|Ph.D Thesis||Department of Chemical Engineering|
|Supervisors:||Prof. Grader Gideon|
|Dr. Shter Gennady|
Ceramics foams are being used in an increasing number of industrial applications such as: high temperature thermal insulation, hot gas particulate filters, hot metal filters, catalyst support and cores in high temperature structural panels. This growing usage stems from the foam’s favorable properties such as low density, low thermal conductivity, thermal stability and high resistance to chemical attack.
The main objective of this project is to develop synthesis methods of high temperature coatings over ceramic foams. Three types of coatings over alumina foams were studied: titania, carbon and sodium tungsten bronze.
In the area of Al2O3/TiO2 foams we investigated the morphological and compositional changes during sintering in the 900-1600oC. Titania was incorporated either during a nonhydrolytic foaming procedure, or by impregnation.
Conductive carbon coatings over ceramic foams were prepared by the foams’ impregnation in a polyurethane solution, followed by pyrolysis of the polymer layer. The intent is to use these carbon coated foams both as stand-alone products and as an under layer in electrolytic or other deposition processes for electrode or catalyst supports applications.
In the tungsten bronze area we focused on the synthesis of bronze powder, determination of its composition, and on the preparation of bronze coatings. The optimal coating method is based on thermal reduction in the system melt/gas using hydrogen. A novel, accurate, and simple method to determine the bronze composition, based on thermo-gravimetric analysis (TGA) in oxidative atmosphere, was developed.
A potential application of such coated foams is high temperature fuel cells electrodes.