Use of the finite element technique to analyze the influence of coating materials, material phase state and the purity on the level of the developed thermal stresses in plasma coating systems under thermal loading conditions

In this investigation, a transient thermal and structure finite element solution has been employed to analyse the level of the thermal stresses developed in plasma coating systems subjected to thermal loading. Plasma coating is used for two main functions: either to protect a base metal against corrosion or erosion; or to minimize wear. A third function is to reduce the temperature of the base metal in the case of thermal barrier applications. In this work cubic, TZP, PSZ zirconia, polycrstalline alumina oxide, 85 and 98% pure alumina-tungsten substrate coating systems were modelled. Coatings with NiCoCrAlY interlayer material were also modelled. Nominal and shear stresses at the critical interface regions (film/interlayer/substrate) were obtained and compared. The results showed that the coating material phase and purity as well as interlayer material and the mismatch of the thermal and mechanical properties between coating and substrate materials influences the level of the thermal stresses. It is also concluded that the finite element technique can be used to optimise the design and the processing of ceramic coating systems.