文摘
Cordierite foams were prepared by replication of polyurethane foams and were coated with three types of carbonxerogels. The dip coating and synthesis conditions were optimized, and the coated foams were characterized exhaustively.The composition of the starting solution, coat loading, and carbonization temperature are the most important parametersdetermining both textural and mechanical properties. Carbon xerogel coatings obtained from aqueous solutions ofresorcinol (R) and formaldehyde (F) are macro-, meso-, and microporous but present the greatest shrinkage, whichcauses a loss of adhesion between ceramic foams and carbon coatings. The coatings from polyfurfuryl alcohol (PFA)and RF-poly(vinyl butyral) (Butvar) resin are highly microporous and present very good adhesion even aftercarbonization. In all cases, coatings induce the improvement of the mechanical properties, which is related to the factthat the coating fills the defects present in the cordierite foams, thereby affecting both the rigidity and the way crackspropagate through the coated samples. These materials, due to the synergetic role of the highly porous coatings andthe tortuous channels of the ceramic foams, are suitable materials for adsorption or catalytic treatments of fluids.