The Experts below are selected from a list of 16743 Experts worldwide ranked by ideXlab platform
Kunwook Chung - One of the best experts on this subject based on the ideXlab platform.
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analysis of a widely tunable long period grating by use of an ultrathin Cladding Layer and higher order Cladding mode coupling
Optics Letters, 2004Co-Authors: Kunwook ChungAbstract:A widely tunable long-period grating in single-mode fiber is analyzed by use of an ultrathin Cladding Layer and higher-order Cladding mode coupling. The numerical simulation shows that a 225-nm tuning range in the newly designed ultrathin long-period grating (Cladding thickness, 35 µm) with third-order Cladding mode coupling can be obtained. The analyzed tuning range is seven times wider than those of the other known long-period gratings. We believe that the proposed highly sensitive long-period grating will be widely used as a gain-flattening filter for ultrawideband optical amplifiers and fast tunable filters in dynamic optical communication systems.
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a highly sensitive long period grating based tunable filter using a unique double Cladding Layer structure
Optics Communications, 2001Co-Authors: Shizhuo Yin, Kunwook Chung, Xin ZhuAbstract:In this paper, we present a highly sensitive long period grating (LPG) with a unique double-Cladding Layer structure including an ultra-thin inner silica Cladding Layer and a low refractive index liquid crystal outer Cladding Layer. By using an ultra-thin Cladding Layer (28 μm in diameter) reduced by chemical etching, the LPG has a single resonant band over a wide range of wavelength and higher sensitivity to the environmental refractive index change. In addition, the high thermal-optic effect of liquid crystal makes it very easy to tune the resonant wavelength by controlling the temperature of the liquid crystal. Thus, a highly sensitive tunable filter can be made. The experimental results show that a tuning efficiency of 2.1 nm/°C is achieved. To the best of our knowledge, this is the highest tuning efficiency ever reported.
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wavelength tuning range enhanced single resonant band fiber filter using a long period grating lpg with ultra thin Cladding Layer
Optical Fiber Communication Conference, 2000Co-Authors: O Leonov, Kunwook Chung, Paul Kurtz, Karl Reichard, Q M ZhangAbstract:A unique fiber filter using a LPG with ultra thin Cladding Layer (/spl sim/32 /spl mu/m) is presented, which has a single resonant band within 1000 nm to 1700 nm wavelength tuning sensitivity as large as 30 nm shift for a 2/spl times/1O-3 surrounding refractive index change.
Jie Sun - One of the best experts on this subject based on the ideXlab platform.
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study on chip morphology and milling characteristics of laser Cladding Layer
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: Yanhua Zhao, Jie SunAbstract:Laser Cladding, which can increase the hardness and wear resistance of the used components, is widely used in remanufacture and sustainable manufacturing field. Generally, laser Cladding Layer should be machined to meet the function as well as the assembly requirements. Milling is an effective means for precision machining. However, there exist great differences of physical and mechanical performances between laser Cladding Layer and substrate material, such as microstructure, hardness, mechanical properties, etc. This produces some new milling problems for laser Cladding Layer. An insightful understanding of milling mechanism of laser Cladding Layer is inevitable. There still lacks the research on this subject, such as chip morphology and mechanical behavior, vibration during laser Cladding Layer milling process, etc. Thus, the change of chip morphology depending on the cutting parameters and microhardness variation was studied. Signal analysis methods of time and frequency domains of cutting forces and machining vibration were used to evaluate the milling characteristics of laser Cladding Layer. The microstructural analysis indicates that shear-induced lamella structures are the basic features for the chip free surface. The height-to-thickness ratio of saw-tooth chips increases with increasing cutting speeds and feeds. Microhardness profiles on the top surfaces of machined chip decrease from the back surface to the bulk chip, and the shear band shows increased hardness. The cutting force and machining vibration acceleration of laser Cladding Layer are higher than those of the KMN steel substrate at the same cutting parameters. The machining vibration is characterized by high vibration in the intermediate position of each Layer and low vibration in the joint surfaces between Layers.
