Browsing by Author "Lin, Chien-Cheng"

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Compositional Dependence of Phase Formation Mechanisms at the Interface Between Titanium and Calcia-Stabilized Zirconia at 1550 degrees C
(2010-11-01)
Chang, Yao-Wen
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
ZrO(2) samples with various CaO contents were fabricated by hot pressing, whereby CaO was dissolved by and/or reacted with ZrO(2) to form a solid solution and/or CaZr(4)O(9), respectively. After a reaction with Ti at 1550 degrees C for 6 h in argon, the interfacial microstructures were characterized using X-ray diffraction and analytical electron microscopy. Experimental results were very different from those found previously in the Y(2)O(3)-ZrO(2) system. The 5 mol% CaO-ZrO(2) sample was relatively stable due to the formation of a thin TiO layer acting as a diffusion barrier phase. However, alpha-Ti(O), beta'-Ti (Zr, O), and/or Ti(2)ZrO were found in 9 or 17 mol% CaO-ZrO(2) due to extensive interdiffusion of Ti, O, and Zr with a much thinner (beta'-Ti+alpha-Ti) layer in 17 mol% CaO-ZrO(2) than in 9 mol% CaO-ZrO(2). Because CaO was hardly dissolved into Ti, it fully remained in the residual ZrO(2), leading to the formation of spherical CaZrO(3) in 9 mol% CaO-ZrO(2) and columnar CaZrO(3) in 17 mol% CaO-ZrO(2). In the region far from the original interface, abundant intergranular alpha-Zr was formed in 5 or 9 mol% CaO-ZrO(2). Scattered alpha-Zr and CaZrO(3) were found in 17 mol% CaO-ZrO(2) because a high concentration of extrinsic oxygen vacancies, which were created by the substitution of Ca(+2) for Zr(+4), effectively retarded the reduction of zirconia.
Compositional Dependence of Phase Formation Mechanisms at the Interface Between Titanium and Calcia-Stabilized Zirconia at 1550 degrees C
(2010-11-01)
Chang, Yao-Wen
;
Lin, Chien-Cheng
;
材料科學與工程學系
;
Department of Materials Science and Engineering
ZrO2 samples with various CaO contents were fabricated by hot pressing, whereby CaO was dissolved by and/or reacted with ZrO2 to form a solid solution and/or CaZr4O9, respectively. After a reaction with Ti at 1550 degrees C for 6 h in argon, the interfacial microstructures were characterized using X-ray diffraction and analytical electron microscopy. Experimental results were very different from those found previously in the Y2O3-ZrO2 system. The 5 mol% CaO-ZrO2 sample was relatively stable due to the formation of a thin TiO layer acting as a diffusion barrier phase. However, alpha-Ti(O), beta'-Ti (Zr, O), and/or Ti2ZrO were found in 9 or 17 mol% CaO-ZrO2 due to extensive interdiffusion of Ti, O, and Zr with a much thinner (beta'-Ti+alpha-Ti) layer in 17 mol% CaO-ZrO2 than in 9 mol% CaO-ZrO2. Because CaO was hardly dissolved into Ti, it fully remained in the residual ZrO2, leading to the formation of spherical CaZrO3 in 9 mol% CaO-ZrO2 and columnar CaZrO3 in 17 mol% CaO-ZrO2. In the region far from the original interface, abundant intergranular alpha-Zr was formed in 5 or 9 mol% CaO-ZrO2. Scattered alpha-Zr and CaZrO3 were found in 17 mol% CaO-ZrO2 because a high concentration of extrinsic oxygen vacancies, which were created by the substitution of Ca+2 for Zr+4, effectively retarded the reduction of zirconia.
