High-Temperature Specific Contact Resistance of Iron Disilicide Soldered to Molybdenum by Field’s Metal

Abstract

The target of this study is to evaluate the suitability of a contact scheme designed for thermoelectric characterization of FeSi 2 -based materials with the combined thermoelectric measurement (CTEM) technique. A Fe 0.95 Co 0.05 Si 2 sample is mounted between the CTEM sample holder blocks made of molybdenum using Field's metal solder. The electrical contact resistance is monitored under thermal cycling up to 580 °C by an in-house built contact resistance in situ monitoring facility. After cycling, the microstructure was studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy on the cross section of the contact zone. For the developed preparation process, the specific contact resistance was found suitably low up to 415 °C (<200 μΩ• cm 2 which is less than 10% of the sample resistance). Above 415 °C, oxidation degrades the electrical contact irreversibly.

Determination of the corrosion-oxidation turning point at the Field’s metal/chromium interface by electrical contact resistance measurement

“…The custom-built CoRIS facility [5] was developed to evaluate the temperature dependence of the electrical contact resistance under thermal cycling. The assembly is vertically inserted between two graphite dies specially designed to keep the Cr blocks geometrically aligned while the solder is in the liquid state.…”

“…Recently, a newly designed facility, named Contact Resistance In-Situ monitoring (CoRIS), was able to trace oxidation progress according to temperature at the Field's metal (FM)/FeSi 2 interface via its effect on the contact resistance [5]. The CoRIS technique could be a powerful tool to detect the corrosionoxidation turning point at liquid metal/solid conductor interfaces.…”