Abstract
Large temperature gradients are present within ceramic powder particles during plasma spray deposition due to their low thermal conductivity. The particles often impinge at the substrate in a semi-molten form which in turn substantially affects the final characteristics of the coating being formed. This study is dedicated to a novel modeling approach of a coupled Eulerian and Lagrangian (CEL) method for both fully molten and semi-molten droplet impingement processes. The simulation provides an insight to the deformation mechanism of the solid core YSZ and illustrates the freezing-induced break-up and spreading at the splat periphery. A 30μm fully molten YSZ particle and an 80μm semi-molten YSZ particle with different core sizes and initial velocity ranging from 100 to 240m/s were examined. The flattened degree for both cases were obtained and compared with experimental and analytical data.
Highlights
Thermal spray technology encompasses several processes which are used to create performance enhancing coatings
The base line model was applied and validated considering a 30 lm fully molten YSZ droplet impinging onto a stainless steel substrate with an initial velocity of 190 m/s
The results show that the temperature is not uniformly distributed over the surfaces
Summary
Thermal spray technology encompasses several processes which are used to create performance enhancing coatings. Despite lack of detailed understanding for the deposition of semi-molten droplet impingement, little modeling and simulation work has been reported, given the challenges of solving both solid and liquid phases simultaneously. Zhu et al / Acta Materialia 90 (2015) 77–87 coating buildup of molten and semi-molten droplets This method is not able to capture the detailed physics during the particle impingement process. According to Li et al [14], brittle materials may possess ductile behavior under particular conditions such as very high temperature or high pressure In this case, modeling the solid core as a rigid body may produce unrealistic results. New approaches are required for simulating both the liquid and the solid part simultaneously in a coupled manner This investigation is the first of its kind, to simulate a semi-molten droplet impingement using a coupled Eulerian and Lagrangian (CEL) approach for thermal spray applications. The flattening degree of the particles are obtained and compared with both experimental and analytical data
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