Abstract: Rapid prototyping is a new group of manufacturing
processes, which allows fabrication of physical of any complexity
using a layer by layer deposition technique directly from a computer
system. The rapid prototyping process greatly reduces the time and
cost necessary to bring a new product to market. The prototypes
made by these systems are used in a range of industrial application
including design evaluation, verification, testing, and as patterns for
casting processes. These processes employ a variety of materials and
mechanisms to build up the layers to build the part. The present work
was to build a FDM prototyping machine that could control the X-Y
motion and material deposition, to generate two-dimensional and
three-dimensional complex shapes. This study focused on the
deposition of wax material. This work was to find out the properties
of the wax materials used in this work in order to enable better
control of the FDM process. This study will look at the integration of
a computer controlled electro-mechanical system with the traditional
FDM additive prototyping process. The characteristics of the wax
were also analysed in order to optimise the model production process.
These included wax phase change temperature, wax viscosity and
wax droplet shape during processing.
Abstract: Ceramic obtained on the base of aluminum oxide has
wide application range, because it has unique properties, for example,
wear-resistance, dielectric characteristics, and exploitation ability at
high temperatures and in corrosive atmosphere. Low temperature
synthesis of α-Al2O3 is energo-economical process and it is topical
for developing technologies of corundum ceramics fabrication. In the present work possibilities of low temperature transformation
of oxyhydroxides in α-Al2O3, during the presence of small amount of
rare–earth elements compounds (also Th, Re), have been discussed.
Aluminum unstable oxyhydroxides have been obtained by hydrolysis
of aluminium isopropoxide, nitrates, sulphate, and chloride in
alkaline environment at 80-90ºC temperatures. β-Al(OH)3 has been
received from aluminum powder by ultrasonic development. Drying
of oxyhydroxide sol has been conducted with presence of various
types seeds, which amount reaches 0,1-0,2% (mas). Neodymium,
holmium, thorium, lanthanum, cerium, gadolinium, disprosium
nitrates and rhenium carbonyls have been used as seeds and they
have been added to the sol specimens in amount of 0.1-0.2% (mas)
calculated on metals. Annealing of obtained gels is carried out at 70–
1100ºC for 2 hrs. The same specimen transforms in α-Al2O3 at
1100ºC. At this temperature in case of presence of lanthanum and
gadolinium transformation takes place by 70-85%. In case of
presence of thorium stabilization of γ-and θ-phases takes place. It is
established, that thorium causes inhibition of α-phase generation at
1100ºC, and at the time when in all other doped specimens α-phase is
generated at lower temperatures (1000-1050ºC). Synthesis of various
type compounds and simultaneous consolidation has developed in the
furnace of OXY-GON. Composite materials containing oxide and
non-oxide components close to theoretical data have been obtained in
this furnace respectively. During the work the following devices have
been used: X-ray diffractometer DRON-3M (Cu-Kα, Ni filter,
2º/min), High temperature vacuum furnace OXY-GON, electronic
scanning microscopes Nikon ECLIPSE LV 150, NMM-800TRF,
planetary mill Pulverisette 7 premium line, SHIMADZU Dynamic
Ultra Micro Hardness Tester, DUH-211S, Analysette 12 Dyna sizer.
Abstract: This paper reports the viability of developing Zn-27Al
alloy matrix hybrid composites reinforced with alumina, graphite and
fly ash (solid waste bye product of coal in thermal power plants).
This research work was aimed at developing low cost-high
performance Zn-27Al matrix composite with low density. Alumina
particulates (Al2O3), graphite added with 0, 2, 3, 4 and 5 wt% fly ash
were utilized to prepare 10wt% reinforcing phase with Zn-27Al alloy
as matrix using two-step stir casting method. Density measurement,
estimated percentage porosity, tensile testing, micro hardness
measurement and optical microscopy were used to assess the
performance of the composites produced. The results show that the
hardness, ultimate tensile strength, and percent elongation of the
hybrid composites decrease with increase in fly ash content. The
maximum decrease in hardness and ultimate tensile strength of
13.72% and 15.25% respectively were observed for composite grade
containing 5wt% fly ash. The percentage elongation of composite
sample without fly ash is 8.9% which is comparable with that of the
sample containing 2wt% fly ash with percentage elongation of 8.8%.
