Papers by Keyword: Contact Resistance

Abstract: Contact resistance is an essential cause of electrical equipment joint heating. An experimental platform was built to measure and compare temperature and contact resistance of memory alloy spring washers and ordinary spring washers when heated by taking the same heavy current, on condition that both of the counterparts had the same initial contact resistance and temperature. Results showed that memory alloy washer were more helpful to limit the joint temperature rise by reducing contact resistance from their features of tempting to restore to original shape when heated to a high temperature. Therefore, the memory alloy washers were proved to have remarkable effect on ensuring safety of electric power equipments and reducing energy loss.

Abstract: Comfort, safety, communication, control with assistance (antilock brake system, seat heating, multi-media, etc...) and safeguarding the environment are many factors which are included in the new generation of vehicles. The increase in the number of electronic and electric system leads to a high level of vehicle control. To answer this high electric power demand, it will be necessary to triple the voltage of the batteries (from 14 to 42 Volts). The objective of this work is to study the arc phenomenon which can occur in an accidental way during the use of a high electric power and particularly during the extraction phase of the male part from the female part of the automotive connector. It was observed that this can be characterized by both its energy and by its temperature. The amplification of the contact current from 14 to 42 VDC considerably increases arc damage.

Abstract: In this paper different techniques for sandwich thin film production, characterization and interfacial reactions have been reviewed in order to understand the kinetic behaviour in the above systems. The contact and composite resistance measurements are the indirect methods for this purpose, while X-ray diffraction studies (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Rutherford backscattering (RBS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), ion sputtering spectrometry (ISS), X-ray photoelectron spectroscopy (XPS) which is also referred to as electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM) are some of the direct methods. Trends indicate that interfacial reactions start at room temperature.

Abstract: At present the wear and friction of pantograph-contact line is studied widely, while the research of the run-in process is little. In the paper they are obtained that the contact area is 0.96mm², contact stress is 73MPa, current density is 520A/mm², the contact resistance is 0.01583 and the contact temperature is 2797K on the surface of slide during the run-in period by the theory calculation. The high temperature of slide surface leads to the oxidation damage. While the carbon film comes into being and the friction surface is tending towards stability.

Abstract: Aiming at electrical contact degradation behavior of beryllium bronze in storage, electrical contact accelerated degradation test was made. Choosing contact resistance as the performance degradation sensitive parameter, studied its degradation behavior by testing contact resistance of beryllium bronze under different temperature after different oxidized times. The result shows that the relationship between contact resistance and oxidized time is exponential and the lifetime of beryllium bronze samples at normal stress is 24.4 years when failure threshold is 100 mΩ and confidence is 95%, which is predicted by Arrhenius model related to temperature.

Abstract: Carbon nanotube has attracted great research attentions due to its outstanding electrical, physical, mechanical, chemical properties. Based on its excellent properties, the carbon nanotube is promising nanoscale material for novel electrical, mechanical, chemical, and biological devices and sensors. However, it is very difficult to control the structure of carbon nanotube during synthesis. A carbon nanotubes film has 3 dimensional structures of interwoven carbon nanotubes as well as unique properties such as transparency, flexibility and good electrical conductivity. More importantly, the properties of carbon nanotubes are ensemble averaged in this formation. In this research, we study the contact resistance between carbon nanotubes film and metal electrode. For most of electrical devices using carbon nanotubes film, it is necessary to have metal electrodes on the film for current path. A resistance at the contact lowers the electrical efficiencies of the devices. Therefore, it is important to measure and characterize the contact resistance and lower it for better efficiencies. The device demonstrated in this study using classical technique for metal contacts provides relatively reliable contact resistance measurements for carbon nanotubes film applications.

Abstract: This paper reviews the recent progress on the research of contact resistance of carbon nanotubes (CNTs), including the contact resistance between CNTs and electrodes/metals and that between CNTs. In particular, the current research advances in improving CNT contact resistance are presented. The challenges in improving CNT contact resistance are also addressed from a practical point of view. A thorough understanding of the electrical contact properties of CNTs helps to explore new methods to improve their contact resistance for full application of this unique group of materials.

Abstract: The electrical characteristics of oxygen functionalized epitaxial graphene and Ti/Au metal contact interfaces were systematically investigated as a function of temperature. As the temperature was increased from 300 K to 673 K, the contact resistance and the sheet resistance decreased by 75% and 33%, respectively. The resistance of oxygen functionalized graphene vs temperature exhibited Arrhenius type behavior with activation energy of 38 meV. The results showed no hysteresis effects in resistance measurements over the temperatures studied here, suggesting the contact interfaces remain stable at high temperatures.

Abstract: In this study, we present the results of alloying nickel as ohmic contact material to n-type 4H-SiC via a continuous wave fiber laser with different laser beam powers and processing times. The laser system exhibits an emitting wavelength of 1070 nm and a beam propagation factor M2 smaller than 1.1. Contact resistance was determined by current-voltage measurement using the two-terminal contact resistance method. The results indicate that a laser beam power of at least 100 W is mandatory to initialize contact silicidation. Although the contact resistance is improvable by longer processing times, our experiments outline the much higher impact of laser beam power to contact silicidation compared with processing time. For laser beam powers of 300 W and processing times of 0.5 s a contact resistance of 6.5 , comparable to contacts alloyed in a lamp heated furnace at 910 °C for 2 min with a contact resistance of 10.3 , was achieved.

Abstract: A novel shuttling polymerase chain reaction (PCR) system is assembled to make temperature uniform in the reaction chamber. The chamber is oscillated by a servo motor and contacted with three different isothermal zones to complete several thermal cycles. The home-made computer code is utilized to investigate the influences of operational parameters on the temperature inside the chamber. Numerical results show that the contact resistances between the heating blocks and the reaction chamber dominate the temperatures inside the PCR chamber. In this work a PCR system that is composed of the PID controller, the moving stage, three aluminum blocks for three different isothermal zones and a reaction chamber is also developed. Experimental results demonstrated that the stability of this shuttling PCR system is confirmed. And results show that DNA templates provided with the yT&A® cloning vector are amplified successfully in this PCR system.