Current projects

Mechanics of Graphene Pleats

Atomically thin materials exhibit striking and unique mechanical behavior. One such case is the formation of spontaneously formed folds. Using scanning probe microscopy and other advanced characterization and modeling tools, we aim to better understand how these self-assembling structures form and explore their applications in devices.
Researchers: Dr. Daniel Sánchez, Li Yuan, Anna Leventhal
Collaborators: Prof. A. T. Charlie Johnson (UPenn), Prof. Ashlie Martini (UC Merced), Prof. Graham Cross (Trinity College Dublin), Prof. Gareth Tribello (Queen’s Univ Belfast)

Frictional Behavior of Monolayer Graphene

Graphene and other 2D materials have shown excellent tribological properties such as structural superlubricity (ultralow friction) resulting from interlayer lattice mismatch. Recently, researchers found that superlubricity can also be achieved for interlayer sliding under high normal pressures (a few GPas), which is called pressure-induced superlubricity. We are interested in the feasibility of such property for a single asperity sliding on a 2D material. Specifically, we are studying the friction between a Si tip and monolayer graphene by means of molecular dynamics (MD) simulations and atomic force microscopy (AFM) tests.

Researchers: Li Yuan

Collaborators: Prof. Ashlie Martini (UC Merced), Prof. Suzhi Li (Xi’an Jiaotong Univ.)

Nanocrystal Anti-Wear Additives in High-Performance Lubricants

Antiwear additives combat contact-induced damage on lubricated machines, like gearboxes or bearings. Nanocrystal additives dispersed in oil form robust solid layers on moving parts, protecting the surfaces even in extreme conditions. We use multiscale testing to study the antiwear mechanisms of nanocrystals in order to engineer higher-quality, eco-friendly lubricants.

Researchers: Parker LaMascus, Dr. Pranjal Nautiyal, Daniel Delghandi

Collaborators: Dr. Andrew Jackson (UPenn), Pixelligent LLC, Argonne National Lab, Lanxess Corporation, Exxon Mobil

Electrical Contacts in NEMS Switches

To solve the energy inefficiency problem as the size of transistors scales down, nanoelectromechanical systems (NEMS) switches are considered a candidate replacement/supplement to solid-state transistors in next-generation electronics. However, the biggest drawback of NEMS switches is the limited lifetime. This project aims to study the fundamental failure mechanisms of electrical contacts in NEMS switch-like conditions, and to find materials that can provide superior mechanical and electrical behaviors and high durability. 

Researchers: Dr. Cangyu Qu

Collaborators: Prof. Maarten P. de Boer (CMU), Prof. Gianluca Piazza (CMU), Prof. David J Srolovitz (City Univ. Hong Kong), Prof. Andrew M. Rappe (UPenn).

Previous projects

  • Tribochemistry of Ultrahard Carbon Films: X-ray Spectromicroscopy Studies
  • Ultrananocrystalline Diamond MEMS: Integration with CMOS Electronics
  • Internal Dissipation in Diamond Microstructures
  • Nanocrystalline Diamond Coatings for Micro Tools
  • Nanomechanical Switches
  • Diamond-Like Carbon Coatings for Nanomechanical Data Storage
  • Ultrananocrystalline Diamond Atomic Force Microscope Probes
  • Nanotribology of Ultrahard Carbon Films
  • Nanotribology of Self-Assembled Monolayers
  • Realistic Contact of Rough Surfaces
  • Negative Stiffness of Carbon Nanotubes
  • Growth and Properties of Nanocrystalline Diamond Films
  • Phononic Contributions to Friction
  • Wrinkling of Polymer Surfaces
  • Calibration of Atomic Force Microscopes