. According to ab-initio calculations of the elastic
moduli, the pure d-TaN was expected to be the hardest member of the d-
TixTa1-xN family. However, the experimentally produced d-TaN coatings
are defective and underdense [4,5]. Here we prove that alloying TiN with
TaN improves the mechanical performance by stabilizing the rocksalt
structure for Ta-rich ternary d-TixTa1-xN coatings, which are harder than
their constituents (TiN, TaN). Indeed, the Ta-rich d-TixTa1-xN coatings were
superior in most aspects of mechanical testing.
[1] S. Veprek, J. Vac. Sci. Technol. A17, 2401 (1999).
[2] L.E. Koutsokeras, G. Abadias, Ch.E. Lekka, G.M. Matenoglou, D.F.
Anagnostopoulos, G.A. Evangelakis, P. Patsalas, Appl. Phys. Lett. 93,
011904 (2008).
[3] G. Abadias, L.E. Koutsokeras, S.N. Dub, G.N. Tolmachova, A. Debelle,
T. Sauvage, and P. Villechaise
J. Vac. Sci. Technol. A 28, 541 (2010).
[4] C.-S. Shin, D. Gall, P. Desjardins, A. Vailionis, H. Kim, I. Petrov, J.E.
Greene, M. Odén, Appl. Phys. Lett. 75, 3808 (1999).
[5] G.M. Matenoglou, L.E. Koutsokeras, Ch.E. Lekka, G. Abadias, S.
Camelio, G.A. Evangelakis, C. Kosmidis, and P. Patsalas, J. Appl. Phys.
104, 124907 (2008).
BP-13 Paramagnetic centers in hard graphite-like amorphous carbon,
A. Viana, C. Marques (marques@ifi.unicamp.br), Universidade Estadual de
Campinas, Brazil
In this work we investigate the origin of paramagnetic centers in hard
graphite-like amorphous carbon. The films were deposited by 1) plasma
enhanced chemical vapor deposition (PECVD) using the decomposition of
methane (CH4) and 2) sputtering, using an argon ion gun to sputter a pure
graphite target. High concentration of sp 2 films was obtained adopting high
bias in the PECVD technique. These films have small band gap (0.5-1.0eV)
and hardness of approximately 15 GPa. The films prepared by the
sputtering technique have sp 2 concentration of approximately 90 %, zero
energy band gap and hardness of 20-30 GPa. Electron spin resonance (ESR)
was performed at the X-band (9.4 GHz) microwave frequency using 100
kHz field modulation. A non-saturating power of 5 mW was adopted. The
ESR measurements revealed an unexpected low density of paramagnetic