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Electrical Resistance Measurements (electrical + resistance_measurement)
Selected AbstractsImproved Aging Characteristics of NTC Thermistor Thin Films Fabricated by a Hybrid Sol,Gel,MOD ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006Dmitry A. Kukuruznyak Negative temperature coefficient thermistor oxide thin films with improved aging characteristics are described. Better thermal stability has been achieved by incorporating sol,gel techniques with metallo-organic decomposition methods. A compositional range was identified whereby borosilicate may incorporate into the thermistor oxides, forming nanocomposites showing thermistor electrical characteristics. Thermistor thin films, with composition Ni0.48Co0.24Cu0.6Mn1.68O4·0.22SiO2·0.15B2O3 were deposited onto glass substrates from a solution containing organic transition metal salts, tetraethyl orthosilicate and triethyl borate. Electrical resistance measurements verified characteristic thermistor behavior. Nanocomposite thin films exhibited a factor of four improvement as compared with pure oxides after aging at 150°C for 500 h. [source] Monotonic and Cyclic Deformation Behaviour of the SiC Particle-Reinforced Aluminium Matrix Composite AMC225xe,ADVANCED ENGINEERING MATERIALS, Issue 4 2010Marek Smaga The monotonic and cyclic deformation behaviour of the aluminium matrix composite AMC225xe , i.e., the aerospace grade aluminium alloy AA 2124 reinforced with 25,vol.-% ultrafine SiC particles , is characterised in detail on the basis of mechanical stress,strain hysteresis curves as well as temperature and electrical resistance measurements. A pronounced difference in plastic strain response is observed between tension and compression under monotonic and cyclic loading. In fully reversed stress-controlled constant amplitude tests, negative plastic mean strains developed. The cyclic deformation behaviour of AMC225xe is characterised by pronounced initial cyclic hardening. The endurance limit is reliably estimated in continuous load increase tests. In particular, electrical resistance data are used as input parameters for fatigue life calculations analogous to the Basquin equation. Microstructural details are investigated by light and scanning electron microscopy. [source] Influences of the Process Chain on the Fatigue Behavior of Samples with Tension Screw Geometry,ADVANCED ENGINEERING MATERIALS, Issue 4 2010Marcus Klein To analyze the influence of the material batch, the structure of the manufacturing process chain, and the process parameters, four different material batches of the quenched and tempered steel SAE 4140 were used to manufacture samples with tension screw geometry. Five different, manufacturing process chains, consisting of the process steps heat treatment, turning, and grinding, were applied. After selected process steps, light and SEM micrographs as well as fatigue experiments were performed. The process itself as well as the process parameters influences the properties of the surface layers and the fatigue behavior in a characteristic manner. For example the variation of the feed rate and cutting speed in the hard-turning process leads to significantly different mechanical properties of the surface layers and residual stress states, which could be correlated with the fatigue behavior. The cyclic deformation behavior of the investigated components can be benchmarked equivalently with stress,strain hysteresis as well as high precision temperature and electrical resistance measurements. The temperature and electrical resistance measurements are suitable for component applications and provide an enormous advantage of information about the fatigue behavior. The temperature changes of the failed areas of the samples with tension screw geometry were significantly higher, a reliable identification of endangered areas is thereby possible. A new test procedure, developed at the Institute of Materials Science and Engineering of the University of Kaiserslautern, with inserted load-free-states during constant amplitude loading, provides the opportunity to detect proceeding fatigue damage in components during inspections. [source] "PHYBAL" a Short-Time Procedure for a Reliable Fatigue Life CalculationADVANCED ENGINEERING MATERIALS, Issue 4 2010Peter Starke Abstract The reliable calculation of the fatigue life of high-strength steels and components requires the systematic investigation of the cyclic deformation behaviour and the comprehensive evaluation of proceeding fatigue damage. Besides mechanical stress-strain hysteresis measurements, temperature and electrical resistance measurements were used for the detailed characterisation of the fatigue behaviour of the steel SAE 4140 in one quenched and tempered, one normalised, one bainitic and one martensitic condition. To guarantee optimal operation conditions the new fatigue life calculation method "PHYBAL" on the basis of generalised Morrow and Basquin equations was developed. It is a short-time procedure which requires the data of only three fatigue tests for a rapid and nevertheless precise determination of S-N (Woehler) curves. Consequently, "PHYBAL" provides the opportunity to reduce significantly experimental time and costs compared to conventional test methods. [source] Glass Fibers with Carbon Nanotube Networks as Multifunctional SensorsADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Shang-lin Gao Abstract A simple approach to deposit multiwalled carbon nanotube (MWNT) networks onto glass fiber surfaces achieving semiconductive MWNT,glass fibers is reported, along with application of fiber/polymer interphases as in-situ multifunctional sensors. This approach demonstrates for the first time that the techniques of conducting electrical resistance measurements could be applicable to glass fibers for in situ sensing of strain and damage; the techniques were previously limited to conductive and semiconductive materials. The electrical properties of the single MWNT,glass fiber and the "unidirectional" fiber/epoxy composite show linear or nonlinear stress/strain, temperature, and relative humidity dependencies, which are capable of detecting piezoresistive effects as well as the local glass transition temperature. The unidirectional composites containing MWNT,glass fibers exhibit ultrahigh anisotropic electrical properties and an ultralow electrical percolation threshold. Based on this approach, the glass fiber,the most widely used reinforcement in composites globally,along with the surface electrical conductivity of MWNTs will stimulate and realize a broad range of multifunctional applications. [source] Optical microscopy imaging method for detection of electromigration: Theory and experimentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007L. H. Li Abstract Electromigration is a microscopic phenomenon involving electric field-induced diffusion, which is very relevant to damage in interconnects. A common method to monitor interconnect degradation is through electrical resistance measurements, which requires direct electrical contacts. It is desirable to develop non-contact methods to monitor electromigration damage formation. Recently, we have proposed a novel Optical Microscopy Imaging Method (OMIM). Here we provide theoretical proof and additional experimental results. OMIM provides a new method for studying electromigration-induced damage. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of Sn doping upon the phase change characteristics of Ge2Sb2Te5PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 14 2004K. Wang Abstract The influence of Sn doping upon the phase change characteristics of Ge2Sb2Te5 alloys has been investigated using four-point-probe electrical resistance measurements, grazing incidence X-ray diffraction (XRD), X-ray reflectometry (XRR) and variable incident angle spectroscopic ellipsometry (VASE), a static tester and atomic force microscopy (AFM). For a Ge2Sb2Te5 alloy doped with 4% Sn, two transition temperatures are observed in the temperature dependent sheet resistance measurements at 125 °C and 250 °C, respectively. The evolution of structures upon annealing, investigated by XRD, reveals that the first transition is caused by the crystallization of the amorphous film to a NaCl-type structure, while the second transition is related to the transition to a hexagonal structure. The density values of 6.02 ± 0.05 g cm,3, 6.38 ± 0.05 gcm,3 and 6.42 ± 0.05 gcm,3 are measured by XRR for the film in the amorphous, NaCl-type and hexagonal structure, respectively. Ultra-fast crystallization, which is correlated with a single NaCl-structure phase and the reduced activation barrier, is demonstrated. Sufficient optical contrast is exhibited and can be correlated with the density change upon crystallization. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||