Browsing by Author "Wang, Wun-Kai"

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Effects of activating flux on Inconel 718 alloy and AISI 304 stainless steel dissimilar TIG welds
(2012)
Lin, Hsuan-Liang
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Hsu, Zhau-Hong
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Wang, Wun-Kai
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機械工程學系
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Department of Mechanical Engineering
The purpose of this work is to investigate the effects of activating flux on the penetration, depth-to-width ratio (DWR), angular distortion and hardness of Inconel 718 alloy and AISI 304 stainless steel (SS) dissimilar welds in the tungsten inert gas (TIG) welding process. In the activated TIG (A-TIG) process, the single component fluxes such as SiO2, NiO, MoO3 and MoS2 and the mixed component fluxes that using 50 % of each single component flux to create six new mixtures were used in the experiment. The experimental results showed that the A-TIG welds coated with 100% SiO2 flux was provided with best DWR of dissimilar welds. In addition, the experimental procedure of A-TIG welding process not only produced a significant increase in penetration and DWR of weld bead, but also improved the angular distortion and hardness of Inconel 718 alloy and AISI 304 SS dissimilar welds.
Nanotribological behavior of ZnO films prepared by atomic layer deposition
(2014-03-01)
Wang, Wun-Kai
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Wen, Hua-Chiang
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Cheng, Chun-Hu
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Chou, Wu-Ching
;
Yau, Wei-Hung
We used atomic layer deposition to form ZnO thin-film coatings on Si substrates and then evaluate the effect of pile-up using the nanoscratch technique under a ramped mode. The wear volume decreased with increasing annealing temperature from room temperature to 400 degrees C for a given load. Elastic-to-plastic deformation occurred during sliding scratch processing between the groove and film for loading penetration of 30 nm. The onset of non-elastic behavior and greater contact pressure were evident for loading penetration of 150 nm; thus, full plastic deformation occurred as a result of a substrate effect. We suspect that elastic-plastic failure events were related to edge bulging between the groove and film, with elastic-plastic deformation attributable to adhesion discontinuities and/or cohesion failure of the ZnO films. (C) 2013 Elsevier Ltd. All rights reserved.
Nanotribological properties of ALD-processed bilayer TiO2/ZnO films
(2014-12-01)
Wang, Wun-Kai
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Wen, Hua-Chiang
;
Cheng, Chun-Hu
;
Hung, Ching-Hua
;
Chou, Wu-Ching
TiO2/ZnO films grown by atomic layer deposition (ALD) demonstrated nanotribological behaviors using scratch testing. TEM profiles obtained an amorphous structure TiO2 and nanocrystalline structure ZnO, whereas the sample has significant interface between the TiO2/ZnO films. The experimental results show the relative XRD peak intensities are mainly contributed by a wurtzite oxide ZnO structure and no signal from the amorphous TiO2. With respect to tribology, increased friction causes plastic deformation between the TiO2 and ZnO films, in addition to delamination and particle loosening. The plastic deformation caused by adhesion and/or cohesion failure is reflected in the nanoscratch traces. The pile-up events at a loading penetration of 30 nm were measured at 21.8 mu N for RT, 22.4 mu N for 300 degrees C, and 36 mu N for 400 degrees C. In comparison to the other conditions, the TiO2/ZnO films annealed at 400 degrees C exhibited higher scratch resistance and friction with large debris, indicating the wear volume is reduced with increased annealing temperature and loading. (C) 2014 Elsevier Ltd. All rights reserved.