Please see Jeff's seminar notice for this Friday to follow: MATERIALS SCIENCE AND ENGINEERING SEMINAR Numerical Modeling of Materials Processes With Fluid-Fluid Interfaces By: Jeffrey Yanke Ph.D. Final Examination Co-Advisors: Prof. M. Krane and Prof. R. Trice ABSTRACT This presentation will focus on the simulation of two very different materials processes: Electroslag remelting (ESR) of meter long, 4500 kg ingots of superalloy and the deposition of micron scale diameter ceramic powders on a substrate via plasma spray deposition. While these two processes occur on vastly different size scales, the common feature in both processes is that the numerical methods that describe the impact and deformation of a liquid ceramic droplet also apply to the interaction between metal and slag in ESR. ESR is a secondary melting technique that passes an AC current through an electrically resistive slag to provide the heat necessary to melt the alloy being cast. The simulation tracks the interface between the slag and metal. The model was validated against industrial scale ESR ingots and was able to predict trends in melt rate, sump depth, macrosegregation, and liquid sump depth correctly. In order to make more qualitative predictions, several constant current ESR runs were simulated focusing on the effects of including freezing slag in the model. Including the solidifying slag in the model was found to have an effect on the melt rate and sump shape but there is too much uncertainty in ESR slag data at this time for quantitative predictions. The second process investigated in this work is the deposition of ceramic coatings via plasma spray deposition. In plasma spray deposition, powderized coating material is injected in to a plasma that melts and carries the powders towards the substrate were they impact, flattening out and freezing. The impacting droplets pile up to form a porous coating. The model is used to simulate this rain of liquid ceramic particles impacting the substrate to form a coating. Trends in local solidification time and porosity are calculated for varying particle sizes and velocities. The predictions of porosity decreasing with increasing particle velocity observed matches experimental results. Date: Friday, March 8, 2013 Time: 10:00 A.M. Place: ARMS 1028 PURDUE MSE [cid:image003.png@01CE1B53.F7BE4340] Lisa Stacey Secretary/Development Assistant Purdue University School of Materials Engineering 765/494-4100
