ICMCTF 2012! - CD-Lab Application Oriented Coating Development

10:20am D2-1-8 Corrosion Resistance and Biocompatibility of
Titanium Coated with Tantalum Pentoxide, Y.S. Sun, H.H. Huang
(hhhuang@ym.edu.tw), National Yang-Ming University, Taiwan
Titanium (Ti) is commonly used as dental implanterial because of its good
corrosion resistance and biocompatibility. Nevertheless, corrosion process
might still happen when Ti metal is implanted in the human body for longterm
application. The tantalum pentoxide (Ta2O5) has superior corrosion
resistance than the titanium dioxide (TiO2) spontaneously formed on Ti
surface. In this study, the Ta2O5 coating was produced on Ti surface using
hydrolysis-condensation process. Surface characteristics, including
chemical composition, microstructure, topography, wettability and substrate
adhesion, of the coating were analyzed. The corrosion resistance of the test
specimens was evaluated using potentiodynamic polarization curve
measurement in simulated blood plasma. The in vitro biocompatibility, in
terms of protein adsorption and cell adhesion, was evaluated. Experimental
data were analyzed using Student’s t-test with a=0.05. Results showed that
the Ta2O5 coating was successfully produced on Ti surface using a simple
hydrolysis-condensation process. TheTa2O5 coating showed a good
adhesion to Ti substrate, and enhanced the corrosion resistance (i.e.
decreased the corrosion rate and anodic current) and biocompatibility (i.e.
improved the protein adsorption and cell adhesion) of Ti surface. We would
conclude that the Ta2O5 coating could be easily produced on Ti surface
using a simple hydrolysis-condensation process. The Ta2O5 coating
provided the Ti surface with better corrosion resistance and in vitro
biocompatibility.
10:40am D2-1-9 Mechanical Properties of Fluorinated DLC and Si
Interlayer on a Ti Biomedical Alloy, C.C. Chou
(cchou@mail.ntou.edu.tw), Y.Y. Wu, National Taiwan Ocean University,
Taiwan, J.W. Lee, Ming Chi University of Technology, Taiwan, J.C.
Huang, Tungnan University, Taiwan, C.H. Yeh, Keelung Chang Gung
Memorial Hospital,Taiwan
Fluorinated diamond-like carbon (F-DLC) films were deposited on
Ti6Al4V substrates by radio frequency plasma enhanced chemical vapor
deposition (rf PECVD) technique using a mixture of methane (CH4) and
tetrafluoromethane (CF4) gases. A 100 nm Si interlayer was coated in
advance by physical vapor deposition (PVD) process to improve the
adhesion between F-DLC and Ti alloy. The structure and surface properties
of F-DLC coatings, prepared by various fluorine flow ratios, were
investigated by using Raman spectroscopy, Fourier transform infrared
spectroscopy, X-ray photoelectron spectroscopy, scanning electron
microscopy, and atomic force microscopy. The mechanical properties were
evaluated by nano-indentation and the adhesion, by nano-scratch. As CF4
flow ratio is promoted in the mixture, CFx group and sp 2 carbon clusters in
the amorphous microstructure increase. However, the etching mechanism
attributed to the fluorine species in the plasma becomes significant when the
CF4/CH4 ratio was higher than 4 in this study. F-DLC film’s Young’s
modulus and hardness were reduced by the increased fluorine content, but
the critical load from the scratch test revealed that the film’s thickness is the
only factor that determines its adhesion strength. The results showed that a
moderate incorporation of the fluorine content in the DLC films can still
maintain acceptable mechanical properties, which, on the other hand,
obtains remarkable benefits of biomedical application.
Tribology & Mechanical Behavior of Coatings and
Engineered Surfaces
Room: Tiki Pavilion - Session E2-3
Mechanical Properties and Adhesion
Moderator: M.T. Lin, National Chung Hsing University,
Taiwan, D. Bahr, Washington State University, US, R.
Chromik, McGill University, Canada
8:00am E2-3-1 Mechanical properties evaluation of the magnetron
sputtered Zr-based metallic glass thin films, C.Y. Chung, Ming Chi
University of Technology, Taiwan, H.W. Chen, J.G. Duh, National Tsing
Hua University, Taiwan, J.W. Lee (jefflee@mail.mcut.edu.tw), Ming Chi
University of Technology, Taiwan
Recently metallic glass thin films represent a class of promising engineering
materials for structural applications. In this work, a series of Zr-based
ZrNiAlSi metallic glass thin films were fabricated by sputtering process.
