The purpose of this study was to investigate the corrosion behavior of four different dental cast... more The purpose of this study was to investigate the corrosion behavior of four different dental casting alloys in artificial saliva solutions with varying pH values. Microstructures were observed using scanning electron microscopy. The corrosion behavior of the experimental alloys in artificial saliva was examined using potentiodynamic polarization measurements. The high noble alloy (Au-8.5Pt-2.6Pd-1.4In) exhibited better corrosion resistance with lower anodic current densities in the pH range of 3–5. The anodic current density of the noble alloy (Au-24.9Pd-19.0Ag-5.5In) decreased as the pH decreased. The noble (Pd-37.7Ag-8.5Sn) and base metal (Ni-25Cr-11.5Mo-1.4Si) alloys exhibited lower corrosion resistance with a relatively high current density at pH 3. Compared with noble alloys, base metal alloys exhibited good corrosion resistance in this study. This makes them a promising material for dental castings considering the complex pH changes in the oral environment.
Background: The main factors to influence on the stroking performance of club head are alloy and ... more Background: The main factors to influence on the stroking performance of club head are alloy and spring-like effect. Design the structure of new club face to create the fairway wood which can show best stroking feeling and let driving distance become longer. Purpose: The club face of fairway wood is processed through the iron alloy heating procedure and CNC to innovate the club head with high spring-like effect (characteristic time). Method: (1) Use 455 stainless steel processed by heating and aging treatment, to do the analysis on microstructure and mechanical properties. (2) Through CNC to design seven different patterns for the back of club face, each pattern for three club head. The total amount is twenty-one. (3) Make finished product be test the characteristic time and the ability of strike by the practical measurement. (4) To analyze after the compare between three-way ANOVA and LSD. Results: After 455 stainless steel was heated in procedure S850℃-A550℃, mechanical properties became superior and had the better malleability, it is suitable for developing the club face of high spring-like effect. Before and after grinding among three-way ANOVA (pattern*thickness*place), did not achieve the significant level on the figure of characteristic time. Through two-way ANOVA (pattern*place and thickness*place), showed the significant deviation before and after grinding. After doing the crash test by 45m/s, all the results can reach the higher limited standard. Summary: 455 stainless steel was designed with the different club face’s thicknesses of fairway wood can make spring-like effect achieve high characteristic time. The much thinner club face let the characteristic time perform highly. But there was no obvious effects from the patterns of the back club face.
Lung cancer is a malignancy with high mortality worldwide, and metastasis occurs at a high freque... more Lung cancer is a malignancy with high mortality worldwide, and metastasis occurs at a high frequency even when cancer spread is not detectable at primary operation. Cancer stemness plays an important role in malignant cancer behavior, treatment resistance, and cancer metastasis. Therefore, understanding the molecular pathogenesis behind cancer-stemness-mediated metastasis and developing effective approaches to prevent metastasis are key issues for improving cancer treatment. In this study, we investigated the role of CD44 stemness marker in lung cancer using in vitro and clinical studies. Immunohistochemical staining of lung cancer tissue specimens revealed that primary tumors with higher CD44 expression showed increased metastasis to regional lymph nodes. Flow cytometry analysis suggested that CD44 positive cells were enriched in the metastatic lymph nodes compared to the primary tumors. CD44 overexpression significantly increased migration and invasion abilities of lung cancer cel...
The effects of the addition of silver on the microstructural variation and antibacterial performa... more The effects of the addition of silver on the microstructural variation and antibacterial performance of 2205 duplex stainless steel after solution and aging treatment were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and antibacterial testing. The microstructure showed that 2205Ag is composed of a ferrite (α) + austenite (γ) duplex phase and Ag-rich nano-precipitates (Ag-NPs). The morphology of the Ag-NPs varied from spherical to polygonal after aging treatment at 450 °C for 4 h. These precipitates were identified as face-centered-cubic structures with a lattice parameter of a = 0.354 nm and a mismatch of δ = 0.84% relative to the austenite matrix. Notably, 2205Ag with polygonal Ag-NPs exhibited excellent antibacterial properties that were superior to those of 2205Ag with spherical Ag-NPs.
