ICMCTF 2012! - CD-Lab Application Oriented Coating Development

polarization resistance and corrosion rate were around 112.19 kOhm cm 2
and 3.66x10 -3 mm/year, these values were 98 % and 99 % better than those
showed by the uncoated 4140 steel substrate (0.65 kOhm and 31.13
mm/year), respectively. With this idea, HfN/VN multilayered have been
designed and deposited on Si(100) and AISI 4140 steel substrates with
bilayer periods (Λ) in a broad range, from nanometers to hundreds of
nanometers, in order to study the microstructural evolution with decreasing
bilayer thickness and their related mechanical and electrochemical
properties in with aim to find novel industrial applications.
Keywords: Multilayer coatings, Magnetron sputtering, Mechanical
properties.
PACS: 61.05.c, 62.20.Qp
Acknowledgements
This research was supported by "El patrimonio Autónomo Fondo Nacional
de Financiamiento para la Ciencia, la Tecnología y la Innovación Francisco
José de Caldas" under contract RC-No. 275-2011. Moreover, the authors
acknowledge the Serveis Científico-Técnics of the Universitat de Barcelona
for TEM analysis.
AP-6 Study of the effect of densification on the mechanical properties
of porous coatings after nano-indentation, X.J. Lu
(xiaojuanlv@hotmail.com), P. Xiao, H. Li, A. Fok, The University of
Manchester, UK
Nano-indentation of a porous ceramic coating leads to crushing and
densification of the coating under the indenter. During indentation, a
densified layer with gradient density was formed beneath the indenter. In
this work, finite element (FE) simulation of indentation on the densified
layer has been carried out to study the effect of the densified area on
measured Young’s modulus from nano-indentation. According to the FE
simulation, the measured Young’s modulus from indentation deviates from
the true Young’s modulus when the size of densified region is much larger
than the indentation region. Based on the simulation results and
experimental results from indentation of a porous yttria stablised zirconia
coating produced in this work, the measured Young’s modulus should be
the true Young’s modulus of the coating.
AP-8 Oxygen incorporation in Cr2AlC, M. to Baben
(to_baben@mch.rwth-aachen.de), L. Shang, J. Emmerlich, J. Schneider,
Materials Chemistry, RWTH Aachen university, Germany
The MAX phase Cr2AlC is a promising candidate for high temperature
applications because of its oxidation resistance, which is comparable to
NiAl [1]. However, neither the early stages of oxidation of Cr2AlC nor the
influence of oxygen impurities in the at % range [1]which are probably
introduced due to processing in high vacuum [2] have been studied.
Oxygen incorporation in Cr2AlC was studied by a combination of ab initio
calculations and combinatorial magnetron sputtering. Cr, Al and C targets
were sputtered in Ar and Ar+O2 atmosphere, leading to three different
oxygen contents in the thin films. From X-ray stress analysis it was
determined how lattice parameters of Cr2AlC are influenced by the oxygen
content.
The energy of formation was calculated for Ti2AlC1-xOx, V2AlC1-xOx and
Cr2AlC1-xOx with O occupying interstitial and substitutional sites. For
Cr2AlC1-xOx the energy difference between interstitial and substitutional
incorporation of oxygen is -0.7 eV/oxygen atom, while it is +2.6 and +1.2
eV/oxygen atom for Ti2AlC1-xOx and V2AlC1-xOx, respectively. This
indicates that oxygen does not substitute carbon, as observed for Ti2AlC1xOx
[2], but is incorporated interstitially in the Al-layer of Cr2AlC1-xOx, even
in the presence of carbon vacancies.
Experimentally, an increase of the a lattice parameter of +0.18% was
observed while the c lattice parameter was hardly affected. These
experimentally determined volume changes are in good agreement with the
predictions from ab initio calculations on interstitial incorporation of
oxygen, corroborating the notion of oxygen interstitials in Cr2AlC. A
solubility limit of 3.5 at% of oxygen was observed under the deposition
conditions studied within this work. An increase of oxygen content above
this limit led to the formation of an x-ray amorphous phase.
[1]: D.E. Hajas et al., Surf. Coat. Technol. (2011),
doi:10.1016/j.surfcoat.2011.03.086.
[2]: J. Rosen et al., Appl. Phys. Let. 92 (2008), 064102.
AP-9 Multicomponent Coatings in Cr-Al-Si-B-(N) System Produced by
Magnetron Sputtering of Composite SHS-Targets, P. Kiryukhantsev-
Korneev (kiruhancev-korneev@yandex.ru), Yu. Pogozhev, D.V. Shtansky,
National University of Science and Technology “MISIS”, Russian
Federation, J. Vlcek, University of West Bohemia, Czech Republic, E.A.
