Search results for " Alloys"
showing 10 items of 1469 documents
Material quality characterization of CdZnTe substrates for HgCdTe epitaxy
2006
Cd1−xZnxTe (CZT) substrates were studied to investigate their bulk and surface properties. Imperfections in CZT substrates affect the quality of Hg1−xCdxTe (MCT) epilayers deposited on them and play a role in limiting the performance of infrared (IR) focal plane arrays. CZT wafers were studied to investigate their bulk and surface properties. Transmission and surface x-ray diffraction techniques, utilizing both a conventional closed-tube x-ray source as well as a synchrotron radiation source, and IR transmission micro-spectroscopy, were used for bulk and surface investigation. Synchrotron radiation offers the capability to combine good spatial resolution and shorter exposure times than conv…
Novel voltage-controlled conditioning circuit applied to the ISFETs temporary drift and thermal dependency
2003
This paper describes a novel conditioning circuit applied to ion-sensitive field-effect transistors/membrane-ion-sensitive field-effect transistors (ISFETs/MEMFETs) sensors. The novel conditioning circuit allows the sensor polarization with the needed either voltage or current required in each application, thanks to two completely independent voltage-controlled blocks (current and voltage blocks). The control of the voltage block is the most critical point in our design because the voltage block maintains the sensor feedback stable, avoiding the thermal and temporary drifts of the sensor feedback.
Novel constant current driver for ISFET/MEMFETs characterization
2001
Abstract In the present work a new constant current driver for ISFETs and MEMFETs sensors has been developed. The proposed circuit maintains the ISFET/MEMFET operation point at constant drain–source current and voltage. The combination of some programmable current sources and an appropriate selection of a simple precision resistor allow a good ISFET/MEMFET polarization. The use of operational amplifiers with low offset and drift are required to provide the buffering function needed by the sensor.
Intraperitoneal adhesions-an ongoing challenge between biomedical engineering and the life sciences
2011
Peritoneal adhesions remain a relevant clinical problem despite the currently available prophylactic barrier materials. So far, the physical separation of traumatized serosa areas using barriers represents the most important clinical strategy for adhesion prevention. However, the optimal material has not yet been found. Further optimization or pharmacological functionalization of these barriers could give an innovative input for peritoneal adhesion prevention. Therefore, a more complete understanding of pathogenesis is required. On the basis of the pathophysiology of adhesion formation the main barriers currently in clinical practice as well as new innovations are discussed in the present r…
Using a neural network for qualitative and quantitative predictions of weld integrity in solid bonding dominated processes
2014
Solid-state bonding occurs in several manufacturing processes, as Friction Stir Welding, Porthole Die Extrusion and Roll Bonding. Proper conditions of pressure, temperature, strain and strain rate are needed in order to get effective bonding in the final component. In the paper, a neural network is set up, trained and used to predict the bonding occurrence starting from the results of specific numerical models developed for each process. The Plata-Piwnik criterion was used in order to define a quantitative parameter taking into account the effectiveness of the bonding. Excellent predictive capability of the network is obtained for each process.
Finite-element simulation of residual stress induced by split-sleeve cold-expansion process of holes
2008
A three-dimensional finite-element simulation was conducted for a split-sleeve cold-expansion process in order to determine the residual stress field around an expanded hole. The commercial FEA software DEFORM-3D™, a Lagrangian implicit code designed for metal forming processes, was used to model the cold-expansion process of a fastener hole. The results show a through-thickness residual stress field in good agreement with the analytical solution developed by Guo. Moreover, the simulation has highlighted the effect of the split sleeve and the plate thickness on the residual stress field. © 2007 Elsevier B.V. All rights reserved.
Analytical bonding criteria for joint integrity prediction in friction stir welding of aluminum alloys
2014
Abstract In this study, two bonding criteria, previously used for porthole die extrusion, are applied to FSW starting from the local value of the main field variables calculated through a specifically developed 3D numerical model of the process. Their applicability and effectiveness have been assessed through an experimental and numerical campaign carried out with the main process parameters varying in a wide range. The pressure–time–flow criterion was demonstrated to be better suited for FSW processes when large welding speed is used.
Influence of M23C6 carbides on the heterogeneous strain development in annealed 420 stainless steel
2020
Understanding the local strain enhancement and lattice distortion resulting from different microstructure features in metal alloys is crucial in many engineering processes. The development of heterogeneous strain not only plays an important role in the work hardening of the material but also in other processes such as recrystallization and damage inheritance and fracture. Isolating the contribution of precipitates to the development of heterogeneous strain can be challenging due to the presence of grain boundaries or other microstructure features that might cause ambiguous interpretation. In this work a statistical analysis of local strains measured by electron back scatter diffraction and …
A general diastereoselective synthesis of highly functionalized ferrocenyl ambiphiles enabled on a large scale by electrochemical purification
2017
International audience; A general synthesis of highly functionalized ferrocenes, which include (P,B)- and (N,B)-ambiphiles, has been developed at a multigram scale. Diastereoselective stepwise modification of di-tert-butylated ferrocenes included the unprecedented separation of electroactive species. Bulky alkyl groups on ferrocenes ensure planar chirality of ambiphiles and enforce closer proximity of antagonist Lewis functions.
Inhibitoren der Korrosion 27 (1). Inhibitoren der Korrosion von Kupfer - Gibt es eine Struktur-Wirkungsbeziehung?
1982
Mehr als 570 Verbindungen der unterschiedlichsten Struktur wurden unter Standardbedingungen im “Schuttelversuch” und pH-statisch auf ihre Korrosionsschutzwirkung gegenuber Kupfer getestet und mit Hilfe eines Computers ausgewertet. Die erhaltenen Ergebnisse stehen relativ haufig in Ubereinstimmung mit Dem “Hart-Weich-Konzept” von Pearson. Eine gezielte Synthese von Inhibitoren, die sich in diesem Konzept orientiert, ist jedoch nicht moglich. Inhibitors of corrosion 27 (1). Inhibitors of the corrosion of copper Does there exist a structure-effect-relation? Over 570 compounds of greatly varying structure have been tested under controlled conditions in agitation and pH-stat experiments designed…