Project title: Mechanical properties and decohesion laws of crystalline Titania-based smart coatings: a multiscale investigation
Supervisors: Dr Daniele Dini, Prof Alessandro De Vita and Prof Nicholas Harrison
This project investigates crystalline TiO2 (both anatase and rutile phases) films deposited on glass and silicon substrates.
Anatase layers are well-suited for aeronautical (self-cleaning, fog-proof glass screens) as well as civil engineering (air and water purification, passive anti-pollution building surfaces, anti-bacterial, anti-viral, fungicidal surfaces for public spaces) applications because of its photo-induced (hyper)-hydrophilic, self-cleaning and antifogging properties. Rutile layers can be used as optical layers with a high refractive index and as protective layers with exceptionally good mechanical properties [1, 2].
Crucially, titanium oxides also form on titanium substrates in turbine engine components (fan) due to fretting and wear at the blade roots attachments and other mechanical joints of interest for the aerospace industry. TiO2 layers on Titanium substrates will therefore also be investigated.
The project focuses on the characterisation of the mechanical properties of different TiO2 layers and their interaction with various substrates using QM/MM simulations . These describe the elastic (~100 nm) and chemical (~1 nm) scales and are used to extract the inter- and intra- granular decohesive laws (e.g. see ) necessary to devise FEM cohesive zone models (mm scale and above) of thin microfilms subjected to indentation. The ultimate aim of the project is to obtain a comprehensive multiscale model of delamination and wear of crystalline TiO2 layers.
 R. Wang, K. Hashimoto, A. Fujishima, M. Chikuni, E. Kojima, A. Kitamura, M. Shimohigoshi, T. Watanabe, “Light-induced amphiphilic surfaces”. Nature 388 (1997).
 O. Zywitzki, T. Modes, H. Sahm, P. Frach, K. Goedicke, D. Glöß, “Structure and properties of crystalline titanium oxide layers deposited by reactive pulse magnetron sputtering”, Surf. Coat. Tech. 180-181 (2004).
 G. Csányi, T. Albaret, M.C. Payne, A. De Vita, “Learn On The Fly: a hybrid classical and quantum-mechanical molecular dynamics simulation”, Phys. Rev. Lett. 93, 175503 (2004).
 V. Yamakov, E. Saether, D.R. Phillips, E.H. Glaessgen, “Molecular-dynamics simulation-based cohesive zone representation of intergranular fracture processes in aluminium”, J. Mech. Phys. Solids 54 (2006).