title: Nanoparticle-wetted surfaces for relays and energy transmission contacts.
abstract: Submonolayer coatings of noble-metal nanoparticle liquids (NPLs) are shown to provide replenishable surfaces with robust asperities and metallic conductivity that extends the durability of electrical relays by 10 to 100 times (depending on the current driven through the contact) as compared to alternative approaches. NPLs are single-component materials consisting of a metal nanoparticle core (5-20 nm Au or Pt nanoparticles) surrounded by a covalently tethered ionic-liquid corona of 1.5 to 2 nm. Common relay failure modes, such as stiction, surface distortion, and contact shorting, are suppressed with the addition of a submonolayer of NPLs to the contact surfaces. This distribution of NPLs results in a force profile for a contact-retraction cycle that is distinct from bare Au contacts and thicker, multilayer coatings of NPLs. Postmortem examination reveals a substantial decrease in topological change of the electrode surface relative to bare contacts, as well as an indication of lateral migration of the nanoparticles from the periphery towards the contact. A general extension of this concept to dynamic physical interfaces experiencing impact, sliding, or rolling affords alternatives to increase reliability and reduced losses for transmittance of electrical and mechanical energy.
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH 45433, USA. andrey.voevodin@wpafb.af.mil
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Voevodin
authors.forename: Richard A
authors.initials: RA
authors.lastname: Vaia
authors.forename: Steven T
authors.initials: ST
authors.lastname: Patton
authors.forename: Steven
authors.initials: S
authors.lastname: Diamanti
authors.forename: Mark
authors.initials: M
authors.lastname: Pender
authors.forename: Mitra
authors.initials: M
authors.lastname: Yoonessi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brubaker
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Hu
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Sanders
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Phillips
authors.forename: Robert I
authors.initials: RI
authors.lastname: MacCuspie
mesh_terms: D003460:Crystallization / Q000379:methods*; D004581:Electronics / Q000295:instrumentation*; D004735:Energy Transfer; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008839:Microelectrodes; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D010316:Particle Size; D017155:Wettability
chemical_list: D046911:Macromolecular Substances; D006046:Gold