Utilizing torch-substrate relative velocity to reduce segmentation crack density in plasma sprayed zirconia for solid oxide cell applications

Abstract

Torch-substrate relative velocity is a plasma spray coating control parameter that affects lamellar thickness, heat transfer from the torch to the substrate, splat dispersion, and segmentation crack density. Within the thermal barrier coating and solid oxide fuel cell/solid oxide electrolysis literature, plasma sprayed coatings are rarely fabricated with velocities that exceed ∼2 m s−1. Here, we explore the effect of torch-substrate relative velocities in the range of 4–20 m s−1 on crack density in thin (10–15 μm) solid oxide cell electrolyte coatings. Crack densities were observed to drop from ∼2.4 to ∼0.04 mm−1 by increasing the torch-substrate relative velocity from 4 to 16 m s−1. In agreement with previous studies performed at lower velocities, crack densities correlate well with plasma torch heat impulse. Full cells were fabricated using torch-substrate relative velocities of 12–20 m s−1.