The fracture toughness of the fly ash containing composites was
however superior to those of composites without fly ash with 5wt%
fly ash containing composite exhibiting the highest fracture
toughness. The results show that fly ash can be utilized as
complementary reinforcement in ZA-27 alloy matrix composite to
reduce cost.
Abstract: Wire Electric Discharge Machining (WEDM) is
thermal machining process capable of machining very hard
electrically conductive material irrespective of their hardness.
WEDM is being widely used to machine micro scale parts with the
high dimensional accuracy and surface finish. The objective of this
paper is to optimize the process parameters of wire EDM to fabricate
the micro channels and to calculate the surface finish and material
removal rate of micro channels fabricated using wire EDM. The
material used is aluminum 6061 alloy. The experiments were
performed using CNC wire cut electric discharge machine. The effect
of various parameters of WEDM like pulse on time (TON) with the
levels (100, 150, 200), pulse off time (TOFF) with the levels (25, 35,
45) and current (IP) with the levels (105, 110, 115) were investigated
to study the effect on output parameter i.e. Surface Roughness and
Material Removal Rate (MRR). Each experiment was conducted
under different conditions of pulse on time, pulse off time and peak
current. For material removal rate, TON and Ip
were the most significant process parameter. MRR increases with the increase in
TON and Ip and decreases with the increase in TOFF. For surface
roughness, TON and Ip have the maximum effect and TOFF was found
out to be less effective.
Abstract: Polymeric micro-cantilevers (Cs) are rapidly
becoming popular for MEMS applications such as chemo- and biosensing
as well as purely electromechanical applications such as
microrelays. Polymer materials present suitable physical and
chemical properties combined with low-cost mass production. Hence,
micro-cantilevers made of polymers indicate much more
biocompatibility and adaptability of rapid prototyping along with
mechanical properties. This research studies the effects of three
process and one size factors on the filling behaviour in micro cavity,
and the role of each in the replication of micro parts using different
polymer materials i.e. polypropylene (PP) SABIC 56M10 and
acrylonitrile butadiene styrene (ABS) Magnum 8434 . In particular,
the following factors are considered: barrel temperature, mould
temperature, injection speed and the thickness of micro features. The
study revealed that the barrel temperature and the injection speed are
the key factors affecting the flow length of micro features replicated
in PP and ABS. For both materials, an increase of feature sizes
improves the melt flow. However, the melt fill of micro features does
not increase linearly with the increase of their thickness.
Abstract: As the Silicon oxide scaled down in MOSFET
technology to few nanometers, gate Direct Tunneling (DT) in
Floating gate (FGMOSFET) devices has become a major concern for
analog designers. FGMOSFET has been used in many low-voltage
and low-power applications, however, there is no accurate model that
account for DT gate leakage in nano-scale. This paper studied and
analyzed different simulation models for FGMOSFET using TSMC
90-nm technology. The simulation results for FGMOSFET cascade
current mirror shows the impact of DT on circuit performance in
terms of current and voltage without the need for fabrication. This
works shows the significance of using an accurate model for
FGMOSFET in nan-scale technologies.
Abstract: The MEMS pressure sensor has been introduced and
presented in this paper. The types of pressure sensor and its theory of
operation are also included. The latest MEMS technology, the
fabrication processes of pressure sensor are explored and discussed.
Besides, various device applications of pressure sensor such as tire
pressure-monitoring system, diesel particulate filter and others are
explained. Due to further miniaturization of the device nowadays, the
pressure sensor with nanotechnology (NEMS) is also reviewed. The
NEMS pressure sensor is expected to have better performance as well
as lower in its cost. It has gained an excellent popularity in many
applications.
