Abstract: Grain boundary character distributions (GBCD) of type 304 stainless steel cold rolled and
then annealed at 1173K were analyzed by electron back scatter diffraction (EBSD). The results
showed that low strain (~6%) followed by long-time annealing (96h) resulted in a GBCD
containing a high fraction of Σ9 and Σ27 boundaries. The connectivity of general high angle grain
boundary (HAB) network was interrupted significantly by Σ3n(n=1,2,3) boundaries(special
Abstract: First-principles calculations based on density functional theory, using PW91 functional
have been performed to study the adsorption of Alkali metal (AM) on C(100)(2×1) surface. The stable
geometries, adsorption energies for all adsorption configurations have been calculated on half a
monolayer and one monolayer. The preferred binding sites have been determined to be valley-bridge
sites at the coverage of 0.5ML. At higher coverage of 1ML, two AM adsorbates were found to reside
in pedestal site and valley-bridge site, respectively. Work function analysis showed that when AMs
are adsorbed on C(100)(2×1) surface, the work function decreases linearly with increasing coverage
and reaches a minimum at Θ=0.5ML. At higher coverage, the work function is increased again, which
may be caused by depolarization effect of the adsorbate.
Abstract: Cr3C2- NiCr and Cr3C2- NiCr-(25) WC-Co coatings were deposited on T22 boiler steel
by High Velocity Oxy-Fuel (HVOF) Technology. The coated as well as the uncoated steel samples
were exposed to the actual boiler environments in a thermal power plant for 1500 hrs under cyclic
conditions to evaluate their erosion-corrosion performance. Weight change measurements were
taken for each sample after every 100 hrs. It has been observed that the weight change trends for
coated steel with Cr3C2- NiCr and Cr3C2- NiCr-(25) WC-Co coatings followed a parabolic trend.
The exposed samples were physically investigated for any macroscopic changes after each cycle of
100 hours. The uncoated steel showed blisters and spallation of its oxide scale, whereas the coated
samples exhibited intact oxide scales, in general. Scanning Electron Microscopy/Energy Dispersive
X-Ray Analysis (SEM/EDAX) was done to characterize morphology of the oxide scales. The
protective nature of coatings has been explained based on the results of the study.
Abstract: Aluminum foam is lightweight structures, energy absorption and thermal management. In
this reason, there is a lot of attention on the aluminum foam as a structural material. The present
papers showed various conventional joining techniques can be applied for foam-sheet structures, i.e.,
riveting, screwing, welding, gluing and soldering. This research presents new joining technique of
Aluminum foam/Aluminum metal using spark plasma sintering (SPS) process. The Aluminum
foam/Aluminum metals were fabricated by changing of various SPS holding temperature and holding
time conditions. With increasing holding temperature and holding time, the tensile stress increased.
The specimen sintered at 550°C for 20 min shows σts = 1.47 MPa. Also, it was found that the SPS
holding time is dominant factor than the holding temperature for sound joining of two joint materials.
Abstract: Fretting damage is a critical problem to prevent failure of press-fitted shaft such as the
rotor of a steam turbine, railway axles or coupling. To clarify the characteristics of surface damage
due to fretting in press-fitted shaft, experimental methods were applied to small-scale specimen with
different bending load conditions. Fatigue tests and interrupted fatigue tests of press-fitted specimen
were carried out by using a rotate bending fatigue test machine. Macroscopic and microscopic
characteristics were examined using scanning electron microscope (SEM), optical microscope or
profilometer. It is found that small fatigue cracks are nucleated early in life regardless of bending
stress, and thus the most portion of fatigue life on press fits can be considered to be crack propagation
process. Most of surface cracks are initiated near the contact edge, and multiple cracks are nucleated
and interconnected. Furthermore, the fretting wear rates at the contact edge increase rapidly at the
initial stage of total fatigue life. It is thus suggested that the fatigue crack nucleation and propagation
process is strongly related to the evolution of surface profile by fretting wear in press fits.
Abstract: Surface treatment of a Co-Cr-W-C based alloy by pack boronizing is performed in this
study. Treating at temperatures between 950 and 1050oC for up to 5 hrs produces a layer-like boride
coating. The phase and composition analysis of the boronized layer is carried out by means of
optical and SEM, EPMA and XRD. The growth of overall boronized layer is observed to obey the
parabolic law, suggesting that it occurs via a diffusion-controlled process. Along with the
microstructural features of the boronized layer, some brief results of the improvements of the wear
property of Co-Cr-W-C alloy by boronizing treatment are presented.
Abstract: A study on chromium matrix composite plated with nanosized diamond powders was
undertaken by employing a standard Sargent bath. Chromium matrix composite plated with
nanosized diamond powders manifested super properties. The microhardness was varied from 890
to 920 HV (load 25 g/f), as compared with 801 HV of pure chromium; the wear resistance was
increased 3-4 times. The potentiodynamic measurement in a chloride medium showed that the
passive current of chromium matrix composite plated with nanosized diamond powder was 6 times
as lower as that of pure chromium. Microscopic observation indicated that nano-diamond powders
were included in the chromium deposit in the form of single and multi crystalline.