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effect of rare earth oxide on the properties of laser Cladding Layer and machining vibration suppressing in side milling
Applied Surface Science, 2014Co-Authors: Yanhua Zhao, Jie SunAbstract:Abstract Laser Cladding, which can increase the hardness and wear resistance of the used components, is widely used in remanufacture and sustainable manufacturing field. Generally, laser Cladding Layer should to be machined to meet the function as well as the assembly requirements. Milling is an effective mean for precision machining. However, there exist great differences of physical and mechanical performances between laser Cladding Layer and substrate material, including microstructure, hardness, wear resistance, etc. This produces some new milling problems for laser Cladding Layer, such as machining vibration which may lead to low productivity and worse surface integrity. Thus, it is necessary to develop a novel laser Cladding powder which can improve the surface hardness and wear resistance, while reducing the machining vibration in milling. Laser Cladding Layer was prepared by FeCr alloy and La 2 O 3 mixed powder. The effect of La 2 O 3 on the coating properties was investigated. Signal analysis methods of the time and frequency domain were used to evaluate the effect of the La 2 O 3 on machining vibration in the side milling laser Cladding Layer. The key findings of this study are: (a) with the La 2 O 3 content increasing, the grain size decreases dramatically and the microstructure of laser Cladding Layer are refine; (b) the hardness and wear resistance of the coatings with La 2 O 3 are improved significantly; and (c) the machining vibrations of laser Cladding Layer with La 2 O 3 are obviously reduced and the chatter is effectively avoided occurring.
Zengda Zou - One of the best experts on this subject based on the ideXlab platform.
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microstructures and properties of low chromium high corrosion resistant tic vc reinforced fe based laser Cladding Layer
Journal of Alloys and Compounds, 2015Co-Authors: Hui Zhang, Yong Zou, Zengda ZouAbstract:Abstract Effects of 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on microstructures and properties of TiC–VC reinforced Fe-based Cladding Layer were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Passive films formed on Cladding Layers surface were investigated by using X-ray photoelectron spectroscopy (XPS) and Mott–Schottky analysis. Results showed that phases of Cladding Layers were α-Fe, γ-Fe, TiC, VC and TiVC 2 . There were no obvious effects of adding 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on Cladding Layers phases. The microstructure of the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was lath martensite and retained austenite. Microhardness of the Cladding Layer with 0.25 wt.%CeO 2 decreased slightly. Microhardness and corrosion resistance of the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 both increased, the corrosion resistance increased 7.33 times while the EIS Nyquist spectrum transformed into a capacitive arc. The passive film formed on the Cladding Layer without Cr and CeO 2 was Fe 3 O 4 which displayed p type semiconductivity. The passive film formed on the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was composed of Fe(OH) 3 and Cr(OH) 3 , which displayed n and p type semiconductivity respectively.
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microstructure and properties of fe based composite coating by laser Cladding fe ti v cr c ceo2 powder
Optics and Laser Technology, 2015Co-Authors: Hui Zhang, Yong Zou, Zengda ZouAbstract:Abstract In situ TiC–VC reinforced Fe-based Cladding Layer was obtained on low carbon steel surface by laser Cladding with Fe–Ti–V–Cr–C–CeO 2 alloy powder. The microstructure, phases and properties of the Cladding Layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe–Ti–V–Cr–C–CeO 2 alloy powder formed a good Cladding Layer without defects such as cracks and pores. The phases of the Cladding Layer were α-Fe, γ-Fe, TiC, VC and TiVC 2 . The microstructures of the Cladding Layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5–2 μm and distributed uniformly in the Cladding Layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC 2 . The Cladding Layer with a hardness of 1030 HV 0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.
Hui Zhang - One of the best experts on this subject based on the ideXlab platform.
