Computer-aided design and prediction of the functional properties of double-layered thermal barrier coatings NiAl-YSZ

Abstract

An approach to the stochastic simulation of the formation process of the lamellar structure of double-layered thermal barrier coatings (TBCs), including high-velocity spraying of NiCrAlY bond layer and atmosphere plasma spraying of YSZ top layer, is proposed. The approach is based on the developed and experimentally verified theoretical foundations which could be used for rapid and sufficiently accurate prediction of thickness and diameter of metal and metal oxide splats depending on the key physical parameters (KPPs): temperature, velocity and size of particle, and substrate temperature. The results are presented, which concern the development of the computational algorithm and the program code for simulation the process of stochastic stacking of splats in the coating with regard for the topography of its surface, which varies dynamically at the spraying, as well as the formation of lamellar structure and porosity of the coating. Results of stochastic simulation of lamellar structure TBCs and its characteristics (microstructure, porosity, roughness) are given in conditions typical for atmospheric plasma spraying (APS) of YSZ top layer and for detonation (D-Gun Spraying) and supersonic flame spraying (HVOF) of bond layer. Comparison of characteristics of coatings for two model splats morphologies at their stochastic stacking on the sprayed surface is presented. The results of numerical experiments are presented through the examples of TBCs thermal spraying, illustrating the performance of the developed computational technology.