Thermo-mechanical testing of TiO2 functional coatings using friction stir processing

TiO2 micro powder was deposited onto an aluminium substrate by Atmospheric Plasma Spraying resulting in 200µm thick coatings. These coatings were characterized, whereby typical layer properties like porosity, layer thickness and hardness were investigated. Subsequently, a thermo-mechanical load was applied on the TiO2 coating by Friction Stir Processing. This testing procedure shows several advantages. First, specific load cycles can be applied at high accuracy using specific parameter sets. Second, different tool geometries can be used for testing, resulting in countless possible load cases and testing scenarios. As a result, the thermal properties of the TiO2 coating were investigated and compared as a function of a stepwise increased testing load. To complete the experimental results, a numerical simulation of the testing process was set up to estimate the transient heat flow of the TiO2 coating during Friction Stir Processing.