Michelle Oyen Editor-in-Chief Materials Science and Engineering: C Dear Editor: I wish to submit ... more Michelle Oyen Editor-in-Chief Materials Science and Engineering: C Dear Editor: I wish to submit a research paper for publication in Materials Science and Engineering: C, titled "Effect of Ti2Cu precipitation on antibacterial property of Ti–5Cu alloy." The paper was coauthored by Ju-Hui Wu, Chih-Yeh Chao, and Yen-Hao Chang. This study set out to examine the antibacterial effects of Ti alloys to which Cu had been added. We found that the solid-solution treatment of a Ti–5Cu alloy failed to provide an acceptable level of antibacterial activity, but the presence of nano-scale Ti2Cu precipitates led to the alloy exhibiting a relatively high antibacterial activity of > 90%. We believe that our study makes a significant contribution to the literature because this would provide a means of overcoming the serious problem of bacterial infection that remains an issue with the implantation of Ti prostheses. Further, we believe that this paper will be of interest to the readership of your journal because the relationship between heat treatment and the antibacterial property has not been explored in Ti based antibacterial materials. The aim of this work is to study the effects of heat treatment on microstructure and antibacterial property of a Ti-5Cu alloy in order to produce an optimal antibacterial material for clinic application. This manuscript has not been published or presented elsewhere in part or in entirety and is not under consideration by another journal. We have read and understood your journal's policies, and we believe that neither the manuscript nor the study violates any of these. There are no conflicts of interest to declare. Thank you for your consideration. I look forward to hearing from you. Sincerely, Je-Kang Du Department of Dentistry Kaohsiung Medical University Hospital Kaohsiung 80708 Taiwan Tel: 886-7-3121101 ext. 7003 Fax: 886-7-3157024 E-mail: [email protected]
The microstructural characteristics and Young’s modulus of the as-cast Ti–15Ta–15Nb alloy are rep... more The microstructural characteristics and Young’s modulus of the as-cast Ti–15Ta–15Nb alloy are reported in this study. On the basis of the examined XRD and TEM results, the microstructure of the current alloy is essentially a mixture (α + β+ α′ + α″ + ω + H) phase. The new H phase has not previously been identified as a known phase in the Ti–Ta–Nb alloy system. On the basis of examination of the Kikuchi maps, the new H phase belongs to a tetragonal structural class with lattice parameters of a = b = 0.328 nm and c = 0.343 nm, denoting an optimal presentation of the atomic arrangement. The relationships of orientation between these phases would be {0001}α//{110}β//{1¯21¯0}ω//{101¯}H and (011¯0)α//(11¯2)β//(1¯010)ω//(121)H. Moreover, the Young’s modulus of the as-cast Ti–15Ta–15Nb alloy is approximately E = 80.2 ± 10.66 GPa. It is implied that the Young’s modulus can be decreased by the mixing of phases, especially with the presence of the H phase.
The aim of this study was to investigate the effect of incorporating low copper (0, 0.5, 1, 1.5, ... more The aim of this study was to investigate the effect of incorporating low copper (0, 0.5, 1, 1.5, and 2 wt.%) additions into as-forged AISI 304 stainless steel (304SS). The microstructures and mechanical properties of the steel were examined using scanning electron microscopy and a universal testing machine. The antibacterial properties of the Cu-bearing 304SS specimens were investigated using Escherichia coli. Each specimen was soaked in artificial saliva to detect the release of copper ions through inductively coupled plasma atomic emission spectrometry. The addition of copper had no significant effect on the microstructure of the as-forged Cu-bearing 304SS, but it slightly increased its maximum tensile strength. The antibacterial rate of the as-cast and as-forged 304SS with 2 wt.% Cu was over 80%, which corresponded to an increase in the release of copper ions. This study demonstrates that low-Cu-content stainless steel can reduce bacteria and can be a suitable material for the or...
To control the degradation rate of magnesium (Mg) alloys, chitosan (CHI) and L-glutamic acid (LGA... more To control the degradation rate of magnesium (Mg) alloys, chitosan (CHI) and L-glutamic acid (LGA) were used as coatings on Mg-Zn-Ca alloys via dip coating. In this study, either two or seven CHI/LGA layers were applied as a coating on Mg-2.8Zn-0.8Ca alloy (ZX31) and Mg-2.8Zn-0.8Ca hemostasis clips (ZX31 clips). The morphologies, compositions, and surface roughness of the specimens were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, and surface measurement devices. The degradation rates and behavior of the specimens were evaluated by immersing them in simulated body fluids and by applying these ZX31 clips on rabbits’ uterine tubes for five weeks. The specimen with seven layers (ZX31(CHI/LGA)7) exhibited improved corrosion behavior when compared with ZX31 or ZX31(CHI/LGA)2, with a reduced degradation rate of the Mg alloy in a simulated body environment. In vivo experiments showed that ZX31 clips exhibited good biocompatibilities in each group...