Abstract: The design of high pressure water jet based polishing
equipment and its fabrication conducted in this study is reported
herein, together with some preliminary test results for assessing its
applicability for HMA surface polishing. This study also provides
preliminary findings concerning the test variables, such as the
rotational speed, the water jet pressure, the abrasive agent used, and
the impact angel that were experimentally investigated in this study. The preliminary findings based on four trial tests (two on large
slab specimens and two on small size gyratory compacted
specimens), however, indicate that both friction and texture values
tend to increase with the polishing durations for two combinations of
pressure and rotation speed of the rotary deck. It seems that the more
polishing action the specimen is subjected to; the aggregate edges are
created such that the surface texture values are increased with the
accompanied increase in friction values. It may be of interest (but
which is outside the scope of this study) to investigate if the similar
trend exist for HMA prepared with aggregate source that is sand and
gravel.
Abstract: This paper presents the design and fabrication of a
novel piezoelectric actuator for a gas micro pump with check valve
having the advantages of miniature size, light weight and low power
consumption. The micro pump is designed to have eight major
components, namely a stainless steel upper cover layer, a piezoelectric
actuator, a stainless steel diaphragm, a PDMS chamber layer, two
stainless steel channel layers with two valve seats, a PDMS check
valve layer with two cantilever-type check valves and an acrylic
substrate. A prototype of the gas micro pump, with a size of 52 mm ×
50 mm × 5.0 mm, is fabricated by precise manufacturing. This device
is designed to pump gases with the capability of performing the
self-priming and bubble-tolerant work mode by maximizing the stroke
volume of the membrane as well as the compression ratio via
minimization of the dead volume of the micro pump chamber and
channel. By experiment apparatus setup, we can get the real-time
values of the flow rate of micro pump and the displacement of the
piezoelectric actuator, simultaneously. The gas micro pump obtained
higher output performance under the sinusoidal waveform of 250 Vpp.
The micro pump achieved the maximum pumping rates of 1185
ml/min and back pressure of 7.14 kPa at the corresponding frequency
of 120 and 50 Hz.
Abstract: Knowledge of bone mechanical properties is important
for bone substitutes design and fabrication, and more efficient
prostheses development. The aim of this study is to characterize the
viscoelastic behavior of bone specimens, through stress relaxation
and fatigue tests performed to trabecular bone samples from bovine
femoral heads. Relaxation tests consisted on preloading the samples
at five different magnitudes and evaluate them for 1020 seconds,
adjusting the results to a KWW mathematical model. Fatigue tests
consisted of 700 load cycles and analyze their status at the end of the
tests. As a conclusion we have that between relaxation stress and
each preload there is linear relation and for samples with initial
Young´s modulus greater than 1.5 GPa showed no effects due fatigue
test loading cycles.
Abstract: Aluminium matrix composites with alumina
reinforcements give superior mechanical & physical properties. Their
applications in several fields like automobile, aerospace, defense,
sports, electronics, bio-medical and other industrial purposes are
becoming essential for the last several decades. In the present work,
fabrication of hybrid composite was done by Stir casting technique
using Al 6061 as a matrix with alumina and silicon carbide (SiC) as
reinforcement materials. The weight percentage of alumina is varied
from 2 to 4% and the silicon carbide weight percentage is maintained
constant at 2%. Hardness and wear tests are performed in the as cast
and heat treated conditions. Age hardening treatment was performed
on the specimen with solutionizing at 550°C, aging at two
temperatures (150 and 200°C) for different time durations. Hardness
distribution curves are drawn and peak hardness values are recorded.
Hardness increase was very sensitive with respect to the decrease in
aging temperature. There was an improvement in wear resistance of
the peak aged material when aged at lower temperature. Also
increase in weight percent of alumina, increases wear resistance at
lower temperature but opposite behavior was seen when aged at
higher temperature.
