The phenomenon of arcing is the major cause of electrical contact degradation in electrical switches. Degradation involves contact erosion and/or welding. The use of special contact material and that of specific material processing may permit contact erosion to be reduced, in particular by shortening the arc duration. A short review of these approaches is presented in the first part of this paper. In the second part, the development of a new self-blowing contact material is described. This material has been tested under dc voltages from 14 V to 42 V. A reduction of the arc duration by a factor of 4 approximately was obtained as was a concomitant reduction of the extinction gap to less than 2 mm. This material will contribute to achieving better reliability in high current-high voltages breaking devices, and will aid in their miniaturization, e.g. in relays.

Automotive suppliers use since decades printed circuit boards (PCB) gold plating pads, as direct contact interface for low current sliding contacts. Several gold plating processes are available on the market, providing various wear behaviour. Some specific galvanic hard gold (AuCo or AuNi). plating was developed on PCB's. This specific plating generates extra costs due to the material quantity and also the process complexity. In a cost driven industry, the challenge is to use a standard low cost PCB for systems requesting high reliability performances. After a brief overview of standard PCB manufacturing processes and especially gold plating processes, the global experimental results of wear behaviour of three different gold plating technologies will be exposed and an explanation of the correlation between surface key parameters and wear out will be provided.

Synthesis and ion transport property studies on hot-pressed Na+ ion conducting solid polymer electrolytes (SPEs): (1-x) PEO: x NaPO3, where x in wt.%, are reported. The compositional dependent conductivity (σ) studies revealed SPE film: (75PEO: 25NaPO3) as the optimum conducting composition (OCC) with room temperature conductivity σ ~ 6.7 × 10-7 S cm-1, which is more than two orders of magnitude higher than that of pure PEO polymer host (σ ~ 3.2 × 10-9 S cm-1). Materials characterization and polymer-salt complexation were done with the help of XRD, FTIR, SEM, DSC techniques. In order to understand the ion transport behaviour in SPEs, the measurement on some basic ionic parameters viz. ionic conductivity (σ), ionic mobility (μ), mobile ion concentration (n), ionic transference number (tion) have been carried out using different experimental techniques. The activation energy (Ea) values involved in the thermally activated conductivity processes have been computed from “log σ - 1/T” Arrhenius plots.


This paper verifies the reliability of the numerical methods in reflecting the experimentation in the field of non-destructive testing by infrared thermography. A non-reinforced concrete slab (1 m × 1 m × 0.25 m) containing four defects was used, two of which had the void type and two had honeycombs type. The defects were situated from 5 cm and 10 cm of the surface. The response of the slab to thermal excitation was investigated by determining the variation of temperature at the top surface of defects and at the slab surface by simulation and experimentation. A good correlation was noted between the numerical results and the experimentation for the three studied durations of thermal excitation (30 min, 60 min and 90 min).

It is well-known that arcing phenomena at the break of contacts affect seriously the reliability and lifetime of contacts. Therefore, many papers have reported arc duration, arc extinction current and other characteristics. Recently, in mobile communication application an electro-mechanical switch is said to be superior to a semiconductor switch in insertion loss and isolation, and a RF (radio frequency) MEMS relay has been intensively developed. Based on the above background it is one of important research topics how the frequency of interrupted current affects the characteristics of breaking arc. However, there are few papers on that topic. In this paper the effect of frequency on arc characteristics is investigated in range of the frequency of interrupted current from 50 Hz to 1 MHz. Consequently the followings can be made clear. At the interruption of peak current 2 A arc extinguishes in terms of arc characteristics and circuit conditions up to the frequency of 200 Hz. Above 200 Hz the arc extinguishes at current zero. The current zero extinction takes place up to 500 kHz. Therefore, arc duration decreases with high frequencies and the contact damage caused by arc is reduced with frequency. However, at frequencies higher than 600 kHz an arc is re-ignited after the current zero and failed to extinguish.

Investigations to determine the electrical contact performance under repeated cycles at low force conditions for carbon-nanotube (CNT) coated surfaces were performed. The surfaces under investigation consisted of multi-walled CNT synthesized on a silicon substrate and coated with a gold film. These planar surfaces were mounted on the tip of a PZT actuator and contacted with a plated Au hemispherical probe. The dynamic applied force used was 1 mN. The contact resistance (Rc) of these surfaces was investigated with the applied force and with repeated loading cycles performed for stability testing. The surfaces were compared with a reference Au–Au contact under the same experimental conditions. This initial study shows the potential for the application of gold coated CNT surfaces as an interface in low force electrical contact applications.

Al-17 wt.% Ni-10 wt.% Cu alloy was prepared by melt spinning technique and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The resulting ribbon microstructure consists of intermetallic Al7Cu4Ni globular-like structure embedded within an aluminum matrix. The resulting effect of rapid solidification on mechanical properties is the enhancement of the alloy hardness up to 700 HV. The ternary phase Al7Cu4Ni exhibits hardness as high as 1300 HV.