Title

Ni-Ru Alloys for Electrical Contact Applications

Date of Completion

January 2011

Keywords

Engineering, Electronics and Electrical|Engineering, Materials Science

Degree

Ph.D.

Abstract

Metallic contact is a ubiquitous method of connecting electrical and electronic components/systems, but the development of unacceptably high contact resistance over time is by far the most common cause of device or system failure. While this can be overcome by the application of a noble metal coating, abrasive wear can re-expose the bare base metal and subsequent oxidation can lead to contact failure. We have developed novel alloys with inherently conducting oxide scales, thereby obviating the need for coatings. We describe here a study of the microstructural characteristics, contact resistance, wear, and corrosion behavior of such alloys in the Ni-Ru system. It is shown that the alloy consists of a FCC Ni-rich matrix with HCP Ru-rich dendrites or precipitates depending on alloying content of Ru. The alloys are heat-treatable since the precipitates can be dissolved in a homogenization treatment and then re-precipitated during aging allowing the electrical, mechanical, and chemical properties to be tailored. The microstructure evolution of the Ni-Ru alloys and the oxide film formed on the alloy surface were studied. The performances of the alloys as potential electrical contact are evaluated in terms of electrical contact resistance, wear behavior, and corrosion resistance.^ The key elements of the research work include: thermodynamic analysis to identify suitable materials systems, lab-scale production of candidate alloys, characterization of base alloy microstructures, ambient exposures to develop native scales on the chosen alloys and characterization of the oxides, measurement of developed contact resistance with oxidization time, and evaluation of the wear and corrosion resistances under various conditions. The research would provide new paradigm for developing the novel electrical contacts. The study and understanding of the developed materials would pave ground for their real application as electrical contact. ^