Direct-bonded Al/Al2O3 using a transient eutectic liquid phase
(1970-01-01)
Cheng, Yun-Hsiang
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Lin, Chien-Cheng
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Lin, Kun-Lin
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材料科學與工程學系
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Department of Materials Science and Engineering
Directed bonding with Al and Al2O3 was achieved using a transient liquid phase (TLP) method after annealing at the low melting point of Al, which deposited Ni, Cu, Ge, and Si on the Al2O3 substrate. Al/Al2O3 microstructures were evaluated using a scanning electron microscopy and transmission electron microscopy. A reaction layer was absent at the Al/Al2O3 interface, and all deposited metal films dissolved into the Al foil and reacted with Al to form an eutectic liquid phase near the interface to wet and join with the Al2O3. Al9Fe2 and Al3Fe intermetallic compounds were formed in the Al substrate because of Fe precipitation, which is an impurity of Al foil, and the reaction with Al at the grain boundaries of Al. The bonding area percentage, shear strength, and thermal conductivity for Al and Al2O3 were assessed using scanning acoustic tomography (SAT), the ISO 13 124 shear strength test, and the laser flash method, respectively. The Al/Al2O3 specimen deposited with the Ni film had the highest shear strength (33.74 MPa), thermal conductivity (42.3 W/mK), and bonding area percentage (96.78%). The Al/Al2O3 specimens deposited with Ge and Si exhibited relatively poor bonding because of the oxidation of Ge and Si at the surface of Al2O3 before bonding with Al.
Effect of yttria on interfacial reactions between titanium melt and hot-pressed yttria/zirconia composites at 1700 degrees C
(2008-07-01)
Lin, Chien-Cheng
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Chang, Yao-Wen
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Lin, Kun-Lin
;
Lin, Kun-Fung
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材料科學與工程學系
Various Y(2)O(3)/ZrO(2) samples were fabricated by hot pressing, whereby Y(2)O(3) was mutually dissolved or reacted with ZrO(2) as a solid solution or Zr(3)Y(4)O(12). Hot-pressed samples were allowed to react with Ti melt at 1700 degrees C for 10 min in argon. Microstructural characterization was conducted using X-ray diffraction and analytical electron microscopy. The Y(2)O(3)/ZrO(2) samples became more stable with increasing Y(2)O(3) because Y(2)O(3) was hardly reacted and dissolved with Ti melt. The incorporation of more than 30 vol% Y(2)O(3) could effectively suppress the reactions in the Ti side, where only a very small amount of alpha-Ti and beta'-Ti was found. When ZrO(2) was dissolved into Ti on the zirconia side near the original interfaces, Y(2)O(3) reprecipitated in the samples containing 30%-70 vol% Y(2)O(3), because the solubility of Y(2)O(3) in Ti was very low. In the region far from the original interface, alpha-Zr, Y(2)O(3), and/or residual Zr(3)Y(4)O(12) were found in the samples containing more than 50 vol% Y(2)O(3) and the amount of alpha-Zr decreased with increasing Y(2)O(3).
Effect of zirconia content on electrical conductivities of mullite/zirconia composites measured by impedance spectroscopy
(2008-08-01)
Ko, Hong-Da
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Lin, Chien-Cheng
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Chin, Kuo-Chuang
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材料科學與工程學系
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Department of Materials Science and Engineering
Electrical conductivities of various mullite/zirconia composites, as well as monolithic mullite and zirconia, were measured using AC impedance spectroscopy from 100 Hz to 10 MHz at temperatures ranging from 150 to 1300 degrees C. The impedance spectra of monolithic zirconia and mullite/zirconia composites showed two semicircles because of the contributions from grains and grain boundaries, while those of monolithic mullite had one semicircle due to the predominant contribution from grains. This indicates that the conductivities of the mullite/zirconia composites increased with zirconia content. The activation energies of electrical conduction in mullite and zirconia were about 65 and 79 kJ/mol, respectively, and those of mullite/zirconia composites were between 65 and 79 kJ/mol. While the conductivities of various composites at I MHz were fitted by Lichtenecker's rule, the general mixing equation could be applied to the conductivities measured at 1 kHz.
