Multiscale Modeling of Hvof Thermal Spray Process

The major physicochemical processes involved in an industrial HVOF thermal spray process (Diamond Jet hybrid gun, Sulzer Metco, Westbury, NY) are studied by a comprehensive multiscale model. The model includes continuum type differential equations that describe the dynamics of gas phase and particles of different sizes, and a rule-based stochastic simulator that predicts the evolution of coating microstructure. On the macroscopic gas/particle dynamics side, the Favre-averaged Navier-Stokes equations and energy balance equations are solved with the renormalization group (RNG) kturbulence model, and the particle trajectories, temperature histories and melting degrees are determined using the 4th order Runge-Kutta method. On the microscopic particle deposition side, the formation of coating microstructure is captured by certain rules that encapsulate the main physical features of particle deposition, deformation, solidification and coating growth. Parametric analysis based on the developed multiscale model is carried out to study the relationship between the macroscopic operating conditions and the particle in-flight behavior as well as the resulting coating microstructure. Copyright c ©2005 IFAC.