Towards a Correlation of Friction and Wear in Amorphous Materials

• Applicant: Professor Dr. Lars Pastewka
• Subject Area: Computer-Aided Design of Materials and Simulation of Materials Behaviour from Atomic to Microscopic Scale ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2014 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258153560

Many engineering surfaces are amorphous (or glassy) because they have been deliberately coated. Amorphous coatings are applied to modify and potentially improve surface properties such as hardness, wear resistance or corrosion resistance. Examples include physical vapor deposition of amorphous carbon and hydrocarbon coatings, or plasma spraying of amorphous metal alloys. Even if surfaces are not deliberately coated, near surface volumes can become glassy due to interaction with their environment: Silicon forms an amorphous surface oxide and diamond amorphizes under sliding action. The latter case is an example of a tribologically induced surface layer, often called a "tribomaterial" or third-body . Tribomaterial can be found on ceramics and metals. Since many materials have experienced tribological load during processing such as machining, polishing or lapping, such amorphous tribomaterial surface layers are likely ubiquitous.Coatings and tribomaterial change surface properties and influence both friction and wear. This project aims to build models for understanding friction and wear of such amorphous materials in a bottom-up approach, i.e. starting from the atomic scale. Individual dissipation channels and their contribution to the friction coefficient and wear rate will be identified in computer simulations. These simulations involve atomic scale methods at the smallest scale, and continuum methods in order to span to the macroscopic mechanical system. They are used to establish a functional relationship between friction and wear. The vision underlying this project is to develop an understanding that eventually enables on-line estimates of wear, ideally by measuring just the friction coefficient. If this was possible, devices could be replaced before breaking down fatally, thus saving energy, material resources and reducing general risk to the operator.

• DFG Programme: Independent Junior Research Groups