Authors: Chang Shuo Chang, Kung Hsu Hou, Ming Der Ger, Chen Kuei Chung, Jen Fin Lin
Abstract: In the present study, SiC reinforced particles were introduced to the Ni-P plating bath, and developed high SiC content composite coatings. Thin films nature properties and mechanical performances were evaluated well. The results showed that the Ni-P alloy embedded SiC particles formed a few cavities, and reduced coatings hardness and wear resistance in as-plated condition. After 400°C heat-treatment, Ni3P crystalline phase formed and reached the max hardness, and conducted excellent trybological performances. SiC particles were decoposited in 600°C and reacted with Ni to form Ni3Si and Ni5Si2, caused the decreasing in hardness.
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Authors: Kung Hsu Hou, Yun Feng Chang, Ming Der Ger
Abstract: Nickel-tungsten (Ni-W) plating process exhibited fewer environmental hazards and lower health hazards than conventional chromium bath processes did, because they had the potential to be substituted for certain future applications. This study attempted to develop Ni-W alloy coatings with different weight percentages of tungsten to produce by using nickel-tungsten citrate electrolyte baths that are deposited by pulse current power source techniques. The composition of the ratio of tungsten/nickel was controlled by the change from ion mass transfer rates for the interface between cathodes and electrolytes that were caused by adjustment by charging the over potential or rest that was regulated by the on-off time during pulse and reverse-pulse current. In this study, the corrosion resistance and the composition of the coatings related to the operating parameters were also discussed through the analyses of the experimental design method. Results were found that Ni-W alloy compositions governed through regulation of pulse and pulse-reverse parameters. The frequencies of electric current, Ton and Toff with pulse duty cycles had great impact on chemical composition and surface morphology for the deposits. Results of the electrochemical tests indicated the pulse plated Ni-W metal alloy coatings in which the corrosion resistance was superior to that of the alloy deposited by the direct current technique.
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Authors: Yun Feng Chang, Kung Hsu Hou, Ming Der Ger
Abstract: The development of optical mold coatings has become a key technology in precision optical components in recent years. Researchers are still seeking ideal electroforming materials capable of resisting higher temperature and improve the lifespan of optical mold. Examples of these materials include Ni-W, and Ni-Mo-P alloy plating, among others. However, the literature rarely mentions these alloys as protective coatings. This may be because coating stability, flatness, and strength cannot achieve the desired protective effects. This study develops a combination of two wet electrochemical processes to form a multi-layer coating on optical molds. This coating consists of Ni-W, and Ni-Mo-P alloys. The proposed treatment process attempts to enhance the mechanical strength of the mold and extend its lifespan. We first used electro-deposition to form a thick-film Ni-W coating, and then applied the electroless plating by nonisothermal deposition method (NITD) to create a Ni-Mo-P thin-film and form a multi-layer coating. We also measured the composition, hardness, and elastic modulus of the protective coating as a reference basis for the development of optical molds. The results of this study reveal the appropriate process parameters to provide the multilayer films with a high strength and flat surface. This article can serve as a reference for the development of optical mold coatings.
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Authors: Chi Yuan Lee, Shuo Jen Lee, Ching Liang Dai, Chin Hua Wu, Ming Der Ger
Abstract: With advances in micro fuel cell development, the production of hydrogen for micro
reformer has become increasingly important. However, some problems regarding the micro
reformer are yet to be resolved. These include reducing the size, reducing the quantity of CO and
combining the fuel cell, among others. Accordingly, in this investigation, a micro temperature
sensor and a heater are combined inside a stainless steel-based micro reformer to measure and
control the temperature and thus improve performance and minimize the concentration of CO.
In this work, micro-electro-mechanical-systems (MEMS) of the micro channel type are
fabricated on a stainless steel substrate to enhance the methanol conversion ratio. The micro
temperature sensor and heater are made of gold and placed inside the micro reformer. Although the
micro temperature sensor and heater have already been used to measure and control temperature in
numerous fields, they have not been employed in micro reformer and commercial products.
Therefore, this study presents a new approach for integrating a micro temperature sensor and heater
in a stainless steel-based micro reformer to minimize the size and improve performance.
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Authors: Kung Hsu Hou, Ming Chang Jeng, Yung Kang Shen, Ming Der Ger
Abstract: In this study, the SiC particles with a mean diameter of 300nm were used to be codeposited
with Ni-P base to produce Ni-P-SiC composite coatings by means of the pulse current
electroforming technology. The relationship between the SiC particles and phosphorous contents in
the composite coatings has been constructed. The wear behavior of the Ni-P-SiC composite
coatings was examined by that measurements data including the wear weight loss, the coefficient of
friction, and the temperature increments under the wear tests, in which were correlated to the
observation and analysis of the worn surface of the composite coatings. Experimental results show
that the wear resistance of Ni-P-SiC composite coatings is superior to Ni-P composite coatings, if
they are under the same level of hardness. In addition, the wear weight loss of Ni-P-SiC composite
coatings is even about 62% less than that of Ni-P composite coatings, if they are based on the same
production conditions. Further more, both the hardness and wear resistance of Ni-P-SiC composite
coatings are superior to pure Ni coating, wherein its wear resistance is even up to 10 times better
than that of pure Ni coating.