Effects of annealing temperature on microstructural development at the interface between zirconia and titanium
(2007-03-01)
Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
The interfacial reaction layers in the Ti/ZrO2 diffusion couples, isothermally annealed in argon at temperatures ranging from 1100 degrees to 1550 degrees C for 6 h, were characterized using scanning electron microscopy and transmission electron microscopy, both attached with an energy-dispersive spectrometer. Very limited reaction occurred between Ti and ZrO2 at 1100 degrees C. A beta'-Ti(Zr, O) layer and a two-phase alpha-Ti(O)+beta'-Ti(Zr, O) layer were found in the titanium side after annealing at T >= 1300 degrees C and T >= 1400 degrees C, respectively. A three-phase layer, consisting of Ti2ZrO+alpha-Ti(O, Zr)+beta'-Ti (O, Zr), was formed after annealing at 1550 degrees C. In the zirconia side near the original interface, beta'-Ti coexisted with fine spherical c-ZrO2-x, which dissolved a significant amount of Y2O3 in solid solution at T >= 1300 degrees C. Further into the ceramic side, the alpha-Zr was formed due to the exsolution of Zr out of the metastable ZrO2-x after annealing at T >= 1300 degrees C: the alpha-Zr was very fine and dense at 1300 degrees C, continuously distributed along grain boundaries at 1400 degrees C, and became coarsened at 1550 degrees C. Zirconia grains grew significantly at T >= 1400 degrees C, with the lenticular t-ZrO2-x being precipitated in c-ZrO2-x. Finally, the microstructural development and diffusion paths in the Ti/ZrO2 diffusion couples annealed at various temperatures were also described with the aid of the Ti-Zr-O ternary phase diagram.
Effects of partial pressure of oxygen on sintering of a ZrO2-30 mol% Ti powder mixture
(2017-07-01)
Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
A powder mixture of ZrO2-30 mol% Ti was sintered at 1500 degrees C/h under various controlled partial pressures of oxygen (PaO2). The microstructure of each sintered sample was characterized using x-ray diffractometry and analytical transmission electron microscopy/energy-dispersive spectroscopy. TiO and highly oxygen-deficient zirconia were found after sintering at PaO2 similar to 2.1 x10(-4) atm, which implies that the oxidation reduction reaction is a controlling mechanism when there is a trace of residual oxygen. When the PaO2 was increased to 1.05x10(-1) atm, the dissolution of residual oxygen and nitrogen in the chamber into the titanium led to the formation of TiO(N) with nitrogen in solid solution. It was inferred that the oxygen in TiO(N) was also supplied by zirconia since the zirconia became oxygen-deficient in the sintered composites. After sintering in air (PaO2 similar to 2.1x10(-1) atm), TiO2 and TiN were formed along with nearly stoichiometric zirconia, indicating that oxygen and nitrogen in air played a major role in the oxidation and nitridization reaction of titanium. The degree of oxygen deficiency x in ZrO2-x decreased with increasing oxygen partial pressure, which led to an increased volume fraction of the monoclinic phase.
Formation mechanisms and atomic configurations of nitride phases at the interface of aluminum nitride and titanium
(2008-08-01)
Chiu, Chia-Hsiang
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Aluminum nitride was bonded with a titanium foil at 1400 degrees C for up to 1 h in Ar. The AlN/Ti interfacial reactions were investigated using analytical electron microscopy. Reaction layers, consisting of delta-TiN, tau(2)-Ti2AlN, gamma-TiAl, alpha(2)-Ti3Al, a two-phase region (alpha(2)-Ti3Al + alpha-Ti), and alpha-Ti (Al, N) solid solution, were observed after annealing at 1400 degrees C for 0.1 h. Among these phases, the alpha(2)-Ti3Al and (alpha(2)-Ti3Al + alpha-Ti) were formed during cooling. Further diffusion of N atoms into the reaction zone precipitates a chopped fiber-like alpha(2)-Ti2AlN in the matrix of gamma-TiAl, with [110](gamma-TiAl)//[11 (2) over bar0](tau 2-Ti2AlN) and (1 (1) over bar(1) over bar)(gamma-TiAl)//(1 (1) over bar0 (3) over bar)(tau 2-Ti2AlN), by substituting N atoms for one-half Al atoms after annealing at 1400 degrees C for 1 h. The released Al atoms, due to the precipitation Of tau(2)-Ti2AlN, resulted in an ordered Al-rich gamma-TiAl or Ti3Al5. Furthermore, the alpha-Ti (Al, N) was nitridized into a lamellar layer (delta-TiN + alpha-Ti) with [110](delta-TiN)//[11 (2) over bar0](alpha-Ti) and (111)(delta-TiN)//(0001)(alpha-Ti).