Ti-6Al-4V, although widely used in dental materials, causes peri-implant inflammation due to the ... more Ti-6Al-4V, although widely used in dental materials, causes peri-implant inflammation due to the long-term accumulation of bacteria around the implant, resulting in bone loss and eventual failure of the implant. This study aims to overcome the problem of dental implant infection by analyzing the influence of Ti-6Al-4V surface characteristics on the quantity of accumulated bacteria. Ti-6Al-4V specimens, each with different surface roughness are produced by mechanical, chemical, and electrolytic polishing. The surface roughness, surface contact angle, surface oxygen content, and surface structure were measured via atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM), drop shape analysis (using sessile drop), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The micro and macro surface roughness are 10.33–120.05 nm and 0.68–2.34 μm, respectively. The surface X direction and Y direction contact angle are 21.38°–96.44° and 18.37°–92.72°, respectivel...
Titanium alloys are widely employed for the fabrication of biomedical devices. In this study, we ... more Titanium alloys are widely employed for the fabrication of biomedical devices. In this study, we designed and developed a Ti-5Al-2.5Cu alloy, which exhibited antibacterial properties. Microstructure and elemental analyses were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). We evaluated the alloy’s antibacterial properties using Escherichia coli in the plate-count method. The cytotoxicity was examined using the MG-63 cell response by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Microstructural analysis revealed that Ti-5Al-2.5Cu exhibited an equiaxed α’ martensite structure after short-term annealing. The heterogeneous and homogeneous α → α + Ti2Cu phase transitions occurred at ~840 and 920 °C, respectively. The antibacterial property for Ti-5Al-2.5Cu was varied by volume fraction in the Ti2Cu and Cu-rich ...
To instill pure Ti with an antibacterial effect, Cu was added by metallurgical alloying to produc... more To instill pure Ti with an antibacterial effect, Cu was added by metallurgical alloying to produce Ti-5 wt% Cu alloy (Ti-5Cu alloy). The precipitation of the likes of Ti 2 Cu in a Ti-Cu alloy is one of the factors that influences its antibacterial property. However, in the present study, Ti-5Cu alloy precipitates with different microstructures were obtained by applying heat treatment at different temperatures and for different durations. After the heat treatment, metallographic, microstructure, and element analyses were performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS). The antibacterial property of the Ti-5Cu alloy was assessed by the plated-count method using Escherichia coli (E. coli). The microstructure analysis revealed that the solution-treated alloy had no precipitation, while the aged alloy contained precipitations of intermetallic Ti 2 Cu compound. The aged alloy exhibited better antibacterial performance as the duration of the aging treatment increased. The optimal heat treatment for Ti-5Cu was found to be aging at 700°C for 4 h, at which point the nucleation formation of the Ti 2 Cu particles would assume an acicular morphology. These acicular precipitates exhibit a high Cu content which, in turn, influences the antibacterial performance.
Journal of the mechanical behavior of biomedical materials, Jan 28, 2018
In order to develop Ti based alloys with promising biocompatibility and matching mechanical respo... more In order to develop Ti based alloys with promising biocompatibility and matching mechanical response with human bone, TiTaNb alloys with 15, 23 and 30 mass% Ta are designed and systematically examined in terms of microstructural evolution and mechanical response. The Ti-30mass%Ta-10mass%Nb is demonstrated to be satisfactory with an elastic modulus ~60 GPa, hardness ~3.1 GPa, and strength ~1250 MPa. The evolution trend of the resulting microstructure and phases as a function of Ta content and annealing temperature are established. The relationship between the various phase amounts and alloy moduli is explored.
Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainle... more Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu 2+ and Ag 2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI) 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr 2 N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr 2 N precipitates. When aged at a lower temperature, which resulted in nano-Cr 2 N precipitation, the specimen possessed the highest antibacterial activity.
The microstructures and mechanical properties of the Fe-10 mass%Al-(5-40)mass%Mn-1.0 mass%C alloy... more The microstructures and mechanical properties of the Fe-10 mass%Al-(5-40)mass%Mn-1.0 mass%C alloys sheet castings have been investigated by using optical microscope (OM), transmission electron microscope (TEM), scanning electron microscope (SEM), experimental model analysis, tensile test and hardness test. Based on the present studies, the macroscopic microstructure of the present alloys are a mixture of austenite (γ) and ferrite (α) duplex phases, and the α phase would decrease with the Mn content increased. In the meantime, according to the examination of TEM, the macroscopic γ phase is a mixture of the γ + fine(Fe, Mn) 3 AlC x (κ) + (Fe, Mn) 3 AlC x (κ) phases and the macroscopic α phase is a mixture of the D0 3 + coarse(Fe, Mn) 3 AlC x (κ) phases. The mechanical properties such as the ultimate tensile strength (UTS), yield strength (Y.S.), elongation of these alloys were in the range of 646-887 MPa, 575-824 MPa, and 16.3-29.2%, respectively. The hardness of these alloys were in the range of HR C 31-44. Moreover, the relationship between hardness and ultimate strength is UTS 20.93HR C. In addition, the damping ratios and Young's modulus of the present alloys were in the range of 0.0603-0.0417, and 139-165 GPa, respectively. It is noted here that the results have never observed by other research workers in the Fe-Al-Mn-C alloy system.