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Authors: Yann Cheng Chen, Sheng Lung Kuo, Jeou Long Lee, Shih Tsung Ke, Chia Hao Wong, Ming Der Ger
Abstract: The influence of surfactant CTAB (cetyl trimethyl ammonium bromide) on electrodeposited
nickel layer has been investigated in this research. Our result shows that CTAB added in
the electrolysis bath can effectively remove the hydrogen to obtain a smoother nickel layer. The
effect of CTAB on the surface roughness is also significant. It may be ascribed to the adsorption of
CTAB on the electrode surface which results in a hindering effect in the electrodeposition process.
Increasing the concentration of CTAB, the grain size of nickel deposit was reduced and the microhardness
of the nickel deposit was therefore improved. The hardness of the metal layer can be
promoted to 450 Hv when 300 ppm CTAB is added.
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Authors: Yu Hsien Chou, Ching Yuan Bai, Ming Der Ger, Shuo Jen Lee, Chi Yuan Lee, Chu Lung Chao
Abstract: This paper describes the performance of Ni-P and Ni-Mo-P alloy coatings deposited by
electroless plating on the aluminum alloy 5052 to evaluate the corrosion resistance, thermal stability
and electro-conductivity of coating assemblies. Corrosion behaviors of the obtained deposits in a
0.5M H2SO4 environment were investigated. The crystalline state and morphologies of Ni-P and Ni-
Mo-P alloys were examined by field emission scanning electron microscopy (FE-SEM). The
experimental results indicate that the Ni-Mo-P coating operated at 70°C and pH 9.0 has a
nanocrystalline structure and its corrosion resistance in a 0.5M H2SO4 environment can be enhanced
by the co-deposition of Mo as compared to Ni-P films. It has also been found that the Ni-Mo-P
ternary alloys reveal good thermal stability after annealing at 400°C. Based on the excellent
performance of Ni-Mo-P ternary alloys, these alloys have a potential to be applied to precision
mould, optical parts mould, and surface metallization of substrates.
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Authors: Shih Tsung Ke, Jeou Long Lee, Yih Min Yeh, Shuo Jen Lee, Ming Der Ger
Abstract: In this study, a Ni-P alloy electroforming nanostructure material with low surface
roughness and low internal stress was developed by using a pulse current. Square-wave cathodic
current modulation was employed to electrodeposit ultrafine-grained Ni-P films from an additivefree
Sulfamate nickel bath. The effect of various factors, such as peak current density, duty cycle
and pulse frequency on the roughness and internal stress were investigated. Pulse current
significantly influences the microstructure of Ni-P alloys. The internal stress and roughness of Ni-P
alloys increased as peak current density increased, but the internal stress of Ni-P alloys decreased as
duty cycle decreased.
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Authors: Shuo Jen Lee, J.J. Lai, Yu Ming Lee, Ming Der Ger, S.W. Cheng
Abstract: Passive film of stainless steels possesses good corrosion resistant property. However, the
passive film formed in nature is not uniform and the quality is not consistent. It is the major causes
for local corrosion. The pitting potential test is a traditional method to test local corrosion of
stainless steels. The local corrosion is usually induced by the break-down of the passive film.
Therefore, it can be utilized to evaluate the quality of the passive film. Also, because the pitting test
is quick and inexpensive, many tests can be performed to evaluate the uniformity of the passive
film. This study focuses on SS316 stainless steel. The specimens were treated with electropolishing
processes. The original and the processed specimens were tested by pitting potential tests. From
these results, the distribution and the uniformity of passive film could be evaluated. An efficient and
inexpensive index of the uniformity of the passive film is proposed.
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Authors: Yung Kang Shen, Yi Lin, Dong Yea Sheu, Ming Der Ger, Yi Han Hu, Rong Hong Hong, Shung Mang Wang
Abstract: This work used micro dispensing technology to fabricate the master of microlens array,
then uses electroforming technology to replication the Ni mold insert of microlens array and finally
used micro hot embossing to replicate the plastic microlens array. This work used the Si10 resin by
AutoStrade Company for dispensing material. The resin material was exposed to 80W halogen
light. The resin will be hardened and become convex by surface tension effect on exposition. It can
be used as the master of microlens array. This work sputtered a silver layer of 150 nm thick on the
master for conducting electricity layer. The electroforming technology replicateed on the Ni mold
insert from the master of microlens array. Finally, the micro hot embossing technology was used to
replicate the molded microlens array. The molding experiment used PMMA and PC optical film.
The experiment studied the influence of processing parameters of hot embossing by processing
temperature, embossing pressure, embossing time and de-molding temperature. This work used the
Taguchi’s Method to search the best processing parameter for molded microlens array. This work
used the microscope, surface profiler and SEM to measure the surface profile of master, mold insert
and molded microlens array. This work also used AFM to measure the surface roughness of master,
mold insert and molded microlens array. In addition, this work measured the optical strength and
the focal length to discuss optical characteristics of molded microlens array.
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