Formation of omega and Ti2Ni phases in a residual Ti-Ni-Ti multilayer between stainless steel and zirconia after bonding at 1173K
(2014-10-03)
Wei, Shen-Hung
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Stainless steel (316L) and 8mol pct Y2O3-stabilized zirconia (8Y-ZrO2) were bonded using a Ti-Ni-Ti multilayer at 1173K (900 degrees C) for 1h. Cross-sectional transmission electron microscopy specimens were prepared by an innovative focused ion beam plus lift-out technique. In addition to acicular alpha-Ti, the dissolution of Fe, Cr, and Ni diffusing outwards from 316L into beta-Ti led to the precipitation of the omega (omega) phase with different variants in the residual Ti foil between 316L and Ni. The omega-phase was not found in the residual Ti foil between Ni and 8Y-ZrO2, while Ti2Ni precipitates were precipitated in some alpha-Ti grains owing to the exclusion of Ni from the beta-Ti.
Interfacial reactions between Ti and Y2O3/Ca4Ti3O10 composites
(1970-01-01)
Lu, Ming-Wei
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Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
In titanium casting, the interfacial reactions between selected Y2O3/Ca4Ti3O10 composites in contact with titanium at 1600 degrees C for 30 minutes in an argon environment were characterized using X-ray diffraction, scanning electron microscopy, and analytical transmission electron microscopy. Before contact with titanium, reaction phases of the Y2O3/Ca4Ti3O10 composites formed through hot pressing at 1500 degrees C or annealing at 1600 degrees C. These phases were identified as Ca4Ti3O10, Y2O3, and minor amounts of CaO. The amount of Ca4Ti3O10 in the composites gradually decreased as the amount of Y2O3 increased. When the Y2O3/Ca4Ti3O10 composites were in contact with titanium, a reaction layer of alpha-Ti and Y2O3 was formed near the interface of the composite side. Large amounts of calcium and oxygen were expelled toward the composite side from Ca4Ti3O10 near the interface to form CaO, which precipitated in the Ca4Ti3O10 and Y2O3 phases. Furthermore, no reaction phases were detected in titanium. Ca4Ti3O10 and Y2O3 can function as diffusion barrier layers to effectively suppress the diffusion of oxygen into titanium.
Investigation of the interactions between titanium and calcium zirconium oxide (CaZrO3) ceramics modified with alumina
(2019-01-01)
Lu, Ming-Wei
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Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Powdered mixtures of CaO, ZrO2 and Al2O3 in various ratios were hot pressed. The mixtures reacted with titanium at 1600 degrees C for 30 min in argon to evaluate the suitable ceramic crucibles for casting of titanium. The interfacial microstructures between titanium and ceramic composites were characterized using X-ray diffractometer, scanning and transmission electron microscope. The produced hot pressed mixtures that were chemically bonded together, contained calcium aluminate (CaAl2O4), calcium dialuminate (CaAl4O7), cubic zirconia (c-ZrO2), and calcium zirconium oxide (CaZrO3). The increase in Al2O3 amount led to the decrease in CaZrO3 amount and an increase in the amount of CaAl2O4, CaAl4O7 and c-ZrO2 due to the reaction of CaO and Al2O3. At the end of the reaction of the ceramic mixtures with Ti at 1600 degrees C for 30 min, the acicular alpha-Ti and beta'-Ti were formed at the interface of Ti and the composites containing up to 10 vol.% Al O-2(3). In composites containing more than 20 vol.% Al2O3, Ti3Al5 was found at the interface instead of alpha-Ti and beta'-Ti. Furthermore, CaZrO3, ZrO2 and Ca3Al2O6 existed on the sides of the ceramic far away from the interface. CaZrO3/Al2O3 composites with less than 20 vol.% Al2O3 could be a potential crucible or mould material for productive applications in titanium casting.
