The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jiuchun Yan - One of the best experts on this subject based on the ideXlab platform.
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cavitation at filler metal Substrate Interface during ultrasonic assisted soldering part ii cavitation erosion effect
Ultrasonics Sonochemistry, 2019Co-Authors: S J Wang, Xuesong Liu, Jiuchun YanAbstract:Abstract Using pure Sn as filler metal, this study investigated cavitation erosion effects during ultrasonic-assisted soldering. The physical process and mechanism of cavitation erosion were revealed. Superior erosion effects were observed under long ultrasonic times, small channel widths, and high ultrasonic powers. Different vibration intensities were obtained inside filler pool. Region I, which was located far from the sonotrode, exhibited a stronger vibration intensity and better erosion effect than those of the other regions. The erosion incubation stage was shorted than 0.5 s at the channel width of 0.2 mm. Complete oxide layer removal was obtained at an ultrasonic time of 2 s under this condition. The violent cavitation stage was shorter than the erosion incubation stage, and the removal of the oxide layer mainly depended on the stable cavitation stage.
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cavitation at filler metal Substrate Interface during ultrasonic assisted soldering part i cavitation characteristics
Ultrasonics Sonochemistry, 2018Co-Authors: S J Wang, Xuesong Liu, Jiuchun YanAbstract:Abstract The cavitation characteristics at filler metal/Substrate Interface during ultrasonic-assisted soldering were first recorded by high-speed photography in this work. Two kinds of bubbles, steady cavitation bubbles and transient cavitation bubbles were observed. Steady cavitation bubbles did not collapse within one acoustic period and could last longer than 50 acoustic periods. Transient cavitation bubbles formed and collapsed within one acoustic period. The cavitation process was divided into two stages based on the cavitation characteristics. The first violent cavitation stage was in fact the degassing process, which lasted approximately 2700 acoustic periods and was affected by the gas content trapped inside the filler metal and the stronger vibration at the initiation stage of ultrasonic-assisted soldering. The second steady cavitation stage had obvious low bubble density and accounted for the most of the soldering process. Higher cavitation densities were observed when small channel width and large ultrasonic power were used because of larger sound pressures inside the filler metal.
Georgios Skordaris - One of the best experts on this subject based on the ideXlab platform.
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Temperature-Dependent Fatigue Strength of Diamond Coating-Substrate Interface Quantified via the Shear Failure Stress
Journal of Materials Engineering and Performance, 2015Co-Authors: Georgios SkordarisAbstract:A dynamic 3D-finite element method (FEM) thermomechanical model is employed for quantifying the temperature-dependent fatigue strength of nanocrystalline diamond (NCD) coating-Substrate Interface. This model simulates dynamically the inclined impact test on NCD-coated cemented carbide inserts considering the temperature-dependent residual stresses in the NCD coating structure. A fatigue damage of the NCD coating-Substrate Interface develops after a certain number of repetitive impacts depending on the applied impact load and temperature. After the Interface fatigue failure, the high compressive residual stresses of the NCD coating structure are released, and the detached coating hikes up at a certain maximum height (bulge formation). The critical impact forces for avoiding the fatigue failure of the NCD coating-Substrate Interface, and the subsequent film detachment after 106 impacts at various temperatures were determined by conducting inclined impact tests up to 400 °C. Considering the critical impact forces, using the mentioned FEM model, the related shear failure stresses in the NCD coating-Substrate Interface at various temperatures were predicted.
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Fatigue Strength of Diamond Coating-Substrate Interface Quantified by a Dynamic Simulation of the Inclined Impact Test
Journal of Materials Engineering and Performance, 2014Co-Authors: Georgios SkordarisAbstract:Fatigue damage of the nanocrystalline diamond coating (NCD) bonding to the cemented carbide Substrate develops when repetitive impact loads are applied onto the film. Thus, the highly compressive residual stresses of a NCD film are released leading to its lifting from the Substrate (bulge formation). The present paper deals with the analytical description of the progressive failure of the NCD coating-Substrate Interface under repetitive impacts. In this context, an advanced 3D-finite element analysis model was developed for the dynamic simulation of the inclined impact test, using the LS-DYNA software. This model considers the high thermal compressive residual stresses developed in the NCD coating structure during cooling from chemical vapour deposition process temperature to ambient one. The fatigue failure of the NCD coating-Substrate Interface is associated with a critical shear failure stress (SFLS). The determined SFLS represents the maximum operational stress permitted in the NCD film-Substrate Interface in order to avoid the coating detachment initiation. According to the results obtained, the successive impacts lead to a progressive weakening of the initial film-Substrate Interface strength depending upon the pretreatments prior to the NCD coating deposition.
S J Wang - One of the best experts on this subject based on the ideXlab platform.
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cavitation at filler metal Substrate Interface during ultrasonic assisted soldering part ii cavitation erosion effect
Ultrasonics Sonochemistry, 2019Co-Authors: S J Wang, Xuesong Liu, Jiuchun YanAbstract:Abstract Using pure Sn as filler metal, this study investigated cavitation erosion effects during ultrasonic-assisted soldering. The physical process and mechanism of cavitation erosion were revealed. Superior erosion effects were observed under long ultrasonic times, small channel widths, and high ultrasonic powers. Different vibration intensities were obtained inside filler pool. Region I, which was located far from the sonotrode, exhibited a stronger vibration intensity and better erosion effect than those of the other regions. The erosion incubation stage was shorted than 0.5 s at the channel width of 0.2 mm. Complete oxide layer removal was obtained at an ultrasonic time of 2 s under this condition. The violent cavitation stage was shorter than the erosion incubation stage, and the removal of the oxide layer mainly depended on the stable cavitation stage.
