Publications

Results 26–50 of 196

Search results

Jump to search filters

Atomistic Origins of Temperature-Dependent Shear Strength in 2D Materials

ACS Applied Nano Materials

Curry, John C.; Hinkle, Adam H.; Babuska, Tomas F.; Wilson, Mark A.; Dugger, Michael T.; Krick, Brandon A.; Argibay, Nicolas A.; Chandross, M.

We present a model that predicts the macroscale temperature-dependent interfacial shear strength of 2D materials like MoS2 based on atomistic mechanisms and energetic barriers to sliding. Atomistic simulations were used to systematically determine the lamellar size-dependent rotation and translation energy barriers, that were used to accurately predict a broad range of experimental data. This framework provides insight about the origins of characteristic shear strengths of 2D materials. ©

More Details
TYPE SAND Report YEAR 2018
DOIOSTIScopus

Achieving Ultralow Wear with Stable Nanocrystalline Metals

Advanced Materials

Curry, John C.; Babuska, Tomas F.; Furnish, Timothy A.; Lu, Ping L.; Adams, David P.; Kustas, Andrew K.; Nation, Brendan L.; Dugger, Michael T.; Chandross, M.; Clark, Blythe C.; Boyce, Brad B.; Schuh, Christopher A.; Argibay, Nicolas A.

Recent work suggests that thermally stable nanocrystallinity in metals is achievable in several binary alloys by modifying grain boundary energies via solute segregation. The remarkable thermal stability of these alloys has been demonstrated in recent reports, with many alloys exhibiting negligible grain growth during prolonged exposure to near-melting temperatures. Pt–Au, a proposed stable alloy consisting of two noble metals, is shown to exhibit extraordinary resistance to wear. Ultralow wear rates, less than a monolayer of material removed per sliding pass, are measured for Pt–Au thin films at a maximum Hertz contact stress of up to 1.1 GPa. This is the first instance of an all-metallic material exhibiting a specific wear rate on the order of 10−9 mm3 N−1 m−1, comparable to diamond-like carbon (DLC) and sapphire. Remarkably, the wear rate of sapphire and silicon nitride probes used in wear experiments are either higher or comparable to that of the Pt–Au alloy, despite the substantially higher hardness of the ceramic probe materials. High-resolution microscopy shows negligible surface microstructural evolution in the wear tracks after 100k sliding passes. Mitigation of fatigue-driven delamination enables a transition to wear by atomic attrition, a regime previously limited to highly wear-resistant materials such as DLC.

More Details
TYPE Journal Article YEAR 2018
DOIOSTIScopus

In-situ tribochemical formation of self-lubricating diamond-like carbon films

Carbon

Argibay, Nicolas A.; Babuska, Tomas F.; Dugger, Michael T.; Lu, Ping L.; Adams, David P.; Nation, Brendan L.; Doyle, Barney L.; Curry, John C.; Pham, Minh P.; Pimentel, Adam S.; Mowry, Curtis D.; Hinkle, Adam H.; Chandross, M.

For this study, diamond-like carbon (DLC) films were tribochemically formed from ambient hydrocarbons on the surface of a highly stable nanocrystalline Pt-Au alloy. A sliding contact between an alumina sphere and Pt-Au coated steel exhibited friction coefficients as low as μ = 0.01 after dry sliding in environments containing trace (ppb) organics. Ex situ analysis indicated that the change in friction coefficient was due to the formation of amorphous carbon films, and Raman spectroscopy and elastic recoil analysis showed that these films consist of sp2/sp3 amorphous carbon with as much as 20% hydrogen. Transmission electron microscopy indicated these films had thicknesses exceeding 100 nm, and were enhanced by the incorporation of worn Pt-Au nanoparticles. The result was highly wear-resistant, low-friction DLC/Pt-Au nanocomposites. Atomistic simulations of hydrocarbons under shear between rigid Pt slabs using a reactive force field showed stress-induced changes in bonding through chain scission, a likely route towards the formation of these coatings. This novel demonstration of in situ tribochemical formation of self-lubricating films has significant impact potential in a wide range of engineering applications.

More Details
TYPE Journal Article YEAR 2018
DOIOSTI
Results 26–50 of 196
Results 26–50 of 196