Microstructural development of the AlN/Ti diffusion couple annealed at 1000 degrees C
(2008-04-01)
Chiu, Chia-Hsiang
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
The microstructural development of an AlN/Ti diffusion couple, annealed at 1000 degrees C in an argon atmosphere for 0.1-36 h, was investigated using analytical scanning electron microscopy and transmission electron microscopy. The decomposition and diffusion of Al and N atoms into Ti gave rise to various reaction layers at the interface. A delta-TiN layer was initially formed in the reaction zone between AlN and Ti, and the alpha(2)-Ti3Al layer subsequently developed between delta-TiN and Ti. Then an intergranular tau(1)-Ti3AlN phase was formed in the delta-TiN layer with the orientation relationships [111](tau 1)- Ti-3 AlN//[111](delta- TiN) and (1 (1) over bar0)(tau 1)-Ti-3 AlN//(1 (1) over bar0)(delta- TiN). The further diffusion of N atoms into the alpha(2)-Ti3Al layer led to the growth of delta-TiN and a twinned alpha(2)-Ti3Al(N) solid solution, wherein N atoms went to one of the octahedral interstitial sites in an orderly manner upon cooling, resulting in the formation of tau(1)-Ti3AlN. The orientation relationships between tau(1)-Ti3AlN and alpha(2)-Ti3Al(N) were [111](tau 1)- Ti-3 AlN// [0001](alpha 2)- Ti3Al(N) and (0 (1) over bar1)(tau 1)- Ti3AlN//((1) over bar(1) over bar 20)(alpha 2)- Ti3Al(N). Finally, diffusion paths are proposed for the interfacial reactions at various stages.
Microstructural evolution and bonding mechanisms of the brazed Ti/ZrO2 joint using an Ag68.8Cu26.7Ti4.5 interlayer at 900 degrees C
(2014-03-14)
Wei, Shen-Hung
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
In this study, 3 mol% Y2O3-stabilized zirconia (3Y-ZrO2) and commercially pure titanium (cp-Ti) joints were fabricated with an Ag68.8Cu26.7Ti4.5 interlayer (Ticusil) at 900 degrees C for various brazing periods. After brazing at 900 degrees C/0.1 h, Ti2Cu, TiCu, Ti3Cu4, and TiCu4 layers were present at the Ti/Ticusil interface, while TiCu and TiO layers were observed at the Ticusil/3Y-ZrO2 interface. In the residual interlayer, clumpy TiCu4 was formed along with the Ag solid phase. After brazing at 900 degrees C/1 h, Ti3Cu3O and Ti2O layers were formed at the interlayer/ZrO2 interface, while Cu2O was precipitated in the residual interlayer with [111](Cu2O)//[111](Ag) and (20 (2) over bar)(Cu2O)//(20 (2) over bar)(Ag). After brazing at 900 degrees C/6 h, a two-phase (alpha-Ti + Ti2Cu) region was observed on the Ti side with [2 (1) over bar(1) over bar0](alpha-Ti)//[100](Ti2Cu) and (0002)(alpha-Ti)//(0 (1) over bar3)(Ti2Cu), while the TiCu layer grew at the expense of Ti3Cu4 and TiCu4. The bonding mechanisms and diffusion paths were explored with the aid of Ag-Cu-Ti and Ti-Cu-O ternary phase diagrams.
Oxygen Diffusivities and Surface Exchange Coefficients in Porous Mullite/Zirconia Composites Measured by the Conductivity Relaxation Method
(2010-01-01)
Ko, Hong-Da
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Oxygen diffusivities and surface exchange coefficients in various porous mullite/zirconia composites were measured at oxygen partial pressures ranging from 20.2 to 2.02 kPa using the conductivity relaxation method. However, the oxygen diffusivities in porous high-zirconia composites could not be determined because of the predominant surface exchange reaction. Oxygen diffusivities and surface exchange coefficients in low-zirconia composites increased with the zirconia content, while the surface exchange coefficients in high-zirconia composites were approximately constant. A percolation threshold of the surface exchange coefficients occured at similar to 40 vol% zirconia for porous zirconia/mullite composites. The oxygen diffusivities in porous low-zirconia composites were independent of the oxygen partial pressure, implying that oxygen diffusion in these composites was related to the migration of oxygen vacancies, whose concentration was independent of the oxygen partial pressure. The surface exchange coefficients of high-zirconia composites decreased with increasing oxygen partial pressure. Finally, it was inferred that the rate-limiting step for oxygen surface exchange could be the charge-transfer process.