Journal of Flow Visualization and Image Processing, 2007
The speed of golf balls can be regarded as the fastest in all ball games. The flying distance of ... more The speed of golf balls can be regarded as the fastest in all ball games. The flying distance of a golf ball is influenced not only by its material, but also by the aerodynamics of the dimple on its surface. By using Computational Fluid Dynamics method, the flow field and aerodynamics characteristics of golf balls can be studied and evaluated before the golf balls are actually manufactured. This work uses FLUENT as its solver and numerical simulations were carried out to estimate the aerodynamics parameters and noise levels for various kinds of golf balls having different dimple configurations. With the obtained aerodynamics parameters, the flying distance and trajectory for a golf ball were determined and visualized. The results showed that the lift coefficient of the golf ball increased if small dimples were added between the original dimples. When launched at small angles, golf balls with deep dimples were found to have greater lift effects than drag effects. Therefore, the golf balls would fly further. As far as noise generation was concerned, deep dimples produced lower noise levels.
International Journal of Minerals, Metallurgy, and Materials, 2012
Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned w... more Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel (SS). The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) at a total implantation dose of 2×10 17 ions/cm 2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS. The implanted layer was characterized by X-ray photoelectron spectroscopy (XPS). Core level XPS spectra indicate that the implanted silver and copper ions exist in metallic state in the implanted layer.
In this study, the effects of spinodal decomposition on the microstructures and mechanical proper... more In this study, the effects of spinodal decomposition on the microstructures and mechanical properties of a TiZrNbTa alloy are investigated. The as-cast TiZrNbTa alloy possesses dual phases of TiZr-rich inter-dendrite (ID) and NbTa-rich dendrite (DR) domains, both of which have a body-centered cubic (BCC) structure. In the DRs of the as-cast alloy, the α and ω precipitates are found to be uniformly distributed. After homogenization at 1100 °C for 24 h followed by water quenching, spinodal decomposition occurs and an interconnected structure with a wavelength of 20 nm is formed. The α and ω precipitates remained in the structure. Such a fine spinodal structure strengthens the alloy effectively. Detailed strengthening calculations were conducted in order to estimate the strengthening contributions from the α and ω precipitates, as well as the spinodal decomposition microstructure.
This investigation elucidated the effects of C and Cr content on the high-temperature microstruct... more This investigation elucidated the effects of C and Cr content on the high-temperature microstructures of Fe–9Al–30Mn–xC–yCr alloys by means of optical microscopy and transmission electron microscopy. With increasing Cr content, the phase transition ...
ABSTRACT The present study investigates the drilling characteristics of a high-strength Fe-8Al-30... more ABSTRACT The present study investigates the drilling characteristics of a high-strength Fe-8Al-30Mn-1C-1Si-3Cr (mass%) biomedical alloy. After machining, a surface-hardening layer with a Vickers hardness number (H-v) equal to 600 was observed. In addition, a gamma -> (gamma + kappa) phase transition was observed in the matrix and at the stress-induced twin boundaries of the surface-hardening layer. K-phase carbides ((Fe,Mn)(3)AlCx) having an L'1(2) structure with the lattice parameter a = 0.375 nm were precipitated. Furthermore, the heat transfer coefficient of the present alloy was 0.083 cal/(cm(2)s degrees C), which was lower than that of AISI 304 stainless steel, which was 0.098 cal/(cm(2)s degrees C). The instantaneous'cutting temperature of the present alloy was approximately 650 degrees C during the machining process. It is believed that the formation of kappa-phase carbides not only decreases the machinability of the present alloy, but also reduces the life of the cutting tool. These features could be useful in further understanding the relationship between the machinability and the microstructure of Fe-Al-Mn C-based alloys, and thus provide information that would be allow these alloys to be used in biomedical and industrial applications, [doi:10.2320/matertrans.M2012107]
Horng-Chih Lin, Tze-Guei Jung, Hsiao-Yi Lin, Chun-Yen Chang, and Tan-Fu Lei Institute of Electron... more Horng-Chih Lin, Tze-Guei Jung, Hsiao-Yi Lin, Chun-Yen Chang, and Tan-Fu Lei Institute of Electronics, National Chiao-Tung University, and National Nano Device Laboratory, Hsin-Chu, 300 Taiwan, Republic of China PJ Wang National Nano Device Laboratory, ...
