ABSTRACT
The past quarter century has brought many changes in our ability to simulate, create, and delicately probe surfaces and structures at ever decreasing scales. Experimentalists have learned to create complex nanostructures, perform ever ‘ner lithography, and pattern single monolayers of graphene. Ultrathin and small structures are readily investigated by tools such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM), which have matured into a broad array of nanoscale surface characterization and imaging techniques widely available on user-friendly commercial platforms. Similarly, these advances provide big opportunities and changes to the ‘eld of tribology. Now, nearly every laboratory is equipped with tools that can examine interfaces having contact widths of atomic dimensions with sub-nN force resolution. Where once it was a challenge for molecular dynamics simulations to include a single atom defect in a lattice, modern simulations include
2.1 Introduction .......................................................................................................5 2.2 What Scienti‘c Issues and Questions Span the Gap? .......................................6 2.3 In Situ Tribology: What’s Happening in the Buried Sliding Interface? .......... 11
2.3.1 What Separates the Surfaces? ............................................................. 12 2.3.2 Where Is Sliding Taking Place? .......................................................... 13 2.3.3 What Is Really Happening in the Contact? ......................................... 15
2.4 Microtribology Instrumentation: Approaches ................................................. 16 2.4.1 AFM .................................................................................................... 16 2.4.2 Low-Load Tribometers ....................................................................... 16 2.4.3 Nanoindentation-Based Tribometers .................................................. 16 2.4.4 MEMS Tribometer Platforms ............................................................. 17 2.4.5 Other Approaches ............................................................................... 19
2.5 Future Outlook ................................................................................................ 19 Acknowledgments .................................................................................................... 19 References ................................................................................................................ 19
thousands of atoms, incorporate amorphous materials, and combine atomic and continuum modeling to tackle larger systems. We now have broad capabilities to examine sliding contacts and adhesion over scales spanning many orders of magnitude, down to the single asperity level.