Oxygen diffusivities in mullite/zirconia composites measured by O-18/O-16 isotope exchange and secondary ion mass spectrometry
(2008-02-01)
Ko, Hong-Da
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Oxygen diffusivities in mullite/zirconia composites were measured by O-18/O-16 isotope exchange and secondary ion mass spectrometry. They exhibited a wide range of values from 10(-21) to 10(-10) m(2)/S at temperatures between 1000 and 1350 C in the composites with 0 to 80 vol% zirconia. At a fixed temperature, oxygen diffusivities m high-zirconia composites were larger by at least eight orders of magnitude than those in low-zirconia composites. The percolation threshold occurred between 30 and 40 vol% zirconia, where oxygen diffusivities dramatically changed. There was a clear tendency of the activation energies of oxygen diffusion in composites to decrease with increasing zirconia contents. The large oxygen diffusivities in the high-zirconia composites were attributed to the interconnected channels of zirconia from the microstructural aspect.
Palladium based cermet composite for hydrogen separation at elevated temperature
(2015-01-15)
Tsai, Yen-Chang
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Lin, Chien-Cheng
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Lin, Wei-Lin
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Wang, Jeng-Han
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Chen, San-Yuan
A cermet composite consisting of palladium and BaCe0.4Zr0.4Gd0.1DY0.1O3-x (BCZGD) is fabricated by mixing palladium and BCZGD powders in a ball mill, followed by pressing and sintering at 1450 degrees C for 24 h in air. The Pd-BCZGD cermet demonstrates impressive hydrogen permeation flux in a mixture of hydrogen and carbon dioxide at elevated temperature, in which the palladium plays the predominant role of facile transport in the hydrogen atoms whereas the BCZGD provides channels for proton conduction. Material characterization including scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermo-gravimetric analysis (TGA) are performed. XRD patterns indicate pure phases of fcc palladium and perovskite BCZGD. SEM images and element mapping suggest a homogeneous mixture of cermet without noticeable defect and phase segregation. TGA results confirm stability of the cermet against carbon dioxide without chemical decomposition. The hydrogen permeation flux is determined via a gas chromatography from 400 to 700 degrees C at various hydrogen concentration gradients. We record a hydrogen flux of 1.25 cm(3) min(-1) cm(-2) in 50% hydrogen and 50% carbon dioxide at 700 degrees C, with a selectivity of H-2/CO2 approaching infinity. (C) 2014 Elsevier B.V. All rights reserved.
Phase transformation and microstructural development of zirconia/stainless steel bonded with a Ti/Ni/Ti interlayer for the potential application in solid oxide fuel cells
(2014-04-28)
Wei, Shen-Hung
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
The 8 mol% yttria-stabilized zirconia (8Y-ZrO2) was bonded to stainless steel 316L at 900 degrees C for 1 h in a protective Ar atmosphere using an interlayer of Ti/Ni/Ti. Interfacial microstructures were characterized using both secondary electron microscope (SEM) and transmission electron microscope (TEM), each with an attached energy dispersive spectroscope (EDS). A layer sequence of sigma-phase/TiFe2/TiFe + beta-Ti/Ti2Fe was observed at the stainless steel 316L/Ti interface, whereas a layer sequence of Ti2Ni/Ti2Ni + TiNi/TiNi3 was found at the Ti/Ni interface. Furthermore, TiO and c-ZrO2-x formed at the Ti/8Y-ZrO2 interface. An acicular alpha-Ti and a fine omega-phase existed along with beta-Ti in the residual Ti foil adjacent to the stainless steel 316L, but alpha-Ti and Ti2Ni were observed within beta-Ti in the other residual Ti foil adjacent to the 8Y-ZrO2. The orientation relationships of the omega-phase and beta-Ti were ${left[ {1bar 10} right]_{{rm{ beta {hbox-} Ti}}}}//{left[ {1bar 210} right]_{rm{omega }}}$ and ${left( {111} right)_{{rm{beta {hbox-} Ti}}}}//{left( {0001} right)_{rm{omega }}}$ , respectively. The microstructural development was elucidated with the aid of Fe-Ti and Ni-Ti binary phase diagrams.