The purpose of this study was to investigate the corrosion behavior of four different dental cast... more The purpose of this study was to investigate the corrosion behavior of four different dental casting alloys in artificial saliva solutions with varying pH values. Microstructures were observed using scanning electron microscopy. The corrosion behavior of the experimental alloys in artificial saliva was examined using potentiodynamic polarization measurements. The high noble alloy (Au-8.5Pt-2.6Pd-1.4In) exhibited better corrosion resistance with lower anodic current densities in the pH range of 3–5. The anodic current density of the noble alloy (Au-24.9Pd-19.0Ag-5.5In) decreased as the pH decreased. The noble (Pd-37.7Ag-8.5Sn) and base metal (Ni-25Cr-11.5Mo-1.4Si) alloys exhibited lower corrosion resistance with a relatively high current density at pH 3. Compared with noble alloys, base metal alloys exhibited good corrosion resistance in this study. This makes them a promising material for dental castings considering the complex pH changes in the oral environment.
Background: The main factors to influence on the stroking performance of club head are alloy and ... more Background: The main factors to influence on the stroking performance of club head are alloy and spring-like effect. Design the structure of new club face to create the fairway wood which can show best stroking feeling and let driving distance become longer. Purpose: The club face of fairway wood is processed through the iron alloy heating procedure and CNC to innovate the club head with high spring-like effect (characteristic time). Method: (1) Use 455 stainless steel processed by heating and aging treatment, to do the analysis on microstructure and mechanical properties. (2) Through CNC to design seven different patterns for the back of club face, each pattern for three club head. The total amount is twenty-one. (3) Make finished product be test the characteristic time and the ability of strike by the practical measurement. (4) To analyze after the compare between three-way ANOVA and LSD. Results: After 455 stainless steel was heated in procedure S850℃-A550℃, mechanical properties became superior and had the better malleability, it is suitable for developing the club face of high spring-like effect. Before and after grinding among three-way ANOVA (pattern*thickness*place), did not achieve the significant level on the figure of characteristic time. Through two-way ANOVA (pattern*place and thickness*place), showed the significant deviation before and after grinding. After doing the crash test by 45m/s, all the results can reach the higher limited standard. Summary: 455 stainless steel was designed with the different club face’s thicknesses of fairway wood can make spring-like effect achieve high characteristic time. The much thinner club face let the characteristic time perform highly. But there was no obvious effects from the patterns of the back club face.
Lung cancer is a malignancy with high mortality worldwide, and metastasis occurs at a high freque... more Lung cancer is a malignancy with high mortality worldwide, and metastasis occurs at a high frequency even when cancer spread is not detectable at primary operation. Cancer stemness plays an important role in malignant cancer behavior, treatment resistance, and cancer metastasis. Therefore, understanding the molecular pathogenesis behind cancer-stemness-mediated metastasis and developing effective approaches to prevent metastasis are key issues for improving cancer treatment. In this study, we investigated the role of CD44 stemness marker in lung cancer using in vitro and clinical studies. Immunohistochemical staining of lung cancer tissue specimens revealed that primary tumors with higher CD44 expression showed increased metastasis to regional lymph nodes. Flow cytometry analysis suggested that CD44 positive cells were enriched in the metastatic lymph nodes compared to the primary tumors. CD44 overexpression significantly increased migration and invasion abilities of lung cancer cel...
The effects of the addition of silver on the microstructural variation and antibacterial performa... more The effects of the addition of silver on the microstructural variation and antibacterial performance of 2205 duplex stainless steel after solution and aging treatment were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and antibacterial testing. The microstructure showed that 2205Ag is composed of a ferrite (α) + austenite (γ) duplex phase and Ag-rich nano-precipitates (Ag-NPs). The morphology of the Ag-NPs varied from spherical to polygonal after aging treatment at 450 °C for 4 h. These precipitates were identified as face-centered-cubic structures with a lattice parameter of a = 0.354 nm and a mismatch of δ = 0.84% relative to the austenite matrix. Notably, 2205Ag with polygonal Ag-NPs exhibited excellent antibacterial properties that were superior to those of 2205Ag with spherical Ag-NPs.
