Multiscale modelling of nanoindentation of multi-layered systems

This thesis presents molecular dynamics simulations of nanoindentation and nanoscratching simulations on a number of oxide. materials. In particular, the oxides studied are used as thin films in optical coatings. These films provide a variety of different functionalities, including reducing infra-red transmission through the glass to lower the heating and cooling costs for buildings. Simulations are performed initially on magnesium oxide, which is studied as a test material due to the simple structure. Simulations are then performed on the rutile and anatase polymorphs of titanium dioxide, which are used in the anti-reflective and self-cleaning part of the coatings, respectively. Finally, simulations are performed into zinc oxide and a silver layer sandwiched between two zinc oxide layers. This multi-layered stack represents the typical structure of the energy saving part of the coatings. Mechanical properties of the thin films have been calculated and compared with experiment. Generally, there is a good level of agreement between the modelling and the experiments. Deformation mechanisms in the different systems have been identified so as to help understand the failure mechanisms in these coatings.