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cavitation at filler metal Substrate Interface during ultrasonic assisted soldering part i cavitation characteristics
Ultrasonics Sonochemistry, 2018Co-Authors: S J Wang, Xuesong Liu, Jiuchun YanAbstract:Abstract The cavitation characteristics at filler metal/Substrate Interface during ultrasonic-assisted soldering were first recorded by high-speed photography in this work. Two kinds of bubbles, steady cavitation bubbles and transient cavitation bubbles were observed. Steady cavitation bubbles did not collapse within one acoustic period and could last longer than 50 acoustic periods. Transient cavitation bubbles formed and collapsed within one acoustic period. The cavitation process was divided into two stages based on the cavitation characteristics. The first violent cavitation stage was in fact the degassing process, which lasted approximately 2700 acoustic periods and was affected by the gas content trapped inside the filler metal and the stronger vibration at the initiation stage of ultrasonic-assisted soldering. The second steady cavitation stage had obvious low bubble density and accounted for the most of the soldering process. Higher cavitation densities were observed when small channel width and large ultrasonic power were used because of larger sound pressures inside the filler metal.
David L Carroll - One of the best experts on this subject based on the ideXlab platform.
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Substrate Interface interactions between carbon nanotubes and the supporting Substrate
Physical Review B, 2002Co-Authors: R Czerw, B Foley, D Tekleab, Angel Rubio, Pulickel M Ajayan, David L CarrollAbstract:By utilizing the current transients in scanning tunneling spectroscopy, the local interfacial electronics between multiwalled carbon nanotubes and several supporting Substrates has been investigated. Voltage offsets in the tunneling spectra are directly correlated with the formation of a dipole layer at the nanotube-Substrate Interface, strongly suggesting the formation of Interface states. Further, a systematic variation in this local potential, as a function of tube diameter, is observed for both metallic Substrates (Au) and semimetallic Substrates (graphite). In both cases, for tubes with diameters between \ensuremath{\sim}5 nm and 30 nm, the interfacial potential is nearly constant as a function of tube diameter. However, for tube diameters 5 nm, a dramatic change in the local potential is observed. Using ab initio techniques, this diameter-dependent electronic interaction is shown to derive from changes in the tube-Substrate hybridization that results from the curvature of the nanotubes.
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Substrate Interface interactions between carbon nanotubes and the supporting Substrate
Physical Review B, 2002Co-Authors: R Czerw, D Tekleab, Angel Rubio, Pulickel M Ajayan, Brian T Foley, David L CarrollAbstract:Over the last several years, an astonishing number of experimental determinations of the electronic transport properties of single-walled carbon nanotubes ~SWNT’s! and multiwalled carbon nanotubes ~MWNT’s! have been made 1‐3 and correlated with a number of theoretical predictions. 4 With only a few exceptions, the experimental focus has been on nanotubes supported on a Substrate of some type, and in all cases a system of contacts has been employed using traditional interconnect materials such as Cu, Au, Pt, and Ag. Thus, all the experimental information we currently have on the electronics of carbon nanotubes involves experimental designs that use metal/semiconductor-nanotube Interfaces, and in most cases these Interfaces include the length of the tube through the support. Clearly an important part of any interpretation of transport results must include interactions that may exist between the nanotube and the support Substrate and contacts. 5 Recent theoretical studies have addressed Fermi-level alignment in Au-SWNT systems and have suggested that a charge transfer should exist at the Interface. 6 Similarly, some tunneling spectroscopy experiments have hinted at the existence of charge transfer between the gold and nanotube systems. 7 However, despite the importance of local Interface interactions in transport measurements, no direct determination of its variation with tube diameter, tube chirality, etc., is yet available. In this paper we present an investigation of the interfacial electronic structure between MWNT’s and a number of support Substrates using current transients in scanning tunneling spectroscopy ~STS!. These studies strongly suggest that charge transfer at the metal/MWNT Interface results from the formation of Interface states in analogy to bulk Schottky barriers. Further, the
Ali Khademhosseini - One of the best experts on this subject based on the ideXlab platform.
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engineering microscale topographies to control the cell Substrate Interface
Biomaterials, 2012Co-Authors: Mehdi Nikkhah, Faramarz Edalat, Sam Manoucheri, Ali KhademhosseiniAbstract:Abstract Cells in their in vivo microenvironment constantly encounter and respond to a multitude of signals. While the role of biochemical signals has long been appreciated, the importance of biophysical signals has only recently been investigated. Biophysical cues are presented in different forms including topography and mechanical stiffness imparted by the extracellular matrix and adjoining cells. Microfabrication technologies have allowed for the generation of biomaterials with microscale topographies to study the effect of biophysical cues on cellular function at the cell–Substrate Interface. Topographies of different geometries and with varying microscale dimensions have been used to better understand cell adhesion, migration, and differentiation at the cellular and sub-cellular scales. Furthermore, quantification of cell-generated forces has been illustrated with micropillar topographies to shed light on the process of mechanotransduction. In this review, we highlight recent advances made in these areas and how they have been utilized for neural, cardiac, and musculoskeletal tissue engineering application.
