Comparison of Sol-Gel Methods for Washcoating Metallic Substrates


Department of Chemical Engineering,Tarbiat Modares University


FeCrAl foils were coated with alumina. Washcoating solutions were prepared using di erent
sol-gel methods. Method A uses an inorganic precursor of aluminum nitrate and a complexing agent
of Acetylactone, method B is a hot hydrolysis of aluminum alkoxide, and method C is a modi cation
of method B, by adding aluminum acetylacetonate. The last method, D, is a hydrolysis of aluminum
alkoxide at room temperature. Washcoating solutions were deposited on FeCrAl foils through dip coating.
Then, the coated foils were dried at 100C and calcined at 600C/3 for 2 hours. Ultrasound vibration
tests showed a good adhesion of washcoat layers. Characteristics of the washcoat layers were determined
by X-Ray Di raction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmet-Telller (BET),
and Thermal Gravimetric Analysis (TGA) tests. Results of BET tests show that surface areas in sol-gel
methods are greater than those found in the suspension method, and the inorganic sol-gel method (method
A) has a lower surface area than those found in organic sol-gel methods.