Abstract: Development of new generation bio-tribological,
multilayer coatings opens an avenue for fabrication of future hightech
functional surfaces. In the presented work, nano-composite,
Cr/CrN+[Cr/ a-C:H implanted by metallic nanocrystals] multilayer
coatings have been developed for surface protection of medical tools.
Thin films were fabricated by a hybrid Pulsed Laser Deposition
technique. Complex microstructure analysis of nanomultilayer
coatings, subjected to mechanical and biological tests, were
performed by means of transmission electron microscopy (TEM).
Microstructure characterization revealed the layered arrangement of
Cr23C6 nanoparticles in multilayer structure. Influence of deposition
conditions on bio-tribological properties of the coatings was studied.
The bio-tests were used as a screening tool for the analyzed
nanomultilayer coatings before they could be deposited on medical
tools. Bio-medical tests were done using fibroblasts. The mechanical
properties of the coatings were investigated by means of a ball-ondisc
mechanical test. The micro hardness was done using Berkovich
indenter. The scratch adhesion test was done using Rockwell
indenter. From the bio-tribological point of view, the optimal
properties had the C106_1 material.
Abstract: This study focuses on a novel method for dispersion
and distribution of reinforcement under high intensive shear stress to
produce metal composites. The polyacrylonitrile (PAN)-based short
carbon fiber (Csf) and Nextel 610 alumina fiber were dispersed under
high intensive shearing at mushy zone in semi-solid of A356 by a
novel method. The bundles and clusters were embedded by
infiltration of slurry into the clusters, thus leading to a uniform
microstructure. The fibers were embedded homogenously into the
aluminum around 576-580°C with around 46% of solid fraction.
Other experiments at 615°C and 568°C which are contained 0% and
90% solid respectively were not successful for dispersion and
infiltration of aluminum into bundles of Csf. The alumina fiber has
been cracked by high shearing load. The morphologies and
crystalline phase were evaluated by SEM and XRD. The adopted
thixo-process effectively improved the adherence and distribution of
Csf into Al that can be developed to produce various composites by
thixomixing.
Abstract: Super steel materials play a vital role in the
construction and fabrication of structural, piping and pipeline
components. In assuring the integrity of onshore and offshore
operating systems, they enable life cycle costs to be minimized. In
this context, Duplex stainless steel (DSS) material related welding on
constructions and fabrications plays a significant role in maintaining
and assuring integrity at an optimal expenditure over the life cycle of
production and process systems as well as associated structures. In
DSS welding, factors such as gap geometry, shielding gas supply
rate, welding current, and type of the welding process are vital to the
final joint performance. Hence, an experimental investigation has
been performed using an engineering robust design approach
(ERDA) to investigate the optimal settings that generate optimal
super DSS (i.e. UNS S32750) joint performance. This manuscript
illustrates the mathematical approach and experimental design,
optimal parameter settings and results of the verification experiment.
Abstract: This paper reports a novel actuating design that uses
the shear deformation of a piezoelectric actuator to deflect a
bulge-diaphragm for driving an array microdroplet ejector. In essence,
we employed a circular-shaped actuator poled radial direction with
remnant polarization normal to the actuating electric field for inducing
the piezoelectric shear effect. The array microdroplet ejector consists
of a shear type piezoelectric actuator, a vibration plate, two chamber
plates, two channel plates and a nozzle plate. The vibration, chamber
and nozzle plate components are fabricated using nickel
electroforming technology, whereas the channel plate is fabricated by
etching of stainless steel. The diaphragm displacement was measured
by the laser two-dimensional scanning vibrometer. The ejected
droplets of the microejector were also observed via an optic
visualization system.
Abstract: An unconventional composite inorganic ceramic
membrane capable of enhancing carbon dioxide emission decline was
fabricated and tested at laboratory scale in conformism to various
environmental guidelines and also to mitigate the effect of global
warming. A review of the existing membrane technologies for carbon
capture including the relevant gas transport mechanisms is presented.