Different amount of nitrogen gas was introduced during thin films
sputtering. The amorphous structures of coatings were determined by a
glancing angle X-ray diffractometer and transmission electron microscope
(TEM), respectively. The surface and cross sectional morphologies of thin
films were examined by a field emission scanning electron microscopy (FE-
SEM). The surface roughness of thin films was explored by atomic force
microscopy (AFM). A nanoindenter, a scratch tester and pin-on-disk wear
tests were used to evaluate the hardness, adhesion and tribological
properties of thin films, respectively. The influences of nitrogen
concentration on the mechanical and tribological properties of metallic glass
thin films were discussed. A proper nitrogen content of metallic glass thin
films was proposed to achieve an amorphous structure with adequate
mechanical properties in this work.
8:20am E2-3-2 Microstructure and mechanical properties of coppertin
shape memory alloy thin films deposited from an anionic liquid
electrolyte, N. Moharrami (noushin.moharrami@ncl.ac.uk), S. Ghosh, S.
Roy, S.J. Bull, Newcastle University, UK
Shape memory alloys (SMA) are finding an increasing range of industrial
applications owing to the fact that a change in shape produced by plastic
deformation can be recovered by heating and the materials may show a
superelastic effect (i.e. plastic deformation is recovered at even at very large
strains). Such materials show great potential as actuators and there has been
considerable interest in developing SMA coatings and assessing them using
nanoindentation tests. Although most work has been done on NiTi and
CuAlZn there remains an interest in developing cheaper, simpler to process
materials for mass market applications. Copper-15%Sn shows the shape
memory effect and may be deposited by electrodeposition on a range of
substrates. Whereas it is difficult to get the correct chemical and phase
composition by plating from aqueous electrolytes good results are obtained
when plating from an ionic liquid. In this study the nanoindentation
response of copper-tin coatings deposited from a Room Temperature Ionic
Liquid (RTIL) has been measured and compared to that of coatings
deposited from an aqueous electrolyte. The results show that the shape
memory effect is enhanced when using the RTIL route.
8:40am E2-3-3 Precipitation and Fatigue in Ni-Ti-Zr Shape Memory
Alloy Thin Films by Combinatorial nanoCalorimetry, J. Vlassak
(vlassak@esag.harvard.edu), Harvard University, US INVITED
The parallel nano-scanning calorimeter (PnSC) is a novel silicon-based
micromachined device for calorimetric measurement of nanoscale materials
in a high-throughput methodology. The device contains an array of
calorimetric sensors, each one of which consists of a silicon nitride
membrane and a tungsten heating element that also serves as a temperature
gauge. The small mass of the individual sensors enables measurements on
samples as small as a few hundred nanograms at heating rates up to 10 4 K/s.
This device was used to study thin-film samples of Ni-Ti-Zr shape memory
alloys to evaluate the effects of high-temperature (900°C) heat treatments
and low-temperature (450°C) thermal cycling on the characteristics of the
martensite transformation. The response of the samples to heat treatments
depends on composition and is controlled by a precipitation mechanism.
Two precipitate types, a Ti2Ni base phase at low Zr concentration and a
Ni10Zr7 base phase at high Zr concentration, affect the martensite
transformation characteristics by altering the composition and the stress
state of the shape memory phase. Thermal fatigue behavior, induced by
thermal cycling, is improved compared to previous results. The most stable
sample demonstrates a transformation temperature reduction of just 11°C
for 100 cycles. The improved stability of the samples is attributed to the
very small grain size of approximately 5-20 nm. The high heating and
cooling rates characteristic of nanocalorimeters allowed this study to be
performed in a high-throughput manner with efficiencies not previously
achieved.
9:20am E2-3-5 Investigation of the elastic-plastic properties of thin
films on polymide substrate under controlled biaxial deformation, S.
Djaziri, Institut P' - Universite de Poitiers, France, D. Faurie (faurie@univparis13.fr),
LSPM-CNRS, Université Paris13, France, P. Renault, E. Le
Bourhis, Institut P' - Universite de Poitiers, France, G. Geandier, Institut
Jean Lamour, France, C. Mocuta, D. Thiaudière, SOLEIL Synchrotron,
France, P. Goudeau, Institut P' - Universite de Poitiers, France
This presentation reports the elastic-plastic behaviour of Au and W thin
films deposited on Kapton® under controlled biaxial loadings thanks to a
biaxial testing device developed on DiffAbs beamline at SOLEIL
synchrotron (Saint-Aubin, France). In-situ tensile tests were carried out
combining 2D synchrotron x-ray diffraction (XRD) and digital-image
correlation (DIC) techniques. First, the elastic behaviour of the composite
metallic film – polymeric substrate was investigated under equi-biaxial and
non-equi-biaxial loading conditions. The results show that the strain
measurements (in the crystalline film by XRD and the substrate by DIC)
match to within 1×10 -4 . This demonstrates the full transmission of strains in
the elastic domain through the film-substrate interface and thus a good
adhesion of the thin film to the substrate. The second part of the paper deals
with higher strains response including plastic strains under equi-biaxial
tensile tests. The elastic limit of the nanostructured thin films was
131 Friday Morning, April 27, 2012