Effects of Slurry Composition and Interfacial Adhesion of Monolithic Coatings on FeCrAl Honeycombs

Abstract

Excellent coating adhesion is a crucial requirement for monolithic catalysts. Within this investigation, a Design of Experiments (DOEs) Taguchi approach was leveraged to construct a 9-factor-3-level matrix encompassing 27 parallel experiments. This framework was employed to scrutinize the pivotal elements influencing the adhesion of FeCrAl metal-based integral coatings, which were prepared using the slurry method. Moreover, an unprecedented endeavor was made to scrutinize the mechanism of coating delamination from the vantage points of macroscopic slurry, microscopic coatings, and nanoscale interfaces. The findings reveal the following: (1) The inclusion of a high-acidity additive (>5%) emerges as one of the pivotal factors in achieving superior adhesion, particularly when the boehmite content exceeds 1%. (2) The existence of binder-filled interstices within the coating, smaller by 1–2 orders of magnitude than the carrier particles, significantly contributes to heightened adhesion. (3) A bonding region of approximately 5 nm is present at the interfaces between carrier particles, resulting in augmented adhesion.