Novel electrical and mechanical characteristics of composites composed of electrically conducting Ni-Cr alloy particles in non-conducting soda-lime glass.

The bulk resistivity of Ni-Cr alloys is inherently constant. Therefore, it is necessary to regulate the cross-section and length of Ni-Cr alloys to achieve the desired electrical resistance. Here, we describe a composite, comprising a soda-lime glass matrix and disk-like Ni-Cr alloy particles, that has variable bulk resistivity. The bulk resistivity of the composite can be controlled accurately by adjusting the volume fraction (30-80 vol% Ni-Cr alloy) and aspect ratio of the particles. Furthermore, the composite's strength and fracture toughness are both improved by microdispersion of the disk-like Ni-Cr alloy particles. A 1/100-scale model resistor based on this composite was found to have attractive properties for electrical power applications, such as an approximately 50% reduction in volume, a 65% reduction in weight, and a 95% reduction in inductance in comparison with a conventional neutral grounding resistor made from special cast iron. Clearly, use of this composite material for fabrication of ubiquitous electrical components would greatly reduce the demand and consumption of Ni and Cr for this application. Several benefits are envisioned from this development, including the fabrication of downsized devices and the availability of lower-cost home appliances and industrial products.