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microstructures and properties of low chromium high corrosion resistant tic vc reinforced fe based laser Cladding Layer
Journal of Alloys and Compounds, 2015Co-Authors: Hui Zhang, Yong Zou, Zengda ZouAbstract:Abstract Effects of 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on microstructures and properties of TiC–VC reinforced Fe-based Cladding Layer were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Passive films formed on Cladding Layers surface were investigated by using X-ray photoelectron spectroscopy (XPS) and Mott–Schottky analysis. Results showed that phases of Cladding Layers were α-Fe, γ-Fe, TiC, VC and TiVC 2 . There were no obvious effects of adding 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on Cladding Layers phases. The microstructure of the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was lath martensite and retained austenite. Microhardness of the Cladding Layer with 0.25 wt.%CeO 2 decreased slightly. Microhardness and corrosion resistance of the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 both increased, the corrosion resistance increased 7.33 times while the EIS Nyquist spectrum transformed into a capacitive arc. The passive film formed on the Cladding Layer without Cr and CeO 2 was Fe 3 O 4 which displayed p type semiconductivity. The passive film formed on the Cladding Layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was composed of Fe(OH) 3 and Cr(OH) 3 , which displayed n and p type semiconductivity respectively.
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microstructure and properties of fe based composite coating by laser Cladding fe ti v cr c ceo2 powder
Optics and Laser Technology, 2015Co-Authors: Hui Zhang, Dongting WuAbstract:Abstract In situ TiC–VC reinforced Fe-based Cladding Layer was obtained on low carbon steel surface by laser Cladding with Fe–Ti–V–Cr–C–CeO 2 alloy powder. The microstructure, phases and properties of the Cladding Layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe–Ti–V–Cr–C–CeO 2 alloy powder formed a good Cladding Layer without defects such as cracks and pores. The phases of the Cladding Layer were α-Fe, γ-Fe, TiC, VC and TiVC 2 . The microstructures of the Cladding Layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5–2 μm and distributed uniformly in the Cladding Layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC 2 . The Cladding Layer with a hardness of 1030 HV 0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.
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microstructure and properties of fe based composite coating by laser Cladding fe ti v cr c ceo2 powder
Optics and Laser Technology, 2015Co-Authors: Hui Zhang, Yong Zou, Zengda ZouAbstract:Abstract In situ TiC–VC reinforced Fe-based Cladding Layer was obtained on low carbon steel surface by laser Cladding with Fe–Ti–V–Cr–C–CeO 2 alloy powder. The microstructure, phases and properties of the Cladding Layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe–Ti–V–Cr–C–CeO 2 alloy powder formed a good Cladding Layer without defects such as cracks and pores. The phases of the Cladding Layer were α-Fe, γ-Fe, TiC, VC and TiVC 2 . The microstructures of the Cladding Layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5–2 μm and distributed uniformly in the Cladding Layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC 2 . The Cladding Layer with a hardness of 1030 HV 0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.
Zong Lei - One of the best experts on this subject based on the ideXlab platform.
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microstructure characteristics of ti3al tic ceramic Layer deposited by laser Cladding
International Journal of Refractory Metals & Hard Materials, 2011Co-Authors: Li Jianing, Chen Chuanzhong, Zong LeiAbstract:Abstract Al + TiC laser Cladding coatings were prepared on Ti–6Al–4V alloy by CO 2 laser Cladding technique. The microstructure, micro-hardness and phase constitutes of the laser Cladding Layer were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and microsclermeter. The results indicated that the laser Cladding Layer solidified into the fine microstructure rapidly, and TiC hard phase was dispersived in the Cladding Layer. When the mass percent of TiC was 40%, the micro-hardness (1100HV 0.2 –1250HV 0.2 ) of Al + TiC Cladding Layer was 3 times more than that of the Ti–6Al–4V alloy substrate (350–370HV 0.2 ). The Cladding Layer mainly consisted of α-Ti (Al), β-Al (Ti), Ti 3 Al, TiAl, Al 3 Ti and TiC phase. There phases were beneficial to improve the hardness and wear resistance of the Cladding Layer.