New Insights about the Fundamental Mechanisms of Friction in MoS2
Abstract not provided.
Publications
Shear-induced softening of nanocrystalline metal interfaces at cryogenic temperatures
Scripta Materialia
We demonstrate inverse Hall-Petch behavior (softening) in pure copper sliding contacts at cryogenic temperatures. By kinetically limiting grain growth, it is possible to generate a quasi-stable ultra-nanocrystalline surface layer with reduced strength. In situ electrical contact resistance measurements were used to determine grain size evolution at the interface, in agreement with reports of softening in highly nanotwinned copper. We also show evidence of a direct correlation between surface grain size and friction coefficient, validating a model linking friction in pure metals and the transition from dislocation mediated plasticity to grain boundary sliding.
DLC from Thin Air: In Situ Formation of DLC on Ultralow Wear Metals
Abstract not provided.
The Promise of Stable Nanocrystalline Metals: Ultra-low Wear and Diamond-like Carbon from Thin Air
Abstract not provided.
Understanding Friction in MoS2 Part 2: Water Oxidation and Run-in
Abstract not provided.
Understanding Friction in MoS2
Abstract not provided.
Low Friction in Metal Contacts: Linking Microstructural Evolution and Tribology
Abstract not provided.
The Remarkable Friction Behavior of Copper at Cryogenic Temperatures
Abstract not provided.
Temperature-Dependent Friction and Wear Behavior of PTFE and MoS2
Tribology Letters
An investigation of the temperature-dependent friction behavior of PTFE, MoS2, and PTFE-on-MoS2 is presented. Friction behavior was measured while continuously varying contact temperature in the range −150 to 175 °C while sliding in dry nitrogen, as well as for self-mated PTFE immersed in liquid nitrogen. These results contrast with previous reports of high-friction transitions and plateaus for pure and composite MoS2 at temperatures below about −20 °C; instead, we have found persistently weak thermal behavior between 0 and −196 °C, providing new insight about the molecular mechanisms of macroscale friction. The temperature-dependent friction behavior characteristic of self-mated PTFE was found also for PTFE-on-MoS2 sliding contacts, suggesting that PTFE friction was defined by subsurface deformation mechanisms and internal friction even when sliding against a lamellar lubricant with extremely low friction coefficient (µ ~ 0.02). The various relaxation temperatures of PTFE were found in the temperature-dependent friction behavior, showing excellent agreement with reported values acquired using rheological techniques measuring energy dissipation through internal friction. Additionally, hysteresis in friction behavior suggests an increase in near-surface crystallinity upon exceeding the high-temperature relaxation, Tα ~ 116 °C.
The Full MoS2 Monty...Environment!
Abstract not provided.
The Full MoS2 Monty...Stress!
Abstract not provided.
The Full MoS2 Monty...Temperature!
Abstract not provided.
Temperature Dependent Wear and Friction of MoS2 (and PTFE!) at the Extremes
Abstract not provided.
Why IS there a correlation between hardness friction and wear of metal contacts? Modifying microstructural mechanistic misconceptions
Abstract not provided.
In-Situ Testing: An Exploration of Increasing Design Complexity
Abstract not provided.
Spark Plasma Sintered MAX Phase Ternary Alloys for Sliding Electrical Contacts
Abstract not provided.
Materials challenges for a novel wind turbine rotary electrical contact technology
Abstract not provided.
Twistact Technology: Enabling More Efficient Large Scale Wind Turbines
Abstract not provided.
Interfacial phenomena in high current density rolling electrical contacts for wind turbines
Abstract not provided.
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