Reaction between titanium and zirconia powders during sintering at 1500 degrees C
(2007-07-01)
Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Zirconia-titanium (ZrO2-Ti) composites have been considered potential thermal barrier graded materials for applications in the aerospace industry. Powder mixtures of Ti and 3 mol% Y2O3 partially stabilized ZrO2 in various ratios were sintered at 1500 degrees C for 1 h in argon. The microstructures of the as-sintered composites were characterized by X-ray diffraction and transmission electron microscopy/energy-dispersive spectroscopy. Ti reacted with and was mutually soluble in ZrO2, resulting in the formation of alpha-Ti(O, Zr), Ti2ZrO, and/or TiO. These oxygen-containing phases extracted oxygen ions from ZrO2, whereby oxygen-deficient ZrO2 was generated. For relatively small Ti/ZrO2 ratios, specimens with <= 30 mol% Ti, TiO were formed as oxygen could be sufficiently supplied by excess ZrO2. For the specimens with >= 50 mol% Ti, lamellar Ti2ZrO was precipitated in alpha-Ti(Zr, O), with no TiO being found. Both m-ZrO2-x and t-ZrO2-x were found in specimens with <= 50 mol% Ti; however, only c-ZrO2-x was formed in the specimen with 70 mol% Ti. As ZrO2 was gradually dissolved into Ti, yttria was retained in ZrO2 because of the very limited solubility of yttria in alpha-Ti(O, Zr) or TiO. The concentration of retained yttria and the degree of oxygen deficiency in ZrO2 increased with the Ti content. The complete dissolution of ZrO2 into Ti was followed by the precipitation of Y2Ti2O7 in the specimen with 90 mol% Ti.
Reactions between Si melt and various ceramics
(2019-01-01)
Lin, Che-Yu
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Lin, Kun-Lin
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Lin, Chien-Cheng
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材料科學與工程學系
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Department of Materials Science and Engineering
Reactions between different kinds of ceramics and silicon were studied to evaluate ceramics as candidates for their use in the process of silicon-crystal growth. Three types of ceramic plates, Al2O3, ZrO2 and quartz (SiO2), were put into contact with a silicon wafer via annealing at 1450 degrees C for 30 min under an Ar atmosphere. Defects appeared at the Si-ceramics interface. Among these, a crack and a dislocation pile up were found at the Si-SiO2 dissolution couple. In addition, two intermetallic compounds, Y2Si2O7 and Zr-Si, produced by the diffusion of Y, O and Zr from the ZrO2 into the Si, were found at the Si-ZrO2 dissolution couple. At the interface of the Si-Al2O3 dissolution couple, no intermetallic compounds and few defects were found. The oxygen concentration and electrical resistivity near the interface were high and gradually decreased away from the interface for all Si-ceramics dissolution couples.
Using intelligent computing and data stream mining for behavioral finance associated with market profile and financial physics
(2018-07-01)
Lin, Chien-Cheng
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Chen, Chun-Sheng
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Chen, An-Pin
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
Day trading has become an important topic of discussion in the last decades, especially with regard to computer program trading or the increasing trend of high-frequency transactions. However, due to the high level of complexity regarding the forecasting of day trading trends, the use of traditional financial analysis or technical indicators for the forecasting of short-term market trends is often ineffective. The main reason is that in addition to the technical analysis of market physical trends, financial market trading behaviors are also often affected by psychological factors such as greed and fear, which are emotions displayed by investors during the transaction process. For this reason, this study will use the neural network to integrate into the financial engineering technology analysis of the physical momentum behavior and market profile theory to quantify controlled learning. The goal is to be able to provide an empirical explanation of the discoveries related to trading behaviors by using trading strategies. Our experiments showed that trading behaviors in the financial market could be explained by the physical trends of a quantitative and technical analysis of the market profile theory. It has also been proven that the financial trading market follows the existence of a certain trading logic. (C) 2017 Elsevier B.V. All rights reserved.