Michelle Oyen Editor-in-Chief Materials Science and Engineering: C Dear Editor: I wish to submit ... more Michelle Oyen Editor-in-Chief Materials Science and Engineering: C Dear Editor: I wish to submit a research paper for publication in Materials Science and Engineering: C, titled "Effect of Ti2Cu precipitation on antibacterial property of Ti–5Cu alloy." The paper was coauthored by Ju-Hui Wu, Chih-Yeh Chao, and Yen-Hao Chang. This study set out to examine the antibacterial effects of Ti alloys to which Cu had been added. We found that the solid-solution treatment of a Ti–5Cu alloy failed to provide an acceptable level of antibacterial activity, but the presence of nano-scale Ti2Cu precipitates led to the alloy exhibiting a relatively high antibacterial activity of > 90%. We believe that our study makes a significant contribution to the literature because this would provide a means of overcoming the serious problem of bacterial infection that remains an issue with the implantation of Ti prostheses. Further, we believe that this paper will be of interest to the readership of your journal because the relationship between heat treatment and the antibacterial property has not been explored in Ti based antibacterial materials. The aim of this work is to study the effects of heat treatment on microstructure and antibacterial property of a Ti-5Cu alloy in order to produce an optimal antibacterial material for clinic application. This manuscript has not been published or presented elsewhere in part or in entirety and is not under consideration by another journal. We have read and understood your journal's policies, and we believe that neither the manuscript nor the study violates any of these. There are no conflicts of interest to declare. Thank you for your consideration. I look forward to hearing from you. Sincerely, Je-Kang Du Department of Dentistry Kaohsiung Medical University Hospital Kaohsiung 80708 Taiwan Tel: 886-7-3121101 ext. 7003 Fax: 886-7-3157024 E-mail: [email protected]
The microstructural characteristics and Young’s modulus of the as-cast Ti–15Ta–15Nb alloy are rep... more The microstructural characteristics and Young’s modulus of the as-cast Ti–15Ta–15Nb alloy are reported in this study. On the basis of the examined XRD and TEM results, the microstructure of the current alloy is essentially a mixture (α + β+ α′ + α″ + ω + H) phase. The new H phase has not previously been identified as a known phase in the Ti–Ta–Nb alloy system. On the basis of examination of the Kikuchi maps, the new H phase belongs to a tetragonal structural class with lattice parameters of a = b = 0.328 nm and c = 0.343 nm, denoting an optimal presentation of the atomic arrangement. The relationships of orientation between these phases would be {0001}α//{110}β//{1¯21¯0}ω//{101¯}H and (011¯0)α//(11¯2)β//(1¯010)ω//(121)H. Moreover, the Young’s modulus of the as-cast Ti–15Ta–15Nb alloy is approximately E = 80.2 ± 10.66 GPa. It is implied that the Young’s modulus can be decreased by the mixing of phases, especially with the presence of the H phase.
The aim of this study was to investigate the effect of incorporating low copper (0, 0.5, 1, 1.5, ... more The aim of this study was to investigate the effect of incorporating low copper (0, 0.5, 1, 1.5, and 2 wt.%) additions into as-forged AISI 304 stainless steel (304SS). The microstructures and mechanical properties of the steel were examined using scanning electron microscopy and a universal testing machine. The antibacterial properties of the Cu-bearing 304SS specimens were investigated using Escherichia coli. Each specimen was soaked in artificial saliva to detect the release of copper ions through inductively coupled plasma atomic emission spectrometry. The addition of copper had no significant effect on the microstructure of the as-forged Cu-bearing 304SS, but it slightly increased its maximum tensile strength. The antibacterial rate of the as-cast and as-forged 304SS with 2 wt.% Cu was over 80%, which corresponded to an increase in the release of copper ions. This study demonstrates that low-Cu-content stainless steel can reduce bacteria and can be a suitable material for the or...
To control the degradation rate of magnesium (Mg) alloys, chitosan (CHI) and L-glutamic acid (LGA... more To control the degradation rate of magnesium (Mg) alloys, chitosan (CHI) and L-glutamic acid (LGA) were used as coatings on Mg-Zn-Ca alloys via dip coating. In this study, either two or seven CHI/LGA layers were applied as a coating on Mg-2.8Zn-0.8Ca alloy (ZX31) and Mg-2.8Zn-0.8Ca hemostasis clips (ZX31 clips). The morphologies, compositions, and surface roughness of the specimens were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, and surface measurement devices. The degradation rates and behavior of the specimens were evaluated by immersing them in simulated body fluids and by applying these ZX31 clips on rabbits’ uterine tubes for five weeks. The specimen with seven layers (ZX31(CHI/LGA)7) exhibited improved corrosion behavior when compared with ZX31 or ZX31(CHI/LGA)2, with a reduced degradation rate of the Mg alloy in a simulated body environment. In vivo experiments showed that ZX31 clips exhibited good biocompatibilities in each group...
Ti-6Al-4V, although widely used in dental materials, causes peri-implant inflammation due to the ... more Ti-6Al-4V, although widely used in dental materials, causes peri-implant inflammation due to the long-term accumulation of bacteria around the implant, resulting in bone loss and eventual failure of the implant. This study aims to overcome the problem of dental implant infection by analyzing the influence of Ti-6Al-4V surface characteristics on the quantity of accumulated bacteria. Ti-6Al-4V specimens, each with different surface roughness are produced by mechanical, chemical, and electrolytic polishing. The surface roughness, surface contact angle, surface oxygen content, and surface structure were measured via atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM), drop shape analysis (using sessile drop), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The micro and macro surface roughness are 10.33–120.05 nm and 0.68–2.34 μm, respectively. The surface X direction and Y direction contact angle are 21.38°–96.44° and 18.37°–92.72°, respectivel...
