Electrical and tribological properties of a Ni–18%Ru alloy for contact applications
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A study of the microstructure, development of contact resistance during oxidation, and abrasive wear behavior for a Ni–18 at.%Ru alloy is presented in this article. It is shown that the alloy can be solutionized and aged, resulting in a fine lamellar mixture of FCC α-Ni and HCP β-Ru phases. Upon oxidation in air for 400 h, the measured contact resistance of the alloy is two orders of magnitude lower than that of pure Ni after 400-h oxidation. This behavior results from the formation of a low-resistivity rutile RuO2 scale on the β phase lamellae, which gives conducting pathways through the insulating NiO scale that forms on the α phase. After an initial run-in period, the steady-state abrasive wear rate measured for the Ni–Ru alloy is an order of magnitude less than that of pure Ni. Since the micro-cutting and flaking wear mechanisms are the same, the differences in the wear rates are ascribed to the presence of the well-dispersed hard Ru-rich β phase. The combination of a low-resistivity self-healing native oxide scale and good wear properties makes the alloy an excellent candidate for electrical contact applications.
KeywordsContact Resistance Oxide Scale Abrasive Wear RuO2 Bulk Conductivity
The authors gratefully acknowledge the support extended by the U. S. Army Research Office through Grant No. W-911-NF0710388.
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