Metal-metal asperity contact: Fundamentals of wear

Wear of materials is a complex phenomenon that is not fully understood despite its presence as a failure mode in many industrial sectors.  The development of instrumented indentation systems (nanoindenters) has provided a platform with which the contact of single asperities can be isolated and studied in well-controlled experiments.  Almost all nanoindentation studies use a hard diamond indenter tip to probe a softer flat polished sample surface.  This project will make a significant change by exploring metal–metal contacts but keeping the advantages of the nanoindenter test platform.  During indentation testing it is likely that significant deformation will occur in the tip as this is less constrained than the substrate.  The engineering and science challenges include designing and making our own metallic tips to mount in the nano-indenter, understanding how tip shape evolves, understanding how the tip material work-hardens, understanding adhesion to substrate as the tip is retracted, and any material transfer that takes place.  The project will use a variety of advanced characterization methods (AFM, SEM, FIB, HR-EBSD, TKD and EDX) to examine indenters and substrates after controlled indentation and/or scratch testing.  The project could also include materials modelling (crystal plasticity FEA) to simulate the contact mechanics.