Parameter Calibration of Ultra-Fine Zirconia-Based Powder Used in Thermal Barrier Coatings for Discrete Element Method (DEM) Simulation Based on an Improved Scaling Scheme

Ultra-fine zirconia-based powder used in thermal barrier coatings is a core raw material for high-performance coatings, but its small particle size causes clogging during discharge. The discrete element method (DEM) can simulate powder flow and is an effective numerical tool to study clogging, yet discrete element parameters of this powder are lacking. In this work, irregular particles were simplified as soft spheres and scaled from D50 = 1.2 µm to D50 = 240 µm using an improved scaling scheme derived from classical particle scaling and similarity principles. The Hertz-Mindlin with Johnson-Kendall-Roberts Version 2 (JKR V2) contact model in EDEM was adopted, with the angle of repose as the calibration response. The two-level fractional factorial design showed that the particle-particle coefficient of static friction had the largest absolute main effect, followed by JKR surface energy and the particle-stainless steel coefficient of static friction. Steepest ascent tests determined optimal ranges: 0.7–0.9 for particle-particle static friction and 0.17–0.27 for JKR surface energy; the particle-stainless steel friction was fixed at its median of 0.45. An orthogonal test combined with linear interpolation yielded the calibrated parameter combination: 0.8 and 0.19, respectively. The simulated angle of repose was 53.87°, which lies within the experimentally measured range of 50–56° and differs by 0.37% from the experimental mean of 53.67°, showing good agreement between the simulation and experiment under the present calibration condition. The calibrated parameters may provide reference values for DEM simulations of similar static or quasi-static conditions; however, their applicability to other granular flow conditions, including discharge, requires further independent validation.