Titanium alloys are widely employed for the fabrication of biomedical devices. In this study, we ... more Titanium alloys are widely employed for the fabrication of biomedical devices. In this study, we designed and developed a Ti-5Al-2.5Cu alloy, which exhibited antibacterial properties. Microstructure and elemental analyses were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). We evaluated the alloy’s antibacterial properties using Escherichia coli in the plate-count method. The cytotoxicity was examined using the MG-63 cell response by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Microstructural analysis revealed that Ti-5Al-2.5Cu exhibited an equiaxed α’ martensite structure after short-term annealing. The heterogeneous and homogeneous α → α + Ti2Cu phase transitions occurred at ~840 and 920 °C, respectively. The antibacterial property for Ti-5Al-2.5Cu was varied by volume fraction in the Ti2Cu and Cu-rich ...
To instill pure Ti with an antibacterial effect, Cu was added by metallurgical alloying to produc... more To instill pure Ti with an antibacterial effect, Cu was added by metallurgical alloying to produce Ti-5 wt% Cu alloy (Ti-5Cu alloy). The precipitation of the likes of Ti 2 Cu in a Ti-Cu alloy is one of the factors that influences its antibacterial property. However, in the present study, Ti-5Cu alloy precipitates with different microstructures were obtained by applying heat treatment at different temperatures and for different durations. After the heat treatment, metallographic, microstructure, and element analyses were performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS). The antibacterial property of the Ti-5Cu alloy was assessed by the plated-count method using Escherichia coli (E. coli). The microstructure analysis revealed that the solution-treated alloy had no precipitation, while the aged alloy contained precipitations of intermetallic Ti 2 Cu compound. The aged alloy exhibited better antibacterial performance as the duration of the aging treatment increased. The optimal heat treatment for Ti-5Cu was found to be aging at 700°C for 4 h, at which point the nucleation formation of the Ti 2 Cu particles would assume an acicular morphology. These acicular precipitates exhibit a high Cu content which, in turn, influences the antibacterial performance.
Journal of the mechanical behavior of biomedical materials, Jan 28, 2018
In order to develop Ti based alloys with promising biocompatibility and matching mechanical respo... more In order to develop Ti based alloys with promising biocompatibility and matching mechanical response with human bone, TiTaNb alloys with 15, 23 and 30 mass% Ta are designed and systematically examined in terms of microstructural evolution and mechanical response. The Ti-30mass%Ta-10mass%Nb is demonstrated to be satisfactory with an elastic modulus ~60 GPa, hardness ~3.1 GPa, and strength ~1250 MPa. The evolution trend of the resulting microstructure and phases as a function of Ta content and annealing temperature are established. The relationship between the various phase amounts and alloy moduli is explored.
Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainle... more Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu 2+ and Ag 2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI) 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr 2 N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr 2 N precipitates. When aged at a lower temperature, which resulted in nano-Cr 2 N precipitation, the specimen possessed the highest antibacterial activity.
The microstructures and mechanical properties of the Fe-10 mass%Al-(5-40)mass%Mn-1.0 mass%C alloy... more The microstructures and mechanical properties of the Fe-10 mass%Al-(5-40)mass%Mn-1.0 mass%C alloys sheet castings have been investigated by using optical microscope (OM), transmission electron microscope (TEM), scanning electron microscope (SEM), experimental model analysis, tensile test and hardness test. Based on the present studies, the macroscopic microstructure of the present alloys are a mixture of austenite (γ) and ferrite (α) duplex phases, and the α phase would decrease with the Mn content increased. In the meantime, according to the examination of TEM, the macroscopic γ phase is a mixture of the γ + fine(Fe, Mn) 3 AlC x (κ) + (Fe, Mn) 3 AlC x (κ) phases and the macroscopic α phase is a mixture of the D0 3 + coarse(Fe, Mn) 3 AlC x (κ) phases. The mechanical properties such as the ultimate tensile strength (UTS), yield strength (Y.S.), elongation of these alloys were in the range of 646-887 MPa, 575-824 MPa, and 16.3-29.2%, respectively. The hardness of these alloys were in the range of HR C 31-44. Moreover, the relationship between hardness and ultimate strength is UTS 20.93HR C. In addition, the damping ratios and Young's modulus of the present alloys were in the range of 0.0603-0.0417, and 139-165 GPa, respectively. It is noted here that the results have never observed by other research workers in the Fe-Al-Mn-C alloy system.