Levashov, National University of Science and Technology “MISIS”,
Russian Federation
The Cr-B-N coatings are promised due to their high hardness, wear- and
corrosion resistance. It is well known that introduction of Si and Al to
different hard coatings (CrN, TiN, and Ti-B-N) improves the tribological
characteristics and oxidation resistance. The aim of present work is to study
the structure and properties of Cr-Al-Si-B-(N) coatings deposited by
magnetron sputtering of composite targets.
Targets were fabricated using the method of self-propagating hightemperature
synthesis (SHS) according to the follow combustion reaction
X(Cr+2B)+(100-X)(4Al+3C+Si3N4) (X=15, 30, and 40). Main advantages
of SHS are follow: self-purification of the final product from impurities
(adsorbed and dissolved) result in high combustion temperature and
combustion rate; achievement of controlled residual porosity of ceramics
due to hot pressing of products follow by high-temperature process of
combustion; synthesis of metastable supersaturated solid solutions.Targets
composition represented by CrB, Cr5Si3, and Cr4Al11 phases.
Magnetron sputtering was performed either in an atmosphere of argon or
reactively in a gaseous mixture of argon and nitrogen. During magnetron
sputtering, the substrate temperature and bias voltage were kept constant in
the range of 300-500 0 C and -500-0 V, respectively. The silicon and alumina
plates, nickel alloy and cemented carbide disks were used as the substrates.
The structure, chemical and phase composition of coatings were studied by
means of X-ray diffraction, transmission and scanning electron microscopy,
Raman spectroscopy, and glow discharge optical emission spectroscopy.
The coatings were characterised in terms of their hardness, elastic modulus,
elastic recovery, adhesion strength, friction coefficient, wear rate, oxidation
resistance, thermal stability, and diffusion barrier properties.
The first experiments demonstrated relatively high hardness till 40 GPa,
Young’s modulus below 270 GPa, elastic recovery up to 50%, oxidation
resistance and good diffusion barrier properties at the temperature high than
1100 0 C.
AP-10 Performance of Advanced Turbocharger Alloys and Coatings at
850-950 o C in Air with Water Vapor, J. Haynes (z15@ornl.gov), B.
Armstrong, B. Pint, Oak Ridge National Laboratory, US
Turbocharged gasoline and diesel engines are of significant interest due to
their capacity to allow smaller displacement automotive engines with
improved fuel economy and lower CO2 emissions. As exhaust temperatures
continue to increase, oxidation resistance and mechanical properties of
exhaust manifolds and turbocharger components will become problematic
for some alloys of interest. This study compared the 850 and 950 o C cyclic
oxidation behavior in air plus 10 vol.% water vapor (simulated exhaust gas)
of IN713C, HR230, MM247, IN939, CW6MC, and two Ti-~48%Al alloys.
The room temperature tensile properties of selected alloys were evaluated
before and after oxidation at 850° and 950°C by using miniature tensile bars
as oxidation specimens. Additionally, selected Ni-based alloys were
aluminized via chemical vapor deposition and/or slurry processes, and the
resultant coating microstructures and 950 o C oxidation behaviors were
compared. The TiAl alloys oxidized more rapidly than the Ni-base alloys or
aluminide coatings after 100, 1-h cycles and scale spallation was observed
at 950°C. However, only minor changes in ductility and tensile strength for
TiAl were observed. Larger decreases in ductility were observed for 713C.
Longer exposures are in progress.
AP-11 Oxidation Behavior of Ni-Ru Films under Glass Hot Pressing,
C.K. Chang, K.Y. Liu, Y.C. Hsiao, F.B. Wu (fbwu@nuu.edu.tw), National
United University, Taiwan
Ni-Ru alloy films are fabricated using r.f. magnetron dual gun cosputtering
process. The Ru content ranges from 10.4 to 53.5 at.% under an input power
control from 10 to 100W, respectively, at a fixed 100W for Ni. The Ni-Ru
coatings with lower Ru contents exhibit a granular structure, while a
significant columnar feature is observed for the Ni46.5Ru53.5 film. The
oxidation behavior of the Ni-Ru films against phosphate glasses are
demonstrated under hot pressing environment. The heat treatment in air are
conducted for comparison. Oxidation reaction penetrates into the Ni-Ru
films over 250 nm at a heat treating temperature of 475°C in air. On the
other hand, a limited oxidation penetration less than 100 nm is found for the
Ni-Ru coatings against phosphate glasses. The granular characteristic and
grain boundaries are responsible for oxidation in air annealing. On the
contrary, the oxidation reaction is suppressed due to depletion of active
oxygen at film/glass contact.
95 Thursday Afternoon Poster Sessions