This result concerns the development of a stable and reliable open-pore ceramic foam trap, with pore size optimised so as to enable good filtration efficiency (above 80%), good particulate penetration in the foam structure (which favours the catalyst-to-particulate contact) and acceptable pressure drop, which would otherwise result in a fuel penalty. Based on the foundry molten metal filter producing know-how, the manufacturing technique adopted for the production of the ceramic foams is based on the coating of open cell polyurethane foams by soaking them into ceramic slurry. Located in the exhaust line, the soot filter by trapping soot, could contribute to the reduction of emission of Diesel engine.
After characterisation and study of commercially available foams and literature review, ceramic foams were prepared. Definition of the composition, an optimisation of the slurry, mechanical tests, an optimisation of the open-pore structure were the different steps to the new recipe definition. Alumina and Mullite toughened by zirconia were the best compromise between mechanical and thermal properties. The common cell densities of the ceramic foam produced for the CATATRAP samples were 50 and 100ppi.