Journal of Flow Visualization and Image Processing, 2007
The speed of golf balls can be regarded as the fastest in all ball games. The flying distance of ... more The speed of golf balls can be regarded as the fastest in all ball games. The flying distance of a golf ball is influenced not only by its material, but also by the aerodynamics of the dimple on its surface. By using Computational Fluid Dynamics method, the flow field and aerodynamics characteristics of golf balls can be studied and evaluated before the golf balls are actually manufactured. This work uses FLUENT as its solver and numerical simulations were carried out to estimate the aerodynamics parameters and noise levels for various kinds of golf balls having different dimple configurations. With the obtained aerodynamics parameters, the flying distance and trajectory for a golf ball were determined and visualized. The results showed that the lift coefficient of the golf ball increased if small dimples were added between the original dimples. When launched at small angles, golf balls with deep dimples were found to have greater lift effects than drag effects. Therefore, the golf balls would fly further. As far as noise generation was concerned, deep dimples produced lower noise levels.
International Journal of Minerals, Metallurgy, and Materials, 2012
Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned w... more Silver or copper ions are often chosen as antibacterial agents. But a few reports are concerned with these two antibacterial agents for preparation of antibacterial stainless steel (SS). The antibacterial properties and corrosion resistance of AISI 420 stainless steel implanted by silver and copper ions were investigated. Due to the cooperative antibacterial effect of silver and copper ions, the Ag/Cu implanted SS showed excellent antibacterial activities against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) at a total implantation dose of 2×10 17 ions/cm 2. Electrochemical polarization curves revealed that the corrosion resistance of Ag/Cu implanted SS was slightly enhanced as compared with that of un-implanted SS. The implanted layer was characterized by X-ray photoelectron spectroscopy (XPS). Core level XPS spectra indicate that the implanted silver and copper ions exist in metallic state in the implanted layer.
In this study, the effects of spinodal decomposition on the microstructures and mechanical proper... more In this study, the effects of spinodal decomposition on the microstructures and mechanical properties of a TiZrNbTa alloy are investigated. The as-cast TiZrNbTa alloy possesses dual phases of TiZr-rich inter-dendrite (ID) and NbTa-rich dendrite (DR) domains, both of which have a body-centered cubic (BCC) structure. In the DRs of the as-cast alloy, the α and ω precipitates are found to be uniformly distributed. After homogenization at 1100 °C for 24 h followed by water quenching, spinodal decomposition occurs and an interconnected structure with a wavelength of 20 nm is formed. The α and ω precipitates remained in the structure. Such a fine spinodal structure strengthens the alloy effectively. Detailed strengthening calculations were conducted in order to estimate the strengthening contributions from the α and ω precipitates, as well as the spinodal decomposition microstructure.
This investigation elucidated the effects of C and Cr content on the high-temperature microstruct... more This investigation elucidated the effects of C and Cr content on the high-temperature microstructures of Fe–9Al–30Mn–xC–yCr alloys by means of optical microscopy and transmission electron microscopy. With increasing Cr content, the phase transition ...
ABSTRACT The present study investigates the drilling characteristics of a high-strength Fe-8Al-30... more ABSTRACT The present study investigates the drilling characteristics of a high-strength Fe-8Al-30Mn-1C-1Si-3Cr (mass%) biomedical alloy. After machining, a surface-hardening layer with a Vickers hardness number (H-v) equal to 600 was observed. In addition, a gamma -> (gamma + kappa) phase transition was observed in the matrix and at the stress-induced twin boundaries of the surface-hardening layer. K-phase carbides ((Fe,Mn)(3)AlCx) having an L'1(2) structure with the lattice parameter a = 0.375 nm were precipitated. Furthermore, the heat transfer coefficient of the present alloy was 0.083 cal/(cm(2)s degrees C), which was lower than that of AISI 304 stainless steel, which was 0.098 cal/(cm(2)s degrees C). The instantaneous'cutting temperature of the present alloy was approximately 650 degrees C during the machining process. It is believed that the formation of kappa-phase carbides not only decreases the machinability of the present alloy, but also reduces the life of the cutting tool. These features could be useful in further understanding the relationship between the machinability and the microstructure of Fe-Al-Mn C-based alloys, and thus provide information that would be allow these alloys to be used in biomedical and industrial applications, [doi:10.2320/matertrans.M2012107]
Horng-Chih Lin, Tze-Guei Jung, Hsiao-Yi Lin, Chun-Yen Chang, and Tan-Fu Lei Institute of Electron... more Horng-Chih Lin, Tze-Guei Jung, Hsiao-Yi Lin, Chun-Yen Chang, and Tan-Fu Lei Institute of Electronics, National Chiao-Tung University, and National Nano Device Laboratory, Hsin-Chu, 300 Taiwan, Republic of China PJ Wang National Nano Device Laboratory, ...
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Papers by Chih-yeh Chao