Single gas permeation experiments using silica modified ceramic
membrane with internal diameter 20mm, outside diameter 25mm and
length of 368mm deposited on a macro porous support was carried
out to investigate individual gas permeation behaviours at different
pressures at room temperature. Membrane fabrication was achieved
using after a dip coating method. Nitrogen, Carbon dioxide, Argon,
Oxygen and Methane pure gases were used to investigate their
individual permeation rates at various pressures. Results show that
the gas flow rate increases with pressure drop. However above a
pressure of 3bar, CO2 permeability ratio to that of the other gases
indicated control of a more selective surface adsorptive transport
mechanism.
Abstract: Objects are usually horizontally sliced when printed by 3D printers. Therefore, if an object to be printed, such as a collection of fibers, originally has natural direction in shape, the printed direction contradicts with the natural direction. By using proper tools, such as field-oriented 3D paint software, field-oriented solid modelers, field-based tool-path generation software, and non-horizontal FDM 3D printers, the natural direction can be modeled and objects can be printed in a direction that is consistent with the natural direction. This consistence results in embodiment of momentum or force in expressions of the printed object. To achieve this goal, several design and manufacturing problems, but not all, have been solved. An application of this method is (Japanese) 3D calligraphy.
Abstract: A numerical model has been developed to investigate the thermally triggered release kinetics for drug delivery using phase change material as shell of microcapsules. Biocompatible material n-Eicosane is used as demonstration. PCM shell of microcapsule will remain in solid form after the drug is taken, so the drug will be encapsulated by the shell, and will not be released until the target body part of lesion is exposed to external heat source, which will thermally trigger the release kinetics, leading to solid-to-liquid phase change. The findings can lead to better understanding on the key effects influencing the phase change process for drug delivery applications. The facile approach to release drug from core/shell structure of microcapsule can be well integrated with organic solvent free fabrication of microcapsules, using double emulsion as template in microfluidic aqueous two phase system.
Abstract: This paper presents the design and fabrication of an
optical window for an optical modulator toward image sensing
applications. An optical window consists of micrometer-order SiO2
capillaries (porous solid) that can modulate transmission light
intensity by moving the liquid in and out of porous solid. A high
optical transmittance of the optical window can be achieved due to
refractive index matching when the liquid is penetrated into the
porous solid. Otherwise, its light transmittance is lower because of
light reflection and scattering by air holes and capillary walls. Silicon
capillaries fabricated by deep reactive ion etching (DRIE) process are
completely oxidized to form the SiO2 capillaries. Therefore, high
aspect ratio SiO2 capillaries can be achieved based on silicon
capillaries formed by DRIE technique. Large compressive stress of
the oxide causes bending of the capillary structure, which is reduced
by optimizing the design of device structure. The large stress of the
optical window can be released via thin supporting beams. A 7.2 mm
x 9.6 mm optical window area toward a fully integrated with the
image sensor format is successfully fabricated and its optical
transmittance is evaluated with and without inserting liquids (ethanol
and matching oil). The achieved modulation range is approximately
20% to 35% with and without liquid penetration in visible region
(wavelength range from 450 nm to 650 nm).
Abstract: Cemented carbide balls are usually implemented in
industry under the environment of high speed, high temperature,
corrosiveness and strong collisions. However, its application is limited
due to high fabrication cost, processing efficiency and quality. A novel
eccentric lapping method with two rotatable lapping plates was
proposed in this paper. A mathematical model was constructed to
analyze the influence of each design parameter on this lapping method.
To validate this new lapping method, an orthogonal experiment was
conducted with cemented carbide balls (YG6). The simulation model
was verified and the optimal lapping parameters were derived. The
results show that the surface roundness of the balls reaches to 0.65um
from 2um in 1 hour using this lapping method. So, using this novel
lapping method, it can effectively improve the machining precision
and efficiency of cemented carbide balls.